text: /* -----------------------------------------------------------------------------
   *
   * (c) The AQUA Project, Glasgow University, 1994-1997
   * (c) The GHC Team, 1998-2006
   *
   * Functions for parsing the argument list.
   *
   * ---------------------------------------------------------------------------*/
  
  #include "PosixSource.h"
  #include "Rts.h"
  
  #include "RtsUtils.h"
  #include "Profiling.h"
  #include "RtsFlags.h"
  #include "sm/OSMem.h"
  
  #ifdef HAVE_CTYPE_H
  #include <ctype.h>
  #endif
  
  #include <string.h>
  
  #ifdef HAVE_UNISTD_H
  #include <unistd.h>
  #endif
  
  #ifdef HAVE_SYS_TYPES_H
  #include <sys/types.h>
  #endif
  
  // Flag Structure
  RTS_FLAGS RtsFlags;
  
  /*
   * Split argument lists
   */
  int     prog_argc = 0;    /* an "int" so as to match normal "argc" */
  char  **prog_argv = NULL;
  int     full_prog_argc = 0;    /* an "int" so as to match normal "argc" */
  char  **full_prog_argv = NULL;
  char   *prog_name = NULL; /* 'basename' of prog_argv[0] */
  int     rts_argc = 0;  /* ditto */
  char  **rts_argv = NULL;
  int     rts_argv_size = 0;
  #if defined(mingw32_HOST_OS)
  // On Windows, we want to use GetCommandLineW rather than argc/argv,
  // but we need to mutate the command line arguments for withProgName and
  // friends. The System.Environment module achieves that using this bit of
  // shared state:
  int       win32_prog_argc = 0;
  wchar_t **win32_prog_argv = NULL;
  #endif
  
  /*
   * constants, used later
   */
  #define RTS 1
  #define PGM 0
  
  /* -----------------------------------------------------------------------------
     Static function decls
     -------------------------------------------------------------------------- */
  
  static void procRtsOpts      (HsBool is_hs_main, int rts_argc0, RtsOptsEnabledEnum enabled);
  
  static void normaliseRtsOpts (void);
  
  static void initStatsFile    (FILE *f);
  
  static int  openStatsFile    (char *filename, const char *FILENAME_FMT,
                                FILE **file_ret);
  
  static StgWord64 decodeSize  (const char *flag, nat offset,
                                StgWord64 min, StgWord64 max);
  
  static void bad_option       (const char *s);
  
  #ifdef TRACING
  static void read_trace_flags(char *arg);
  #endif
  
  static void errorUsage      (void) GNU_ATTRIBUTE(__noreturn__);
  
  static char *  copyArg  (char *arg);
  static char ** copyArgv (int argc, char *argv[]);
  static void    freeArgv (int argc, char *argv[]);
  
  static void errorRtsOptsDisabled(HsBool is_hs_main, const char *s);
  
  /* -----------------------------------------------------------------------------
   * Command-line option parsing routines.
   * ---------------------------------------------------------------------------*/
  
  void initRtsFlagsDefaults(void)
  {
      StgWord64 maxStkSize = 8 * getPhysicalMemorySize() / 10;
      // if getPhysicalMemorySize fails just move along with an 8MB limit
      if (maxStkSize == 0)
          maxStkSize = 8 * 1024 * 1024;
  
      RtsFlags.GcFlags.statsFile          = NULL;
      RtsFlags.GcFlags.giveStats          = NO_GC_STATS;
  
      RtsFlags.GcFlags.maxStkSize         = maxStkSize / sizeof(W_);
      RtsFlags.GcFlags.initialStkSize     = 1024 / sizeof(W_);
      RtsFlags.GcFlags.stkChunkSize       = (32 * 1024) / sizeof(W_);
      RtsFlags.GcFlags.stkChunkBufferSize = (1 * 1024) / sizeof(W_);
  
      RtsFlags.GcFlags.minAllocAreaSize   = (512 * 1024)        / BLOCK_SIZE;
      RtsFlags.GcFlags.minOldGenSize      = (1024 * 1024)       / BLOCK_SIZE;
      RtsFlags.GcFlags.maxHeapSize        = 0;    /* off by default */
      RtsFlags.GcFlags.heapSizeSuggestion = 0;    /* none */
      RtsFlags.GcFlags.heapSizeSuggestionAuto = rtsFalse;
      RtsFlags.GcFlags.pcFreeHeap         = 3;    /* 3% */
      RtsFlags.GcFlags.oldGenFactor       = 2;
      RtsFlags.GcFlags.generations        = 2;
      RtsFlags.GcFlags.squeezeUpdFrames   = rtsTrue;
      RtsFlags.GcFlags.compact            = rtsFalse;
      RtsFlags.GcFlags.compactThreshold   = 30.0;
      RtsFlags.GcFlags.sweep              = rtsFalse;
      RtsFlags.GcFlags.idleGCDelayTime    = USToTime(300000); // 300ms
  #ifdef THREADED_RTS
      RtsFlags.GcFlags.doIdleGC           = rtsTrue;
  #else
      RtsFlags.GcFlags.doIdleGC           = rtsFalse;
  #endif
  
  #if osf3_HOST_OS
  /* ToDo: Perhaps by adjusting this value we can make linking without
   * -static work (i.e., not generate a core-dumping executable)? */
  # if SIZEOF_VOID_P == 8
      RtsFlags.GcFlags.heapBase           = 0x180000000L;
  # else
  #  error I have no idea where to begin the heap on a non-64-bit osf3 machine.
  # endif
  #else
      RtsFlags.GcFlags.heapBase           = 0;   /* means don't care */
  #endif
  
  #ifdef DEBUG
      RtsFlags.DebugFlags.scheduler       = rtsFalse;
      RtsFlags.DebugFlags.interpreter     = rtsFalse;
      RtsFlags.DebugFlags.weak            = rtsFalse;
      RtsFlags.DebugFlags.gccafs          = rtsFalse;
      RtsFlags.DebugFlags.gc              = rtsFalse;
      RtsFlags.DebugFlags.block_alloc     = rtsFalse;
      RtsFlags.DebugFlags.sanity          = rtsFalse;
      RtsFlags.DebugFlags.stable          = rtsFalse;
      RtsFlags.DebugFlags.stm             = rtsFalse;
      RtsFlags.DebugFlags.prof            = rtsFalse;
      RtsFlags.DebugFlags.apply           = rtsFalse;
      RtsFlags.DebugFlags.linker          = rtsFalse;
      RtsFlags.DebugFlags.squeeze         = rtsFalse;
      RtsFlags.DebugFlags.hpc             = rtsFalse;
      RtsFlags.DebugFlags.sparks          = rtsFalse;
  #endif
  
  #if defined(PROFILING)
      RtsFlags.CcFlags.doCostCentres      = 0;
  #endif /* PROFILING */
  
      RtsFlags.ProfFlags.doHeapProfile      = rtsFalse;
      RtsFlags.ProfFlags. heapProfileInterval = USToTime(100000); // 100ms
  
  #ifdef PROFILING
      RtsFlags.ProfFlags.includeTSOs        = rtsFalse;
      RtsFlags.ProfFlags.showCCSOnException = rtsFalse;
      RtsFlags.ProfFlags.maxRetainerSetSize = 8;
      RtsFlags.ProfFlags.ccsLength          = 25;
      RtsFlags.ProfFlags.modSelector        = NULL;
      RtsFlags.ProfFlags.descrSelector      = NULL;
      RtsFlags.ProfFlags.typeSelector       = NULL;
      RtsFlags.ProfFlags.ccSelector         = NULL;
      RtsFlags.ProfFlags.ccsSelector        = NULL;
      RtsFlags.ProfFlags.retainerSelector   = NULL;
      RtsFlags.ProfFlags.bioSelector        = NULL;
  #endif
  
  #ifdef TRACING
      RtsFlags.TraceFlags.tracing       = TRACE_NONE;
      RtsFlags.TraceFlags.timestamp     = rtsFalse;
      RtsFlags.TraceFlags.scheduler     = rtsFalse;
      RtsFlags.TraceFlags.gc            = rtsFalse;
      RtsFlags.TraceFlags.sparks_sampled= rtsFalse;
      RtsFlags.TraceFlags.sparks_full   = rtsFalse;
      RtsFlags.TraceFlags.user          = rtsFalse;
  #endif
  
