commands/patch/backupfile.c

   1 /*
   2  * $OpenBSD: backupfile.c,v 1.19 2006/03/11 19:41:30 otto Exp $
   3  * $DragonFly: src/usr.bin/patch/backupfile.c,v 1.5 2008/08/11 00:05:06 joerg Exp $
   4  * $NetBSD: backupfile.c,v 1.14 2008/09/19 18:33:34 joerg Exp $
   5  */
   6
   7 /*
   8  * backupfile.c -- make Emacs style backup file names
   9  *
  10  * Copyright (C) 1990 Free Software Foundation, Inc.
  11  *
  12  * This program is free software; you can redistribute it and/or modify it
  13  * without restriction.
  14  *
  15  * This program is distributed in the hope that it will be useful, but WITHOUT
  16  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  17  * FITNESS FOR A PARTICULAR PURPOSE.
  18  */
  19
  20 /*
  21  * David MacKenzie <djm@ai.mit.edu>. Some algorithms adapted from GNU Emacs.
  22  */
  23
  24 #include <sys/cdefs.h>
  25
  26 #include <ctype.h>
  27 #include <dirent.h>
  28 #include <libgen.h>
  29 #include <stdio.h>
  30 #include <stdlib.h>
  31 #include <string.h>
  32 #include <unistd.h>
  33
  34 #include "backupfile.h"
  35
  36
  37 #define ISDIGIT(c) (isascii ((unsigned char)c) && isdigit ((unsigned char)c))
  38
  39 /* Which type of backup file names are generated. */
  40 enum backup_type backup_type = none;
  41
  42 /*
  43  * The extension added to file names to produce a simple (as opposed to
  44  * numbered) backup file name.
  45  */
  46 const char      *simple_backup_suffix = "~";
  47
  48 static char     *concat(const char *, const char *);
  49 static char     *make_version_name(const char *, int);
  50 static int      max_backup_version(const char *, const char *);
  51 static int      version_number(const char *, const char *, size_t);
  52 static int      argmatch(const char *, const char **);
  53 static void     invalid_arg(const char *, const char *, int);
  54
  55 /*
  56  * Return the name of the new backup file for file FILE, allocated with
  57  * malloc.  Return 0 if out of memory. FILE must not end with a '/' unless it
  58  * is the root directory. Do not call this function if backup_type == none.
  59  */
  60 char *
  61 find_backup_file_name(const char *file)
  62 {
  63         char    *dir, *base_versions, *tmp_file;
  64         int     highest_backup;
  65
  66         if (backup_type == simple)
  67                 return concat(file, simple_backup_suffix);
  68         tmp_file = strdup(file);
  69         if (tmp_file == NULL)
  70                 return NULL;
  71         base_versions = concat(basename(tmp_file), ".~");
  72         free(tmp_file);
  73         if (base_versions == NULL)
  74                 return NULL;
  75         tmp_file = strdup(file);
  76         if (tmp_file == NULL) {
  77                 free(base_versions);
  78                 return NULL;
  79         }
  80         dir = dirname(tmp_file);
  81         if (dir == NULL) {
  82                 free(base_versions);
  83                 free(tmp_file);
  84                 return NULL;
  85         }
  86         highest_backup = max_backup_version(base_versions, dir);
  87         free(base_versions);
  88         free(tmp_file);
  89         if (backup_type == numbered_existing && highest_backup == 0)
  90                 return concat(file, simple_backup_suffix);
  91         return make_version_name(file, highest_backup + 1);
  92 }
  93
  94 /*
  95  * Return the number of the highest-numbered backup file for file FILE in
  96  * directory DIR.  If there are no numbered backups of FILE in DIR, or an
  97  * error occurs reading DIR, return 0. FILE should already have ".~" appended
  98  * to it.
  99  */
 100 static int
 101 max_backup_version(const char *file, const char *dir)
 102 {
 103         DIR     *dirp;
 104         struct dirent   *dp;
 105         int     highest_version, this_version;
 106         size_t  file_name_length;
 107
 108         dirp = opendir(dir);
 109         if (dirp == NULL)
 110                 return 0;
 111
 112         highest_version = 0;
 113         file_name_length = strlen(file);
 114
 115         while ((dp = readdir(dirp)) != NULL) {
 116                 if (strlen(dp->d_name) <= file_name_length)
 117                         continue;
 118
 119                 this_version = version_number(file, dp->d_name, file_name_length);
 120                 if (this_version > highest_version)
 121                         highest_version = this_version;
 122         }
 123         closedir(dirp);
 124         return highest_version;
 125 }
 126
 127 /*
 128  * Return a string, allocated with malloc, containing "FILE.~VERSION~".
