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 1.5 2008/08/11 00:05:06 joerg Exp $
   4  * $NetBSD$
   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 __RCSID("$NetBSD$");
  26
  27 #include <ctype.h>
  28 #include <dirent.h>
  29 #include <libgen.h>
  30 #include <stdio.h>
  31 #include <stdlib.h>
  32 #include <string.h>
  33 #include <unistd.h>
  34
  35 #include "backupfile.h"
  36
  37
  38 #define ISDIGIT(c) (isascii ((unsigned char)c) && isdigit ((unsigned char)c))
  39
  40 /* Which type of backup file names are generated. */
  41 enum backup_type backup_type = none;
  42
  43 /*
  44  * The extension added to file names to produce a simple (as opposed to
  45  * numbered) backup file name.
  46  */
  47 const char      *simple_backup_suffix = "~";
  48
  49 static char     *concat(const char *, const char *);
  50 static char     *make_version_name(const char *, int);
  51 static int      max_backup_version(const char *, const char *);
  52 static int      version_number(const char *, const char *, size_t);
  53 static int      argmatch(const char *, const char **);
  54 static void     invalid_arg(const char *, const char *, int);
  55
  56 /*
  57  * Return the name of the new backup file for file FILE, allocated with
  58  * malloc.  Return 0 if out of memory. FILE must not end with a '/' unless it
  59  * is the root directory. Do not call this function if backup_type == none.
  60  */
  61 char *
  62 find_backup_file_name(const char *file)
  63 {
  64         char    *dir, *base_versions, *tmp_file;
  65         int     highest_backup;
  66
  67         if (backup_type == simple)
  68                 return concat(file, simple_backup_suffix);
  69         tmp_file = strdup(file);
  70         if (tmp_file == NULL)
  71                 return NULL;
  72         base_versions = concat(basename(tmp_file), ".~");
  73         free(tmp_file);
  74         if (base_versions == NULL)
  75                 return NULL;
  76         tmp_file = strdup(file);
  77         if (tmp_file == NULL) {
  78                 free(base_versions);
  79                 return NULL;
  80         }
  81         dir = dirname(tmp_file);
  82         if (dir == NULL) {
  83                 free(base_versions);
  84                 free(tmp_file);
  85                 return NULL;
  86         }
  87         highest_backup = max_backup_version(base_versions, dir);
  88         free(base_versions);
  89         free(tmp_file);
  90         if (backup_type == numbered_existing && highest_backup == 0)
  91                 return concat(file, simple_backup_suffix);
  92         return make_version_name(file, highest_backup + 1);
  93 }
  94
  95 /*
  96  * Return the number of the highest-numbered backup file for file FILE in
  97  * directory DIR.  If there are no numbered backups of FILE in DIR, or an
  98  * error occurs reading DIR, return 0. FILE should already have ".~" appended
  99  * to it.
 100  */
 101 static int
 102 max_backup_version(const char *file, const char *dir)
 103 {
 104         DIR     *dirp;
 105         struct dirent   *dp;
 106         int     highest_version, this_version;
 107         size_t  file_name_length;
 108
 109         dirp = opendir(dir);
 110         if (dirp == NULL)
 111                 return 0;
 112
 113         highest_version = 0;
 114         file_name_length = strlen(file);
 115
 116         while ((dp = readdir(dirp)) != NULL) {
 117                 if (dp->d_namlen <= file_name_length)
 118                         continue;
 119
 120                 this_version = version_number(file, dp->d_name, file_name_length);
 121                 if (this_version > highest_version)
 122                         highest_version = this_version;
 123         }
 124         closedir(dirp);
 125         return highest_version;
 126 }
 127
 128 /*
 129  * Return a string, allocated with malloc, containing "FILE.~VERSION~".
 130  * Return 0 if out of memory.
