+++ /dev/null
-/* provide a chdir function that tries not to fail due to ENAMETOOLONG
- Copyright (C) 2004 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
- the Free Software Foundation; either version 2, or (at your option)
- any later version.
-
- This program is distributed in the hope that it will be useful,
- but WITHOUT ANY WARRANTY; without even the implied warranty of
- MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
- 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, write to the Free Software Foundation,
- Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. */
-
-/* written by Jim Meyering */
-
-#include <config.h>
-
-#include "chdir.h"
-
-/* Disable the definition of chdir to rpl_chdir (from chdir.h) in this
- file. Otherwise, we'd get conflicting prototypes for rpl_chdir on
- most systems. */
-#undef chdir
-
-#include <stdlib.h>
-#include <stdbool.h>
-#include <string.h>
-#include <errno.h>
-#include <stdio.h>
-#include <assert.h>
-#include <limits.h>
-
-#include "mempcpy.h"
-#include "openat.h"
-
-#ifndef O_DIRECTORY
-# define O_DIRECTORY 0
-#endif
-
-#ifndef MIN
-# define MIN(a, b) ((a) < (b) ? (a) : (b))
-#endif
-
-#ifndef PATH_MAX
-# ifdef MAXPATHLEN
-# define PATH_MAX MAXPATHLEN
-# else
-# error "use this module only if your system defines PATH_MAX"
-# endif
-#endif
-
-/* FIXME: this use of `MIN' is our sole concession to arbitrary limitations.
- If, for some system, PATH_MAX is larger than 8191 and you call
- rpl_chdir with a directory name that is longer than PATH_MAX,
- yet that contains a single component that is more than 8191 bytes
- long, then this function will fail. */
-#define MAX_COMPONENT_LENGTH MIN (PATH_MAX - 1, 8 * 1024)
-
-struct cd_buf
-{
- /* FIXME maybe allocate this via malloc, rather than using the stack.
- But that would be the sole use of malloc. Is it worth it to
- let chdir fail due to a low-memory condition?
- But when using malloc, and assuming we remove the `concession'
- above, we'll still have to avoid allocating 2^31 bytes on
- systems that define PATH_MAX to very large number.
- Ideally, we'd allocate enough to deal with most names, and
- dynamically increase the buffer size only necessary. */
- char buffer[MAX_COMPONENT_LENGTH + 1];
- char *avail;
- int fd;
-};
-
-/* Like memchr, but return the number of bytes from MEM
- to the first occurrence of C thereafter. Search only
- LEN bytes. Return LEN if C is not found. */
-static inline size_t
-memchrcspn (char const *mem, int c, size_t len)
-{
- char const *found = memchr (mem, c, len);
- if (!found)
- return len;
-
- len = found - mem;
- return len;
-}
-
-static void
-cdb_init (struct cd_buf *cdb)
-{
- cdb->avail = cdb->buffer;
- cdb->fd = AT_FDCWD;
-}
-
-static inline bool
-cdb_empty (struct cd_buf const *cdb)
-{
- return cdb->avail == cdb->buffer;
-}
-
-static inline int
-cdb_fchdir (struct cd_buf const *cdb)
-{
- return fchdir (cdb->fd);
-}
-
-static int
-cdb_advance_fd (struct cd_buf *cdb, char const *dir)
-{
- int new_fd = openat (cdb->fd, dir, O_RDONLY | O_DIRECTORY);
- if (new_fd < 0)
- {
- new_fd = openat (cdb->fd, dir, O_WRONLY | O_DIRECTORY);
- if (new_fd < 0)
- return -1;
- }
-
- if (cdb->fd != AT_FDCWD)
- close (cdb->fd);
- cdb->fd = new_fd;
-
- return 0;
-}
-
-static int
-cdb_flush (struct cd_buf *cdb)
-{
- if (cdb_empty (cdb))
- return 0;
-
- cdb->avail[0] = '\0';
- if (cdb_advance_fd (cdb, cdb->buffer) != 0)
- return -1;
-
- cdb->avail = cdb->buffer;
-
- return 0;
-}
-
-static void
-cdb_free (struct cd_buf *cdb)
-{
- if (0 <= cdb->fd && close (cdb->fd) != 0)
- abort ();
-}
-
-static int
-cdb_append (struct cd_buf *cdb, char const *s, size_t len)
-{
- char const *end = cdb->buffer + sizeof cdb->buffer;
-
- /* Insert a slash separator if there is a preceding byte
- and it's not a slash. */
- bool need_slash = (cdb->buffer < cdb->avail && cdb->avail[-1] != '/');
- size_t n_free;
-
- if (sizeof cdb->buffer < len + 1)
- {
- /* This single component is too long. */
- errno = ENAMETOOLONG;
- return -1;
- }
-
- /* See if there's enough room for the `/', the new component and
- a trailing NUL. */
- n_free = end - cdb->avail;
- if (n_free < need_slash + len + 1)
- {
- if (cdb_flush (cdb) != 0)
- return -1;
- need_slash = false;
- }
-
- if (need_slash)
- *(cdb->avail)++ = '/';
-
- cdb->avail = mempcpy (cdb->avail, s, len);
- return 0;
-}
-
-/* This is a wrapper around chdir that works even on PATH_MAX-limited
- systems. It handles an arbitrarily long directory name by extracting
- and processing manageable portions of the name. On systems without
- the openat syscall, this means changing the working directory to
- more and more `distant' points along the long directory name and
- then restoring the working directory.
