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/* $OpenBSD: backupfile.c,v 1.21 2013/11/26 13:19:07 deraadt Exp $ */ |
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/* |
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* backupfile.c -- make Emacs style backup file names Copyright (C) 1990 Free |
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* Software Foundation, Inc. |
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* |
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* This program is free software; you can redistribute it and/or modify it |
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* without restriction. |
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* |
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* This program is distributed in the hope that it will be useful, but WITHOUT |
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* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or |
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* FITNESS FOR A PARTICULAR PURPOSE. |
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*/ |
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/* |
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* David MacKenzie <djm@ai.mit.edu>. Some algorithms adapted from GNU Emacs. |
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*/ |
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#include <ctype.h> |
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#include <dirent.h> |
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#include <libgen.h> |
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#include <stdio.h> |
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#include <stdlib.h> |
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#include <string.h> |
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#include <unistd.h> |
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#include "backupfile.h" |
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#define ISDIGIT(c) (isascii (c) && isdigit (c)) |
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/* Which type of backup file names are generated. */ |
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enum backup_type backup_type = none; |
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/* |
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* The extension added to file names to produce a simple (as opposed to |
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* numbered) backup file name. |
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*/ |
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char *simple_backup_suffix = "~"; |
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static char *concat(const char *, const char *); |
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static char *make_version_name(const char *, int); |
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static int max_backup_version(const char *, const char *); |
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static int version_number(const char *, const char *, size_t); |
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static int argmatch(const char *, const char **); |
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static void invalid_arg(const char *, const char *, int); |
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/* |
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* Return the name of the new backup file for file FILE, allocated with |
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* malloc. Return 0 if out of memory. FILE must not end with a '/' unless it |
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* is the root directory. Do not call this function if backup_type == none. |
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*/ |
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char * |
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find_backup_file_name(const char *file) |
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{ |
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char *dir, *base_versions; |
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int highest_backup; |
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✗✓ |
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if (backup_type == simple) |
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return concat(file, simple_backup_suffix); |
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base_versions = concat(basename(file), ".~"); |
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✗✓ |
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if (base_versions == NULL) |
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return NULL; |
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dir = dirname(file); |
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✗✓ |
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if (dir == NULL) { |
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free(base_versions); |
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return NULL; |
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} |
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highest_backup = max_backup_version(base_versions, dir); |
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free(base_versions); |
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✓✗ |
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if (backup_type == numbered_existing && highest_backup == 0) |
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return concat(file, simple_backup_suffix); |
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return make_version_name(file, highest_backup + 1); |
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} |
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/* |
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* Return the number of the highest-numbered backup file for file FILE in |
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* directory DIR. If there are no numbered backups of FILE in DIR, or an |
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* error occurs reading DIR, return 0. FILE should already have ".~" appended |
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* to it. |
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*/ |
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static int |
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max_backup_version(const char *file, const char *dir) |
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{ |
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DIR *dirp; |
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struct dirent *dp; |
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int highest_version, this_version; |
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size_t file_name_length; |
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dirp = opendir(dir); |
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✗✓ |
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if (dirp == NULL) |
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return 0; |
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highest_version = 0; |
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file_name_length = strlen(file); |
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✓✓ |
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while ((dp = readdir(dirp)) != NULL) { |
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✓✓ |
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if (dp->d_namlen <= file_name_length) |
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continue; |
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this_version = version_number(file, dp->d_name, file_name_length); |
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✓✗ |
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if (this_version > highest_version) |
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highest_version = this_version; |
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} |
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closedir(dirp); |
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return highest_version; |
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} |
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/* |
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* Return a string, allocated with malloc, containing "FILE.~VERSION~". |
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* Return 0 if out of memory. |
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*/ |
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static char * |
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make_version_name(const char *file, int version) |
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{ |
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char *backup_name; |
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if (asprintf(&backup_name, "%s.~%d~", file, version) == -1) |
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return NULL; |
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return backup_name; |
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} |
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/* |
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* If BACKUP is a numbered backup of BASE, return its version number; |
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* otherwise return 0. BASE_LENGTH is the length of BASE. BASE should |
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* already have ".~" appended to it. |
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*/ |
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static int |
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version_number(const char *base, const char *backup, size_t base_length) |
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{ |
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int version; |
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const char *p; |
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version = 0; |
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✗✓✗✗
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if (!strncmp(base, backup, base_length) && |
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ISDIGIT((unsigned char)backup[base_length])) { |
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for (p = &backup[base_length]; ISDIGIT((unsigned char)*p); ++p) |
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version = version * 10 + *p - '0'; |
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if (p[0] != '~' || p[1]) |
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version = 0; |
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} |
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return version; |
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} |
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/* |
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* Return the newly-allocated concatenation of STR1 and STR2. If out of |
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* memory, return 0. |
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*/ |
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static char * |
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concat(const char *str1, const char *str2) |
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{ |
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char *newstr; |
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✗✓ |
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if (asprintf(&newstr, "%s%s", str1, str2) == -1) |
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return NULL; |
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return newstr; |
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} |
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/* |
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* If ARG is an unambiguous match for an element of the null-terminated array |
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* OPTLIST, return the index in OPTLIST of the matched element, else -1 if it |
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* does not match any element or -2 if it is ambiguous (is a prefix of more |
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* than one element). |
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*/ |
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static int |
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argmatch(const char *arg, const char **optlist) |
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{ |
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int i; /* Temporary index in OPTLIST. */ |
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size_t arglen; /* Length of ARG. */ |
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int matchind = -1; /* Index of first nonexact match. */ |
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int ambiguous = 0; /* If nonzero, multiple nonexact match(es). */ |
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arglen = strlen(arg); |
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/* Test all elements for either exact match or abbreviated matches. */ |
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for (i = 0; optlist[i]; i++) { |
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if (!strncmp(optlist[i], arg, arglen)) { |
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if (strlen(optlist[i]) == arglen) |
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/* Exact match found. */ |
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return i; |
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else if (matchind == -1) |
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/* First nonexact match found. */ |
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matchind = i; |
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else |
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/* Second nonexact match found. */ |
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ambiguous = 1; |
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} |
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} |
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if (ambiguous) |
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return -2; |
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else |
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return matchind; |
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} |
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/* |
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* Error reporting for argmatch. KIND is a description of the type of entity |
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* that was being matched. VALUE is the invalid value that was given. PROBLEM |
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* is the return value from argmatch. |
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*/ |
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static void |
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invalid_arg(const char *kind, const char *value, int problem) |
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{ |
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fprintf(stderr, "patch: "); |
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if (problem == -1) |
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fprintf(stderr, "invalid"); |
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else /* Assume -2. */ |
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fprintf(stderr, "ambiguous"); |
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fprintf(stderr, " %s `%s'\n", kind, value); |
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} |
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static const char *backup_args[] = { |
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"never", "simple", "nil", "existing", "t", "numbered", 0 |
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}; |
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static enum backup_type backup_types[] = { |
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simple, simple, numbered_existing, |
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numbered_existing, numbered, numbered |
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}; |
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/* |
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* Return the type of backup indicated by VERSION. Unique abbreviations are |
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* accepted. |
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*/ |
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enum backup_type |
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get_version(const char *version) |
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{ |
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int i; |
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if (version == NULL || *version == '\0') |
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return numbered_existing; |
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i = argmatch(version, backup_args); |
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if (i >= 0) |
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return backup_types[i]; |
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invalid_arg("version control type", version, i); |
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exit(2); |
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} |