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|
/*
* Copyright (C) 2000-2006 Erik Andersen <andersen@uclibc.org>
*
* Licensed under the LGPL v2.1, see the file COPYING.LIB in this tarball.
*/
/* These functions find the absolute path to the current working directory. */
#include <stdlib.h>
#include <errno.h>
#include <sys/stat.h>
#include <dirent.h>
#include <string.h>
#include <unistd.h>
#include <sys/param.h>
#include <sys/syscall.h>
libc_hidden_proto(getcwd)
libc_hidden_proto(getpagesize)
/* Experimentally off - libc_hidden_proto(strcat) */
/* Experimentally off - libc_hidden_proto(strcpy) */
/* Experimentally off - libc_hidden_proto(strncpy) */
/* Experimentally off - libc_hidden_proto(strlen) */
libc_hidden_proto(opendir)
libc_hidden_proto(readdir)
libc_hidden_proto(closedir)
/* libc_hidden_proto(stat) */
#ifdef __NR_getcwd
# define __NR___syscall_getcwd __NR_getcwd
static __always_inline
_syscall2(int, __syscall_getcwd, char *, buf, unsigned long, size)
#else
/* If the syscall is not present, we have to walk up the
* directory tree till we hit the root. Now we _could_
* use /proc/self/cwd if /proc is mounted... That approach
* is left an an exercise for the reader... */
/* Seems a few broken filesystems (like coda) don't like this */
/* #undef FAST_DIR_SEARCH_POSSIBLE on Linux */
/* Routine to find the step back down */
static char *search_dir(dev_t this_dev, ino_t this_ino, char *path_buf, int path_size)
{
DIR *dp;
struct dirent *d;
char *ptr;
int slen;
struct stat st;
# ifdef FAST_DIR_SEARCH_POSSIBLE
/* The test is for ELKS lib 0.0.9, this should be fixed in the real kernel */
int slow_search = (sizeof(ino_t) != sizeof(d->d_ino));
# endif
if (stat(path_buf, &st) < 0) {
goto oops;
}
# ifdef FAST_DIR_SEARCH_POSSIBLE
if (this_dev != st.st_dev)
slow_search = 1;
# endif
slen = strlen(path_buf);
ptr = path_buf + slen - 1;
if (*ptr != '/') {
if (slen + 2 > path_size) {
goto oops;
}
strcpy(++ptr, "/");
slen++;
}
slen++;
dp = opendir(path_buf);
if (dp == 0) {
goto oops;
}
while ((d = readdir(dp)) != 0) {
# ifdef FAST_DIR_SEARCH_POSSIBLE
if (slow_search || this_ino == d->d_ino) {
# endif
if (slen + strlen(d->d_name) > path_size) {
goto oops;
}
strcpy(ptr + 1, d->d_name);
if (stat(path_buf, &st) < 0)
continue;
if (st.st_ino == this_ino && st.st_dev == this_dev) {
closedir(dp);
return path_buf;
}
# ifdef FAST_DIR_SEARCH_POSSIBLE
}
# endif
}
closedir(dp);
return 0;
oops:
__set_errno(ERANGE);
return 0;
}
/* Routine to go up tree */
static char *recurser(char *path_buf, int path_size, dev_t root_dev, ino_t root_ino)
{
struct stat st;
dev_t this_dev;
ino_t this_ino;
if (stat(path_buf, &st) < 0) {
if (errno != EFAULT)
goto oops;
return 0;
}
this_dev = st.st_dev;
this_ino = st.st_ino;
if (this_dev == root_dev && this_ino == root_ino) {
if (path_size < 2) {
goto oops;
}
strcpy(path_buf, "/");
return path_buf;
}
if (strlen(path_buf) + 4 > path_size) {
goto oops;
}
strcat(path_buf, "/..");
if (recurser(path_buf, path_size, root_dev, root_ino) == 0)
return 0;
return search_dir(this_dev, this_ino, path_buf, path_size);
oops:
__set_errno(ERANGE);
return 0;
}
static __always_inline
int __syscall_getcwd(char * buf, unsigned long size)
{
int len;
char *cwd;
struct stat st;
int olderrno;
olderrno = errno;
len = -1;
/* get stat for root to have a valid parameters for the terminating condition */
if (stat("/", &st) < 0) {
/* root dir not found! */
return -1;
}
/* start with actual dir */
if (buf) strncpy(buf, ".", size);
cwd = recurser(buf, size, st.st_dev, st.st_ino);
if (cwd) {
len = strlen(buf) + 1;
__set_errno(olderrno);
}
return len;
}
#endif /* __NR_getcwd */
char *getcwd(char *buf, size_t size)
{
int ret;
char *path;
size_t alloc_size = size;
if (size == 0) {
if (buf != NULL) {
__set_errno(EINVAL);
return NULL;
}
alloc_size = MAX (PATH_MAX, getpagesize ());
}
path=buf;
if (buf == NULL) {
path = malloc(alloc_size);
if (path == NULL)
return NULL;
}
ret = __syscall_getcwd(path, alloc_size);
if (ret >= 0)
{
if (buf == NULL && size == 0)
buf = realloc(path, ret);
if (buf == NULL)
buf = path;
return buf;
}
if (buf == NULL)
free (path);
return NULL;
}
libc_hidden_def(getcwd)
|
