text: /*      $NetBSD: meta.c,v 1.17 2011/05/04 20:38:32 sjg Exp $ */
  
  /*
   * Implement 'meta' mode.
   * Adapted from John Birrell's patches to FreeBSD make.
   * --sjg
   */
  /*
   * Copyright (c) 2009-2010, Juniper Networks, Inc.
   * Portions Copyright (c) 2009, John Birrell.
   * 
   * Redistribution and use in source and binary forms, with or without
   * modification, are permitted provided that the following conditions 
   * are met: 
   * 1. Redistributions of source code must retain the above copyright
   *    notice, this list of conditions and the following disclaimer. 
   * 2. Redistributions in binary form must reproduce the above copyright
   *    notice, this list of conditions and the following disclaimer in the
   *    documentation and/or other materials provided with the distribution.  
   * 
   * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
   * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
   * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
   * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
   * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
   * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
   * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
   * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
   * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
   * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
   * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 
   */
  #if defined(USE_META)
  
  #ifdef HAVE_CONFIG_H
  # include "config.h"
  #endif
  #include <sys/stat.h>
  #include <sys/ioctl.h>
  #include <fcntl.h>
  #include <libgen.h>
  #include <errno.h>
  #if !defined(HAVE_CONFIG_H) || defined(HAVE_ERR_H)
  #include <err.h>
  #endif
  
  #include "make.h"
  #include "job.h"
  
  #ifdef HAVE_FILEMON_H
  # include <filemon.h>
  #endif
  #if !defined(USE_FILEMON) && defined(FILEMON_SET_FD)
  # define USE_FILEMON
  #endif
  
  static BuildMon Mybm;			/* for compat */
  static Lst metaBailiwick;			/* our scope of control */
  
  Boolean useMeta = FALSE;
  static Boolean useFilemon = FALSE;
  static Boolean writeMeta = FALSE;
  static Boolean metaEnv = FALSE;		/* don't save env unless asked */
  static Boolean metaVerbose = FALSE;
  static Boolean metaIgnoreCMDs = FALSE;	/* ignore CMDs in .meta files */
  static Boolean metaCurdirOk = FALSE;	/* write .meta in .CURDIR Ok? */
  
  extern Boolean forceJobs;
  extern Boolean comatMake;
  
  #define	MAKE_META_PREFIX	".MAKE.META.PREFIX"
  
  #ifndef N2U
  # define N2U(n, u)   (((n) + ((u) - 1)) / (u))
  #endif
  #ifndef ROUNDUP
  # define ROUNDUP(n, u)   (N2U((n), (u)) * (u))
  #endif
  
  #if !defined(HAVE_STRSEP)
  # define strsep(s, d) stresep((s), (d), 0)
  #endif
  
  /*
   * Filemon is a kernel module which snoops certain syscalls.
   *
   * C chdir
   * E exec
   * F [v]fork
   * L [sym]link
   * M rename
   * R read
   * W write
   * S stat
   *
   * See meta_oodate below - we mainly care about 'E' and 'R'.
   *
   * We can still use meta mode without filemon, but 
   * the benefits are more limited.
   */
  #ifdef USE_FILEMON
  # ifndef _PATH_FILEMON
  #   define _PATH_FILEMON "/dev/filemon"
  # endif
  
  /*
   * Open the filemon device.
   */
  static void
  filemon_open(BuildMon *pbm)
  {
      int retry;
      
      pbm->mon_fd = pbm->filemon_fd = -1;
      if (!useFilemon)
  	return;
  
      for (retry = 5; retry >= 0; retry--) {
  	if ((pbm->filemon_fd = open(_PATH_FILEMON, O_RDWR)) >= 0)
  	    break;
      }
  
      if (pbm->filemon_fd < 0) {
  	useFilemon = FALSE;
  	warn("Could not open %s", _PATH_FILEMON);
  	return;
      }
  
      /*
       * We use a file outside of '.'
       * to avoid a FreeBSD kernel bug where unlink invalidates
       * cwd causing getcwd to do a lot more work.
       * We only care about the descriptor.
       */
      pbm->mon_fd = mkTempFile("filemon.XXXXXX", NULL);
      if (ioctl(pbm->filemon_fd, FILEMON_SET_FD, &pbm->mon_fd) < 0) {
  	err(1, "Could not set filemon file descriptor!");
      }
      /* we don't need these once we exec */
      (void)fcntl(pbm->mon_fd, F_SETFD, 1);
      (void)fcntl(pbm->filemon_fd, F_SETFD, 1);
  }
  
  /*
   * Read the build monitor output file and write records to the target's
   * metadata file.
   */
  static void
  filemon_read(FILE *mfp, int fd)
  {
      FILE *fp;
      char buf[BUFSIZ];
  
      /* Check if we're not writing to a meta data file.*/
      if (mfp == NULL) {
  	if (fd >= 0)
  	    close(fd);			/* not interested */
  	return;
      }
      /* rewind */
      lseek(fd, SEEK_SET, 0);
      if ((fp = fdopen(fd, "r")) == NULL)
  	err(1, "Could not read build monitor file '%d'", fd);
  
      fprintf(mfp, "-- filemon acquired metadata --\n");
  
      while (fgets(buf, sizeof(buf), fp)) {
  	fprintf(mfp, "%s", buf);
      }
      fflush(mfp);
      clearerr(fp);
      fclose(fp);
  }
  #endif
  
