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/* $OpenBSD: backupfile.c,v 1.20 2009/10/27 23:59:41 deraadt Exp $ */
/*
* backupfile.c -- make Emacs style backup file names Copyright (C) 1990 Free
* Software Foundation, Inc.
*
* This program is free software; you can redistribute it and/or modify it
* without restriction.
*
* This program is distributed in the hope that it will be useful, but WITHOUT
* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
* FITNESS FOR A PARTICULAR PURPOSE.
*/
/*
* David MacKenzie <djm@ai.mit.edu>. Some algorithms adapted from GNU Emacs.
*/
#include <ctype.h>
#include <dirent.h>
#include <libgen.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include "backupfile.h"
#define ISDIGIT(c) (isascii (c) && isdigit (c))
/* Which type of backup file names are generated. */
enum backup_type backup_type = none;
/*
* The extension added to file names to produce a simple (as opposed to
* numbered) backup file name.
*/
char *simple_backup_suffix = "~";
static char *concat(const char *, const char *);
static char *make_version_name(const char *, int);
static int max_backup_version(const char *, const char *);
static int version_number(const char *, const char *, size_t);
static int argmatch(const char *, const char **);
static void invalid_arg(const char *, const char *, int);
/*
* Return the name of the new backup file for file FILE, allocated with
* malloc. Return 0 if out of memory. FILE must not end with a '/' unless it
* is the root directory. Do not call this function if backup_type == none.
*/
char *
find_backup_file_name(const char *file)
{
char *dir, *base_versions;
int highest_backup;
if (backup_type == simple)
return concat(file, simple_backup_suffix);
base_versions = concat(basename(file), ".~");
if (base_versions == NULL)
return NULL;
dir = dirname(file);
if (dir == NULL) {
free(base_versions);
return NULL;
}
highest_backup = max_backup_version(base_versions, dir);
free(base_versions);
if (backup_type == numbered_existing && highest_backup == 0)
return concat(file, simple_backup_suffix);
return make_version_name(file, highest_backup + 1);
}
/*
* Return the number of the highest-numbered backup file for file FILE in
* directory DIR. If there are no numbered backups of FILE in DIR, or an
* error occurs reading DIR, return 0. FILE should already have ".~" appended
* to it.
*/
static int
max_backup_version(const char *file, const char *dir)
{
DIR *dirp;
struct dirent *dp;
int highest_version, this_version;
size_t file_name_length;
dirp = opendir(dir);
if (dirp == NULL)
return 0;
highest_version = 0;
file_name_length = strlen(file);
while ((dp = readdir(dirp)) != NULL) {
if (dp->d_namlen <= file_name_length)
continue;
this_version = version_number(file, dp->d_name, file_name_length);
if (this_version > highest_version)
highest_version = this_version;
}
closedir(dirp);
return highest_version;
}
/*
* Return a string, allocated with malloc, containing "FILE.~VERSION~".
* Return 0 if out of memory.
*/
static char *
make_version_name(const char *file, int version)
{
char *backup_name;
if (asprintf(&backup_name, "%s.~%d~", file, version) == -1)
return NULL;
return backup_name;
}
/*
* If BACKUP is a numbered backup of BASE, return its version number;
* otherwise return 0. BASE_LENGTH is the length of BASE. BASE should
* already have ".~" appended to it.
*/
static int
version_number(const char *base, const char *backup, size_t base_length)
{
int version;
const char *p;
version = 0;
if (!strncmp(base, backup, base_length) && ISDIGIT(backup[base_length])) {
for (p = &backup[base_length]; ISDIGIT(*p); ++p)
version = version * 10 + *p - '0';
if (p[0] != '~' || p[1])
version = 0;
}
return version;
}
/*
* Return the newly-allocated concatenation of STR1 and STR2. If out of
* memory, return 0.
*/
static char *
concat(const char *str1, const char *str2)
{
char *newstr;
if (asprintf(&newstr, "%s%s", str1, str2) == -1)
return NULL;
return newstr;
}
/*
* If ARG is an unambiguous match for an element of the null-terminated array
* OPTLIST, return the index in OPTLIST of the matched element, else -1 if it
* does not match any element or -2 if it is ambiguous (is a prefix of more
* than one element).
*/
static int
argmatch(const char *arg, const char **optlist)
{
int i; /* Temporary index in OPTLIST. */
size_t arglen; /* Length of ARG. */
int matchind = -1; /* Index of first nonexact match. */
int ambiguous = 0; /* If nonzero, multiple nonexact match(es). */
arglen = strlen(arg);
/* Test all elements for either exact match or abbreviated matches. */
for (i = 0; optlist[i]; i++) {
if (!strncmp(optlist[i], arg, arglen)) {
if (strlen(optlist[i]) == arglen)
/* Exact match found. */
return i;
else if (matchind == -1)
/* First nonexact match found. */
matchind = i;
else
/* Second nonexact match found. */
ambiguous = 1;
}
}
if (ambiguous)
return -2;
else
return matchind;
}
/*
* Error reporting for argmatch. KIND is a description of the type of entity
* that was being matched. VALUE is the invalid value that was given. PROBLEM
* is the return value from argmatch.
*/
static void
invalid_arg(const char *kind, const char *value, int problem)
{
fprintf(stderr, "patch: ");
if (problem == -1)
fprintf(stderr, "invalid");
else /* Assume -2. */
fprintf(stderr, "ambiguous");
fprintf(stderr, " %s `%s'\n", kind, value);
}
static const char *backup_args[] = {
"never", "simple", "nil", "existing", "t", "numbered", 0
};
static enum backup_type backup_types[] = {
simple, simple, numbered_existing,
numbered_existing, numbered, numbered
};
/*
* Return the type of backup indicated by VERSION. Unique abbreviations are
* accepted.
*/
enum backup_type
get_version(const char *version)
{
int i;
if (version == NULL || *version == '\0')
return numbered_existing;
i = argmatch(version, backup_args);
if (i >= 0)
return backup_types[i];
invalid_arg("version control type", version, i);
exit(2);
}
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