144 lines
3 KiB
C
Executable file
144 lines
3 KiB
C
Executable file
/* getcwd() - get the name of the current working directory.
|
|
* Author: Kees J. Bot
|
|
* 30 Apr 1989
|
|
*/
|
|
#define nil 0
|
|
#define chdir _chdir
|
|
#define closedir _closedir
|
|
#define getcwd _getcwd
|
|
#define opendir _opendir
|
|
#define readdir _readdir
|
|
#define rewinddir _rewinddir
|
|
#define stat _stat
|
|
#include <sys/types.h>
|
|
#include <sys/stat.h>
|
|
#include <errno.h>
|
|
#include <unistd.h>
|
|
#include <dirent.h>
|
|
#include <limits.h>
|
|
#include <string.h>
|
|
|
|
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;
|
|
}
|
|
|
|
char *getcwd(char *path, size_t size)
|
|
{
|
|
struct stat above, current, tmp;
|
|
struct dirent *entry;
|
|
DIR *d;
|
|
char *p, *up, *dotdot;
|
|
int cycle;
|
|
|
|
if (path == nil || size <= 1) { errno= EINVAL; return nil; }
|
|
|
|
p= path + size;
|
|
*--p = 0;
|
|
|
|
if (stat(".", ¤t) < 0) return nil;
|
|
|
|
while (1) {
|
|
dotdot= "..";
|
|
if (stat(dotdot, &above) < 0) { recover(p); return nil; }
|
|
|
|
if (above.st_dev == current.st_dev
|
|
&& above.st_ino == current.st_ino)
|
|
break; /* Root dir found */
|
|
|
|
if ((d= opendir(dotdot)) == nil) { recover(p); return nil; }
|
|
|
|
/* 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)) == nil) {
|
|
switch (++cycle) {
|
|
case 1:
|
|
rewinddir(d);
|
|
continue;
|
|
case 2:
|
|
closedir(d);
|
|
errno= ENOENT;
|
|
recover(p);
|
|
return nil;
|
|
}
|
|
}
|
|
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 nil;
|
|
}
|
|
closedir(d);
|
|
|
|
if (chdir(dotdot) < 0) { recover(p); return nil; }
|
|
p= up;
|
|
|
|
current= above;
|
|
}
|
|
if (recover(p) < 0) return nil; /* 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 path;
|
|
}
|