  /*
   * when realpath() fails,
   * we use this, to clean up ./ and ../
   */
  static void
  eat_dots(char *buf, size_t bufsz, int dots)
  {
      char *cp;
      char *cp2;
      const char *eat;
      size_t eatlen;
  
      switch (dots) {
      case 1:
  	eat = "/./";
  	eatlen = 2;
  	break;
      case 2:
  	eat = "/../";
  	eatlen = 3;
  	break;
      default:
  	return;
      }
      
      do {
  	cp = strstr(buf, eat);
  	if (cp) {
  	    cp2 = cp + eatlen;
  	    if (dots == 2 && cp > buf) {
  		do {
  		    cp--;
  		} while (cp > buf && *cp != '/');
  	    }
  	    if (*cp == '/') {
  		strlcpy(cp, cp2, bufsz - (cp - buf));
  	    } else {
  		return;			/* can't happen? */
  	    }
  	}
      } while (cp);
  }
  
  static char *
  meta_name(struct GNode *gn, char *mname, size_t mnamelen,
  	  const char *dname,
  	  const char *tname)
  {
      char buf[MAXPATHLEN];
      char cwd[MAXPATHLEN];
      char *rp;
      char *cp;
      char *tp;
      char *p[4];				/* >= number of possible uses */
      int i;
  
      i = 0;
      if (!dname)
  	dname = Var_Value(".OBJDIR", gn, &p[i++]);
      if (!tname)
  	tname = Var_Value(TARGET, gn, &p[i++]);
  
      if (realpath(dname, cwd))
  	dname = cwd;
  
      /*
       * Weed out relative paths from the target file name.
       * We have to be careful though since if target is a
       * symlink, the result will be unstable.
       * So we use realpath() just to get the dirname, and leave the
       * basename as given to us.
       */
      if ((cp = strrchr(tname, '/'))) {
  	if (realpath(tname, buf)) {
  	    if ((rp = strrchr(buf, '/'))) {
  		rp++;
  		cp++;
  		if (strcmp(cp, rp) != 0)
  		    strlcpy(rp, cp, sizeof(buf) - (rp - buf));
  	    }
  	    tname = buf;
  	} else {
  	    /*
  	     * We likely have a directory which is about to be made.
  	     * We pretend realpath() succeeded, to have a chance
  	     * of generating the same meta file name that we will
  	     * next time through.
  	     */
  	    if (tname[0] == '/') {
  		strlcpy(buf, tname, sizeof(buf));
  	    } else {
  		snprintf(buf, sizeof(buf), "%s/%s", cwd, tname);
  	    }
  	    eat_dots(buf, sizeof(buf), 1);	/* ./ */
  	    eat_dots(buf, sizeof(buf), 2);	/* ../ */
  	    tname = buf;
  	}
      }
      /* on some systems dirname may modify its arg */
      tp = bmake_strdup(tname);
      if (strcmp(dname, dirname(tp)) == 0)
  	snprintf(mname, mnamelen, "%s.meta", tname);
      else {
  	snprintf(mname, mnamelen, "%s/%s.meta", dname, tname);
  
  	/*
  	 * Replace path separators in the file name after the
  	 * current object directory path.
  	 */
  	cp = mname + strlen(dname) + 1;
  
  	while (*cp != '\0') {
  	    if (*cp == '/')
  		*cp = '_';
  	    cp++;
  	}
      }
      free(tp);
      for (i--; i >= 0; i--) {
  	if (p[i])
  	    free(p[i]);
      }
      return (mname);
  }
  
  /*
   * Return true if running ${.MAKE}
   * Bypassed if target is flagged .MAKE
   */
  static int
  is_submake(void *cmdp, void *gnp)
  {
      static char *p_make = NULL;
      static int p_len;
      char  *cmd = cmdp;
      GNode *gn = gnp;
      char *mp = NULL;
      char *cp;
      char *cp2;
      int rc = 0;				/* keep looking */
  
      if (!p_make) {
  	p_make = Var_Value(".MAKE", gn, &cp);
  	p_len = strlen(p_make);
      }
      cp = strchr(cmd, '$');
      if ((cp)) {
  	mp = Var_Subst(NULL, cmd, gn, FALSE);
  	cmd = mp;
      }
      cp2 = strstr(cmd, p_make);
      if ((cp2)) {
  	switch (cp2[p_len]) {
  	case '\0':
  	case ' ':
  	case '\t':
  	case '\n':
  	    rc = 1;
  	    break;
  	}
  	if (cp2 > cmd && rc > 0) {
  	    switch (cp2[-1]) {
  	    case ' ':
  	    case '\t':
  	    case '\n':
  		break;
  	    default:
  		rc = 0;			/* no match */
  		break;
  	    }
  	}
      }
      if (mp)
  	free(mp);
      return (rc);
  }
  
  typedef struct meta_file_s {
      FILE *fp;
      GNode *gn;
  } meta_file_t;
  
  static int
  printCMD(void *cmdp, void *mfpp)
  {
      meta_file_t *mfp = mfpp;
      char *cmd = cmdp;
      char *cp = NULL;
  
      if (strchr(cmd, '$')) {
  	cmd = cp = Var_Subst(NULL, cmd, mfp->gn, FALSE);
      }
      fprintf(mfp->fp, "CMD %s\n", cmd);
      if (cp)
  	free(cp);
      return 0;
  }
  
