Don't call lstat() before readlink() just to see if it's a symlink,

as readlink() will tell you that more cheaply.

ok millert@

diff --git a/lib/libc/stdlib/realpath.c b/lib/libc/stdlib/realpath.c
index 27f1a29..c691252 100644 (file)
--- a/lib/libc/stdlib/realpath.c
+++ b/lib/libc/stdlib/realpath.c
@@ -1,4 +1,4 @@
-/*     $OpenBSD: realpath.c,v 1.20 2015/10/13 20:55:37 millert Exp $ */
+/*     $OpenBSD: realpath.c,v 1.21 2016/08/28 04:08:59 guenther Exp $ */
 /*
  * Copyright (c) 2003 Constantin S. Svintsoff <kostik@iclub.nsu.ru>
  *
@@ -27,8 +27,6 @@
  * SUCH DAMAGE.
  */
 
-#include <sys/stat.h>
-
 #include <errno.h>
 #include <stdlib.h>
 #include <string.h>
@@ -47,7 +45,6 @@
 char *
 realpath(const char *path, char *resolved)
 {
-       struct stat sb;
        char *p, *q, *s;
        size_t left_len, resolved_len;
        unsigned symlinks;
@@ -148,21 +145,27 @@ realpath(const char *path, char *resolved)
                        errno = ENAMETOOLONG;
                        goto err;
                }
-               if (lstat(resolved, &sb) != 0) {
-                       if (errno == ENOENT && p == NULL) {
-                               errno = serrno;
-                               return (resolved);
+               slen = readlink(resolved, symlink, sizeof(symlink) - 1);
+               if (slen < 0) {
+                       switch (errno) {
+                       case EINVAL:
+                               /* not a symlink, continue to next component */
+                               continue;
+                       case ENOENT:
+                               if (p == NULL) {
+                                       errno = serrno;
+                                       return (resolved);
+                               }
+                               /* FALLTHROUGH */
+                       default:
+                               goto err;
                        }
-                       goto err;
-               }
-               if (S_ISLNK(sb.st_mode)) {
+               } else {
                        if (symlinks++ > SYMLOOP_MAX) {
                                errno = ELOOP;
                                goto err;
                        }
-                       slen = readlink(resolved, symlink, sizeof(symlink) - 1);
-                       if (slen < 0)
-                               goto err;
+
                        symlink[slen] = '\0';
                        if (symlink[0] == '/') {
                                resolved[1] = 0;

diff --git a/libexec/ld.so/dl_realpath.c b/libexec/ld.so/dl_realpath.c
index 498ee3c..91a8668 100644 (file)
--- a/libexec/ld.so/dl_realpath.c
+++ b/libexec/ld.so/dl_realpath.c
@@ -1,4 +1,4 @@
-/*     $OpenBSD: dl_realpath.c,v 1.3 2014/10/19 03:56:28 doug Exp $ */
+/*     $OpenBSD: dl_realpath.c,v 1.4 2016/08/28 04:08:59 guenther Exp $ */
 /*
  * Copyright (c) 2003 Constantin S. Svintsoff <kostik@iclub.nsu.ru>
  *
@@ -28,11 +28,10 @@
  */
 
 #include <sys/types.h>
+#include <sys/errno.h>
 #include <limits.h>
 #include "archdep.h"
 
-#define ENOENT -2
-
 /*
  * This file was copied from libc/stdlib/realpath.c and modified for ld.so's
  * syscall method which returns -errno.
@@ -48,12 +47,11 @@
 char *
 _dl_realpath(const char *path, char *resolved)
 {
-       struct stat sb;
        const char *p, *s;
        char *q;
        size_t left_len, resolved_len;
        unsigned symlinks;
-       int slen, mem_allocated, ret;
+       int slen, mem_allocated;
        char left[PATH_MAX], next_token[PATH_MAX], symlink[PATH_MAX];
 
        if (path[0] == '\0') {
@@ -135,27 +133,33 @@ _dl_realpath(const char *path, char *resolved)
                }
 
                /*
-                * Append the next path component and lstat() it. If
-                * lstat() fails we still can return successfully if
-                * there are no more path components left.
+                * Append the next path component and readlink() it. If
+                * readlink() fails we still can return successfully if
+                * it wasn't a exists but isn't a symlink, or if there
+                * are no more path components left.
                 */
                resolved_len = _dl_strlcat(resolved, next_token, PATH_MAX);
                if (resolved_len >= PATH_MAX) {
                        goto err;
                }
-               if ((ret = _dl_lstat(resolved, &sb)) != 0) {
-                       if (ret == ENOENT && p == NULL) {
-                               return (resolved);
+               slen = _dl_readlink(resolved, symlink, sizeof(symlink) - 1);
+               if (slen < 0) {
+                       switch (slen) {
+                       case -EINVAL:
+                               /* not a symlink, continue to next component */
+                               continue;
+                       case -ENOENT:
+                               if (p == NULL)
+                                       return (resolved);
+                               /* FALLTHROUGH */
+                       default:
+                               goto err;
                        }
-                       goto err;
-               }
-               if (S_ISLNK(sb.st_mode)) {
+               } else {
                        if (symlinks++ > SYMLOOP_MAX) {
                                goto err;
                        }
-                       slen = _dl_readlink(resolved, symlink, sizeof(symlink) - 1);
-                       if (slen < 0)
-                               goto err;
+
                        symlink[slen] = '\0';
                        if (symlink[0] == '/') {
                                resolved[1] = 0;