shm_open与shm_ulink的实现2

#include <unistd.h>

#if ! _POSIX_MAPPED_FILES
#include <rt/shm_open.c>

#else

#include <errno.h>
#include <sys/mman.h>
#include <fcntl.h>
#include <string.h>
#include <stdlib.h>
#include <paths.h>

#define SHMDIR (_PATH_DEV "shm/")

/* Open shared memory object.  */
int
shm_open (const char *name, int oflag, mode_t mode)
{
  size_t namelen;
  char *fname;
  int fd;

  /* Construct the filename.  */
  while (name[0] == '/')
    ++name;

  if (name[0] == '/0')
    {
      /* The name "/" is not supported.  */
      __set_errno (EINVAL);
      return -1;
    }

  namelen = strlen (name);
  fname = (char *) __alloca (sizeof SHMDIR - 1 + namelen + 1);
  __mempcpy (__mempcpy (fname, SHMDIR, sizeof SHMDIR - 1),
      name, namelen + 1);

  fd = open (name, oflag, mode);
  if (fd != -1)
    {
      /* We got a descriptor.  Now set the FD_CLOEXEC bit.  */
      int flags = fcntl (fd, F_GETFD, 0);

      if (__builtin_expect (flags, 0) != -1)
 {
   flags |= FD_CLOEXEC;
   flags = fcntl (fd, F_SETFD, flags);
 }

      if (flags == -1)
 {
   /* Something went wrong.  We cannot return the descriptor.  */
   int save_errno = errno;
   close (fd);
   fd = -1;
   __set_errno (save_errno);
 }
    }

  return fd;
}

#endif

 

#include <unistd.h>

#if ! _POSIX_MAPPED_FILES
#include <rt/shm_unlink.c>

#else

#include <errno.h>
#include <sys/mman.h>
#include <string.h>
#include <stdlib.h>
#include <paths.h>

#define SHMDIR (_PATH_DEV "shm/")

/* Remove shared memory object.  */
int
shm_unlink (const char *name)
{
  size_t namelen;
  char *fname;

  /* Construct the filename.  */
  while (name[0] == '/')
    ++name;

  if (name[0] == '/0')
    {
      /* The name "/" is not supported.  */
      __set_errno (EINVAL);
      return -1;
    }

  namelen = strlen (name);
  fname = (char *) __alloca (sizeof SHMDIR - 1 + namelen + 1);
  __mempcpy (__mempcpy (fname, SHMDIR, sizeof SHMDIR - 1),
      name, namelen + 1);

  return unlink (name);
}

#endif