  /*
   * Certain node types never get a .meta file
   */
  #define SKIP_META_TYPE(_type) do { \
      if ((gn->type & __CONCAT(OP_, _type))) {	\
  	if (DEBUG(META)) { \
  	    fprintf(debug_file, "Skipping meta for %s: .%s\n", \
  		    gn->name, __STRING(_type));		       \
  	} \
  	return (NULL); \
      } \
  } while (0)
  
  static FILE *
  meta_create(BuildMon *pbm, GNode *gn)
  {
      extern char **environ;
      meta_file_t mf;
      char buf[MAXPATHLEN];
      char objdir[MAXPATHLEN];
      char **ptr;
      const char *dname;
      const char *tname;
      char *fname;
      const char *cp;
      char *p[4];				/* >= possible uses */
      int i;
      struct stat fs;
  
      
      /* This may be a phony node which we don't want meta data for... */
      /* Skip .meta for .BEGIN, .END, .ERROR etc as well. */
      /* Or it may be explicitly flagged as .NOMETA */
      SKIP_META_TYPE(NOMETA);
      /* Unless it is explicitly flagged as .META */
      if (!(gn->type & OP_META)) {
  	SKIP_META_TYPE(PHONY);
  	SKIP_META_TYPE(SPECIAL);
  	SKIP_META_TYPE(MAKE);
      }
  
      mf.fp = NULL;
      
      i = 0;
      
      dname = Var_Value(".OBJDIR", gn, &p[i++]);
      tname = Var_Value(TARGET, gn, &p[i++]);
      
      /* The object directory may not exist. Check it.. */
      if (stat(dname, &fs) != 0) {
  	if (DEBUG(META))
  	    fprintf(debug_file, "Skipping meta for %s: no .OBJDIR\n",
  		    gn->name);
  	goto out;
      }
      /* Check if there are no commands to execute. */
      if (Lst_IsEmpty(gn->commands)) {
  	if (DEBUG(META))
  	    fprintf(debug_file, "Skipping meta for %s: no commands\n",
  		    gn->name);
  	goto out;
      }
  
      /* make sure these are canonical */
      if (realpath(dname, objdir))
  	dname = objdir;
  
      /* If we aren't in the object directory, don't create a meta file. */
      if (!metaCurdirOk && strcmp(curdir, dname) == 0) {
  	if (DEBUG(META))
  	    fprintf(debug_file, "Skipping meta for %s: .OBJDIR == .CURDIR\n",
  		    gn->name);
  	goto out;
      }
      if (!(gn->type & OP_META)) {
  	/* We do not generate .meta files for sub-makes */
  	if (Lst_ForEach(gn->commands, is_submake, gn)) {
  	    if (DEBUG(META))
  		fprintf(debug_file, "Skipping meta for %s: .MAKE\n",
  			gn->name);
  	    goto out;
  	}
      }
  
      if (metaVerbose) {
  	char *mp;
  
  	/* Describe the target we are building */
  	mp = Var_Subst(NULL, "${" MAKE_META_PREFIX "}", gn, 0);
  	if (*mp)
  	    fprintf(stdout, "%s\n", mp);
  	free(mp);
      }
      /* Get the basename of the target */
      if ((cp = strrchr(tname, '/')) == NULL) {
  	cp = tname;
      } else {
  	cp++;
      }
  
      fflush(stdout);
  
      if (strcmp(cp, makeDependfile) == 0)
  	goto out;
  
      if (!writeMeta)
  	/* Don't create meta data. */
  	goto out;
  
      fname = meta_name(gn, pbm->meta_fname, sizeof(pbm->meta_fname),
  		      dname, tname);
  
  #ifdef DEBUG_META_MODE
      if (DEBUG(META))
  	fprintf(debug_file, "meta_create: %s\n", fname);
  #endif
  
      if ((mf.fp = fopen(fname, "w")) == NULL)
  	err(1, "Could not open meta file '%s'", fname);
  
      fprintf(mf.fp, "# Meta data file %s\n", fname);
  
      mf.gn = gn;
  
      Lst_ForEach(gn->commands, printCMD, &mf);
  
      fprintf(mf.fp, "CWD %s\n", getcwd(buf, sizeof(buf)));
      fprintf(mf.fp, "TARGET %s\n", tname);
  
      if (metaEnv) {
  	for (ptr = environ; *ptr != NULL; ptr++)
  	    fprintf(mf.fp, "ENV %s\n", *ptr);
      }
  
      fprintf(mf.fp, "-- command output --\n");
      fflush(mf.fp);
  
