usr.bin/patch/backupfile.c

   1 /*-
   2  * Copyright (C) 1990 Free Software Foundation, Inc.
   3  *
   4  * This program is free software; you can redistribute it and/or modify it
   5  * without restriction.
   6  *
   7  * This program is distributed in the hope that it will be useful, but WITHOUT
   8  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
   9  * FITNESS FOR A PARTICULAR PURPOSE.
  10  *
  11  * backupfile.c -- make Emacs style backup file names
  12  *
  13  * David MacKenzie <djm@ai.mit.edu>. Some algorithms adapted from GNU Emacs.
  14  *
  15  * $OpenBSD: backupfile.c,v 1.20 2009/10/27 23:59:41 deraadt Exp $
  16  * $FreeBSD: head/usr.bin/patch/backupfile.c 285772 2015-07-21 22:57:27Z cem $
  17  */
  18
  19 #include <ctype.h>
  20 #include <dirent.h>
  21 #include <libgen.h>
  22 #include <stdio.h>
  23 #include <stdlib.h>
  24 #include <string.h>
  25 #include <unistd.h>
  26
  27 #include "backupfile.h"
  28
  29
  30 #define ISDIGIT(c) (isascii ((unsigned char)c) && isdigit ((unsigned char)c))
  31
  32 /* Which type of backup file names are generated. */
  33 enum backup_type backup_type = none;
  34
  35 /*
  36  * The extension added to file names to produce a simple (as opposed to
  37  * numbered) backup file name.
  38  */
  39 const char      *simple_backup_suffix = "~";
  40
  41 static char     *concat(const char *, const char *);
  42 static char     *make_version_name(const char *, int);
  43 static int      max_backup_version(const char *, const char *);
  44 static int      version_number(const char *, const char *, size_t);
  45 static int      argmatch(const char *, const char **);
  46 static void     invalid_arg(const char *, const char *, int);
  47
  48 /*
  49  * Return the name of the new backup file for file FILE, allocated with
  50  * malloc.  Return 0 if out of memory. FILE must not end with a '/' unless it
  51  * is the root directory. Do not call this function if backup_type == none.
  52  */
  53 char *
  54 find_backup_file_name(const char *file)
  55 {
  56         char    *dir, *base_versions, *tmp_file;
  57         int     highest_backup;
  58
  59         if (backup_type == simple)
  60                 return concat(file, simple_backup_suffix);
  61         tmp_file = strdup(file);
  62         if (tmp_file == NULL)
  63                 return NULL;
  64         base_versions = concat(basename(tmp_file), ".~");
  65         free(tmp_file);
  66         if (base_versions == NULL)
  67                 return NULL;
  68         tmp_file = strdup(file);
  69         if (tmp_file == NULL) {
  70                 free(base_versions);
  71                 return NULL;
  72         }
  73         dir = dirname(tmp_file);
  74         if (dir == NULL) {
  75                 free(base_versions);
  76                 free(tmp_file);
  77                 return NULL;
  78         }
  79         highest_backup = max_backup_version(base_versions, dir);
  80         free(base_versions);
  81         free(tmp_file);
  82         if (backup_type == numbered_existing && highest_backup == 0)
  83                 return concat(file, simple_backup_suffix);
  84         return make_version_name(file, highest_backup + 1);
  85 }
  86
  87 /*
  88  * Return the number of the highest-numbered backup file for file FILE in
  89  * directory DIR.  If there are no numbered backups of FILE in DIR, or an
  90  * error occurs reading DIR, return 0. FILE should already have ".~" appended
  91  * to it.
  92  */
  93 static int
  94 max_backup_version(const char *file, const char *dir)
  95 {
  96         DIR     *dirp;
  97         struct dirent   *dp;
  98         int     highest_version, this_version;
  99         size_t  file_name_length;
 100
 101         dirp = opendir(dir);
 102         if (dirp == NULL)
 103                 return 0;
 104
 105         highest_version = 0;
 106         file_name_length = strlen(file);
 107
 108         while ((dp = readdir(dirp)) != NULL) {
 109 #ifdef _DIRENT_HAVE_D_NAMLEN
 110                 if (dp->d_namlen <= file_name_length)
 111 #else
 112                 if (strlen(dp->d_name) <= file_name_length)
 113 #endif
 114                         continue;
 115
 116                 this_version = version_number(file, dp->d_name, file_name_length);
 117                 if (this_version > highest_version)
 118                         highest_version = this_version;
 119         }
 120         closedir(dirp);
 121         return highest_version;
 122 }
 123
 124 /*
 125  * Return a string, allocated with malloc, containing "FILE.~VERSION~".
