+++ /dev/null
-/* backupfile.c -- make Emacs style backup file names
-
- Copyright (C) 1990, 1991, 1992, 1993, 1994, 1995, 1996, 1997, 1998,
- 1999, 2000, 2001, 2002, 2003, 2004, 2005, 2006 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 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
- 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, see <http://www.gnu.org/licenses/>. */
-
-/* Written by Paul Eggert and David MacKenzie.
- Some algorithms adapted from GNU Emacs. */
-
-#include <config.h>
-
-#include "backupfile.h"
-
-#include "argmatch.h"
-#include "dirname.h"
-#include "xalloc.h"
-
-#include <errno.h>
-#include <stdbool.h>
-#include <stdlib.h>
-#include <string.h>
-
-#include <limits.h>
-
-#include <unistd.h>
-
-#include <dirent.h>
-#ifndef _D_EXACT_NAMLEN
-# define _D_EXACT_NAMLEN(dp) strlen ((dp)->d_name)
-#endif
-#if D_INO_IN_DIRENT
-# define REAL_DIR_ENTRY(dp) ((dp)->d_ino != 0)
-#else
-# define REAL_DIR_ENTRY(dp) 1
-#endif
-
-#if ! (HAVE_PATHCONF && defined _PC_NAME_MAX)
-# define pathconf(file, option) (errno = -1)
-#endif
-
-#ifndef _POSIX_NAME_MAX
-# define _POSIX_NAME_MAX 14
-#endif
-#ifndef SIZE_MAX
-# define SIZE_MAX ((size_t) -1)
-#endif
-
-#if defined _XOPEN_NAME_MAX
-# define NAME_MAX_MINIMUM _XOPEN_NAME_MAX
-#else
-# define NAME_MAX_MINIMUM _POSIX_NAME_MAX
-#endif
-
-#ifndef HAVE_DOS_FILE_NAMES
-# define HAVE_DOS_FILE_NAMES 0
-#endif
-#ifndef HAVE_LONG_FILE_NAMES
-# define HAVE_LONG_FILE_NAMES 0
-#endif
-
-/* ISDIGIT differs from isdigit, as follows:
- - Its arg may be any int or unsigned int; it need not be an unsigned char
- or EOF.
- - It's typically faster.
- POSIX says that only '0' through '9' are digits. Prefer ISDIGIT to
- ISDIGIT unless it's important to use the locale's definition
- of `digit' even when the host does not conform to POSIX. */
-#define ISDIGIT(c) ((unsigned int) (c) - '0' <= 9)
-
-/* The results of opendir() in this file are not used with dirfd and fchdir,
- therefore save some unnecessary work in fchdir.c. */
-#undef opendir
-#undef closedir
-
-/* The extension added to file names to produce a simple (as opposed
- to numbered) backup file name. */
-char const *simple_backup_suffix = "~";
-
-
-/* If FILE (which was of length FILELEN before an extension was
- appended to it) is too long, replace the extension with the single
- char E. If the result is still too long, remove the char just
- before E. */
-
-static void
-check_extension (char *file, size_t filelen, char e)
-{
- char *base = last_component (file);
- size_t baselen = base_len (base);
- size_t baselen_max = HAVE_LONG_FILE_NAMES ? 255 : NAME_MAX_MINIMUM;
-
- if (HAVE_DOS_FILE_NAMES || NAME_MAX_MINIMUM < baselen)
- {
- /* The new base name is long enough to require a pathconf check. */
- long name_max;
-
- /* Temporarily modify the buffer into its parent directory name,
- invoke pathconf on the directory, and then restore the buffer. */
- char tmp[sizeof "."];
- memcpy (tmp, base, sizeof ".");
- strcpy (base, ".");
- errno = 0;
- name_max = pathconf (file, _PC_NAME_MAX);
- if (0 <= name_max || errno == 0)
- {
- long size = baselen_max = name_max;
- if (name_max != size)
- baselen_max = SIZE_MAX;
- }