      Var_Append(".MAKE.META.FILES", fname, VAR_GLOBAL);
      Var_Append(".MAKE.META.CREATED", fname, VAR_GLOBAL);
      
   out:
      for (i--; i >= 0; i--) {
  	if (p[i])
  	    free(p[i]);
      }
  
      return (mf.fp);
  }
  
  static Boolean
  boolValue(char *s)
  {
      switch(*s) {
      case '0':
      case 'N':
      case 'n':
      case 'F':
      case 'f':
  	return FALSE;
      }
      return TRUE;
  }
  
  void
  meta_init(const char *make_mode)
  {
      static int once = 0;
      char *cp;
  
      useMeta = TRUE;
      useFilemon = TRUE;
      writeMeta = TRUE;
  
      if (make_mode) {
  	if (strstr(make_mode, "env"))
  	    metaEnv = TRUE;
  	if (strstr(make_mode, "verb"))
  	    metaVerbose = TRUE;
  	if (strstr(make_mode, "read"))
  	    writeMeta = FALSE;
  	if (strstr(make_mode, "nofilemon"))
  	    useFilemon = FALSE;
  	if ((cp = strstr(make_mode, "curdirok="))) {
  	    metaCurdirOk = boolValue(&cp[9]);
  	}
  	if (strstr(make_mode, "ignore-cmd"))
  	    metaIgnoreCMDs = TRUE;
  	/* for backwards compatability */
  	Var_Set(".MAKE.META_CREATED", "${.MAKE.META.CREATED}", VAR_GLOBAL, 0);
  	Var_Set(".MAKE.META_FILES", "${.MAKE.META.FILES}", VAR_GLOBAL, 0);
      }
      if (metaVerbose && !Var_Exists(MAKE_META_PREFIX, VAR_GLOBAL)) {
  	/*
  	 * The default value for MAKE_META_PREFIX
  	 * prints the absolute path of the target.
  	 * This works be cause :H will generate '.' if there is no /
  	 * and :tA will resolve that to cwd.
  	 */
  	Var_Set(MAKE_META_PREFIX, "Building ${.TARGET:H:tA}/${.TARGET:T}", VAR_GLOBAL, 0);
      }
      if (once)
  	return;
      once = 1;
      memset(&Mybm, 0, sizeof(Mybm));
      /*
       * We consider ourselves master of all within ${.MAKE.META.BAILIWICK}
       */
      metaBailiwick = Lst_Init(FALSE);
      cp = Var_Subst(NULL, "${.MAKE.META.BAILIWICK:O:u:tA}", VAR_GLOBAL, 0);
      if (cp) {
  	str2Lst_Append(metaBailiwick, cp, NULL);
      }
  }
  
  /*
   * In each case below we allow for job==NULL
   */
  void
  meta_job_start(Job *job, GNode *gn)
  {
      BuildMon *pbm;
  
      if (job != NULL) {
  	pbm = &job->bm;
      } else {
  	pbm = &Mybm;
      }
      pbm->mfp = meta_create(pbm, gn);
  #ifdef USE_FILEMON_ONCE
      /* compat mode we open the filemon dev once per command */
      if (job == NULL)
  	return;
  #endif
  #ifdef USE_FILEMON
      if (pbm->mfp != NULL && useFilemon) {
  	filemon_open(pbm);
      } else {
  	pbm->mon_fd = pbm->filemon_fd = -1;
      }
  #endif
  }
  
  /*
   * The child calls this before doing anything.
   * It does not disturb our state.
   */
  void
  meta_job_child(Job *job)
  {
  #ifdef USE_FILEMON
      BuildMon *pbm;
      pid_t pid;
  
      if (job != NULL) {
  	pbm = &job->bm;
      } else {
  	pbm = &Mybm;
      }
      pid = getpid();
      if (pbm->mfp != NULL && useFilemon) {
  	if (ioctl(pbm->filemon_fd, FILEMON_SET_PID, &pid) < 0) {
  	    err(1, "Could not set filemon pid!");
  	}
      }
  #endif
  }
  
  void
  meta_job_error(Job *job, GNode *gn, int flags, int status)
  {
      char cwd[MAXPATHLEN];
      BuildMon *pbm;
  
      if (job != NULL) {
  	pbm = &job->bm;
      } else {
  	if (!gn)
  	    gn = job->node;
  	pbm = &Mybm;
      }
      if (pbm->mfp != NULL) {
  	fprintf(pbm->mfp, "*** Error code %d%s\n",
  		status,
  		(flags & JOB_IGNERR) ?
  		"(ignored)" : "");
      }
      if (gn) {
  	Var_Set(".ERROR_TARGET", gn->path ? gn->path : gn->name, VAR_GLOBAL, 0);
      }
      getcwd(cwd, sizeof(cwd));
      Var_Set(".ERROR_CWD", cwd, VAR_GLOBAL, 0);
      if (pbm && pbm->meta_fname[0]) {
  	Var_Set(".ERROR_META_FILE", pbm->meta_fname, VAR_GLOBAL, 0);
      }
      meta_job_finish(job);
  }
  
  void
  meta_job_output(Job *job, char *cp, const char *nl)
  {
      BuildMon *pbm;
      
      if (job != NULL) {
  	pbm = &job->bm;
      } else {
  	pbm = &Mybm;
      }
      if (pbm->mfp != NULL) {
  	if (metaVerbose) {
  	    static char *meta_prefix = NULL;
  	    static int meta_prefix_len;
  
