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/* getcwd() - get the name of the current working directory.
* Author: Kees J. Bot
* 30 Apr 1989
*/
#include <sys/cdefs.h>
#include "namespace.h"
#include <sys/types.h>
#include <sys/stat.h>
#include <errno.h>
#include <unistd.h>
#include <dirent.h>
#include <limits.h>
#include <string.h>
/* libc-private interface */
int __getcwd(char *, size_t);
static int addpath(const char *path, char **ap, const char *entry)
/* Add the name of a directory entry at the front of the path being built.
* Note that the result always starts with a slash.
*/
{
const char *e= entry;
char *p= *ap;
while (*e != 0) e++;
while (e > entry && p > path) *--p = *--e;
if (p == path) return -1;
*--p = '/';
*ap= p;
return 0;
}
static int recover(char *p)
/* Undo all those chdir("..")'s that have been recorded by addpath. This
* has to be done entry by entry, because the whole pathname may be too long.
*/
{
int e= errno, slash;
char *p0;
while (*p != 0) {
p0= ++p;
do p++; while (*p != 0 && *p != '/');
slash= *p; *p= 0;
if (chdir(p0) < 0) return -1;
*p= slash;
}
errno= e;
return 0;
}
int __getcwd(char *path, size_t size)
{
struct stat above, current, tmp;
struct dirent *entry;
DIR *d;
char *p, *up;
const char *dotdot = "..";
int cycle;
if (path == NULL || size <= 1) { errno= EINVAL; return -1; }
p= path + size;
*--p = 0;
if (stat(".", ¤t) < 0) return -1;
while (1) {
if (stat(dotdot, &above) < 0) { recover(p); return -1; }
if (above.st_dev == current.st_dev
&& above.st_ino == current.st_ino)
break; /* Root dir found */
if ((d= opendir(dotdot)) == NULL) { recover(p); return -1; }
/* Cycle is 0 for a simple inode nr search, or 1 for a search
* for inode *and* device nr.
*/
cycle= above.st_dev == current.st_dev ? 0 : 1;
do {
char name[3 + NAME_MAX + 1];
tmp.st_ino= 0;
if ((entry= readdir(d)) == NULL) {
switch (++cycle) {
case 1:
rewinddir(d);
continue;
case 2:
closedir(d);
errno= ENOENT;
recover(p);
return -1;
}
}
if (strcmp(entry->d_name, ".") == 0) continue;
if (strcmp(entry->d_name, "..") == 0) continue;
switch (cycle) {
case 0:
/* Simple test on inode nr. */
if (entry->d_ino != current.st_ino) continue;
/*FALL THROUGH*/
case 1:
/* Current is mounted. */
strcpy(name, "../");
strcpy(name+3, entry->d_name);
if (stat(name, &tmp) < 0) continue;
break;
}
} while (tmp.st_ino != current.st_ino
|| tmp.st_dev != current.st_dev);
up= p;
if (addpath(path, &up, entry->d_name) < 0) {
closedir(d);
errno = ERANGE;
recover(p);
return -1;
}
closedir(d);
if (chdir(dotdot) < 0) { recover(p); return -1; }
p= up;
current= above;
}
if (recover(p) < 0) return -1; /* Undo all those chdir("..")'s. */
if (*p == 0) *--p = '/'; /* Cwd is "/" if nothing added */
if (p > path) strcpy(path, p); /* Move string to start of path. */
return 0;
}
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