- memcpy (base, tmp, sizeof ".");
- }
-
- if (HAVE_DOS_FILE_NAMES && baselen_max <= 12)
- {
- /* Live within DOS's 8.3 limit. */
- char *dot = strchr (base, '.');
- if (!dot)
- baselen_max = 8;
- else
- {
- char const *second_dot = strchr (dot + 1, '.');
- baselen_max = (second_dot
- ? second_dot - base
- : dot + 1 - base + 3);
- }
- }
-
- if (baselen_max < baselen)
- {
- baselen = file + filelen - base;
- if (baselen_max <= baselen)
- baselen = baselen_max - 1;
- base[baselen] = e;
- base[baselen + 1] = '\0';
- }
-}
-
-/* Returned values for NUMBERED_BACKUP. */
-
-enum numbered_backup_result
- {
- /* The new backup name is the same length as an existing backup
- name, so it's valid for that directory. */
- BACKUP_IS_SAME_LENGTH,
-
- /* Some backup names already exist, but the returned name is longer
- than any of them, and its length should be checked. */
- BACKUP_IS_LONGER,
-
- /* There are no existing backup names. The new name's length
- should be checked. */
- BACKUP_IS_NEW
- };
-
-/* *BUFFER contains a file name. Store into *BUFFER the next backup
- name for the named file, with a version number greater than all the
- existing numbered backups. Reallocate *BUFFER as necessary; its
- initial allocated size is BUFFER_SIZE, which must be at least 4
- bytes longer than the file name to make room for the initially
- appended ".~1". FILELEN is the length of the original file name.
- The returned value indicates what kind of backup was found. If an
- I/O or other read error occurs, use the highest backup number that
- was found. */
-
-static enum numbered_backup_result
-numbered_backup (char **buffer, size_t buffer_size, size_t filelen)
-{
- enum numbered_backup_result result = BACKUP_IS_NEW;
- DIR *dirp;
- struct dirent *dp;
- char *buf = *buffer;
- size_t versionlenmax = 1;
- char *base = last_component (buf);
- size_t base_offset = base - buf;
- size_t baselen = base_len (base);
-
- /* Temporarily modify the buffer into its parent directory name,
- open the directory, and then restore the buffer. */
- char tmp[sizeof "."];
- memcpy (tmp, base, sizeof ".");
- strcpy (base, ".");
- dirp = opendir (buf);
- memcpy (base, tmp, sizeof ".");
- strcpy (base + baselen, ".~1~");
-
- if (!dirp)
- return result;
-
- while ((dp = readdir (dirp)) != NULL)
- {
- char const *p;
- char *q;
- bool all_9s;
- size_t versionlen;
- size_t new_buflen;
-
- if (! REAL_DIR_ENTRY (dp) || _D_EXACT_NAMLEN (dp) < baselen + 4)
- continue;
-
- if (memcmp (buf + base_offset, dp->d_name, baselen + 2) != 0)
- continue;
-
- p = dp->d_name + baselen + 2;
-
- /* Check whether this file has a version number and if so,
- whether it is larger. Use string operations rather than
- integer arithmetic, to avoid problems with integer overflow. */
-
- if (! ('1' <= *p && *p <= '9'))
- continue;
- all_9s = (*p == '9');
- for (versionlen = 1; ISDIGIT (p[versionlen]); versionlen++)
- all_9s &= (p[versionlen] == '9');
-
- if (! (p[versionlen] == '~' && !p[versionlen + 1]
- && (versionlenmax < versionlen
- || (versionlenmax == versionlen
- && memcmp (buf + filelen + 2, p, versionlen) <= 0))))
- continue;
-
- /* This directory has the largest version number seen so far.