  	    if (!meta_prefix) {
  		char *cp2;
  
  		meta_prefix = Var_Subst(NULL, "${" MAKE_META_PREFIX "}", VAR_GLOBAL, 0);
  		if ((cp2 = strchr(meta_prefix, '$')))
  		    meta_prefix_len = cp2 - meta_prefix;
  		else
  		    meta_prefix_len = strlen(meta_prefix);
  	    }
  	    if (strncmp(cp, meta_prefix, meta_prefix_len) == 0) {
  		cp = strchr(cp+1, '\n');
  		if (!cp++)
  		    return;
  	    }
  	}
  	fprintf(pbm->mfp, "%s%s", cp, nl);
      }
  }
  
  void
  meta_cmd_finish(void *pbmp)
  {
  #ifdef USE_FILEMON
      BuildMon *pbm = pbmp;
  
      if (!pbm)
  	pbm = &Mybm;
  
      if (pbm->filemon_fd >= 0) {
  	close(pbm->filemon_fd);
  	filemon_read(pbm->mfp, pbm->mon_fd);
  	pbm->filemon_fd = pbm->mon_fd = -1;
      }
  #endif
  }
  
  void
  meta_job_finish(Job *job)
  {
      BuildMon *pbm;
  
      if (job != NULL) {
  	pbm = &job->bm;
      } else {
  	pbm = &Mybm;
      }
      if (pbm->mfp != NULL) {
  	meta_cmd_finish(pbm);
  	fclose(pbm->mfp);
  	pbm->mfp = NULL;
  	pbm->meta_fname[0] = '\0';
      }
  }
  
  /*
   * Fetch a full line from fp - growing bufp if needed
   * Return length in bufp.
   */
  static int 
  fgetLine(char **bufp, size_t *szp, int o, FILE *fp)
  {
      char *buf = *bufp;
      size_t bufsz = *szp;
      struct stat fs;
      int x;
  
      if (fgets(&buf[o], bufsz - o, fp) != NULL) {
      check_newline:
  	x = o + strlen(&buf[o]);
  	if (buf[x - 1] == '\n')
  	    return x;
  	/*
  	 * We need to grow the buffer.
  	 * The meta file can give us a clue.
  	 */
  	if (fstat(fileno(fp), &fs) == 0) {
  	    size_t newsz;
  	    char *p;
  
  	    newsz = ROUNDUP((fs.st_size / 2), BUFSIZ);
  	    if (newsz <= bufsz)
  		newsz = ROUNDUP(fs.st_size, BUFSIZ);
  	    if (DEBUG(META)) 
  		fprintf(debug_file, "growing buffer %u -> %u\n",
  			bufsz, newsz);
  	    p = bmake_realloc(buf, newsz);
  	    if (p) {
  		*bufp = buf = p;
  		*szp = bufsz = newsz;
  		/* fetch the rest */
  		if (!fgets(&buf[x], bufsz - x, fp))
  		    return x;		/* truncated! */
  		goto check_newline;
  	    }
  	}
      }
      return 0;
  }
  
  static int
  prefix_match(void *p, void *q)
  {
      const char *prefix = p;
      const char *path = q;
      size_t n = strlen(prefix);
  
      return (0 == strncmp(path, prefix, n));
  }
  
  static int
  string_match(const void *p, const void *q)
  {
      const char *p1 = p;
      const char *p2 = q;
  
      return strcmp(p1, p2);
  }
  
  
  /*
   * When running with 'meta' functionality, a target can be out-of-date
   * if any of the references in it's meta data file is more recent.
   * We have to track the latestdir on a per-process basis.
   */
  #define LDIR_VNAME_FMT ".meta.%d.ldir"
  
  Boolean
  meta_oodate(GNode *gn, Boolean oodate)
  {
      static char *tmpdir = NULL;
      static char cwd[MAXPATHLEN];
      char ldir_vname[64];
      char latestdir[MAXPATHLEN];
      char fname[MAXPATHLEN];
      char fname1[MAXPATHLEN];
      char fname2[MAXPATHLEN];
      char *p;
      char *cp;
      static size_t cwdlen = 0;
      static size_t tmplen = 0;
      FILE *fp;
      Boolean ignoreOODATE = FALSE;
      Lst missingFiles;
      
      if (oodate)
  	return oodate;		/* we're done */
  
      missingFiles = Lst_Init(FALSE);
  
      /*
       * We need to check if the target is out-of-date. This includes
       * checking if the expanded command has changed. This in turn
       * requires that all variables are set in the same way that they
       * would be if the target needs to be re-built.
       */
      Make_DoAllVar(gn);
  
      meta_name(gn, fname, sizeof(fname), NULL, NULL);
  
