/* backupfile.c -- make Emacs style backup file names Copyright (C) 1990-1997, 1998, 1999 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; see the file COPYING. If not, write to the Free Software Foundation, 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. */ /* Written by David MacKenzie . Some algorithms adapted from GNU Emacs. */ #if HAVE_CONFIG_H # include #endif #include #include #include #include #if HAVE_STRING_H # include #else # include #endif #if HAVE_DIRENT_H # include # define NLENGTH(direct) strlen ((direct)->d_name) #else # define dirent direct # define NLENGTH(direct) ((size_t) (direct)->d_namlen) # if HAVE_SYS_NDIR_H # include # endif # if HAVE_SYS_DIR_H # include # endif # if HAVE_NDIR_H # include # endif #endif #if CLOSEDIR_VOID /* Fake a return value. */ # define CLOSEDIR(d) (closedir (d), 0) #else # define CLOSEDIR(d) closedir (d) #endif #if STDC_HEADERS # include #else char *malloc (); #endif #ifndef HAVE_DECL_GETENV char *getenv (); #endif char *base_name PARAMS ((char const *)); #if HAVE_DIRENT_H || HAVE_NDIR_H || HAVE_SYS_DIR_H || HAVE_SYS_NDIR_H # define HAVE_DIR 1 #else # define HAVE_DIR 0 #endif #if HAVE_LIMITS_H # include #endif #ifndef CHAR_BIT # define CHAR_BIT 8 #endif /* Upper bound on the string length of an integer converted to string. 302 / 1000 is ceil (log10 (2.0)). Subtract 1 for the sign bit; add 1 for integer division truncation; add 1 more for a minus sign. */ #define INT_STRLEN_BOUND(t) ((sizeof (t) * CHAR_BIT - 1) * 302 / 1000 + 2) /* ISDIGIT differs from isdigit, as follows: - Its arg may be any int or unsigned int; it need not be an unsigned char. - It's guaranteed to evaluate its argument exactly once. - It's typically faster. Posix 1003.2-1992 section 2.5.2.1 page 50 lines 1556-1558 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) (c) - '0' <= 9) #if D_INO_IN_DIRENT # define REAL_DIR_ENTRY(dp) ((dp)->d_ino != 0) #else # define REAL_DIR_ENTRY(dp) 1 #endif /* The extension added to file names to produce a simple (as opposed to numbered) backup file name. */ const char *simple_backup_suffix = "~"; static int max_backup_version PARAMS ((const char *, const char *)); static int version_number PARAMS ((const char *, const char *, size_t)); /* Return the name of the new backup file for file FILE, allocated with malloc. Return 0 if out of memory. FILE must not end with a '/' unless it is the root directory. Do not call this function if backup_type == none. */ char * find_backup_file_name (const char *file, enum backup_type backup_type) { size_t backup_suffix_size_max; size_t file_len = strlen (file); size_t numbered_suffix_size_max = INT_STRLEN_BOUND (int) + 4; char *s; const char *suffix = simple_backup_suffix; /* Allow room for simple or `.~N~' backups. */ backup_suffix_size_max = strlen (simple_backup_suffix) + 1; if (HAVE_DIR && backup_suffix_size_max < numbered_suffix_size_max) backup_suffix_size_max = numbered_suffix_size_max; s = malloc (file_len + backup_suffix_size_max + numbered_suffix_size_max); if (s) { strcpy (s, file); #if HAVE_DIR if (backup_type != simple) { int highest_backup; size_t dir_len = base_name (s) - s; strcpy (s + dir_len, "."); highest_backup = max_backup_version (file + dir_len, s); if (! (backup_type == numbered_existing && highest_backup == 0)) { char *numbered_suffix = s + (file_len + backup_suffix_size_max); sprintf (numbered_suffix, ".~%d~", highest_backup + 1); suffix = numbered_suffix; } strcpy (s, file); } #endif /* HAVE_DIR */ addext (s, suffix, '~'); } return s; } #if HAVE_DIR /* Return the number of the highest-numbered backup file for file FILE in directory DIR. If there are no numbered backups of FILE in DIR, or an error occurs reading DIR, return 0. */ static int max_backup_version (const char *file, const char *dir) { DIR *dirp; struct dirent *dp; int highest_version; int this_version; size_t file_name_length; dirp = opendir (dir); if (!dirp) return 0; highest_version = 0; file_name_length = strlen (file); while ((dp = readdir (dirp)) != 0) { if (!REAL_DIR_ENTRY (dp) || NLENGTH (dp) < file_name_length + 4) continue; this_version = version_number (file, dp->d_name, file_name_length); if (this_version > highest_version) highest_version = this_version; } if (CLOSEDIR (dirp)) return 0; return highest_version; } /* If BACKUP is a numbered backup of BASE, return its version number; otherwise return 0. BASE_LENGTH is the length of BASE. */ static int version_number (const char *base, const char *backup, size_t base_length) { int version; const char *p; version = 0; if (strncmp (base, backup, base_length) == 0 && backup[base_length] == '.' && backup[base_length + 1] == '~') { for (p = &backup[base_length + 2]; ISDIGIT (*p); ++p) version = version * 10 + *p - '0'; if (p[0] != '~' || p[1]) version = 0; } return version; } #endif /* HAVE_DIR */ static const char * const backup_args[] = { /* In a series of synonyms, present the most meaning full first, so that argmatch_valid be more readable. */ "none", "off", "simple", "never", "existing", "nil", "numbered", "t", 0 }; static const enum backup_type backup_types[] = { none, none, simple, simple, numbered_existing, numbered_existing, numbered, numbered }; /* Return the type of backup specified by VERSION. If VERSION is NULL or the empty string, return numbered_existing. If VERSION is invalid or ambiguous, fail with a diagnostic appropriate for the specified CONTEXT. Unambiguous abbreviations are accepted. */ enum backup_type get_version (const char *context, const char *version) { if (version == 0 || *version == 0) return numbered_existing; 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 (const char *context, const char *version) { if (version && *version) return get_version (context, version); else return get_version ("$VERSION_CONTROL", getenv ("VERSION_CONTROL")); }