  #ifdef PROFILING
      // When profiling we want a lot more ticks
      RtsFlags.MiscFlags.tickInterval     = USToTime(1000);  // 1ms
  #else
      RtsFlags.MiscFlags.tickInterval     = DEFAULT_TICK_INTERVAL;
  #endif
      RtsFlags.ConcFlags.ctxtSwitchTime   = USToTime(20000); // 20ms
  
      RtsFlags.MiscFlags.install_signal_handlers = rtsTrue;
      RtsFlags.MiscFlags.machineReadable = rtsFalse;
      RtsFlags.MiscFlags.linkerMemBase    = 0;
  
  #ifdef THREADED_RTS
      RtsFlags.ParFlags.nNodes            = 1;
      RtsFlags.ParFlags.migrate           = rtsTrue;
      RtsFlags.ParFlags.parGcEnabled      = 1;
      RtsFlags.ParFlags.parGcGen          = 0;
      RtsFlags.ParFlags.parGcLoadBalancingEnabled = rtsTrue;
      RtsFlags.ParFlags.parGcLoadBalancingGen = 1;
      RtsFlags.ParFlags.parGcNoSyncWithIdle   = 0;
      RtsFlags.ParFlags.setAffinity       = 0;
  #endif
  
  #if defined(THREADED_RTS)
      RtsFlags.ParFlags.maxLocalSparks    = 4096;
  #endif /* THREADED_RTS */
  
  #ifdef TICKY_TICKY
      RtsFlags.TickyFlags.showTickyStats   = rtsFalse;
      RtsFlags.TickyFlags.tickyFile        = NULL;
  #endif
  
  #ifdef USE_PAPI
      /* By default no special measurements taken */
      RtsFlags.PapiFlags.eventType        = 0;
      RtsFlags.PapiFlags.numUserEvents    = 0;
  #endif
  }
  
  static const char *
  usage_text[] = {
  "",
  "Usage: <prog> <args> [+RTS <rtsopts> | -RTS <args>] ... --RTS <args>",
  "",
  "   +RTS    Indicates run time system options follow",
  "   -RTS    Indicates program arguments follow",
  "  --RTS    Indicates that ALL subsequent arguments will be given to the",
  "           program (including any of these RTS flags)",
  "",
  "The following run time system options are available:",
  "",
  "  -?       Prints this message and exits; the program is not executed",
  "  --info   Print information about the RTS used by this program",
  "",
  "  -K<size>  Sets the maximum stack size (default: 80% of the heap)",
  "            Egs: -K32k -K512k -K8M",
  "  -ki<size> Sets the initial thread stack size (default 1k)  Egs: -ki4k -ki2m",
  "  -kc<size> Sets the stack chunk size (default 32k)",
  "  -kb<size> Sets the stack chunk buffer size (default 1k)",
  "",
  "  -A<size> Sets the minimum allocation area size (default 512k) Egs: -A1m -A10k",
  "  -M<size> Sets the maximum heap size (default unlimited)  Egs: -M256k -M1G",
  "  -H<size> Sets the minimum heap size (default 0M)   Egs: -H24m  -H1G",
  "  -m<n>    Minimum % of heap which must be available (default 3%)",
  "  -G<n>    Number of generations (default: 2)",
  "  -c<n>    Use in-place compaction instead of copying in the oldest generation",
  "           when live data is at least <n>% of the maximum heap size set with",
  "           -M (default: 30%)",
  "  -c       Use in-place compaction for all oldest generation collections",
  "           (the default is to use copying)",
  "  -w       Use mark-region for the oldest generation (experimental)",
  #if defined(THREADED_RTS)
  "  -I<sec>  Perform full GC after <sec> idle time (default: 0.3, 0 == off)",
  #endif
  "",
  "  -T         Collect GC statistics (useful for in-program statistics access)",
  "  -t[<file>] One-line GC statistics (if <file> omitted, uses stderr)",
  "  -s[<file>] Summary  GC statistics (if <file> omitted, uses stderr)",
  "  -S[<file>] Detailed GC statistics (if <file> omitted, uses stderr)",
  "",
  "",
  "  -Z       Don't squeeze out update frames on stack overflow",
  "  -B       Sound the bell at the start of each garbage collection",
  #if defined(PROFILING)
  "",
  "  -p       Time/allocation profile        (output file <program>.prof)",
  "  -P       More detailed Time/Allocation profile",
  "  -Pa      Give information about *all* cost centres",
  
  # if defined(PROFILING)
  "",
  "  -h<break-down> Heap residency profile (hp2ps) (output file <program>.hp)",
  "     break-down: c = cost centre stack (default)",
  "                 m = module",
  "                 d = closure description",
  "                 y = type description",
  "                 r = retainer",
  "                 b = biography (LAG,DRAG,VOID,USE)",
  "  A subset of closures may be selected thusly:",
  "    -hc<cc>,...  specific cost centre(s) (top of stack only)",
  "    -hC<cc>,...  specific cost centre(s) (anywhere in stack)",
  "    -hm<mod>...  all cost centres from the specified modules(s)",
  "    -hd<des>,... closures with specified closure descriptions",
  "    -hy<typ>...  closures with specified type descriptions",
  "    -hr<cc>...   closures with specified retainers",
  "    -hb<bio>...  closures with specified biographies (lag,drag,void,use)",
  "",
  "  -R<size>       Set the maximum retainer set size (default: 8)",
  "",
  "  -L<chars>      Maximum length of a cost-centre stack in a heap profile",
  "                 (default: 25)",
  "",
  "  -xt            Include threads (TSOs) in a heap profile",
  "",
  "  -xc      Show current cost centre stack on raising an exception",
  # endif
  #endif /* PROFILING or PAR */
  
  #ifdef TRACING
  "",
  "  -l[flags]  Log events in binary format to the file <program>.eventlog",
  #  ifdef DEBUG
  "  -v[flags]  Log events to stderr",
  #  endif
  "             where [flags] can contain:",
  "                s    scheduler events",
  "                g    GC and heap events",
  "                p    par spark events (sampled)",
  "                f    par spark events (full detail)",
  "                u    user events (emitted from Haskell code)",
  "                a    all event classes above",
  #  ifdef DEBUG
  "                t    add time stamps (only useful with -v)",
  #  endif
  "               -x    disable an event class, for any flag above",
  "             the initial enabled event classes are 'sgpu'",
  #endif
  
  #if !defined(PROFILING)
  "",
  "  -h       Heap residency profile (output file <program>.hp)",
  #endif
  "  -i<sec>  Time between heap profile samples (seconds, default: 0.1)",
  "",
  #if defined(TICKY_TICKY)
  "  -r<file>  Produce ticky-ticky statistics (with -rstderr for stderr)",
  "",
  #endif
  "  -C<secs>  Context-switch interval in seconds.",
  "            0 or no argument means switch as often as possible.",
  "            Default: 0.02 sec.",
  "  -V<secs>  Master tick interval in seconds (0 == disable timer).",
  "            This sets the resolution for -C and the heap profile timer -i,",
  "            and is the frequence of time profile samples.",
  #ifdef PROFILING
  "            Default: 0.001 sec.",
  #else
  "            Default: 0.01 sec.",
  #endif
  "",
  #if defined(DEBUG)
  "  -Ds  DEBUG: scheduler",
  "  -Di  DEBUG: interpreter",
  "  -Dw  DEBUG: weak",
  "  -DG  DEBUG: gccafs",
  "  -Dg  DEBUG: gc",
  "  -Db  DEBUG: block",
  "  -DS  DEBUG: sanity",
  "  -Dt  DEBUG: stable",
  "  -Dp  DEBUG: prof",
  "  -Da  DEBUG: apply",
  "  -Dl  DEBUG: linker",
  "  -Dm  DEBUG: stm",
  "  -Dz  DEBUG: stack squeezing",
  "  -Dc  DEBUG: program coverage",
  "  -Dr  DEBUG: sparks",
  "",
  "     NOTE: DEBUG events are sent to stderr by default; add -l to create a",
  "     binary event log file instead.",
  "",
  #endif /* DEBUG */
  #if defined(THREADED_RTS) && !defined(NOSMP)
  "  -N[<n>]   Use <n> processors (default: 1, -N alone determines",
  "            the number of processors to use automatically)",
  "  -qg[<n>]  Use parallel GC only for generations >= <n>",
  "            (default: 0, -qg alone turns off parallel GC)",
  "  -qb[<n>]  Use load-balancing in the parallel GC only for generations >= <n>",
  "            (default: 1, -qb alone turns off load-balancing)",
  "  -qa       Use the OS to set thread affinity (experimental)",
  "  -qm       Don't automatically migrate threads between CPUs",
  "  -qi<n>    If a processor has been idle for the last <n> GCs, do not",
  "            wake it up for a non-load-balancing parallel GC.",
  "            (0 disables,  default: 0)",
  #endif
  "  --install-signal-handlers=<yes|no>",
  "            Install signal handlers (default: yes)",
  #if defined(THREADED_RTS)
  "  -e<n>     Maximum number of outstanding local sparks (default: 4096)",
  #endif
  #if defined(x86_64_HOST_ARCH)
  "  -xm       Base address to mmap memory in the GHCi linker",
  "            (hex; must be <80000000)",
  #endif
  #if defined(USE_PAPI)
  "  -aX       CPU performance counter measurements using PAPI",
  "            (use with the -s<file> option).  X is one of:",
  "",
  /* "            y - cycles", */
  "            1 - level 1 cache misses",
  "            2 - level 2 cache misses",
  "            b - branch mispredictions",
  "            s - stalled cycles",
  "            e - cache miss and branch misprediction events",
  "            +PAPI_EVENT   - collect papi preset event PAPI_EVENT",
  "            #NATIVE_EVENT - collect native event NATIVE_EVENT (in hex)",
  #endif
  "",
  "RTS options may also be specified using the GHCRTS environment variable.",
  "",
  "Other RTS options may be available for programs compiled a different way.",
  "The GHC User's Guide has full details.",
  "",
  0
  };
  
