/* Make a file's ancestor directories.
- Copyright (C) 2006 Free Software Foundation, Inc.
+ Copyright (C) 2006, 2009-2013 Free Software Foundation, Inc.
- This program is free software; you can redistribute it and/or modify
+ 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.
+ the Free Software Foundation; either version 3 of the License, 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
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., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA. */
+ along with this program. If not, see <http://www.gnu.org/licenses/>. */
/* Written by Paul Eggert. */
-#ifdef HAVE_CONFIG_H
-# include <config.h>
-#endif
+#include <config.h>
#include "mkancesdirs.h"
-#include <errno.h>
+#include <sys/types.h>
#include <sys/stat.h>
+#include <fcntl.h>
-#include "dirname.h"
-#include "stat-macros.h"
-
-/* Return 0 if FILE is a directory, otherwise -1 (setting errno). */
+#include <errno.h>
+#include <unistd.h>
-static int
-test_dir (char const *file)
-{
- struct stat st;
- if (stat (file, &st) == 0)
- {
- if (S_ISDIR (st.st_mode))
- return 0;
- errno = ENOTDIR;
- }
- return -1;
-}
+#include "dirname.h"
+#include "savewd.h"
/* Ensure that the ancestor directories of FILE exist, using an
algorithm that should work even if two processes execute this
- function in parallel. Temporarily modify FILE by storing '\0'
- bytes into it, to access the ancestor directories.
-
- Create any ancestor directories that don't already exist, by
- invoking MAKE_DIR (ANCESTOR, MAKE_DIR_ARG). This function should
- return zero if successful, -1 (setting errno) otherwise.
+ function in parallel. Modify FILE as necessary to access the
+ ancestor directories, but restore FILE to an equivalent value
+ if successful.
- If successful, return 0 with FILE set back to its original value;
- otherwise, return -1 (setting errno), storing a '\0' into *FILE so
- that it names the ancestor directory that had problems. */
+ WD points to the working directory, using the conventions of
+ savewd.
-int
-mkancesdirs (char *file,
- int (*make_dir) (char const *, void *),
- void *make_dir_arg)
+ Create any ancestor directories that don't already exist, by
+ invoking MAKE_DIR (FILE, COMPONENT, MAKE_DIR_ARG). This function
+ should return 0 if successful and the resulting directory is
+ readable, 1 if successful but the resulting directory might not be
+ readable, -1 (setting errno) otherwise. If COMPONENT is relative,
+ it is relative to the temporary working directory, which may differ
+ from *WD.
+
+ Ordinarily MAKE_DIR is executed with the working directory changed
+ to reflect the already-made prefix, and mkancesdirs returns with
+ the working directory changed a prefix of FILE. However, if the
+ initial working directory cannot be saved in a file descriptor,
+ MAKE_DIR is invoked in a subprocess and this function returns in
+ both the parent and child process, so the caller should not assume
+ any changed state survives other than the EXITMAX component of WD,
+ and the caller should take care that the parent does not attempt to
+ do the work that the child is doing.
+
+ If successful and if this process can go ahead and create FILE,
+ return the length of the prefix of FILE that has already been made.
+ If successful so far but a child process is doing the actual work,
+ return -2. If unsuccessful, return -1 and set errno. */
+
+ptrdiff_t
+mkancesdirs (char *file, struct savewd *wd,
+ int (*make_dir) (char const *, char const *, void *),
+ void *make_dir_arg)
{
- /* This algorithm is O(N**2) but in typical practice the fancier
- O(N) algorithms are slower. */
-
/* Address of the previous directory separator that follows an
ordinary byte in a file name in the left-to-right scan, or NULL
if no such separator precedes the current location P. */
char *sep = NULL;
- char const *prefix_end = file + FILE_SYSTEM_PREFIX_LEN (file);
- char *p;
- char c;
-
- /* Search backward through FILE using mkdir to create the
- furthest-away ancestor that is needed. This loop isn't needed
- for correctness, but typically ancestors already exist so this
- loop speeds things up a bit.
-
- This loop runs a bit faster if errno initially contains an error
- number corresponding to a failed access to FILE. However, things
- work correctly regardless of errno's initial value. */
+ /* Address of the leftmost file name component that has not yet
+ been processed. */
+ char *component = file;
- for (p = last_component (file); prefix_end < p; p--)
- if (ISSLASH (*p) && ! ISSLASH (p[-1]))
- {
- *p = '\0';
-
- if (errno == ENOENT && make_dir (file, make_dir_arg) == 0)
- {
- *p = '/';
- break;
- }
-
- if (errno != ENOENT)
- {
- if (test_dir (file) == 0)
- {
- *p = '/';
- break;
- }
- if (errno != ENOENT)
- return -1;
- }
-
- *p = '/';
- }
+ char *p = file + FILE_SYSTEM_PREFIX_LEN (file);
+ char c;
+ bool made_dir = false;
- /* Scan forward through FILE, creating directories along the way.
- Try mkdir before stat, so that the procedure works even when two
- or more processes are executing it in parallel. */
+ /* Scan forward through FILE, creating and chdiring into directories
+ along the way. Try MAKE_DIR before chdir, so that the procedure
+ works even when two or more processes are executing it in
+ parallel. Isolate each file name component by having COMPONENT
+ point to its start and SEP point just after its end. */
while ((c = *p++))
if (ISSLASH (*p))
{
- if (! ISSLASH (c))
- sep = p;
+ if (! ISSLASH (c))
+ sep = p;
}
else if (ISSLASH (c) && *p && sep)
{
- *sep = '\0';
- if (make_dir (file, make_dir_arg) != 0 && test_dir (file) != 0)
- return -1;
- *sep = '/';
+ /* Don't bother to make or test for "." since it does not
+ affect the algorithm. */
+ if (! (sep - component == 1 && component[0] == '.'))
+ {
+ int make_dir_errno = 0;
+ int savewd_chdir_options = 0;
+ int chdir_result;
+
+ /* Temporarily modify FILE to isolate this file name
+ component. */
+ *sep = '\0';
+
+ /* Invoke MAKE_DIR on this component, except don't bother
+ with ".." since it must exist if its "parent" does. */
+ if (sep - component == 2
+ && component[0] == '.' && component[1] == '.')
+ made_dir = false;
+ else
+ switch (make_dir (file, component, make_dir_arg))
+ {
+ case -1:
+ make_dir_errno = errno;
+ break;
+
+ case 0:
+ savewd_chdir_options |= SAVEWD_CHDIR_READABLE;
+ /* Fall through. */
+ case 1:
+ made_dir = true;
+ break;
+ }
+
+ if (made_dir)
+ savewd_chdir_options |= SAVEWD_CHDIR_NOFOLLOW;
+
+ chdir_result =
+ savewd_chdir (wd, component, savewd_chdir_options, NULL);
+
+ /* Undo the temporary modification to FILE, unless there
+ was a failure. */
+ if (chdir_result != -1)
+ *sep = '/';
+
+ if (chdir_result != 0)
+ {
+ if (make_dir_errno != 0 && errno == ENOENT)
+ errno = make_dir_errno;
+ return chdir_result;
+ }
+ }
+
+ component = p;
}
-
- return 0;
+ return component - file;
}
projects / gnulib.git / blobdiff