  #ifdef DEBUG_META_MODE
      if (DEBUG(META))
  	fprintf(debug_file, "meta_oodate: %s\n", fname);
  #endif
  
      if ((fp = fopen(fname, "r")) != NULL) {
  	static char *buf = NULL;
  	static size_t bufsz;
  	int lineno = 0;
  	int lastpid = 0;
  	int pid;
  	int f = 0;
  	int x;
  	LstNode ln;
  	struct stat fs;
  
  	if (!buf) {
  	    bufsz = 8 * BUFSIZ;
  	    buf = bmake_malloc(bufsz);
  	}
  
  	if (!cwdlen) {
  	    if (getcwd(cwd, sizeof(cwd)) == NULL)
  		err(1, "Could not get current working directory");
  	    cwdlen = strlen(cwd);
  	}
  
  	if (!tmpdir) {
  	    tmpdir = getTmpdir();
  	    tmplen = strlen(tmpdir);
  	}
  
  	/* we want to track all the .meta we read */
  	Var_Append(".MAKE.META.FILES", fname, VAR_GLOBAL);
  
  	ln = Lst_First(gn->commands);
  	while (!oodate && (x = fgetLine(&buf, &bufsz, 0, fp)) > 0) {
  	    lineno++;
  	    if (buf[x - 1] == '\n')
  		buf[x - 1] = '\0';
  	    else
  		warnx("%s: %d: line truncated at %u", fname, lineno, x);
  
  	    /* Find the start of the build monitor section. */
  	    if (!f) {
  		if (strncmp(buf, "-- filemon", 10) == 0) {
  		    f = 1;
  		    continue;
  		}
  		if (strncmp(buf, "# buildmon", 10) == 0) {
  		    f = 1;
  		    continue;
  		}
  	    }		    
  
  	    /* Delimit the record type. */
  	    p = buf;
  #ifdef DEBUG_META_MODE
  	    if (DEBUG(META))
  		fprintf(debug_file, "%s: %d: %s\n", fname, lineno, buf);
  #endif
  	    strsep(&p, " ");
  	    if (f) {
  		/*
  		 * We are in the 'filemon' output section.
  		 * Each record from filemon follows the general form:
  		 *
  		 * <key> <pid> <data>
  		 *
  		 * Where:
  		 * <key> is a single letter, denoting the syscall.
  		 * <pid> is the process that made the syscall.
  		 * <data> is the arguments (of interest).
  		 */
  		switch(buf[0]) {
  		case '#':		/* comment */
  		case 'V':		/* version */
  		    break;
  		default:
  		    /*
  		     * We need to track pathnames per-process.
  		     *
  		     * Each process run by make, starts off in the 'CWD'
  		     * recorded in the .meta file, if it chdirs ('C')
  		     * elsewhere we need to track that - but only for
  		     * that process.  If it forks ('F'), we initialize
  		     * the child to have the same cwd as its parent.
  		     *
  		     * We also need to track the 'latestdir' of
  		     * interest.  This is usually the same as cwd, but
  		     * not if a process is reading directories.
  		     *
  		     * Each time we spot a different process ('pid')
  		     * we save the current value of 'latestdir' in a
  		     * variable qualified by 'lastpid', and
  		     * re-initialize 'latestdir' to any pre-saved
  		     * value for the current 'pid' and 'CWD' if none.
  		     */
  		    pid = atoi(p);
  		    if (pid > 0 && pid != lastpid) {
  			char *ldir;
  			char *tp;
  		    
  			if (lastpid > 0) {
  			    /* We need to remember this. */
  			    Var_Set(ldir_vname, latestdir, VAR_GLOBAL, 0);
  			}
  			snprintf(ldir_vname, sizeof(ldir_vname), LDIR_VNAME_FMT, pid);
  			lastpid = pid;
  			ldir = Var_Value(ldir_vname, VAR_GLOBAL, &tp);
  			if (ldir) {
  			    strlcpy(latestdir, ldir, sizeof(latestdir));
  			    if (tp)
  				free(tp);
  			} else 
  			    strlcpy(latestdir, cwd, sizeof(latestdir));
  		    }
  		    /* Skip past the pid. */
  		    if (strsep(&p, " ") == NULL)
  			continue;
  #ifdef DEBUG_META_MODE
  		    if (DEBUG(META))
  			fprintf(debug_file, "%s: %d: cwd=%s ldir=%s\n", fname, lineno, cwd, latestdir);
  #endif
  		    break;
  		}
  
  		/* Process according to record type. */
  		switch (buf[0]) {
  		case 'X':		/* eXit */
  		    Var_Delete(ldir_vname, VAR_GLOBAL);
  		    lastpid = 0;	/* no need to save ldir_vname */
  		    break;
  
  		case 'F':		/* [v]Fork */
  		    {
  			char cldir[64];
  			int child;
  
  			child = atoi(p);
  			if (child > 0) {
  			    snprintf(cldir, sizeof(cldir), LDIR_VNAME_FMT, child);
  			    Var_Set(cldir, latestdir, VAR_GLOBAL, 0);
  			}
  		    }
  		    break;
  
  		case 'C':		/* Chdir */
  		    /* Update the latest directory. */
  		    strlcpy(latestdir, p, sizeof(latestdir));
  		    break;
  
  		case 'M':		/* renaMe */
  		    if (Lst_IsEmpty(missingFiles))
  			break;
  		    /* 'L' and 'M' put single quotes around the args */
  		    if (*p == '\'') {
  			char *ep;
  