  STATIC_INLINE rtsBool
  strequal(const char *a, const char * b)
  {
      return(strcmp(a, b) == 0);
  }
  
  // We can't predict up front how much space we'll need for rts_argv,
  // because it involves parsing ghc_rts_opts and GHCRTS, so we
  // expand it on demand.
  static void appendRtsArg (char *arg)
  {
      if (rts_argc == rts_argv_size) {
          rts_argv_size *= 2;
          rts_argv = stgReallocBytes(rts_argv, rts_argv_size * sizeof (char *),
                                     "RtsFlags.c:appendRtsArg");
      }
      rts_argv[rts_argc++] = arg;
  }
  
  static void splitRtsFlags(const char *s)
  {
      const char *c1, *c2;
      char *t;
  
      c1 = s;
      do {
          while (isspace(*c1)) { c1++; };
          c2 = c1;
          while (!isspace(*c2) && *c2 != '\0') { c2++; };
  
          if (c1 == c2) { break; }
  
          t = stgMallocBytes(c2-c1+1, "RtsFlags.c:splitRtsFlags()");
          strncpy(t, c1, c2-c1);
          t[c2-c1] = '\0';
          appendRtsArg(t);
  
          c1 = c2;
      } while (*c1 != '\0');
  }
  
  static void
  errorRtsOptsDisabled(HsBool is_hs_main, const char *s) {
      char *advice;
      if (is_hs_main) {
          advice = "Link with -rtsopts to enable them.";
      } else {
          advice = "Use hs_init_with_rtsopts() to enable them.";
      }
      errorBelch(s, advice);
  }
  
  /* -----------------------------------------------------------------------------
     Parse the command line arguments, collecting options for the RTS.
  
     On return:
       - argv[] is *modified*, any RTS options have been stripped out
       - *argc  contains the new count of arguments in argv[]
  
       - rts_argv[]  (global) contains a copy of the collected RTS args
       - rts_argc    (global) contains the count of args in rts_argv
  
       - prog_argv[] (global) contains a copy of the non-RTS args (== argv)
       - prog_argc   (global) contains the count of args in prog_argv
  
       - prog_name   (global) contains the basename of prog_argv[0]
  
    -------------------------------------------------------------------------- */
  
  void setupRtsFlags (int *argc, char *argv[],
                      RtsOptsEnabledEnum rtsOptsEnabled,
                      const char *ghc_rts_opts,
                      HsBool is_hs_main)
  {
      nat mode;
      nat total_arg;
      nat arg, rts_argc0;
  
      setProgName (argv);
      total_arg = *argc;
      arg = 1;
  
      if (*argc > 1) { *argc = 1; };
      rts_argc = 0;
  
      rts_argv_size = total_arg + 1;
      rts_argv = stgMallocBytes(rts_argv_size * sizeof (char *), "setupRtsFlags");
  
      rts_argc0 = rts_argc;
  
      // process arguments from the -with-rtsopts compile-time flag first
      // (arguments from the GHCRTS environment variable and the command
      // line override these).
      {
          if (ghc_rts_opts != NULL) {
              splitRtsFlags(ghc_rts_opts);
              // opts from ghc_rts_opts are always enabled:
              procRtsOpts(is_hs_main, rts_argc0, RtsOptsAll);
              rts_argc0 = rts_argc;
          }
      }
  
      // process arguments from the GHCRTS environment variable next
      // (arguments from the command line override these).
      {
          char *ghc_rts = getenv("GHCRTS");
  
          if (ghc_rts != NULL) {
              if (rtsOptsEnabled == RtsOptsNone) {
                  errorRtsOptsDisabled(is_hs_main, "Warning: Ignoring GHCRTS variable as RTS options are disabled.\n         %s");
                  // We don't actually exit, just warn
              } else {
                  splitRtsFlags(ghc_rts);
                  procRtsOpts(is_hs_main, rts_argc0, rtsOptsEnabled);
                  rts_argc0 = rts_argc;
              }
          }
      }
  
      // Split arguments (argv) into PGM (argv) and RTS (rts_argv) parts
      //   argv[0] must be PGM argument -- leave in argv
  
      for (mode = PGM; arg < total_arg; arg++) {
          // The '--RTS' argument disables all future +RTS ... -RTS processing.
          if (strequal("--RTS", argv[arg])) {
              arg++;
              break;
          }
          // The '--' argument is passed through to the program, but
          // disables all further +RTS ... -RTS processing.
          else if (strequal("--", argv[arg])) {
              break;
          }
          else if (strequal("+RTS", argv[arg])) {
              mode = RTS;
          }
          else if (strequal("-RTS", argv[arg])) {
              mode = PGM;
          }
          else if (mode == RTS) {
              appendRtsArg(copyArg(argv[arg]));
          }
          else {
              argv[(*argc)++] = argv[arg];
          }
      }
      // process remaining program arguments
      for (; arg < total_arg; arg++) {
          argv[(*argc)++] = argv[arg];
      }
      argv[*argc] = (char *) 0;
  
      procRtsOpts(is_hs_main, rts_argc0, rtsOptsEnabled);
  
      appendRtsArg((char *)0);
      rts_argc--; // appendRtsArg will have bumped it for the NULL (#7227)
  
      normaliseRtsOpts();
  
      setProgArgv(*argc, argv);
  
      if (RtsFlags.GcFlags.statsFile != NULL) {
          initStatsFile (RtsFlags.GcFlags.statsFile);
      }
      if (RtsFlags.TickyFlags.tickyFile != NULL) {
          initStatsFile (RtsFlags.GcFlags.statsFile);
      }
  }
  
  /* -----------------------------------------------------------------------------
   * procRtsOpts: Process rts_argv between rts_argc0 and rts_argc.
   * -------------------------------------------------------------------------- */
  
  #if defined(HAVE_UNISTD_H) && defined(HAVE_SYS_TYPES_H) && !defined(mingw32_HOST_OS)
  static void checkSuid(HsBool is_hs_main, RtsOptsEnabledEnum enabled)
  {
      if (enabled == RtsOptsSafeOnly) {
          /* This doesn't cover linux/posix capabilities like CAP_DAC_OVERRIDE,
             we'd have to link with -lcap for that. */
          if ((getuid() != geteuid()) || (getgid() != getegid())) {
              errorRtsOptsDisabled(is_hs_main, "RTS options are disabled for setuid binaries. %s");
              stg_exit(EXIT_FAILURE);
          }
      }
  }
  #else
  static void checkSuid(HsBool is_hs_main STG_UNUSED, RtsOptsEnabledEnum enabled STG_UNUSED)
  {
  }
  #endif
  
  static void checkUnsafe(HsBool is_hs_main, RtsOptsEnabledEnum enabled)
  {
      if (enabled == RtsOptsSafeOnly) {
          errorRtsOptsDisabled(is_hs_main, "Most RTS options are disabled. %s");
          stg_exit(EXIT_FAILURE);
      }
  }
  
  static void procRtsOpts (HsBool is_hs_main, int rts_argc0, RtsOptsEnabledEnum rtsOptsEnabled)
  {
      rtsBool error = rtsFalse;
      int arg;
  
      if (!(rts_argc0 < rts_argc)) return;
  
      if (rtsOptsEnabled == RtsOptsNone) {
          errorRtsOptsDisabled(is_hs_main, "RTS options are disabled. %s");
          stg_exit(EXIT_FAILURE);
      }
  
      checkSuid(is_hs_main, rtsOptsEnabled);
  
