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/*
* This file is part of the Green End SFTP Server.
* Copyright (C) 2007, 2011 Richard Kettlewell
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* 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. See the GNU
* General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307
* USA
*/
/** @file realpath.c @brief Implementation of sftp_find_realpath() */
#include "sftpcommon.h"
#include "utils.h"
#include "alloc.h"
#include "debug.h"
#include <string.h>
#include <stdlib.h>
#include <unistd.h>
#include <assert.h>
#include <errno.h>
#include <limits.h>
static char *process_path(struct allocator *a, char *result, size_t *nresultp,
const char *path, unsigned flags);
char *sftp_find_realpath(struct allocator *a, const char *path,
unsigned flags) {
char *cwd, *abspath, *result = 0;
size_t nresult = 0;
D(("sftp_find_realpath '%s' %#x", path, flags));
/* Default is current directory */
if(path[0] == 0)
path = ".";
/* Convert relative paths to absolute paths */
if(path[0] != '/') {
if(!(cwd = sftp_getcwd(a)))
return 0;
assert(cwd[0] == '/');
abspath = sftp_alloc(a, strlen(cwd) + strlen(path) + 2);
strcpy(abspath, cwd);
strcat(abspath, "/");
strcat(abspath, path);
path = abspath;
D(("convert relative path to '%s'", path));
}
/* The result always starts with a / */
result = sftp_str_append(a, result, &nresult, "/");
/* All the work happens below */
return process_path(a, result, &nresult, path, flags);
}
/** @brief Canonicalize a path
* @param a Allocator for result
* @param result Result so far
* @param nresultp Size of current result
* @param path Path to process
* @param flags Flags as for sftp_find_realpath()
* @return Modified result
*/
static char *process_path(struct allocator *a, char *result, size_t *nresultp,
const char *path, unsigned flags) {
D(("process_path path='%s' result='%s'", path, result));
while(*path) {
if(*path == '/')
++path;
else {
/* Find the next path element */
const size_t elementlen = strcspn(path, "/");
if(elementlen == 1 && path[0] == '.')
/* Stay where we are */
;
else if(elementlen == 2 && path[0] == '.' && path[1] == '.') {
/* Go up one level */
char *const ls = strrchr(result, '/');
assert(ls != 0);
if(ls != result)
*ls = 0;
else
strcpy(result, "/"); /* /.. = / */
D(("result[0] -> '%s'", result));
} else {
const size_t oldresultlen = strlen(result);
/* Append the new path element */
if(result[1])
result = sftp_str_append(a, result, nresultp, "/");
result = sftp_str_appendn(a, result, nresultp, path, elementlen);
D(("result[1] -> '%s'", result));
/* If we're following symlinks, see if the path so far points to a
* link */
if(flags & RP_READLINK) {
const char *const target = sftp_do_readlink(a, result);
if(target) {
if(target[0] == '/')
/* Absolute symlink, go back to the root */
strcpy(result, "/");
else
/* Relative symlink, lose the last path element */
result[oldresultlen] = 0;
/* Process all! the elements of the link target */
if(!(result = process_path(a, result, nresultp, target, flags)))
return result;
} else {
switch(errno) {
case EINVAL:
/* Not a link. Proceed. */
break;
default:
if((flags & RP_MUST_EXIST)) {
/* Nonexistent files are bad. Return an error. */
D(("error reading link: %s", strerror(errno)));
return 0;
}
/* Nonexistent files are OK. Proceed. */
break;
}
}
}
D(("result[2] -> '%s'", result));
}
path += elementlen;
}
}
D(("returning '%s'", result));
return result;
}
/*
Local Variables:
c-basic-offset:2
comment-column:40
fill-column:79
indent-tabs-mode:nil
End:
*/
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