text: /*
   * os-posix-lib.c
   *
   * Copyright (c) 2003-2008 Fabrice Bellard
   * Copyright (c) 2010 Red Hat, Inc.
   *
   * QEMU library functions on POSIX which are shared between QEMU and
   * the QEMU tools.
   *
   * Permission is hereby granted, free of charge, to any person obtaining a copy
   * of this software and associated documentation files (the "Software"), to deal
   * in the Software without restriction, including without limitation the rights
   * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
   * copies of the Software, and to permit persons to whom the Software is
   * furnished to do so, subject to the following conditions:
   *
   * The above copyright notice and this permission notice shall be included in
   * all copies or substantial portions of the Software.
   *
   * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
   * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
   * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
   * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
   * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
   * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
   * THE SOFTWARE.
   */
  
  /* The following block of code temporarily renames the daemon() function so the
     compiler does not see the warning associated with it in stdlib.h on OSX */
  #ifdef __APPLE__
  #define daemon qemu_fake_daemon_function
  #include <stdlib.h>
  #undef daemon
  extern int daemon(int, int);
  #endif
  
  #if defined(__linux__) && (defined(__x86_64__) || defined(__arm__))
     /* Use 2 MiB alignment so transparent hugepages can be used by KVM.
        Valgrind does not support alignments larger than 1 MiB,
        therefore we need special code which handles running on Valgrind. */
  #  define QEMU_VMALLOC_ALIGN (512 * 4096)
  #elif defined(__linux__) && defined(__s390x__)
     /* Use 1 MiB (segment size) alignment so gmap can be used by KVM. */
  #  define QEMU_VMALLOC_ALIGN (256 * 4096)
  #else
  #  define QEMU_VMALLOC_ALIGN getpagesize()
  #endif
  #define HUGETLBFS_MAGIC       0x958458f6
  
  #include <termios.h>
  #include <unistd.h>
  
  #include <glib/gprintf.h>
  
  #include "config-host.h"
  #include "sysemu/sysemu.h"
  #include "trace.h"
  #include "qemu/sockets.h"
  #include <sys/mman.h>
  #include <libgen.h>
  #include <setjmp.h>
  #include <sys/signal.h>
  
  #ifdef CONFIG_LINUX
  #include <sys/syscall.h>
  #include <sys/vfs.h>
  #endif
  
  #ifdef __FreeBSD__
  #include <sys/sysctl.h>
  #endif
  
  int qemu_get_thread_id(void)
  {
  #if defined(__linux__)
      return syscall(SYS_gettid);
  #else
      return getpid();
  #endif
  }
  
  int qemu_daemon(int nochdir, int noclose)
  {
      return daemon(nochdir, noclose);
  }
  
  void *qemu_oom_check(void *ptr)
  {
      if (ptr == NULL) {
          fprintf(stderr, "Failed to allocate memory: %s\n", strerror(errno));
          abort();
      }
      return ptr;
  }
  
  void *qemu_memalign(size_t alignment, size_t size)
  {
      void *ptr;
  
      if (alignment < sizeof(void*)) {
          alignment = sizeof(void*);
      }
  
  #if defined(_POSIX_C_SOURCE) && !defined(__sun__)
      int ret;
      ret = posix_memalign(&ptr, alignment, size);
      if (ret != 0) {
          fprintf(stderr, "Failed to allocate %zu B: %s\n",
                  size, strerror(ret));
          abort();
      }
  #elif defined(CONFIG_BSD)
      ptr = qemu_oom_check(valloc(size));
  #else
      ptr = qemu_oom_check(memalign(alignment, size));
  #endif
      trace_qemu_memalign(alignment, size, ptr);
      return ptr;
  }
  