      // Process RTS (rts_argv) part: mainly to determine statsfile
      for (arg = rts_argc0; arg < rts_argc; arg++) {
  
          /* We handle RtsOptsSafeOnly mode by declaring each option as
             either OPTION_SAFE or OPTION_UNSAFE. To make sure we cover
             every branch we use an option_checked flag which is reset
             at the start each iteration and checked at the end. */
          rtsBool option_checked = rtsFalse;
  
  #define OPTION_SAFE option_checked = rtsTrue;
  #define OPTION_UNSAFE checkUnsafe(is_hs_main, rtsOptsEnabled); option_checked = rtsTrue;
  
          if (rts_argv[arg][0] != '-') {
              fflush(stdout);
              errorBelch("unexpected RTS argument: %s", rts_argv[arg]);
              error = rtsTrue;
  
          } else {
  
              switch(rts_argv[arg][1]) {
  
                /* process: general args, then PROFILING-only ones, then
                   CONCURRENT-only, TICKY-only (same order as defined in
                   RtsFlags.lh); within those groups, mostly in
                   case-insensitive alphabetical order.  Final group is
                   x*, which allows for more options.
                */
  
  #ifdef TICKY_TICKY
  # define TICKY_BUILD_ONLY(x) x
  #else
  # define TICKY_BUILD_ONLY(x) \
  errorBelch("the flag %s requires the program to be built with -ticky", rts_argv[arg]); \
  error = rtsTrue;
  #endif
  
  #ifdef PROFILING
  # define PROFILING_BUILD_ONLY(x)   x
  #else
  # define PROFILING_BUILD_ONLY(x) \
  errorBelch("the flag %s requires the program to be built with -prof", rts_argv[arg]); \
  error = rtsTrue;
  #endif
  
  #ifdef TRACING
  # define TRACING_BUILD_ONLY(x)   x
  #else
  # define TRACING_BUILD_ONLY(x) \
  errorBelch("the flag %s requires the program to be built with -eventlog or -debug", rts_argv[arg]); \
  error = rtsTrue;
  #endif
  
  #ifdef THREADED_RTS
  # define THREADED_BUILD_ONLY(x)      x
  #else
  # define THREADED_BUILD_ONLY(x) \
  errorBelch("the flag %s requires the program to be built with -threaded", rts_argv[arg]); \
  error = rtsTrue;
  #endif
  
  #ifdef DEBUG
  # define DEBUG_BUILD_ONLY(x) x
  #else
  # define DEBUG_BUILD_ONLY(x) \
  errorBelch("the flag %s requires the program to be built with -debug", rts_argv[arg]); \
  error = rtsTrue;
  #endif
  
                /* =========== GENERAL ========================== */
                case '?':
                  OPTION_SAFE;
                  error = rtsTrue;
                  break;
  
                /* This isn't going to allow us to keep related options
                   together as we add more --* flags. We really need a
                   proper options parser. */
                case '-':
                    if (strequal("install-signal-handlers=yes",
                                 &rts_argv[arg][2])) {
                        OPTION_UNSAFE;
                        RtsFlags.MiscFlags.install_signal_handlers = rtsTrue;
                    }
                    else if (strequal("install-signal-handlers=no",
                                 &rts_argv[arg][2])) {
                        OPTION_UNSAFE;
                        RtsFlags.MiscFlags.install_signal_handlers = rtsFalse;
                    }
                    else if (strequal("machine-readable",
                                 &rts_argv[arg][2])) {
                        OPTION_UNSAFE;
                        RtsFlags.MiscFlags.machineReadable = rtsTrue;
                    }
                    else if (strequal("info",
                                 &rts_argv[arg][2])) {
                        OPTION_SAFE;
                        printRtsInfo();
                        stg_exit(0);
                    }
                    else {
                        OPTION_SAFE;
                        errorBelch("unknown RTS option: %s",rts_argv[arg]);
                        error = rtsTrue;
                    }
                    break;
                case 'A':
                    OPTION_UNSAFE;
                    RtsFlags.GcFlags.minAllocAreaSize
                        = decodeSize(rts_argv[arg], 2, BLOCK_SIZE, HS_INT_MAX)
                             / BLOCK_SIZE;
                    break;
  
  #ifdef USE_PAPI
                case 'a':
                  OPTION_UNSAFE;
                  switch(rts_argv[arg][2]) {
                  case '1':
                    RtsFlags.PapiFlags.eventType = PAPI_FLAG_CACHE_L1;
                    break;
                  case '2':
                    RtsFlags.PapiFlags.eventType = PAPI_FLAG_CACHE_L2;
                    break;
                  case 'b':
                    RtsFlags.PapiFlags.eventType = PAPI_FLAG_BRANCH;
                    break;
                  case 's':
                    RtsFlags.PapiFlags.eventType = PAPI_FLAG_STALLS;
                    break;
                  case 'e':
                    RtsFlags.PapiFlags.eventType = PAPI_FLAG_CB_EVENTS;
                    break;
                  case '+':
                  case '#':
                    if (RtsFlags.PapiFlags.numUserEvents >= MAX_PAPI_USER_EVENTS) {
                        errorBelch("maximum number of PAPI events reached");
                        stg_exit(EXIT_FAILURE);
                    }
                    nat eventNum  = RtsFlags.PapiFlags.numUserEvents++;
                    char kind     = rts_argv[arg][2];
                    nat eventKind = kind == '+' ? PAPI_PRESET_EVENT_KIND : PAPI_NATIVE_EVENT_KIND;
  
                    RtsFlags.PapiFlags.userEvents[eventNum] = rts_argv[arg] + 3;
                    RtsFlags.PapiFlags.eventType = PAPI_USER_EVENTS;
                    RtsFlags.PapiFlags.userEventsKind[eventNum] = eventKind;
                    break;
                  default:
                    bad_option( rts_argv[arg] );
                  }
                  break;
  #endif
  
                case 'B':
                  OPTION_UNSAFE;
                  RtsFlags.GcFlags.ringBell = rtsTrue;
                  break;
  
                case 'c':
                    OPTION_UNSAFE;
                    if (rts_argv[arg][2] != '\0') {
                        RtsFlags.GcFlags.compactThreshold =
                            atof(rts_argv[arg]+2);
                    } else {
                        RtsFlags.GcFlags.compact = rtsTrue;
                    }
                    break;
  
                case 'w':
                  OPTION_UNSAFE;
                  RtsFlags.GcFlags.sweep = rtsTrue;
                  break;
  
                case 'F':
                  OPTION_UNSAFE;
                  RtsFlags.GcFlags.oldGenFactor = atof(rts_argv[arg]+2);
  
                  if (RtsFlags.GcFlags.oldGenFactor < 0)
                    bad_option( rts_argv[arg] );
                  break;
  
                case 'D':
                OPTION_SAFE;
                DEBUG_BUILD_ONLY(
                {
                    char *c;
  
