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glibc  2.9
Functions
canonicalize.c File Reference
#include <assert.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <limits.h>
#include <sys/param.h>
#include <sys/stat.h>
#include <errno.h>
#include <stddef.h>
#include <shlib-compat.h>

Go to the source code of this file.

Functions

char * __realpath (const char *name, char *resolved)
 versioned_symbol (libc, __realpath, realpath, GLIBC_2_3)
char * __canonicalize_file_name (const char *name)

Function Documentation

char* __canonicalize_file_name ( const char *  name)

Definition at line 243 of file canonicalize.c.

{
  return __realpath (name, NULL);
}

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char* __realpath ( const char *  name,
char *  resolved 
)

Definition at line 44 of file canonicalize.c.

{
  char *rpath, *dest, *extra_buf = NULL;
  const char *start, *end, *rpath_limit;
  long int path_max;
  int num_links = 0;

  if (name == NULL)
    {
      /* As per Single Unix Specification V2 we must return an error if
        either parameter is a null pointer.  We extend this to allow
        the RESOLVED parameter to be NULL in case the we are expected to
        allocate the room for the return value.  */
      __set_errno (EINVAL);
      return NULL;
    }

  if (name[0] == '\0')
    {
      /* As per Single Unix Specification V2 we must return an error if
        the name argument points to an empty string.  */
      __set_errno (ENOENT);
      return NULL;
    }

#ifdef PATH_MAX
  path_max = PATH_MAX;
#else
  path_max = pathconf (name, _PC_PATH_MAX);
  if (path_max <= 0)
    path_max = 1024;
#endif

  if (resolved == NULL)
    {
      rpath = malloc (path_max);
      if (rpath == NULL)
       return NULL;
    }
  else
    rpath = resolved;
  rpath_limit = rpath + path_max;

  if (name[0] != '/')
    {
      if (!__getcwd (rpath, path_max))
       {
         rpath[0] = '\0';
         goto error;
       }
      dest = __rawmemchr (rpath, '\0');
    }
  else
    {
      rpath[0] = '/';
      dest = rpath + 1;
    }

  for (start = end = name; *start; start = end)
    {
      struct stat64 st;
      int n;

      /* Skip sequence of multiple path-separators.  */
      while (*start == '/')
       ++start;

      /* Find end of path component.  */
      for (end = start; *end && *end != '/'; ++end)
       /* Nothing.  */;

      if (end - start == 0)
       break;
      else if (end - start == 1 && start[0] == '.')
       /* nothing */;
      else if (end - start == 2 && start[0] == '.' && start[1] == '.')
       {
         /* Back up to previous component, ignore if at root already.  */
         if (dest > rpath + 1)
           while ((--dest)[-1] != '/');
       }
      else
       {
         size_t new_size;

         if (dest[-1] != '/')
           *dest++ = '/';

         if (dest + (end - start) >= rpath_limit)
           {
             ptrdiff_t dest_offset = dest - rpath;
             char *new_rpath;

             if (resolved)
              {
                __set_errno (ENAMETOOLONG);
                if (dest > rpath + 1)
                  dest--;
                *dest = '\0';
                goto error;
              }
             new_size = rpath_limit - rpath;
             if (end - start + 1 > path_max)
              new_size += end - start + 1;
             else
              new_size += path_max;
             new_rpath = (char *) realloc (rpath, new_size);
             if (new_rpath == NULL)
              goto error;
             rpath = new_rpath;
             rpath_limit = rpath + new_size;

             dest = rpath + dest_offset;
           }

         dest = __mempcpy (dest, start, end - start);
         *dest = '\0';

         if (__lxstat64 (_STAT_VER, rpath, &st) < 0)
           goto error;

         if (S_ISLNK (st.st_mode))
           {
             char *buf = __alloca (path_max);
             size_t len;

             if (++num_links > MAXSYMLINKS)
              {
                __set_errno (ELOOP);
                goto error;
              }

             n = __readlink (rpath, buf, path_max - 1);
             if (n < 0)
              goto error;
             buf[n] = '\0';

             if (!extra_buf)
              extra_buf = __alloca (path_max);

             len = strlen (end);
             if ((long int) (n + len) >= path_max)
              {
                __set_errno (ENAMETOOLONG);
                goto error;
              }

             /* Careful here, end may be a pointer into extra_buf... */
             memmove (&extra_buf[n], end, len + 1);
             name = end = memcpy (extra_buf, buf, n);

             if (buf[0] == '/')
              dest = rpath + 1;    /* It's an absolute symlink */
             else
              /* Back up to previous component, ignore if at root already: */
              if (dest > rpath + 1)
                while ((--dest)[-1] != '/');
           }
         else if (!S_ISDIR (st.st_mode) && *end != '\0')
           {
             __set_errno (ENOTDIR);
             goto error;
           }
       }
    }
  if (dest > rpath + 1 && dest[-1] == '/')
    --dest;
  *dest = '\0';

  assert (resolved == NULL || resolved == rpath);
  return rpath;

error:
  assert (resolved == NULL || resolved == rpath);
  if (resolved == NULL)
    free (rpath);
  return NULL;
}

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versioned_symbol ( libc  ,
__realpath  ,
realpath  ,
GLIBC_2_3   
)