  /* alloc shared memory pages */
  void *qemu_anon_ram_alloc(size_t size)
  {
      size_t align = QEMU_VMALLOC_ALIGN;
      size_t total = size + align - getpagesize();
      void *ptr = mmap(0, total, PROT_READ | PROT_WRITE,
                       MAP_ANONYMOUS | MAP_PRIVATE, -1, 0);
      size_t offset = QEMU_ALIGN_UP((uintptr_t)ptr, align) - (uintptr_t)ptr;
  
      if (ptr == MAP_FAILED) {
          return NULL;
      }
  
      ptr += offset;
      total -= offset;
  
      if (offset > 0) {
          munmap(ptr - offset, offset);
      }
      if (total > size) {
          munmap(ptr + size, total - size);
      }
  
      trace_qemu_anon_ram_alloc(size, ptr);
      return ptr;
  }
  
  void qemu_vfree(void *ptr)
  {
      trace_qemu_vfree(ptr);
      free(ptr);
  }
  
  void qemu_anon_ram_free(void *ptr, size_t size)
  {
      trace_qemu_anon_ram_free(ptr, size);
      if (ptr) {
          munmap(ptr, size);
      }
  }
  
  void qemu_set_block(int fd)
  {
      int f;
      f = fcntl(fd, F_GETFL);
      fcntl(fd, F_SETFL, f & ~O_NONBLOCK);
  }
  
  void qemu_set_nonblock(int fd)
  {
      int f;
      f = fcntl(fd, F_GETFL);
      fcntl(fd, F_SETFL, f | O_NONBLOCK);
  }
  
  int socket_set_fast_reuse(int fd)
  {
      int val = 1, ret;
  
      ret = setsockopt(fd, SOL_SOCKET, SO_REUSEADDR,
                       (const char *)&val, sizeof(val));
  
      assert(ret == 0);
  
      return ret;
  }
  
  void qemu_set_cloexec(int fd)
  {
      int f;
      f = fcntl(fd, F_GETFD);
      fcntl(fd, F_SETFD, f | FD_CLOEXEC);
  }
  
  /*
   * Creates a pipe with FD_CLOEXEC set on both file descriptors
   */
  int qemu_pipe(int pipefd[2])
  {
      int ret;
  
  #ifdef CONFIG_PIPE2
      ret = pipe2(pipefd, O_CLOEXEC);
      if (ret != -1 || errno != ENOSYS) {
          return ret;
      }
  #endif
      ret = pipe(pipefd);
      if (ret == 0) {
          qemu_set_cloexec(pipefd[0]);
          qemu_set_cloexec(pipefd[1]);
      }
  
      return ret;
  }
  
  int qemu_utimens(const char *path, const struct timespec *times)
  {
      struct timeval tv[2], tv_now;
      struct stat st;
      int i;
  #ifdef CONFIG_UTIMENSAT
      int ret;
  
      ret = utimensat(AT_FDCWD, path, times, AT_SYMLINK_NOFOLLOW);
      if (ret != -1 || errno != ENOSYS) {
          return ret;
      }
  #endif
      /* Fallback: use utimes() instead of utimensat() */
  
      /* happy if special cases */
      if (times[0].tv_nsec == UTIME_OMIT && times[1].tv_nsec == UTIME_OMIT) {
          return 0;
      }
      if (times[0].tv_nsec == UTIME_NOW && times[1].tv_nsec == UTIME_NOW) {
          return utimes(path, NULL);
      }
  
      /* prepare for hard cases */
      if (times[0].tv_nsec == UTIME_NOW || times[1].tv_nsec == UTIME_NOW) {
          gettimeofday(&tv_now, NULL);
      }
      if (times[0].tv_nsec == UTIME_OMIT || times[1].tv_nsec == UTIME_OMIT) {
          stat(path, &st);
      }
  
      for (i = 0; i < 2; i++) {
          if (times[i].tv_nsec == UTIME_NOW) {
              tv[i].tv_sec = tv_now.tv_sec;
              tv[i].tv_usec = tv_now.tv_usec;
          } else if (times[i].tv_nsec == UTIME_OMIT) {
              tv[i].tv_sec = (i == 0) ? st.st_atime : st.st_mtime;
              tv[i].tv_usec = 0;
          } else {
              tv[i].tv_sec = times[i].tv_sec;
              tv[i].tv_usec = times[i].tv_nsec / 1000;
          }
      }
  
