simplify and fix getcwd

The fallback code is not used as all supported kernels have the
syscall. Check if a absolute path is returned from syscall.

libc/sysdeps/linux/common/getcwd.c

@@ -16,154 +16,10 @@
 #include <sys/syscall.h>
 
 
-
-#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) {
-	    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) {
-			    closedir(dp);
-			    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;
@@ -184,7 +40,7 @@ char *getcwd(char *buf, size_t size)
 	    return NULL;
     }
     ret = __syscall_getcwd(path, alloc_size);
-    if (ret >= 0)
+    if (ret > 0 && path[0] == '/')
     {
 	if (buf == NULL && size == 0)
 	    buf = realloc(path, ret);