 129  * Return 0 if out of memory.
 130  */
 131 static char *
 132 make_version_name(const char *file, int version)
 133 {
 134         char    *backup_name;
 135         int len = strlen(file)+20;
 136
 137         if(!(backup_name = malloc(len)))
 138                 return NULL;
 139
 140         if (snprintf(backup_name, len, "%s.~%d~", file, version) == -1)
 141                 return NULL;
 142
 143         return backup_name;
 144 }
 145
 146 /*
 147  * If BACKUP is a numbered backup of BASE, return its version number;
 148  * otherwise return 0.  BASE_LENGTH is the length of BASE. BASE should
 149  * already have ".~" appended to it.
 150  */
 151 static int
 152 version_number(const char *base, const char *backup, size_t base_length)
 153 {
 154         int             version;
 155         const char      *p;
 156
 157         version = 0;
 158         if (!strncmp(base, backup, base_length) && ISDIGIT(backup[base_length])) {
 159                 for (p = &backup[base_length]; ISDIGIT(*p); ++p)
 160                         version = version * 10 + *p - '0';
 161                 if (p[0] != '~' || p[1])
 162                         version = 0;
 163         }
 164         return version;
 165 }
 166
 167 /*
 168  * Return the newly-allocated concatenation of STR1 and STR2. If out of
 169  * memory, return 0.
 170  */
 171 static char  *
 172 concat(const char *str1, const char *str2)
 173 {
 174         char    *newstr;
 175         int len = strlen(str1) + strlen(str2) + 1;
 176
 177         if(!(newstr = malloc(strlen(str1) + strlen(str2) + 1)))
 178                 return NULL;
 179
 180         if (snprintf(newstr, len, "%s%s", str1, str2) == -1)
 181                 return NULL;
 182
 183         return newstr;
 184 }
 185
 186 /*
 187  * If ARG is an unambiguous match for an element of the null-terminated array
 188  * OPTLIST, return the index in OPTLIST of the matched element, else -1 if it
 189  * does not match any element or -2 if it is ambiguous (is a prefix of more
 190  * than one element).
 191  */
 192 static int
 193 argmatch(const char *arg, const char **optlist)
 194 {
 195         int     i;      /* Temporary index in OPTLIST. */
 196         size_t  arglen; /* Length of ARG. */
 197         int     matchind = -1;  /* Index of first nonexact match. */
 198         int     ambiguous = 0;  /* If nonzero, multiple nonexact match(es). */
 199
 200         arglen = strlen(arg);
 201
 202         /* Test all elements for either exact match or abbreviated matches.  */
 203         for (i = 0; optlist[i]; i++) {
 204                 if (!strncmp(optlist[i], arg, arglen)) {
 205                         if (strlen(optlist[i]) == arglen)
 206                                 /* Exact match found.  */
 207                                 return i;
 208                         else if (matchind == -1)
 209                                 /* First nonexact match found.  */
 210                                 matchind = i;
 211                         else
 212                                 /* Second nonexact match found.  */
 213                                 ambiguous = 1;
 214                 }
 215         }
 216         if (ambiguous)
 217                 return -2;
 218         else
 219                 return matchind;
 220 }
 221
 222 /*
 223  * Error reporting for argmatch. KIND is a description of the type of entity
 224  * that was being matched. VALUE is the invalid value that was given. PROBLEM
 225  * is the return value from argmatch.
 226  */
 227 static void
 228 invalid_arg(const char *kind, const char *value, int problem)
 229 {
 230         fprintf(stderr, "patch: ");
 231         if (problem == -1)
 232                 fprintf(stderr, "invalid");
 233         else                    /* Assume -2. */
 234                 fprintf(stderr, "ambiguous");
 235         fprintf(stderr, " %s `%s'\n", kind, value);
 236 }
 237
 238 static const char *backup_args[] = {
 239         "never", "simple", "nil", "existing", "t", "numbered", 0
 240 };
 241
 242 static enum backup_type backup_types[] = {
 243         simple, simple, numbered_existing,
 244         numbered_existing, numbered, numbered
 245 };
 246
 247 /*
 248  * Return the type of backup indicated by VERSION. Unique abbreviations are
 249  * accepted.
 250  */
 251 enum backup_type
 252 get_version(const char *version)
 253 {
 254         int     i;
 255
 256         if (version == NULL || *version == '\0')
 257                 return numbered_existing;
 258         i = argmatch(version, backup_args);
 259         if (i >= 0)
 260                 return backup_types[i];
 261         invalid_arg("version control type", version, i);
 262         exit(2);
 263 }