- If any of those attempts to change or restore the working directory
- fails, this function exits nonzero.
-
- Note that this function may still fail with errno == ENAMETOOLONG,
- but only if the specified directory name contains a component that
- is long enough to provoke such a failure all by itself (e.g. if the
- component is longer than PATH_MAX on systems that define PATH_MAX). */
-
-int
-rpl_chdir (char const *dir)
-{
- int e = chdir (dir);
- if (e == 0 || errno != ENAMETOOLONG)
- return e;
-
- {
- size_t len = strlen (dir);
- char const *dir_end = dir + len;
- char const *d;
- struct cd_buf cdb;
-
- cdb_init (&cdb);
-
- /* If DIR is the empty string, then the chdir above
- must have failed and set errno to ENOENT. */
- assert (0 < len);
-
- if (*dir == '/')
- {
- /* Names starting with exactly two slashes followed by at least
- one non-slash are special --
- for example, in some environments //Hostname/file may
- denote a file on a different host.
- Preserve those two leading slashes. Treat all other
- sequences of slashes like a single one. */
- if (3 <= len && dir[1] == '/' && dir[2] != '/')
- {
- size_t name_len = 1 + strcspn (dir + 3, "/");
- if (cdb_append (&cdb, dir, 2 + name_len) != 0)
- goto Fail;
- /* Advance D to next slash or to end of string. */
- d = dir + 2 + name_len;
- assert (*d == '/' || *d == '\0');
- }
- else
- {
- if (cdb_append (&cdb, "/", 1) != 0)
- goto Fail;
- d = dir + 1;
- }
- }
- else
- {
- d = dir;
- }
-
- while (1)
- {
- /* Skip any slashes to find start of next component --
- or the end of DIR. */
- char const *start = d + strspn (d, "/");
- if (*start == '\0')
- {
- if (cdb_flush (&cdb) != 0)
- goto Fail;
- break;
- }
- /* If the remaining portion is no longer than PATH_MAX, then
- flush anything that is buffered and do the rest in one chunk. */
- if (dir_end - start <= PATH_MAX)
- {
- if (cdb_flush (&cdb) != 0
- || cdb_advance_fd (&cdb, start) != 0)
- goto Fail;
- break;
- }
-
- len = memchrcspn (start, '/', dir_end - start);
- assert (len == strcspn (start, "/"));
- d = start + len;
- if (cdb_append (&cdb, start, len) != 0)
- goto Fail;
- }
-
- if (cdb_fchdir (&cdb) != 0)
- goto Fail;
-
- cdb_free (&cdb);
- return 0;
-
- Fail:
- {
- int saved_errno = errno;
- cdb_free (&cdb);
- errno = saved_errno;
- return -1;
- }
- }
-}
-
-#if TEST_CHDIR
-
-# include <stdio.h>
-# include "closeout.h"
-# include "error.h"
-
-char *program_name;
-
-int
-main (int argc, char *argv[])
-{
- char *line = NULL;
- size_t n = 0;
- int len;
-
- program_name = argv[0];
- atexit (close_stdout);
-
- len = getline (&line, &n, stdin);
- if (len < 0)
- {
- int saved_errno = errno;
- if (feof (stdin))
- exit (0);
-
- error (EXIT_FAILURE, saved_errno,
- "reading standard input");
- }
- else if (len == 0)
- exit (0);
-
- if (line[len-1] == '\n')
- line[len-1] = '\0';
-
- if (rpl_chdir (line) != 0)
- error (EXIT_FAILURE, errno,
- "chdir failed: %s", line);
-
- {
- /* Using `pwd' here makes sense only if it is a robust implementation,
- like the one in coreutils after the 2004-04-19 changes. */
- char const *cmd = "pwd";
- execlp (cmd, (char *) NULL);
- error (EXIT_FAILURE, errno, "%s", cmd);
- }
-
- /* not reached */
- abort ();
-}
-#endif
-
-/*
-Local Variables:
-compile-command: "gcc -DTEST_CHDIR=1 -DHAVE_CONFIG_H -I.. -g -O -W -Wall chdir.c libfetish.a"
-End:
-*/
+++ /dev/null
-/* provide a chdir function that tries not to fail due to ENAMETOOLONG
- Copyright (C) 2004 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
- the Free Software Foundation; either version 2, or (at your option)
- any later version.
-
- This program is distributed in the hope that it will be useful,
- but WITHOUT ANY WARRANTY; without even the implied warranty of
- MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
- 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, write to the Free Software Foundation,
- Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. */
-
-/* Written by Jim Meyering. */
-
-/* Include the headers that might declare chdir so that they will not
- cause confusion if included after this file. */
-
-#include <unistd.h>
-
-/* If necessary, systematically rename identifiers so that they do not
- collide with the system function. Renaming avoids problems with
- some compilers and linkers. */
-
-#ifdef __CHDIR_PREFIX
-# undef chdir
-# define __CHDIR_CONCAT(x, y) x ## y
-# define __CHDIR_XCONCAT(x, y) __CHDIR_CONCAT (x, y)
-# define __CHDIR_ID(y) __CHDIR_XCONCAT (__CHDIR_PREFIX, y)
-# define chdir __CHDIR_ID (chdir)
-int chdir (char const *dir);
-#endif
projects / thirdparty / coreutils.git / commitdiff