 126  * Return 0 if out of memory.
 127  */
 128 static char *
 129 make_version_name(const char *file, int version)
 130 {
 131         char    *backup_name;
 132
 133         if (asprintf(&backup_name, "%s.~%d~", file, version) == -1)
 134                 return NULL;
 135         return backup_name;
 136 }
 137
 138 /*
 139  * If BACKUP is a numbered backup of BASE, return its version number;
 140  * otherwise return 0.  BASE_LENGTH is the length of BASE. BASE should
 141  * already have ".~" appended to it.
 142  */
 143 static int
 144 version_number(const char *base, const char *backup, size_t base_length)
 145 {
 146         int             version;
 147         const char      *p;
 148
 149         version = 0;
 150         if (!strncmp(base, backup, base_length) && ISDIGIT(backup[base_length])) {
 151                 for (p = &backup[base_length]; ISDIGIT(*p); ++p)
 152                         version = version * 10 + *p - '0';
 153                 if (p[0] != '~' || p[1])
 154                         version = 0;
 155         }
 156         return version;
 157 }
 158
 159 /*
 160  * Return the newly-allocated concatenation of STR1 and STR2. If out of
 161  * memory, return 0.
 162  */
 163 static char  *
 164 concat(const char *str1, const char *str2)
 165 {
 166         char    *newstr;
 167
 168         if (asprintf(&newstr, "%s%s", str1, str2) == -1)
 169                 return NULL;
 170         return newstr;
 171 }
 172
 173 /*
 174  * If ARG is an unambiguous match for an element of the null-terminated array
 175  * OPTLIST, return the index in OPTLIST of the matched element, else -1 if it
 176  * does not match any element or -2 if it is ambiguous (is a prefix of more
 177  * than one element).
 178  */
 179 static int
 180 argmatch(const char *arg, const char **optlist)
 181 {
 182         int     i;      /* Temporary index in OPTLIST. */
 183         size_t  arglen; /* Length of ARG. */
 184         int     matchind = -1;  /* Index of first nonexact match. */
 185         int     ambiguous = 0;  /* If nonzero, multiple nonexact match(es). */
 186
 187         arglen = strlen(arg);
 188
 189         /* Test all elements for either exact match or abbreviated matches.  */
 190         for (i = 0; optlist[i]; i++) {
 191                 if (!strncmp(optlist[i], arg, arglen)) {
 192                         if (strlen(optlist[i]) == arglen)
 193                                 /* Exact match found.  */
 194                                 return i;
 195                         else if (matchind == -1)
 196                                 /* First nonexact match found.  */
 197                                 matchind = i;
 198                         else
 199                                 /* Second nonexact match found.  */
 200                                 ambiguous = 1;
 201                 }
 202         }
 203         if (ambiguous)
 204                 return -2;
 205         else
 206                 return matchind;
 207 }
 208
 209 /*
 210  * Error reporting for argmatch. KIND is a description of the type of entity
 211  * that was being matched. VALUE is the invalid value that was given. PROBLEM
 212  * is the return value from argmatch.
 213  */
 214 static void
 215 invalid_arg(const char *kind, const char *value, int problem)
 216 {
 217         fprintf(stderr, "patch: ");
 218         if (problem == -1)
 219                 fprintf(stderr, "invalid");
 220         else                    /* Assume -2. */
 221                 fprintf(stderr, "ambiguous");
 222         fprintf(stderr, " %s `%s'\n", kind, value);
 223 }
 224
 225 static const char *backup_args[] = {
 226         "none", "never", "simple", "nil", "existing", "t", "numbered", 0
 227 };
 228
 229 static enum backup_type backup_types[] = {
 230         none, simple, simple, numbered_existing,
 231         numbered_existing, numbered, numbered
 232 };
 233
 234 /*
 235  * Return the type of backup indicated by VERSION. Unique abbreviations are
 236  * accepted.
 237  */
 238 enum backup_type
 239 get_version(const char *version)
 240 {
 241         int     i;
 242
 243         if (version == NULL || *version == '\0')
 244                 return numbered_existing;
 245         i = argmatch(version, backup_args);
 246         if (i >= 0)
 247                 return backup_types[i];
 248         invalid_arg("version control type", version, i);
 249         exit(2);
 250 }