122 lines
2.9 KiB
C
122 lines
2.9 KiB
C
|
/* getcwd - get current working directory Author: Terrence W. Holm */
|
||
|
|
|
||
|
|
/* Directly derived from Adri Koppes' pwd(1).
|
||
|
|
* Modified by Andy Tanenbaum for POSIX (29 Oct. 1989)
|
||
|
|
*/
|
||
|
|
|
||
|
|
#include <lib.h>
|
||
|
|
#include <sys/stat.h>
|
||
|
|
#include <fcntl.h>
|
||
|
|
#include <sys/dir.h>
|
||
|
|
#define getcwd _getcwd
|
||
|
|
#include <unistd.h>
|
||
|
|
#include <string.h>
|
||
|
|
|
||
|
|
#define DIRECT_SIZE (sizeof (struct direct))
|
||
|
|
|
||
|
|
PRIVATE _PROTOTYPE(void, go_back(char *path) );
|
||
|
|
|
||
|
|
char *getcwd(buffer, size)
|
||
|
|
char *buffer;
|
||
|
|
int size;
|
||
|
|
/* Get current working directory. */
|
||
|
|
{
|
||
|
|
int same_device, found, fd;
|
||
|
|
char *r, path[PATH_MAX + 1], temp_name[NAME_MAX + 1];
|
||
|
|
struct stat current, parent, dir_entry;
|
||
|
|
struct direct d;
|
||
|
|
|
||
|
|
if (buffer == (char *)NULL || size <= 0) {
|
||
|
|
errno = EINVAL;
|
||
|
|
return((char *)NULL);
|
||
|
|
}
|
||
|
|
path[0] = '\0';
|
||
|
|
|
||
|
|
/* Get the inode for the current directory */
|
||
|
|
if (stat(".", ¤t) == -1) return((char *)NULL);
|
||
|
|
if ((current.st_mode & S_IFMT) != S_IFDIR) return((char *)NULL);
|
||
|
|
|
||
|
|
/* Run backwards up the directory tree, grabbing dir names on the way. */
|
||
|
|
while (1) {
|
||
|
|
same_device = 0;
|
||
|
|
found = 0;
|
||
|
|
|
||
|
|
/* Get the inode for the parent directory */
|
||
|
|
if (chdir("..") == -1) return((char *)NULL);
|
||
|
|
if (stat(".", &parent) == -1) return((char *)NULL);
|
||
|
|
if ((parent.st_mode & S_IFMT) != S_IFDIR) return((char *)NULL);
|
||
|
|
if (current.st_dev == parent.st_dev) same_device = 1;
|
||
|
|
|
||
|
|
/* At the root, "." is the same as ".." */
|
||
|
|
if (same_device && current.st_ino == parent.st_ino) break;
|
||
|
|
|
||
|
|
/* Search the parent directory for the current entry */
|
||
|
|
if ((fd = open(".", O_RDONLY)) == -1) return((char *)NULL);
|
||
|
|
while (!found && read(fd, (char *)&d, DIRECT_SIZE) == DIRECT_SIZE) {
|
||
|
|
if (d.d_ino == 0L) continue; /* empty slot */
|
||
|
|
if (same_device) {
|
||
|
|
if (current.st_ino == d.d_ino) found = 1;
|
||
|
|
} else {
|
||
|
|
temp_name[0] = '\0';
|
||
|
|
strncat(temp_name, d.d_name, NAME_MAX);
|
||
|
|
if (stat(temp_name, &dir_entry) == -1) {
|
||
|
|
close(fd);
|
||
|
|
go_back(path);
|
||
|
|
return((char *)NULL);
|
||
|
|
}
|
||
|
|
if (current.st_dev == dir_entry.st_dev &&
|
||
|
|
current.st_ino == dir_entry.st_ino)
|
||
|
|
found = 1;
|
||
|
|
}
|
||
|
|
}
|
||
|
|
|
||
|
|
close(fd);
|
||
|
|
if (!found) {
|
||
|
|
go_back(path);
|
||
|
|
return((char *)NULL);
|
||
|
|
}
|
||
|
|
if (strlen(path) + NAME_MAX + 1 > PATH_MAX) {
|
||
|
|
errno = ERANGE;
|
||
|
|
go_back(path);
|
||
|
|
return((char *)NULL);
|
||
|
|
}
|
||
|
|
strcat(path, "/");
|
||
|
|
strncat(path, d.d_name, NAME_MAX);
|
||
|
|
current.st_dev = parent.st_dev;
|
||
|
|
current.st_ino = parent.st_ino;
|
||
|
|
}
|
||
|
|
|
||
|
|
/* Copy the reversed path name into <buffer> */
|
||
|
|
if (strlen(path) + 1 > size) {
|
||
|
|
errno = ERANGE;
|
||
|
|
go_back(path);
|
||
|
|
return((char *)NULL);
|
||
|
|
}
|
||
|
|
if (strlen(path) == 0) {
|
||
|
|
strcpy(buffer, "/");
|
||
|
|
return(buffer);
|
||
|
|
}
|
||
|
|
*buffer = '\0';
|
||
|
|
while ((r = strrchr(path, '/')) != (char *)NULL) {
|
||
|
|
strcat(buffer, r);
|
||
|
|
*r = '\0';
|
||
|
|
}
|
||
|
|
return(chdir(buffer) ? (char *)NULL : buffer);
|
||
|
|
}
|
||
|
|
|
||
|
|
PRIVATE void go_back(path)
|
||
|
|
char *path;
|
||
|
|
{
|
||
|
|
/* If getcwd() gets in trouble and can't complete normally, reverse the
|
||
|
|
* path built so far and change there so we end up in the directory that
|
||
|
|
* we started in.
|
||
|
|
*/
|
||
|
|
|
||
|
|
char *r;
|
||
|
|
|
||
|
|
while ((r = strrchr(path, '/')) != (char *)NULL) {
|
||
|
|
chdir(r+1);
|
||
|
|
*r = '\0';
|
||
|
|
}
|
||
|
|
}
|