                    for (c  = rts_argv[arg] + 2; *c != '\0'; c++) {
                        switch (*c) {
                        case 's':
                            RtsFlags.DebugFlags.scheduler = rtsTrue;
                            break;
                        case 'i':
                            RtsFlags.DebugFlags.interpreter = rtsTrue;
                            break;
                        case 'w':
                            RtsFlags.DebugFlags.weak = rtsTrue;
                            break;
                        case 'G':
                            RtsFlags.DebugFlags.gccafs = rtsTrue;
                            break;
                        case 'g':
                            RtsFlags.DebugFlags.gc = rtsTrue;
                            break;
                        case 'b':
                            RtsFlags.DebugFlags.block_alloc = rtsTrue;
                            break;
                        case 'S':
                            RtsFlags.DebugFlags.sanity = rtsTrue;
                            break;
                        case 't':
                            RtsFlags.DebugFlags.stable = rtsTrue;
                            break;
                        case 'p':
                            RtsFlags.DebugFlags.prof = rtsTrue;
                            break;
                        case 'l':
                            RtsFlags.DebugFlags.linker = rtsTrue;
                            break;
                        case 'a':
                            RtsFlags.DebugFlags.apply = rtsTrue;
                            break;
                        case 'm':
                            RtsFlags.DebugFlags.stm = rtsTrue;
                            break;
                        case 'z':
                            RtsFlags.DebugFlags.squeeze = rtsTrue;
                            break;
                        case 'c':
                            RtsFlags.DebugFlags.hpc = rtsTrue;
                            break;
                        case 'r':
                            RtsFlags.DebugFlags.sparks = rtsTrue;
                            break;
                        default:
                            bad_option( rts_argv[arg] );
                        }
                    }
                    // -Dx also turns on -v.  Use -l to direct trace
                    // events to the .eventlog file instead.
                    RtsFlags.TraceFlags.tracing = TRACE_STDERR;
                })
                break;
  
                case 'K':
                    OPTION_UNSAFE;
                    RtsFlags.GcFlags.maxStkSize =
                        decodeSize(rts_argv[arg], 2, sizeof(W_), HS_WORD_MAX) / sizeof(W_);
                    break;
  
                case 'k':
                  OPTION_UNSAFE;
                  switch(rts_argv[arg][2]) {
                  case 'c':
                    RtsFlags.GcFlags.stkChunkSize =
                        decodeSize(rts_argv[arg], 3, sizeof(W_), HS_WORD_MAX) / sizeof(W_);
                    break;
                  case 'b':
                    RtsFlags.GcFlags.stkChunkBufferSize =
                        decodeSize(rts_argv[arg], 3, sizeof(W_), HS_WORD_MAX) / sizeof(W_);
                    break;
                  case 'i':
                    RtsFlags.GcFlags.initialStkSize =
                        decodeSize(rts_argv[arg], 3, sizeof(W_), HS_WORD_MAX) / sizeof(W_);
                    break;
                  default:
                    RtsFlags.GcFlags.initialStkSize =
                        decodeSize(rts_argv[arg], 2, sizeof(W_), HS_WORD_MAX) / sizeof(W_);
                    break;
                  }
                  break;
  
                case 'M':
                    OPTION_UNSAFE;
                    RtsFlags.GcFlags.maxHeapSize =
                        decodeSize(rts_argv[arg], 2, BLOCK_SIZE, HS_WORD_MAX) / BLOCK_SIZE;
                    /* user give size in *bytes* but "maxHeapSize" is in *blocks* */
                    break;
  
                case 'm':
                    OPTION_UNSAFE;
                    RtsFlags.GcFlags.pcFreeHeap = atof(rts_argv[arg]+2);
  
                    if (RtsFlags.GcFlags.pcFreeHeap < 0 ||
                        RtsFlags.GcFlags.pcFreeHeap > 100)
                        bad_option( rts_argv[arg] );
                    break;
  
                case 'G':
                    OPTION_UNSAFE;
                    RtsFlags.GcFlags.generations =
                        decodeSize(rts_argv[arg], 2, 1, HS_INT_MAX);
                    break;
  
                case 'H':
                    OPTION_UNSAFE;
                    if (rts_argv[arg][2] == '\0') {
                        RtsFlags.GcFlags.heapSizeSuggestionAuto = rtsTrue;
                    } else {
                        RtsFlags.GcFlags.heapSizeSuggestion =
                            (nat)(decodeSize(rts_argv[arg], 2, BLOCK_SIZE, HS_WORD_MAX) / BLOCK_SIZE);
                    }
                    break;
  
                case 'I': /* idle GC delay */
                  OPTION_UNSAFE;
                  if (rts_argv[arg][2] == '\0') {
                    /* use default */
                  } else {
                      Time t = fsecondsToTime(atof(rts_argv[arg]+2));
                      if (t == 0) {
                          RtsFlags.GcFlags.doIdleGC = rtsFalse;
                      } else {
                          RtsFlags.GcFlags.doIdleGC = rtsTrue;
                          RtsFlags.GcFlags.idleGCDelayTime = t;
                      }
                  }
                  break;
  
                case 'T':
                    OPTION_SAFE;
                    RtsFlags.GcFlags.giveStats = COLLECT_GC_STATS;
                    break; /* Don't initialize statistics file. */
  
                case 'S':
                    OPTION_SAFE; /* but see below */
                    RtsFlags.GcFlags.giveStats = VERBOSE_GC_STATS;
                    goto stats;
  
                case 's':
                    OPTION_SAFE; /* but see below */
                    RtsFlags.GcFlags.giveStats = SUMMARY_GC_STATS;
                    goto stats;
  
                case 't':
                    OPTION_SAFE; /* but see below */
                    RtsFlags.GcFlags.giveStats = ONELINE_GC_STATS;
                    goto stats;
  
              stats:
                  {
                      int r;
                      if (rts_argv[arg][2] != '\0') {
                        OPTION_UNSAFE;
                      }
                      r = openStatsFile(rts_argv[arg]+2, NULL,
                                        &RtsFlags.GcFlags.statsFile);
                      if (r == -1) { error = rtsTrue; }
                  }
                  break;
  
                case 'Z':
                  OPTION_UNSAFE;
                  RtsFlags.GcFlags.squeezeUpdFrames = rtsFalse;
                  break;
  
                /* =========== PROFILING ========================== */
  
                case 'P': /* detailed cost centre profiling (time/alloc) */
                case 'p': /* cost centre profiling (time/alloc) */
                  OPTION_SAFE;
                  PROFILING_BUILD_ONLY(
                  switch (rts_argv[arg][2]) {
                    case 'a':
                      RtsFlags.CcFlags.doCostCentres = COST_CENTRES_ALL;
                      break;
                    default:
                        if (rts_argv[arg][1] == 'P') {
                            RtsFlags.CcFlags.doCostCentres =
                                COST_CENTRES_VERBOSE;
                        } else {
                            RtsFlags.CcFlags.doCostCentres =
                                COST_CENTRES_SUMMARY;
                        }
                        break;
                  }
                  ) break;
  
                case 'R':
                    OPTION_SAFE;
                    PROFILING_BUILD_ONLY(
                        RtsFlags.ProfFlags.maxRetainerSetSize = atof(rts_argv[arg]+2);
                    ) break;
                case 'L':
                    OPTION_SAFE;
                    PROFILING_BUILD_ONLY(
                        RtsFlags.ProfFlags.ccsLength = atof(rts_argv[arg]+2);
                        if(RtsFlags.ProfFlags.ccsLength <= 0) {
                          bad_option(rts_argv[arg]);
                        }
                    ) break;
                case 'h': /* serial heap profile */
  #if !defined(PROFILING)
                  OPTION_UNSAFE;
                  switch (rts_argv[arg][2]) {
                    case '\0':
                    case 'T':
                      RtsFlags.ProfFlags.doHeapProfile = HEAP_BY_CLOSURE_TYPE;
                      break;
                    default:
                      errorBelch("invalid heap profile option: %s",rts_argv[arg]);
                      error = rtsTrue;
                  }
  #else
                  OPTION_SAFE;
                  PROFILING_BUILD_ONLY(
                  switch (rts_argv[arg][2]) {
                  case '\0':
                  case 'C':
                  case 'c':
                  case 'M':
                  case 'm':
                  case 'D':
                  case 'd':
                  case 'Y':
                  case 'y':
                  case 'R':
                  case 'r':
                  case 'B':
                  case 'b':
                      if (rts_argv[arg][2] != '\0' && rts_argv[arg][3] != '\0') {
                          {
                              char *left  = strchr(rts_argv[arg], '{');
                              char *right = strrchr(rts_argv[arg], '}');
  
                              // curly braces are optional, for
                              // backwards compat.
                              if (left)
                                  left = left+1;
                              else
                                  left = rts_argv[arg] + 3;
  
                              if (!right)
                                  right = rts_argv[arg] + strlen(rts_argv[arg]);
  
                              *right = '\0';
  