- Append this highest numbered extension to the file name,
- prepending '0' to the number if it is all 9s. */
-
- versionlenmax = all_9s + versionlen;
- result = (all_9s ? BACKUP_IS_LONGER : BACKUP_IS_SAME_LENGTH);
- new_buflen = filelen + 2 + versionlenmax + 1;
- if (buffer_size <= new_buflen)
- {
- buf = xnrealloc (buf, 2, new_buflen);
- buffer_size = new_buflen * 2;
- }
- q = buf + filelen;
- *q++ = '.';
- *q++ = '~';
- *q = '0';
- q += all_9s;
- memcpy (q, p, versionlen + 2);
-
- /* Add 1 to the version number. */
-
- q += versionlen;
- while (*--q == '9')
- *q = '0';
- ++*q;
- }
-
- closedir (dirp);
- *buffer = buf;
- return result;
-}
-
-/* Return the name of the new backup file for the existing file FILE,
- allocated with malloc. Report an error and fail if out of memory.
- Do not call this function if backup_type == no_backups. */
-
-char *
-find_backup_file_name (char const *file, enum backup_type backup_type)
-{
- size_t filelen = strlen (file);
- char *s;
- size_t ssize;
- bool simple = true;
-
- /* Allow room for simple or ".~N~" backups. The guess must be at
- least sizeof ".~1~", but otherwise will be adjusted as needed. */
- size_t simple_backup_suffix_size = strlen (simple_backup_suffix) + 1;
- size_t backup_suffix_size_guess = simple_backup_suffix_size;
- enum { GUESS = sizeof ".~12345~" };
- if (backup_suffix_size_guess < GUESS)
- backup_suffix_size_guess = GUESS;
-
- ssize = filelen + backup_suffix_size_guess + 1;
- s = xmalloc (ssize);
- memcpy (s, file, filelen + 1);
-
- if (backup_type != simple_backups)
- switch (numbered_backup (&s, ssize, filelen))
- {
- case BACKUP_IS_SAME_LENGTH:
- return s;
-
- case BACKUP_IS_LONGER:
- simple = false;
- break;
-
- case BACKUP_IS_NEW:
- simple = (backup_type == numbered_existing_backups);
- break;
- }
-
- if (simple)
- memcpy (s + filelen, simple_backup_suffix, simple_backup_suffix_size);
- check_extension (s, filelen, '~');
- return s;
-}
-
-static char const * const backup_args[] =
-{
- /* In a series of synonyms, present the most meaningful first, so
- that argmatch_valid be more readable. */
- "none", "off",
- "simple", "never",
- "existing", "nil",
- "numbered", "t",
- NULL
-};
-
-static const enum backup_type backup_types[] =
-{
- no_backups, no_backups,
- simple_backups, simple_backups,
- numbered_existing_backups, numbered_existing_backups,
- numbered_backups, numbered_backups
-};
-
-/* Ensure that these two vectors have the same number of elements,
- not counting the final NULL in the first one. */
-ARGMATCH_VERIFY (backup_args, backup_types);
-
-/* Return the type of backup specified by VERSION.
- If VERSION is NULL or the empty string, return numbered_existing_backups.
- If VERSION is invalid or ambiguous, fail with a diagnostic appropriate
- for the specified CONTEXT. Unambiguous abbreviations are accepted. */
-
-enum backup_type
-get_version (char const *context, char const *version)
-{
- if (version == 0 || *version == 0)
- return numbered_existing_backups;
- else
- return XARGMATCH (context, version, backup_args, backup_types);
-}
-
-
-/* Return the type of backup specified by VERSION.
- If VERSION is NULL, use the value of the envvar VERSION_CONTROL.
- If the specified string is invalid or ambiguous, fail with a diagnostic
- appropriate for the specified CONTEXT.
- Unambiguous abbreviations are accepted. */
-
-enum backup_type
-xget_version (char const *context, char const *version)
-{
- if (version && *version)
- return get_version (context, version);
- else
- return get_version ("$VERSION_CONTROL", getenv ("VERSION_CONTROL"));
-}
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