 131  */
 132 static char *
 133 make_version_name(const char *file, int version)
 134 {
 135         char    *backup_name;
 136
 137         if (asprintf(&backup_name, "%s.~%d~", file, version) == -1)
 138                 return NULL;
 139         return backup_name;
 140 }
 141
 142 /*
 143  * If BACKUP is a numbered backup of BASE, return its version number;
 144  * otherwise return 0.  BASE_LENGTH is the length of BASE. BASE should
 145  * already have ".~" appended to it.
 146  */
 147 static int
 148 version_number(const char *base, const char *backup, size_t base_length)
 149 {
 150         int             version;
 151         const char      *p;
 152
 153         version = 0;
 154         if (!strncmp(base, backup, base_length) && ISDIGIT(backup[base_length])) {
 155                 for (p = &backup[base_length]; ISDIGIT(*p); ++p)
 156                         version = version * 10 + *p - '0';
 157                 if (p[0] != '~' || p[1])
 158                         version = 0;
 159         }
 160         return version;
 161 }
 162
 163 /*
 164  * Return the newly-allocated concatenation of STR1 and STR2. If out of
 165  * memory, return 0.
 166  */
 167 static char  *
 168 concat(const char *str1, const char *str2)
 169 {
 170         char    *newstr;
 171
 172         if (asprintf(&newstr, "%s%s", str1, str2) == -1)
 173                 return NULL;
 174         return newstr;
 175 }
 176
 177 /*
 178  * If ARG is an unambiguous match for an element of the null-terminated array
 179  * OPTLIST, return the index in OPTLIST of the matched element, else -1 if it
 180  * does not match any element or -2 if it is ambiguous (is a prefix of more
 181  * than one element).
 182  */
 183 static int
 184 argmatch(const char *arg, const char **optlist)
 185 {
 186         int     i;      /* Temporary index in OPTLIST. */
 187         size_t  arglen; /* Length of ARG. */
 188         int     matchind = -1;  /* Index of first nonexact match. */
 189         int     ambiguous = 0;  /* If nonzero, multiple nonexact match(es). */
 190
 191         arglen = strlen(arg);
 192
 193         /* Test all elements for either exact match or abbreviated matches.  */
 194         for (i = 0; optlist[i]; i++) {
 195                 if (!strncmp(optlist[i], arg, arglen)) {
 196                         if (strlen(optlist[i]) == arglen)
 197                                 /* Exact match found.  */
 198                                 return i;
 199                         else if (matchind == -1)
 200                                 /* First nonexact match found.  */
 201                                 matchind = i;
 202                         else
 203                                 /* Second nonexact match found.  */
 204                                 ambiguous = 1;
 205                 }
 206         }
 207         if (ambiguous)
 208                 return -2;
 209         else
 210                 return matchind;
 211 }
 212
 213 /*
 214  * Error reporting for argmatch. KIND is a description of the type of entity
 215  * that was being matched. VALUE is the invalid value that was given. PROBLEM
 216  * is the return value from argmatch.
 217  */
 218 static void
 219 invalid_arg(const char *kind, const char *value, int problem)
 220 {
 221         fprintf(stderr, "patch: ");
 222         if (problem == -1)
 223                 fprintf(stderr, "invalid");
 224         else                    /* Assume -2. */
 225                 fprintf(stderr, "ambiguous");
 226         fprintf(stderr, " %s `%s'\n", kind, value);
 227 }
 228
 229 static const char *backup_args[] = {
 230         "never", "simple", "nil", "existing", "t", "numbered", 0
 231 };
 232
 233 static enum backup_type backup_types[] = {
 234         simple, simple, numbered_existing,
 235         numbered_existing, numbered, numbered
 236 };
 237
 238 /*
 239  * Return the type of backup indicated by VERSION. Unique abbreviations are
 240  * accepted.
 241  */
 242 enum backup_type
 243 get_version(const char *version)
 244 {
 245         int     i;
 246
 247         if (version == NULL || *version == '\0')
 248                 return numbered_existing;
 249         i = argmatch(version, backup_args);
 250         if (i >= 0)
 251                 return backup_types[i];
 252         invalid_arg("version control type", version, i);
 253         exit(2);
 254 }