                              switch (rts_argv[arg][2]) {
                              case 'c': // cost centre label select
                                  RtsFlags.ProfFlags.ccSelector = left;
                                  break;
                              case 'C':
                                  RtsFlags.ProfFlags.ccsSelector = left;
                                  break;
                              case 'M':
                              case 'm': // cost centre module select
                                  RtsFlags.ProfFlags.modSelector = left;
                                  break;
                              case 'D':
                              case 'd': // closure descr select
                                  RtsFlags.ProfFlags.descrSelector = left;
                                  break;
                              case 'Y':
                              case 'y': // closure type select
                                  RtsFlags.ProfFlags.typeSelector = left;
                                  break;
                              case 'R':
                              case 'r': // retainer select
                                  RtsFlags.ProfFlags.retainerSelector = left;
                                  break;
                              case 'B':
                              case 'b': // biography select
                                  RtsFlags.ProfFlags.bioSelector = left;
                                  break;
                              }
                          }
                          break;
                      }
  
                      if (RtsFlags.ProfFlags.doHeapProfile != 0) {
                          errorBelch("multiple heap profile options");
                          error = rtsTrue;
                          break;
                      }
  
                      switch (rts_argv[arg][2]) {
                      case '\0':
                      case 'C':
                      case 'c':
                          RtsFlags.ProfFlags.doHeapProfile = HEAP_BY_CCS;
                          break;
                      case 'M':
                      case 'm':
                            RtsFlags.ProfFlags.doHeapProfile = HEAP_BY_MOD;
                            break;
                      case 'D':
                      case 'd':
                            RtsFlags.ProfFlags.doHeapProfile = HEAP_BY_DESCR;
                            break;
                      case 'Y':
                      case 'y':
                            RtsFlags.ProfFlags.doHeapProfile = HEAP_BY_TYPE;
                            break;
                      case 'R':
                      case 'r':
                            RtsFlags.ProfFlags.doHeapProfile = HEAP_BY_RETAINER;
                            break;
                      case 'B':
                      case 'b':
                            RtsFlags.ProfFlags.doHeapProfile = HEAP_BY_LDV;
                            break;
                      }
                      break;
  
                  default:
                      errorBelch("invalid heap profile option: %s",rts_argv[arg]);
                      error = rtsTrue;
                  }
                  )
  #endif /* PROFILING */
                  break;
  
                case 'i': /* heap sample interval */
                  OPTION_UNSAFE;
                  if (rts_argv[arg][2] == '\0') {
                    /* use default */
                  } else {
                      RtsFlags.ProfFlags.heapProfileInterval =
                          fsecondsToTime(atof(rts_argv[arg]+2));
                  }
                  break;
  
                /* =========== CONCURRENT ========================= */
                case 'C': /* context switch interval */
                  OPTION_UNSAFE;
                  if (rts_argv[arg][2] == '\0')
                      RtsFlags.ConcFlags.ctxtSwitchTime = 0;
                  else {
                      RtsFlags.ConcFlags.ctxtSwitchTime =
                          fsecondsToTime(atof(rts_argv[arg]+2));
                  }
                  break;
  
                case 'V': /* master tick interval */
                  OPTION_UNSAFE;
                  if (rts_argv[arg][2] == '\0') {
                      // turns off ticks completely
                      RtsFlags.MiscFlags.tickInterval = 0;
                  } else {
                      RtsFlags.MiscFlags.tickInterval =
                          fsecondsToTime(atof(rts_argv[arg]+2));
                  }
                  break;
  
  #if !defined(NOSMP)
                case 'N':
                  OPTION_SAFE;
                  THREADED_BUILD_ONLY(
                  if (rts_argv[arg][2] == '\0') {
  #if defined(PROFILING)
                      RtsFlags.ParFlags.nNodes = 1;
  #else
                      RtsFlags.ParFlags.nNodes = getNumberOfProcessors();
  #endif
                  } else {
                      int nNodes;
                      OPTION_SAFE; /* but see extra checks below... */
                      nNodes = strtol(rts_argv[arg]+2, (char **) NULL, 10);
                      if (nNodes <= 0) {
                        errorBelch("bad value for -N");
                        error = rtsTrue;
                      }
                      if (rtsOptsEnabled == RtsOptsSafeOnly &&
                          nNodes > (int)getNumberOfProcessors()) {
                        errorRtsOptsDisabled(is_hs_main, "Using large values for -N is not allowed by default. %s");
                        stg_exit(EXIT_FAILURE);
                      }
                      RtsFlags.ParFlags.nNodes = (nat)nNodes;
                  }
                  ) break;
  
                case 'g':
                  OPTION_UNSAFE;
                  THREADED_BUILD_ONLY(
                      switch (rts_argv[arg][2]) {
                      case '1':
                          // backwards compat only
                          RtsFlags.ParFlags.parGcEnabled = rtsFalse;
                          break;
                      default:
                          errorBelch("unknown RTS option: %s",rts_argv[arg]);
                          error = rtsTrue;
                          break;
                      }
                      ) break;
  
                case 'q':
                  OPTION_UNSAFE;
                  THREADED_BUILD_ONLY(
                      switch (rts_argv[arg][2]) {
                      case '\0':
                          errorBelch("incomplete RTS option: %s",rts_argv[arg]);
                          error = rtsTrue;
                          break;
                      case 'g':
                          if (rts_argv[arg][3] == '\0') {
                              RtsFlags.ParFlags.parGcEnabled = rtsFalse;
                          } else {
                              RtsFlags.ParFlags.parGcEnabled = rtsTrue;
                              RtsFlags.ParFlags.parGcGen
                                  = strtol(rts_argv[arg]+3, (char **) NULL, 10);
                          }
                          break;
                      case 'b':
                          if (rts_argv[arg][3] == '\0') {
                              RtsFlags.ParFlags.parGcLoadBalancingEnabled = rtsFalse;
                          }
                          else {
                              RtsFlags.ParFlags.parGcLoadBalancingEnabled = rtsTrue;
                              RtsFlags.ParFlags.parGcLoadBalancingGen
                                  = strtol(rts_argv[arg]+3, (char **) NULL, 10);
                          }
                          break;
                      case 'i':
                          RtsFlags.ParFlags.parGcNoSyncWithIdle
                              = strtol(rts_argv[arg]+3, (char **) NULL, 10);
                          break;
                      case 'a':
                          RtsFlags.ParFlags.setAffinity = rtsTrue;
                          break;
                      case 'm':
                          RtsFlags.ParFlags.migrate = rtsFalse;
                          break;
                      case 'w':
                          // -qw was removed; accepted for backwards compat
                          break;
                      default:
                          errorBelch("unknown RTS option: %s",rts_argv[arg]);
                          error = rtsTrue;
                          break;
                      }
                      ) break;
  #endif
                /* =========== PARALLEL =========================== */
                case 'e':
                  OPTION_UNSAFE;
                  THREADED_BUILD_ONLY(
                  if (rts_argv[arg][2] != '\0') {
                      RtsFlags.ParFlags.maxLocalSparks
                        = strtol(rts_argv[arg]+2, (char **) NULL, 10);
                      if (RtsFlags.ParFlags.maxLocalSparks <= 0) {
                        errorBelch("bad value for -e");
                        error = rtsTrue;
                      }
                  }
                  ) break;
  
                /* =========== TICKY ============================== */
  
                case 'r': /* Basic profiling stats */
                  OPTION_SAFE;
                  TICKY_BUILD_ONLY(
  
                  RtsFlags.TickyFlags.showTickyStats = rtsTrue;
  
                  {
                      int r;
                      if (rts_argv[arg][2] != '\0') {
                        OPTION_UNSAFE;
                      }
                      r = openStatsFile(rts_argv[arg]+2,
                                        TICKY_FILENAME_FMT,
                                        &RtsFlags.TickyFlags.tickyFile);
                      if (r == -1) { error = rtsTrue; }
                  }
                  ) break;
  
                /* =========== TRACING ---------=================== */
  
                case 'l':
                    OPTION_SAFE;
                    TRACING_BUILD_ONLY(
                        RtsFlags.TraceFlags.tracing = TRACE_EVENTLOG;
                        read_trace_flags(&rts_argv[arg][2]);
                        );
                    break;
  
                case 'v':
                    OPTION_SAFE;
                    DEBUG_BUILD_ONLY(
                        RtsFlags.TraceFlags.tracing = TRACE_STDERR;
                        read_trace_flags(&rts_argv[arg][2]);
                        );
                    break;
  
