/* Create /proc/self/fd-related names for subfiles of open directories.
- Copyright (C) 2006, 2009-2010 Free Software Foundation, Inc.
+ Copyright (C) 2006, 2009-2018 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
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
- along with this program. If not, see <http://www.gnu.org/licenses/>. */
+ along with this program. If not, see <https://www.gnu.org/licenses/>. */
/* Written by Paul Eggert. */
#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,
- therefore save some unnecessary work in fchdir.c.
- FIXME - if the kernel ever adds support for multi-thread safety for
- avoiding standard fds, then we should use open_safer. */
-#undef open
-#undef close
-
-#define PROC_SELF_FD_FORMAT "/proc/self/fd/%d/%s"
-
-#define PROC_SELF_FD_NAME_SIZE_BOUND(len) \
- (sizeof PROC_SELF_FD_FORMAT - sizeof "%d%s" \
- + INT_STRLEN_BOUND (int) + (len) + 1)
+#ifdef __KLIBC__
+# include <InnoTekLIBC/backend.h>
+#endif
+#include "intprops.h"
-/* 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. */
+/* Set BUF to the name of the subfile of the directory identified by
+ FD, where the subfile is named FILE. If successful, return BUF if
+ the result fits in BUF, dynamically allocated memory otherwise.
+ Return NULL (setting errno) on error. */
char *
openat_proc_name (char buf[OPENAT_BUFFER_SIZE], int fd, char const *file)
{
- static int proc_status = 0;
+ char *result = buf;
+ int dirlen;
/* Make sure the caller gets ENOENT when appropriate. */
if (!*file)
return buf;
}
- if (! proc_status)
- {
- /* Set PROC_STATUS to a positive value if /proc/self/fd is
- reliable, and a negative value otherwise. Solaris 10
- /proc/self/fd mishandles "..", and any file name might expand
- to ".." after symbolic link expansion, so avoid /proc/self/fd
- if it mishandles "..". Solaris 10 has openat, but this
- 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);
- 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);
- close (proc_self_fd);
- }
- }
-
- if (proc_status < 0)
- return NULL;
- else
- {
- size_t bufsize = PROC_SELF_FD_NAME_SIZE_BOUND (strlen (file));
- char *result = (bufsize < OPENAT_BUFFER_SIZE ? buf : xmalloc (bufsize));
- sprintf (result, PROC_SELF_FD_FORMAT, fd, file);
- return result;
- }
+#ifndef __KLIBC__
+# define PROC_SELF_FD_FORMAT "/proc/self/fd/%d/"
+ {
+ enum {
+ PROC_SELF_FD_DIR_SIZE_BOUND
+ = (sizeof PROC_SELF_FD_FORMAT - (sizeof "%d" - 1)
+ + INT_STRLEN_BOUND (int))
+ };
+
+ static int proc_status = 0;
+ if (! proc_status)
+ {
+ /* Set PROC_STATUS to a positive value if /proc/self/fd is
+ reliable, and a negative value otherwise. Solaris 10
+ /proc/self/fd mishandles "..", and any file name might expand
+ to ".." after symbolic link expansion, so avoid /proc/self/fd
+ if it mishandles "..". Solaris 10 has openat, but this
+ problem is exhibited on code that built on Solaris 8 and
+ running on Solaris 10. */
+
+ 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
+ {
+ /* 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_DIR_SIZE_BOUND + sizeof "../fd" - 1];
+ sprintf (dotdot_buf, PROC_SELF_FD_FORMAT "../fd", proc_self_fd);
+ proc_status = access (dotdot_buf, F_OK) ? -1 : 1;
+ close (proc_self_fd);
+ }
+ }
+
+ if (proc_status < 0)
+ return NULL;
+ else
+ {
+ size_t bufsize = PROC_SELF_FD_DIR_SIZE_BOUND + strlen (file);
+ if (OPENAT_BUFFER_SIZE < bufsize)
+ {
+ result = malloc (bufsize);
+ if (! result)
+ return NULL;
+ }
+
+ dirlen = sprintf (result, PROC_SELF_FD_FORMAT, fd);
+ }
+ }
+#else
+ /* OS/2 kLIBC provides a function to retrieve a path from a fd. */
+ {
+ char dir[_MAX_PATH];
+ size_t bufsize;
+
+ if (__libc_Back_ioFHToPath (fd, dir, sizeof dir))
+ return NULL;
+
+ dirlen = strlen (dir);
+ bufsize = dirlen + 1 + strlen (file) + 1; /* 1 for '/', 1 for null */
+ if (OPENAT_BUFFER_SIZE < bufsize)
+ {
+ result = malloc (bufsize);
+ if (! result)
+ return NULL;
+ }
+
+ strcpy (result, dir);
+ result[dirlen++] = '/';
+ }
+#endif
+
+ strcpy (result + dirlen, file);
+ return result;
}
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