usr.bin/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 1.4 2007/09/29 23:11:10 swildner Exp $
   4  */
   5
   6 /*
   7  * backupfile.c -- make Emacs style backup file names Copyright (C) 1990 Free
   8  * Software Foundation, Inc.
   9  *
  10  * This program is free software; you can redistribute it and/or modify it
  11  * without restriction.
  12  *
  13  * This program is distributed in the hope that it will be useful, but WITHOUT
  14  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  15  * FITNESS FOR A PARTICULAR PURPOSE.
  16  */
  17
  18 /*
  19  * David MacKenzie <djm@ai.mit.edu>. Some algorithms adapted from GNU Emacs.
  20  */
  21
  22 #include <ctype.h>
  23 #include <dirent.h>
  24 #include <libgen.h>
  25 #include <stdio.h>
  26 #include <stdlib.h>
  27 #include <string.h>
  28 #include <unistd.h>
  29
  30 #include "backupfile.h"
  31
  32
  33 #define ISDIGIT(c) (isascii ((unsigned char)c) && isdigit ((unsigned char)c))
  34
  35 /* Which type of backup file names are generated. */
  36 enum backup_type backup_type = none;
  37
  38 /*
  39  * The extension added to file names to produce a simple (as opposed to
  40  * numbered) backup file name.
  41  */
  42 const char      *simple_backup_suffix = "~";
  43
  44 static char     *concat(const char *, const char *);
  45 static char     *make_version_name(const char *, int);
  46 static int      max_backup_version(const char *, const char *);
  47 static int      version_number(const char *, const char *, size_t);
  48 static int      argmatch(const char *, const char **);
  49 static void     invalid_arg(const char *, const char *, int);
  50
  51 /*
  52  * Return the name of the new backup file for file FILE, allocated with
  53  * malloc.  Return 0 if out of memory. FILE must not end with a '/' unless it
  54  * is the root directory. Do not call this function if backup_type == none.
  55  */
  56 char *
  57 find_backup_file_name(const char *file)
  58 {
  59         char    *dir, *base_versions, *tmp_file;
  60         int     highest_backup;
  61
  62         if (backup_type == simple)
  63                 return concat(file, simple_backup_suffix);
  64         tmp_file = strdup(file);
  65         if (tmp_file == NULL)
  66                 return NULL;
  67         base_versions = concat(basename(tmp_file), ".~");
  68         free(tmp_file);
  69         if (base_versions == NULL)
  70                 return NULL;
  71         tmp_file = strdup(file);
  72         if (tmp_file == NULL) {
  73                 free(base_versions);
  74                 return NULL;
  75         }
  76         dir = dirname(tmp_file);
  77         if (dir == NULL) {
  78                 free(base_versions);
  79                 free(tmp_file);
  80                 return NULL;
  81         }
  82         highest_backup = max_backup_version(base_versions, dir);
  83         free(base_versions);
  84         free(tmp_file);
  85         if (backup_type == numbered_existing && highest_backup == 0)
  86                 return concat(file, simple_backup_suffix);
  87         return make_version_name(file, highest_backup + 1);
  88 }
  89
  90 /*
  91  * Return the number of the highest-numbered backup file for file FILE in
  92  * directory DIR.  If there are no numbered backups of FILE in DIR, or an
  93  * error occurs reading DIR, return 0. FILE should already have ".~" appended
  94  * to it.
  95  */
  96 static int
  97 max_backup_version(const char *file, const char *dir)
  98 {
  99         DIR     *dirp;
 100         struct dirent   *dp;
 101         int     highest_version, this_version;
 102         size_t  file_name_length;
 103
 104         dirp = opendir(dir);
 105         if (dirp == NULL)
 106                 return 0;
 107
 108         highest_version = 0;
 109         file_name_length = strlen(file);
 110
 111         while ((dp = readdir(dirp)) != NULL) {
 112                 if (dp->d_namlen <= file_name_length)
 113                         continue;
 114
 115                 this_version = version_number(file, dp->d_name, file_name_length);
 116                 if (this_version > highest_version)
 117                         highest_version = this_version;
 118         }
 119         closedir(dirp);
 120         return highest_version;
 121 }
 122
 123 /*
 124  * Return a string, allocated with malloc, containing "FILE.~VERSION~".