                /* =========== EXTENDED OPTIONS =================== */
  
                case 'x': /* Extend the argument space */
                  switch(rts_argv[arg][2]) {
                    case '\0':
                      OPTION_SAFE;
                      errorBelch("incomplete RTS option: %s",rts_argv[arg]);
                      error = rtsTrue;
                      break;
  
                  case 'b': /* heapBase in hex; undocumented */
                      OPTION_UNSAFE;
                      if (rts_argv[arg][3] != '\0') {
                          RtsFlags.GcFlags.heapBase
                              = strtol(rts_argv[arg]+3, (char **) NULL, 16);
                      } else {
                          errorBelch("-xb: requires argument");
                          error = rtsTrue;
                      }
                      break;
  
  #if defined(x86_64_HOST_ARCH)
                  case 'm': /* linkerMemBase */
                      OPTION_UNSAFE;
                      if (rts_argv[arg][3] != '\0') {
                          RtsFlags.MiscFlags.linkerMemBase
                              = strtol(rts_argv[arg]+3, (char **) NULL, 16);
                          if (RtsFlags.MiscFlags.linkerMemBase > 0x80000000) {
                              errorBelch("-xm: value must be <80000000");
                              error = rtsTrue;
                          }
                      } else {
                          RtsFlags.MiscFlags.linkerMemBase = 0;
                      }
                      break;
  #endif
  
                  case 'c': /* Debugging tool: show current cost centre on an exception */
                      OPTION_SAFE;
                      PROFILING_BUILD_ONLY(
                          RtsFlags.ProfFlags.showCCSOnException = rtsTrue;
                          );
                      break;
  
                  case 't':  /* Include memory used by TSOs in a heap profile */
                      OPTION_SAFE;
                      PROFILING_BUILD_ONLY(
                          RtsFlags.ProfFlags.includeTSOs = rtsTrue;
                          );
                      break;
  
                    /* The option prefix '-xx' is reserved for future extension.  KSW 1999-11. */
  
                    default:
                      OPTION_SAFE;
                      errorBelch("unknown RTS option: %s",rts_argv[arg]);
                      error = rtsTrue;
                      break;
                  }
                  break;  /* defensive programming */
  
                /* =========== OH DEAR ============================ */
                default:
                  OPTION_SAFE;
                  errorBelch("unknown RTS option: %s",rts_argv[arg]);
                  error = rtsTrue;
                  break;
              }
  
              if (!option_checked) {
                  /* Naughty! Someone didn't use OPTION_UNSAFE / OPTION_SAFE for
                     an option above */
                  errorBelch("Internal error in the RTS options parser");
                  stg_exit(EXIT_FAILURE);
              }
          }
      }
  
      if (error) errorUsage();
  }
  
  /* -----------------------------------------------------------------------------
   * normaliseRtsOpts: Set some derived values, and make sure things are
   * within sensible ranges.
   * -------------------------------------------------------------------------- */
  
  static void normaliseRtsOpts (void)
  {
      if (RtsFlags.MiscFlags.tickInterval < 0) {
          RtsFlags.MiscFlags.tickInterval = DEFAULT_TICK_INTERVAL;
      }
  
      // If the master timer is disabled, turn off the other timers.
      if (RtsFlags.MiscFlags.tickInterval == 0) {
          RtsFlags.ConcFlags.ctxtSwitchTime  = 0;
          RtsFlags.GcFlags.idleGCDelayTime   = 0;
          RtsFlags.ProfFlags.heapProfileInterval = 0;
      }
  
      // Determine what tick interval we should use for the RTS timer
      // by taking the shortest of the various intervals that we need to
      // monitor.
      if (RtsFlags.ConcFlags.ctxtSwitchTime > 0) {
          RtsFlags.MiscFlags.tickInterval =
              stg_min(RtsFlags.ConcFlags.ctxtSwitchTime,
                      RtsFlags.MiscFlags.tickInterval);
      }
  
      if (RtsFlags.GcFlags.idleGCDelayTime > 0) {
          RtsFlags.MiscFlags.tickInterval =
              stg_min(RtsFlags.GcFlags.idleGCDelayTime,
                      RtsFlags.MiscFlags.tickInterval);
      }
  
      if (RtsFlags.ProfFlags.heapProfileInterval > 0) {
          RtsFlags.MiscFlags.tickInterval =
              stg_min(RtsFlags.ProfFlags.heapProfileInterval,
                      RtsFlags.MiscFlags.tickInterval);
      }
  
      if (RtsFlags.ConcFlags.ctxtSwitchTime > 0) {
          RtsFlags.ConcFlags.ctxtSwitchTicks =
              RtsFlags.ConcFlags.ctxtSwitchTime /
              RtsFlags.MiscFlags.tickInterval;
      } else {
          RtsFlags.ConcFlags.ctxtSwitchTicks = 0;
      }
  
      if (RtsFlags.ProfFlags.heapProfileInterval > 0) {
          RtsFlags.ProfFlags.heapProfileIntervalTicks =
              RtsFlags.ProfFlags.heapProfileInterval /
              RtsFlags.MiscFlags.tickInterval;
      } else {
          RtsFlags.ProfFlags.heapProfileIntervalTicks = 0;
      }
  
      if (RtsFlags.GcFlags.stkChunkBufferSize >
          RtsFlags.GcFlags.stkChunkSize / 2) {
          errorBelch("stack chunk buffer size (-kb) must be less than 50%% of the stack chunk size (-kc)");
          errorUsage();
      }
  }
  
  static void errorUsage (void)
  {
      const char **p;
  
      fflush(stdout);
      for (p = usage_text; *p; p++)
          errorBelch("%s", *p);
      stg_exit(EXIT_FAILURE);
  }
  
  static void
  stats_fprintf(FILE *f, char *s, ...)
  {
      va_list ap;
      va_start(ap,s);
      if (f == NULL) {
          vdebugBelch(s, ap);
      } else {
          vfprintf(f, s, ap);
      }
      va_end(ap);
  }
  
  /* -----------------------------------------------------------------------------
   * openStatsFile: open a file in which to put some runtime stats
   * -------------------------------------------------------------------------- */
  
  static int // return -1 on error
  openStatsFile (char *filename,           // filename, or NULL
                 const char *filename_fmt, // if filename == NULL, use
                                           // this fmt with sprintf to
                                           // generate the filename.  %s
                                           // expands to the program name.
                 FILE **file_ret)          // return the FILE*
  {
      FILE *f = NULL;
  
      if (strequal(filename, "stderr")
          || (filename_fmt == NULL && *filename == '\0')) {
          f = NULL; /* NULL means use debugBelch */
      } else {
          if (*filename != '\0') {  /* stats file specified */
              f = fopen(filename,"w");
          } else {
              char stats_filename[STATS_FILENAME_MAXLEN]; /* default <program>.<ext> */
              sprintf(stats_filename, filename_fmt, prog_name);
              f = fopen(stats_filename,"w");
          }
          if (f == NULL) {
              errorBelch("Can't open stats file %s\n", filename);
              return -1;
          }
      }
      *file_ret = f;
  
      return 0;
  }
  
  /* -----------------------------------------------------------------------------
   * initStatsFile: write a line to the file containing the program name
   * and the arguments it was invoked with.
  -------------------------------------------------------------------------- */
  
  static void initStatsFile (FILE *f)
  {
      /* Write prog_argv and rts_argv into start of stats file */
      int count;
      for (count = 0; count < prog_argc; count++) {
          stats_fprintf(f, "%s ", prog_argv[count]);
      }
      stats_fprintf(f, "+RTS ");
      for (count = 0; count < rts_argc; count++)
          stats_fprintf(f, "%s ", rts_argv[count]);
      stats_fprintf(f, "\n");
  }
  
  /* -----------------------------------------------------------------------------
   * decodeSize: parse a string containing a size, like 300K or 1.2M
  -------------------------------------------------------------------------- */
  
  static StgWord64
  decodeSize(const char *flag, nat offset, StgWord64 min, StgWord64 max)
  {
      char c;
      const char *s;
      StgDouble m;
      StgWord64 val;
  
      s = flag + offset;
  
      if (!*s)
      {
          m = 0;
      }
      else
      {
          m = atof(s);
          c = s[strlen(s)-1];
  
          if (c == 'g' || c == 'G')
              m *= 1024*1024*1024;
          else if (c == 'm' || c == 'M')
              m *= 1024*1024;
          else if (c == 'k' || c == 'K')
              m *= 1024;
          else if (c == 'w' || c == 'W')
              m *= sizeof(W_);
      }
  
      val = (StgWord64)m;
  
      if (m < 0 || val < min || val > max) {
          // printf doesn't like 64-bit format specs on Windows
          // apparently, so fall back to unsigned long.
          errorBelch("error in RTS option %s: size outside allowed range (%" FMT_Word " - %" FMT_Word ")", flag, (W_)min, (W_)max);
          stg_exit(EXIT_FAILURE);
      }
  
      return val;
  }
  
  #if defined(TRACING)
  static void read_trace_flags(char *arg)
  {
      char *c;
      rtsBool enabled = rtsTrue;
      /* Syntax for tracing flags currently looks like:
       *
       *   -l    To turn on eventlog tracing with default trace classes
       *   -lx   Turn on class 'x' (for some class listed below)
       *   -l-x  Turn off class 'x'
       *   -la   Turn on all classes
       *   -l-a  Turn off all classes
       *
       * This lets users say things like:
       *   -la-p    "all but sparks"
       *   -l-ap    "only sparks"
       */
  