      return utimes(path, &tv[0]);
  }
  
  char *
  qemu_get_local_state_pathname(const char *relative_pathname)
  {
      return g_strdup_printf("%s/%s", CONFIG_QEMU_LOCALSTATEDIR,
                             relative_pathname);
  }
  
  void qemu_set_tty_echo(int fd, bool echo)
  {
      struct termios tty;
  
      tcgetattr(fd, &tty);
  
      if (echo) {
          tty.c_lflag |= ECHO | ECHONL | ICANON | IEXTEN;
      } else {
          tty.c_lflag &= ~(ECHO | ECHONL | ICANON | IEXTEN);
      }
  
      tcsetattr(fd, TCSANOW, &tty);
  }
  
  static char exec_dir[PATH_MAX];
  
  void qemu_init_exec_dir(const char *argv0)
  {
      char *dir;
      char *p = NULL;
      char buf[PATH_MAX];
  
      assert(!exec_dir[0]);
  
  #if defined(__linux__)
      {
          int len;
          len = readlink("/proc/self/exe", buf, sizeof(buf) - 1);
          if (len > 0) {
              buf[len] = 0;
              p = buf;
          }
      }
  #elif defined(__FreeBSD__)
      {
          static int mib[4] = {CTL_KERN, KERN_PROC, KERN_PROC_PATHNAME, -1};
          size_t len = sizeof(buf) - 1;
  
          *buf = '\0';
          if (!sysctl(mib, ARRAY_SIZE(mib), buf, &len, NULL, 0) &&
              *buf) {
              buf[sizeof(buf) - 1] = '\0';
              p = buf;
          }
      }
  #endif
      /* If we don't have any way of figuring out the actual executable
         location then try argv[0].  */
      if (!p) {
          if (!argv0) {
              return;
          }
          p = realpath(argv0, buf);
          if (!p) {
              return;
          }
      }
      dir = dirname(p);
  
      pstrcpy(exec_dir, sizeof(exec_dir), dir);
  }
  
  char *qemu_get_exec_dir(void)
  {
      return g_strdup(exec_dir);
  }
  
  static sigjmp_buf sigjump;
  
  static void sigbus_handler(int signal)
  {
      siglongjmp(sigjump, 1);
  }
  
  static size_t fd_getpagesize(int fd)
  {
  #ifdef CONFIG_LINUX
      struct statfs fs;
      int ret;
  
      if (fd != -1) {
          do {
              ret = fstatfs(fd, &fs);
          } while (ret != 0 && errno == EINTR);
  
          if (ret == 0 && fs.f_type == HUGETLBFS_MAGIC) {
              return fs.f_bsize;
          }
      }
  #endif
  
      return getpagesize();
  }
  
  void os_mem_prealloc(int fd, char *area, size_t memory)
  {
      int ret;
      struct sigaction act, oldact;
      sigset_t set, oldset;
  
      memset(&act, 0, sizeof(act));
      act.sa_handler = &sigbus_handler;
      act.sa_flags = 0;
  
      ret = sigaction(SIGBUS, &act, &oldact);
      if (ret) {
          perror("os_mem_prealloc: failed to install signal handler");
          exit(1);
      }
  
      /* unblock SIGBUS */
      sigemptyset(&set);
      sigaddset(&set, SIGBUS);
      pthread_sigmask(SIG_UNBLOCK, &set, &oldset);
  
      if (sigsetjmp(sigjump, 1)) {
          fprintf(stderr, "os_mem_prealloc: failed to preallocate pages\n");
          exit(1);
      } else {
          int i;
          size_t hpagesize = fd_getpagesize(fd);
  
          /* MAP_POPULATE silently ignores failures */
          memory = (memory + hpagesize - 1) & -hpagesize;
          for (i = 0; i < (memory / hpagesize); i++) {
              memset(area + (hpagesize * i), 0, 1);
          }
  
          ret = sigaction(SIGBUS, &oldact, NULL);
          if (ret) {
              perror("os_mem_prealloc: failed to reinstall signal handler");
              exit(1);
          }
  
          pthread_sigmask(SIG_SETMASK, &oldset, NULL);
      }
  }
  