 125  * Return 0 if out of memory.
 126  */
 127 static char *
 128 make_version_name(const char *file, int version)
 129 {
 130         char    *backup_name;
 131
 132         if (asprintf(&backup_name, "%s.~%d~", file, version) == -1)
 133                 return NULL;
 134         return backup_name;
 135 }
 136
 137 /*
 138  * If BACKUP is a numbered backup of BASE, return its version number;
 139  * otherwise return 0.  BASE_LENGTH is the length of BASE. BASE should
 140  * already have ".~" appended to it.
 141  */
 142 static int
 143 version_number(const char *base, const char *backup, size_t base_length)
 144 {
 145         int             version;
 146         const char      *p;
 147
 148         version = 0;
 149         if (!strncmp(base, backup, base_length) && ISDIGIT(backup[base_length])) {
 150                 for (p = &backup[base_length]; ISDIGIT(*p); ++p)
 151                         version = version * 10 + *p - '0';
 152                 if (p[0] != '~' || p[1])
 153                         version = 0;
 154         }
 155         return version;
 156 }
 157
 158 /*
 159  * Return the newly-allocated concatenation of STR1 and STR2. If out of
 160  * memory, return 0.
 161  */
 162 static char  *
 163 concat(const char *str1, const char *str2)
 164 {
 165         char    *newstr;
 166
 167         if (asprintf(&newstr, "%s%s", str1, str2) == -1)
 168                 return NULL;
 169         return newstr;
 170 }
 171
 172 /*
 173  * If ARG is an unambiguous match for an element of the null-terminated array
 174  * OPTLIST, return the index in OPTLIST of the matched element, else -1 if it
 175  * does not match any element or -2 if it is ambiguous (is a prefix of more
 176  * than one element).
 177  */
 178 static int
 179 argmatch(const char *arg, const char **optlist)
 180 {
 181         int     i;      /* Temporary index in OPTLIST. */
 182         size_t  arglen; /* Length of ARG. */
 183         int     matchind = -1;  /* Index of first nonexact match. */
 184         int     ambiguous = 0;  /* If nonzero, multiple nonexact match(es). */
 185
 186         arglen = strlen(arg);
 187
 188         /* Test all elements for either exact match or abbreviated matches.  */
 189         for (i = 0; optlist[i]; i++) {
 190                 if (!strncmp(optlist[i], arg, arglen)) {
 191                         if (strlen(optlist[i]) == arglen)
 192                                 /* Exact match found.  */
 193                                 return i;
 194                         else if (matchind == -1)
 195                                 /* First nonexact match found.  */
 196                                 matchind = i;
 197                         else
 198                                 /* Second nonexact match found.  */
 199                                 ambiguous = 1;
 200                 }
 201         }
 202         if (ambiguous)
 203                 return -2;
 204         else
 205                 return matchind;
 206 }
 207
 208 /*
 209  * Error reporting for argmatch. KIND is a description of the type of entity
 210  * that was being matched. VALUE is the invalid value that was given. PROBLEM
 211  * is the return value from argmatch.
 212  */
 213 static void
 214 invalid_arg(const char *kind, const char *value, int problem)
 215 {
 216         fprintf(stderr, "patch: ");
 217         if (problem == -1)
 218                 fprintf(stderr, "invalid");
 219         else                    /* Assume -2. */
 220                 fprintf(stderr, "ambiguous");
 221         fprintf(stderr, " %s `%s'\n", kind, value);
 222 }
 223
 224 static const char *backup_args[] = {
 225         "never", "simple", "nil", "existing", "t", "numbered", 0
 226 };
 227
 228 static enum backup_type backup_types[] = {
 229         simple, simple, numbered_existing,
 230         numbered_existing, numbered, numbered
 231 };
 232
 233 /*
 234  * Return the type of backup indicated by VERSION. Unique abbreviations are
 235  * accepted.
 236  */
 237 enum backup_type
 238 get_version(const char *version)
 239 {
 240         int     i;
 241
 242         if (version == NULL || *version == '\0')
 243                 return numbered_existing;
 244         i = argmatch(version, backup_args);
 245         if (i >= 0)
 246                 return backup_types[i];
 247         invalid_arg("version control type", version, i);
 248         exit(2);
 249 }