      /* Start by turning on the default tracing flags.
       *
       * Currently this is all the trace classes, except full-detail sparks.
       * Similarly, in future we might default to slightly less verbose
       * scheduler or GC tracing.
       */
      RtsFlags.TraceFlags.scheduler      = rtsTrue;
      RtsFlags.TraceFlags.gc             = rtsTrue;
      RtsFlags.TraceFlags.sparks_sampled = rtsTrue;
      RtsFlags.TraceFlags.user           = rtsTrue;
  
      for (c  = arg; *c != '\0'; c++) {
          switch(*c) {
          case '\0':
              break;
          case '-':
              enabled = rtsFalse;
              break;
          case 'a':
              RtsFlags.TraceFlags.scheduler      = enabled;
              RtsFlags.TraceFlags.gc             = enabled;
              RtsFlags.TraceFlags.sparks_sampled = enabled;
              RtsFlags.TraceFlags.sparks_full    = enabled;
              RtsFlags.TraceFlags.user           = enabled;
              enabled = rtsTrue;
              break;
  
          case 's':
              RtsFlags.TraceFlags.scheduler = enabled;
              enabled = rtsTrue;
              break;
          case 'p':
              RtsFlags.TraceFlags.sparks_sampled = enabled;
              enabled = rtsTrue;
              break;
          case 'f':
              RtsFlags.TraceFlags.sparks_full = enabled;
              enabled = rtsTrue;
              break;
          case 't':
              RtsFlags.TraceFlags.timestamp = enabled;
              enabled = rtsTrue;
              break;
          case 'g':
              RtsFlags.TraceFlags.gc        = enabled;
              enabled = rtsTrue;
              break;
          case 'u':
              RtsFlags.TraceFlags.user      = enabled;
              enabled = rtsTrue;
              break;
          default:
              errorBelch("unknown trace option: %c",*c);
              break;
          }
      }
  }
  #endif
  
  static void GNU_ATTRIBUTE(__noreturn__)
  bad_option(const char *s)
  {
    errorBelch("bad RTS option: %s", s);
    stg_exit(EXIT_FAILURE);
  }
  
  /* ----------------------------------------------------------------------------
     Copying and freeing argc/argv
     ------------------------------------------------------------------------- */
  
  static char * copyArg(char *arg)
  {
      char *new_arg = stgMallocBytes(strlen(arg) + 1, "copyArg");
      strcpy(new_arg, arg);
      return new_arg;
  }
  
  static char ** copyArgv(int argc, char *argv[])
  {
      int i;
      char **new_argv;
  
      new_argv = stgCallocBytes(argc + 1, sizeof (char *), "copyArgv 1");
      for (i = 0; i < argc; i++) {
          new_argv[i] = copyArg(argv[i]);
      }
      new_argv[argc] = NULL;
      return new_argv;
  }
  
  static void freeArgv(int argc, char *argv[])
  {
      int i;
      if (argv != NULL) {
          for (i = 0; i < argc; i++) {
              stgFree(argv[i]);
          }
          stgFree(argv);
      }
  }
  
  /* -----------------------------------------------------------------------------
     Getting/Setting the program's arguments.
  
     These are used by System.Environment, and parts of the RTS.
     -------------------------------------------------------------------------- */
  
  void
  setProgName(char *argv[])
  {
      char *last_slash;
  
      if (argv[0] == NULL) { // #7037
          prog_name = "";
          return;
      }
  
      /* Remove directory from argv[0] -- default files in current directory */
  #if !defined(mingw32_HOST_OS)
      if ( (last_slash = (char *) strrchr(argv[0], '/')) != NULL ) {
          prog_name = last_slash+1;
     } else {
          prog_name = argv[0];
     }
  #else
      last_slash = argv[0] + (strlen(argv[0]) - 1);
      while ( last_slash > argv[0] ) {
          if ( *last_slash == '/' || *last_slash == '\\' ) {
              prog_name = last_slash+1;
              return;
          }
          last_slash--;
      }
      prog_name = argv[0];
  #endif
  }
  
  void
  getProgArgv(int *argc, char **argv[])
  {
      if (argc) { *argc = prog_argc; }
      if (argv) { *argv = prog_argv; }
  }
  
  void
  setProgArgv(int argc, char *argv[])
  {
      prog_argc = argc;
      prog_argv = copyArgv(argc,argv);
      setProgName(prog_argv);
  }
  
  static void
  freeProgArgv(void)
  {
      freeArgv(prog_argc,prog_argv);
      prog_argc = 0;
      prog_argv = NULL;
  }
  
  /* ----------------------------------------------------------------------------
     The full argv - a copy of the original program's argc/argv
     ------------------------------------------------------------------------- */
  
  void
  setFullProgArgv(int argc, char *argv[])
  {
      full_prog_argc = argc;
      full_prog_argv = copyArgv(argc,argv);
  }
  
  /* These functions record and recall the full arguments, including the
     +RTS ... -RTS options. The reason for adding them was so that the
     ghc-inplace program can pass /all/ the arguments on to the real ghc. */
  void
  getFullProgArgv(int *argc, char **argv[])
  {
      if (argc) { *argc = full_prog_argc; }
      if (argv) { *argv = full_prog_argv; }
  }
  
  void
  freeFullProgArgv (void)
  {
      freeArgv(full_prog_argc, full_prog_argv);
      full_prog_argc = 0;
      full_prog_argv = NULL;
  }
  
  /* ----------------------------------------------------------------------------
     The Win32 argv
     ------------------------------------------------------------------------- */
  
  #if defined(mingw32_HOST_OS)
  void freeWin32ProgArgv (void);
  
  void
  freeWin32ProgArgv (void)
  {
      int i;
  
      if (win32_prog_argv != NULL) {
          for (i = 0; i < win32_prog_argc; i++) {
              stgFree(win32_prog_argv[i]);
          }
          stgFree(win32_prog_argv);
      }
  
      win32_prog_argc = 0;
      win32_prog_argv = NULL;
  }
  
  void
  getWin32ProgArgv(int *argc, wchar_t **argv[])
  {
      *argc = win32_prog_argc;
      *argv = win32_prog_argv;
  }
  
  void
  setWin32ProgArgv(int argc, wchar_t *argv[])
  {
          int i;
  
          freeWin32ProgArgv();
  
      win32_prog_argc = argc;
          if (argv == NULL) {
                  win32_prog_argv = NULL;
                  return;
          }
  
      win32_prog_argv = stgCallocBytes(argc + 1, sizeof (wchar_t *),
                                      "setWin32ProgArgv 1");
      for (i = 0; i < argc; i++) {
          win32_prog_argv[i] = stgMallocBytes((wcslen(argv[i]) + 1) * sizeof(wchar_t),
                                             "setWin32ProgArgv 2");
          wcscpy(win32_prog_argv[i], argv[i]);
      }
      win32_prog_argv[argc] = NULL;
  }
  #endif
  
  /* ----------------------------------------------------------------------------
     The RTS argv
     ------------------------------------------------------------------------- */
  
  static void
  freeRtsArgv(void)
  {
      freeArgv(rts_argc,rts_argv);
      rts_argc = 0;
      rts_argv = NULL;
      rts_argv_size = 0;
  }
  
  /* ----------------------------------------------------------------------------
     All argvs
     ------------------------------------------------------------------------- */
  
  void freeRtsArgs(void)
  {
  #if defined(mingw32_HOST_OS)
      freeWin32ProgArgv();
  #endif
      freeFullProgArgv();
      freeProgArgv();
      freeRtsArgv();
  }
  