  			p++;
  			if ((ep = strchr(p, '\'')))
  			    *ep = '\0';
  		    }
  		    /* FALLTHROUGH */
  		case 'D':		/* unlink */
  		    if (*p == '/' && !Lst_IsEmpty(missingFiles)) {
  			/* remove p from the missingFiles list if present */
  			if ((ln = Lst_Find(missingFiles, p, string_match)) != NULL) {
  			    char *tp = Lst_Datum(ln);
  			    Lst_Remove(missingFiles, ln);
  			    free(tp);
  			}
  		    }
  		    break;
  		case 'L':		/* Link */
  		    /* we want the target */
  		    if (strsep(&p, " ") == NULL)
  			continue;
  		    /* 'L' and 'M' put single quotes around the args */
  		    if (*p == '\'') {
  			char *ep;
  
  			p++;
  			if ((ep = strchr(p, '\'')))
  			    *ep = '\0';
  		    }
  		    /* FALLTHROUGH */
  		case 'W':		/* Write */
  		    /*
  		     * If a file we generated within our bailiwick
  		     * but outside of .OBJDIR is missing,
  		     * we need to do it again. 
  		     */
  		    /* ignore non-absolute paths */
  		    if (*p != '/')
  			break;
  
  		    if (Lst_IsEmpty(metaBailiwick))
  			break;
  
  		    /* ignore cwd - normal dependencies handle those */
  		    if (strncmp(p, cwd, cwdlen) == 0)
  			break;
  
  		    if (!Lst_ForEach(metaBailiwick, prefix_match, p))
  			break;
  
  		    /* tmpdir might be within */
  		    if (tmplen > 0 && strncmp(p, tmpdir, tmplen) == 0)
  			break;
  
  		    /* ignore anything containing the string "tmp" */
  		    if ((strstr("tmp", p)))
  			break;
  
  		    if (stat(p, &fs) < 0) {
  			Lst_AtEnd(missingFiles, bmake_strdup(p));
  		    }
  		    break;
  		case 'R':		/* Read */
  		case 'E':		/* Exec */
  		    /*
  		     * Check for runtime files that can't
  		     * be part of the dependencies because
  		     * they are _expected_ to change.
  		     */
  		    if (strncmp(p, "/tmp/", 5) == 0 ||
  			(tmplen > 0 && strncmp(p, tmpdir, tmplen) == 0))
  			break;
  
  		    if (strncmp(p, "/var/", 5) == 0)
  			break;
  
  		    /* Ignore device files. */
  		    if (strncmp(p, "/dev/", 5) == 0)
  			break;
  
  		    /* Ignore /etc/ files. */
  		    if (strncmp(p, "/etc/", 5) == 0)
  			break;
  
  		    /*
  		     * The rest of the record is the file name.
  		     * Check if it's not an absolute path.
  		     */
  		    {
  			char *sdirs[4];
  			char **sdp;
  			int sdx = 0;
  			int found = 0;
  
  			if (*p == '/') {
  			    sdirs[sdx++] = p; /* done */
  			} else {
  			    if (strcmp(".", p) == 0)
  				continue;  /* no point */
  
  			    /* Check vs latestdir */
  			    snprintf(fname1, sizeof(fname1), "%s/%s", latestdir, p);
  			    sdirs[sdx++] = fname1;
  
  			    if (strcmp(latestdir, cwd) != 0) {
  				/* Check vs cwd */
  				snprintf(fname2, sizeof(fname2), "%s/%s", cwd, p);
  				sdirs[sdx++] = fname2;
  			    }
  			}
  			sdirs[sdx++] = NULL;
  
  			for (sdp = sdirs; *sdp && !found; sdp++) {
  #ifdef DEBUG_META_MODE
  			    if (DEBUG(META))
  				fprintf(debug_file, "%s: %d: looking for: %s\n", fname, lineno, *sdp);
  #endif
  			    if (stat(*sdp, &fs) == 0) {
  				found = 1;
  				p = *sdp;
  			    }
  			}
  			if (found) {
  #ifdef DEBUG_META_MODE
  			    if (DEBUG(META))
  				fprintf(debug_file, "%s: %d: found: %s\n", fname, lineno, p);
  #endif
  			    if (!S_ISDIR(fs.st_mode) &&
  				fs.st_mtime > gn->mtime) {
  				if (DEBUG(META))
  				    fprintf(debug_file, "%s: %d: file '%s' is newer than the target...\n", fname, lineno, p);
  				oodate = TRUE;
  			    } else if (S_ISDIR(fs.st_mode)) {
  				/* Update the latest directory. */
  				realpath(p, latestdir);
  			    }
  			} else if (errno == ENOENT && *p == '/' &&
  				   strncmp(p, cwd, cwdlen) != 0) {
  			    /*
  			     * A referenced file outside of CWD is missing.
  			     * We cannot catch every eventuality here...
  			     */
  			    if (DEBUG(META))
  				fprintf(debug_file, "%s: %d: file '%s' may have moved?...\n", fname, lineno, p);
  			    oodate = TRUE;
  			}
  		    }
  		    break;
  		default:
  		    break;
  		}
  	    } else if (strcmp(buf, "CMD") == 0) {
  		/*
  		 * Compare the current command with the one in the
  		 * meta data file.
  		 */
  		if (ln == NULL) {
  		    if (DEBUG(META))
  			fprintf(debug_file, "%s: %d: there were more build commands in the meta data file than there are now...\n", fname, lineno);
  		    oodate = TRUE;
  		} else {
  		    char *cmd = (char *)Lst_Datum(ln);
  
