hbase

heirloom base
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backupfile.c (6393B)


      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  * $FreeBSD$
     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 		if (strlen(dp->d_name) <= file_name_length)
    110 			continue;
    111 
    112 		this_version = version_number(file, dp->d_name, file_name_length);
    113 		if (this_version > highest_version)
    114 			highest_version = this_version;
    115 	}
    116 	closedir(dirp);
    117 	return highest_version;
    118 }
    119 
    120 /*
    121  * Return a string, allocated with malloc, containing "FILE.~VERSION~".
    122  * Return 0 if out of memory.
    123  */
    124 static char *
    125 make_version_name(const char *file, int version)
    126 {
    127 	char	*backup_name;
    128 
    129 	if (asprintf(&backup_name, "%s.~%d~", file, version) == -1)
    130 		return NULL;
    131 	return backup_name;
    132 }
    133 
    134 /*
    135  * If BACKUP is a numbered backup of BASE, return its version number;
    136  * otherwise return 0.  BASE_LENGTH is the length of BASE. BASE should
    137  * already have ".~" appended to it.
    138  */
    139 static int
    140 version_number(const char *base, const char *backup, size_t base_length)
    141 {
    142 	int		version;
    143 	const char	*p;
    144 
    145 	version = 0;
    146 	if (!strncmp(base, backup, base_length) && ISDIGIT(backup[base_length])) {
    147 		for (p = &backup[base_length]; ISDIGIT(*p); ++p)
    148 			version = version * 10 + *p - '0';
    149 		if (p[0] != '~' || p[1])
    150 			version = 0;
    151 	}
    152 	return version;
    153 }
    154 
    155 /*
    156  * Return the newly-allocated concatenation of STR1 and STR2. If out of
    157  * memory, return 0.
    158  */
    159 static char  *
    160 concat(const char *str1, const char *str2)
    161 {
    162 	char	*newstr;
    163 
    164 	if (asprintf(&newstr, "%s%s", str1, str2) == -1)
    165 		return NULL;
    166 	return newstr;
    167 }
    168 
    169 /*
    170  * If ARG is an unambiguous match for an element of the null-terminated array
    171  * OPTLIST, return the index in OPTLIST of the matched element, else -1 if it
    172  * does not match any element or -2 if it is ambiguous (is a prefix of more
    173  * than one element).
    174  */
    175 static int
    176 argmatch(const char *arg, const char **optlist)
    177 {
    178 	int	i;	/* Temporary index in OPTLIST. */
    179 	size_t	arglen;	/* Length of ARG. */
    180 	int	matchind = -1;	/* Index of first nonexact match. */
    181 	int	ambiguous = 0;	/* If nonzero, multiple nonexact match(es). */
    182 
    183 	arglen = strlen(arg);
    184 
    185 	/* Test all elements for either exact match or abbreviated matches.  */
    186 	for (i = 0; optlist[i]; i++) {
    187 		if (!strncmp(optlist[i], arg, arglen)) {
    188 			if (strlen(optlist[i]) == arglen)
    189 				/* Exact match found.  */
    190 				return i;
    191 			else if (matchind == -1)
    192 				/* First nonexact match found.  */
    193 				matchind = i;
    194 			else
    195 				/* Second nonexact match found.  */
    196 				ambiguous = 1;
    197 		}
    198 	}
    199 	if (ambiguous)
    200 		return -2;
    201 	else
    202 		return matchind;
    203 }
    204 
    205 /*
    206  * Error reporting for argmatch. KIND is a description of the type of entity
    207  * that was being matched. VALUE is the invalid value that was given. PROBLEM
    208  * is the return value from argmatch.
    209  */
    210 static void
    211 invalid_arg(const char *kind, const char *value, int problem)
    212 {
    213 	fprintf(stderr, "patch: ");
    214 	if (problem == -1)
    215 		fprintf(stderr, "invalid");
    216 	else			/* Assume -2. */
    217 		fprintf(stderr, "ambiguous");
    218 	fprintf(stderr, " %s `%s'\n", kind, value);
    219 }
    220 
    221 static const char *backup_args[] = {
    222 	"never", "simple", "nil", "existing", "t", "numbered", 0
    223 };
    224 
    225 static enum backup_type backup_types[] = {
    226 	simple, simple, numbered_existing,
    227 	numbered_existing, numbered, numbered
    228 };
    229 
    230 /*
    231  * Return the type of backup indicated by VERSION. Unique abbreviations are
    232  * accepted.
    233  */
    234 enum backup_type
    235 get_version(const char *version)
    236 {
    237 	int	i;
    238 
    239 	if (version == NULL || *version == '\0')
    240 		return numbered_existing;
    241 	i = argmatch(version, backup_args);
    242 	if (i >= 0)
    243 		return backup_types[i];
    244 	invalid_arg("version control type", version, i);
    245 	exit(2);
    246 }