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git://git.sv.gnu.org/coreutils.git
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133 lines
3.6 KiB
C
133 lines
3.6 KiB
C
/* Make a file's ancestor directories.
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Copyright (C) 2006 Free Software Foundation, Inc.
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This program is free software; you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation; either version 2, or (at your option)
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any later version.
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This program is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with this program; if not, write to the Free Software Foundation,
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Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA. */
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/* Written by Paul Eggert. */
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#ifdef HAVE_CONFIG_H
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# include <config.h>
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#endif
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#include "mkancesdirs.h"
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#include <errno.h>
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#include <sys/stat.h>
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#include "dirname.h"
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#include "stat-macros.h"
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/* Return 0 if FILE is a directory, otherwise -1 (setting errno). */
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static int
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test_dir (char const *file)
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{
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struct stat st;
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if (stat (file, &st) == 0)
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{
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if (S_ISDIR (st.st_mode))
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return 0;
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errno = ENOTDIR;
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}
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return -1;
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}
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/* Ensure that the ancestor directories of FILE exist, using an
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algorithm that should work even if two processes execute this
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function in parallel. Temporarily modify FILE by storing '\0'
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bytes into it, to access the ancestor directories.
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Create any ancestor directories that don't already exist, by
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invoking MAKE_DIR (ANCESTOR, MAKE_DIR_ARG). This function should
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return zero if successful, -1 (setting errno) otherwise.
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If successful, return 0 with FILE set back to its original value;
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otherwise, return -1 (setting errno), storing a '\0' into *FILE so
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that it names the ancestor directory that had problems. */
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int
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mkancesdirs (char *file,
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int (*make_dir) (char const *, void *),
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void *make_dir_arg)
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{
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/* This algorithm is O(N**2) but in typical practice the fancier
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O(N) algorithms are slower. */
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/* Address of the previous directory separator that follows an
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ordinary byte in a file name in the left-to-right scan, or NULL
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if no such separator precedes the current location P. */
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char *sep = NULL;
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char const *prefix_end = file + FILE_SYSTEM_PREFIX_LEN (file);
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char *p;
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char c;
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/* Search backward through FILE using mkdir to create the
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furthest-away ancestor that is needed. This loop isn't needed
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for correctness, but typically ancestors already exist so this
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loop speeds things up a bit.
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This loop runs a bit faster if errno initially contains an error
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number corresponding to a failed access to FILE. However, things
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work correctly regardless of errno's initial value. */
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for (p = last_component (file); prefix_end < p; p--)
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if (ISSLASH (*p) && ! ISSLASH (p[-1]))
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{
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*p = '\0';
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if (errno == ENOENT && make_dir (file, make_dir_arg) == 0)
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{
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*p = '/';
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break;
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}
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if (errno != ENOENT)
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{
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if (test_dir (file) == 0)
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{
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*p = '/';
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break;
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}
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if (errno != ENOENT)
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return -1;
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}
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*p = '/';
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}
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/* Scan forward through FILE, creating directories along the way.
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Try mkdir before stat, so that the procedure works even when two
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or more processes are executing it in parallel. */
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while ((c = *p++))
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if (ISSLASH (*p))
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{
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if (! ISSLASH (c))
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sep = p;
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}
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else if (ISSLASH (c) && *p && sep)
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{
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*sep = '\0';
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if (make_dir (file, make_dir_arg) != 0 && test_dir (file) != 0)
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return -1;
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*sep = '/';
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}
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return 0;
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}
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