  		    if (!ignoreOODATE) {
  			if (strstr(cmd, "$?"))
  			    ignoreOODATE = TRUE;
  			else if ((cp = strstr(cmd, ".OODATE"))) {
  			    /* check for $[{(].OODATE[)}] */
  			    if (cp > cmd + 2 && cp[-2] == '$')
  				ignoreOODATE = TRUE;
  			}
  			if (ignoreOODATE && DEBUG(META))
  			    fprintf(debug_file, "%s: %d: cannot compare commands using .OODATE\n", fname, lineno);
  		    }
  		    cmd = Var_Subst(NULL, cmd, gn, TRUE);
  
  		    if ((cp = strchr(cmd, '\n'))) {
  			int n;
  
  			/*
  			 * This command contains newlines, we need to
  			 * fetch more from the .meta file before we
  			 * attempt a comparison.
  			 */
  			/* first put the newline back at buf[x - 1] */
  			buf[x - 1] = '\n';
  			do {
  			    /* now fetch the next line */
  			    if ((n = fgetLine(&buf, &bufsz, x, fp)) <= 0)
  				break;
  			    x = n;
  			    lineno++;
  			    if (buf[x - 1] != '\n') {
  				warnx("%s: %d: line truncated at %u", fname, lineno, x);
  				break;
  			    }
  			    cp = strchr(++cp, '\n');
  			} while (cp);
  			if (buf[x - 1] == '\n')
  			    buf[x - 1] = '\0';
  		    }
  		    if (!ignoreOODATE &&
  			!(gn->type & OP_NOMETA_CMP) &&
  			strcmp(p, cmd) != 0) {
  			if (DEBUG(META))
  			    fprintf(debug_file, "%s: %d: a build command has changed\n%s\nvs\n%s\n", fname, lineno, p, cmd);
  			if (!metaIgnoreCMDs)
  			    oodate = TRUE;
  		    }
  		    free(cmd);
  		    ln = Lst_Succ(ln);
  		}
  	    } else if (strcmp(buf, "CWD") == 0) {
  		/*
  		 * Check if there are extra commands now
  		 * that weren't in the meta data file.
  		 */
  		if (!oodate && ln != NULL) {
  		    if (DEBUG(META))
  			fprintf(debug_file, "%s: %d: there are extra build commands now that weren't in the meta data file\n", fname, lineno);
  		    oodate = TRUE;
  		}
  		if (strcmp(p, cwd) != 0) {
  		    if (DEBUG(META))
  			fprintf(debug_file, "%s: %d: the current working directory has changed from '%s' to '%s'\n", fname, lineno, p, curdir);
  		    oodate = TRUE;
  		}
  	    }
  	}
  
  	fclose(fp);
  	if (!Lst_IsEmpty(missingFiles)) {
  	    if (DEBUG(META))
  		fprintf(debug_file, "%s: missing files: %s...\n",
  			fname, (char *)Lst_Datum(Lst_First(missingFiles)));
  	    oodate = TRUE;
  	    Lst_Destroy(missingFiles, (FreeProc *)free);
  	}
      }
      if (oodate && ignoreOODATE) {
  	/*
  	 * Target uses .OODATE, so we need to re-compute it.
  	 * We need to clean up what Make_DoAllVar() did.
  	 */
  	Var_Delete(ALLSRC, gn);
  	Var_Delete(OODATE, gn);
  	gn->flags &= ~DONE_ALLSRC;
      }
      return oodate;
  }
  
  /* support for compat mode */
  
  static int childPipe[2];
  
  void
  meta_compat_start(void)
  {
  #ifdef USE_FILEMON_ONCE
      /*
       * We need to re-open filemon for each cmd.
       */
      BuildMon *pbm = &Mybm;
      
      if (pbm->mfp != NULL && useFilemon) {
  	filemon_open(pbm);
      } else {
  	pbm->mon_fd = pbm->filemon_fd = -1;
      }
  #endif
      if (pipe(childPipe) < 0)
  	Punt("Cannot create pipe: %s", strerror(errno));
      /* Set close-on-exec flag for both */
      (void)fcntl(childPipe[0], F_SETFD, 1);
      (void)fcntl(childPipe[1], F_SETFD, 1);
  }
  
  void
  meta_compat_child(void)
  {
      meta_job_child(NULL);
      if (dup2(childPipe[1], 1) < 0 ||
  	dup2(1, 2) < 0) {
  	execError("dup2", "pipe");
  	_exit(1);
      }
  }
  
  void
  meta_compat_parent(void)
  {
      FILE *fp;
      char buf[BUFSIZ];
      
      close(childPipe[1]);			/* child side */
      fp = fdopen(childPipe[0], "r");
      while (fgets(buf, sizeof(buf), fp)) {
  	meta_job_output(NULL, buf, "");
  	printf("%s", buf);
      }
      fclose(fp);
  }
  
  #endif	/* USE_META */
  