/* Create /proc/self/fd-related names for subfiles of open directories.
- Copyright (C) 2006, 2009-2010 Free Software Foundation, Inc.
+ Copyright (C) 2006, 2009-2012 Free Software Foundation, Inc.
This program is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
#include <fcntl.h>
#include <stdio.h>
+#include <stdlib.h>
#include <string.h>
#include <unistd.h>
-#include "dirname.h"
#include "intprops.h"
-#include "same-inode.h"
-#include "xalloc.h"
/* The results of open() in this file are not used with fchdir,
and we do not leak fds to any single-threaded code that could use stdio,
/* Set BUF to the expansion of PROC_SELF_FD_FORMAT, using FD and FILE
respectively for %d and %s. If successful, return BUF if the
result fits in BUF, dynamically allocated memory otherwise. But
- return NULL if /proc is not reliable. */
+ return NULL if /proc is not reliable, either because the operating
+ system support is lacking or because memory is low. */
char *
openat_proc_name (char buf[OPENAT_BUFFER_SIZE], int fd, char const *file)
{
problem is exhibited on code that built on Solaris 8 and
running on Solaris 10. */
- int proc_self_fd = open ("/proc/self/fd", O_RDONLY);
+ int proc_self_fd = open ("/proc/self/fd",
+ O_SEARCH | O_DIRECTORY | O_NOCTTY | O_NONBLOCK);
if (proc_self_fd < 0)
proc_status = -1;
else
{
- struct stat proc_self_fd_dotdot_st;
- struct stat proc_self_st;
- char dotdot_buf[PROC_SELF_FD_NAME_SIZE_BOUND (sizeof ".." - 1)];
- sprintf (dotdot_buf, PROC_SELF_FD_FORMAT, proc_self_fd, "..");
- proc_status =
- ((stat (dotdot_buf, &proc_self_fd_dotdot_st) == 0
- && stat ("/proc/self", &proc_self_st) == 0
- && SAME_INODE (proc_self_fd_dotdot_st, proc_self_st))
- ? 1 : -1);
+ /* Detect whether /proc/self/fd/%i/../fd exists, where %i is the
+ number of a file descriptor open on /proc/self/fd. On Linux,
+ that name resolves to /proc/self/fd, which was opened above.
+ However, on Solaris, it may resolve to /proc/self/fd/fd, which
+ cannot exist, since all names in /proc/self/fd are numeric. */
+ char dotdot_buf[PROC_SELF_FD_NAME_SIZE_BOUND (sizeof "../fd" - 1)];
+ sprintf (dotdot_buf, PROC_SELF_FD_FORMAT, proc_self_fd, "../fd");
+ proc_status = access (dotdot_buf, F_OK) ? -1 : 1;
close (proc_self_fd);
}
}
else
{
size_t bufsize = PROC_SELF_FD_NAME_SIZE_BOUND (strlen (file));
- char *result = (bufsize < OPENAT_BUFFER_SIZE ? buf : xmalloc (bufsize));
+ char *result = buf;
+ if (OPENAT_BUFFER_SIZE < bufsize)
+ {
+ result = malloc (bufsize);
+ if (! result)
+ return NULL;
+ }
sprintf (result, PROC_SELF_FD_FORMAT, fd, file);
return result;
}