[src/netbsd-7]: src/lib/librt Pull up following revision(s) (requested by mar...

[snj <snj%NetBSD.org@localhost>]

details:   https://anonhg.NetBSD.org/src/rev/c3c2b2ce42b3
branches:  netbsd-7
changeset: 799866:c3c2b2ce42b3
user:      snj <snj%NetBSD.org@localhost>
date:      Tue Mar 22 09:04:19 2016 +0000

description:
Pull up following revision(s) (requested by martin in ticket #1144):
        lib/librt/shm.c: revisions 1.2, 1.3
Allow /var/shm to be a symlink to a properly set up directory.
--
Simplify previous by just doing an open() on the directory and then using
the fstat* family to test for all relevant details.
Clean up buffer sizes and clarify a length check. Based on input from dholland.

diffstat:

 lib/librt/shm.c |  51 ++++++++++++++++++++++++++++-----------------------
 1 files changed, 28 insertions(+), 23 deletions(-)

diffs (111 lines):

diff -r 53c6f5c7ffb9 -r c3c2b2ce42b3 lib/librt/shm.c
--- a/lib/librt/shm.c   Sun Mar 13 12:16:40 2016 +0000
+++ b/lib/librt/shm.c   Tue Mar 22 09:04:19 2016 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: shm.c,v 1.1 2013/12/19 19:11:50 rmind Exp $    */
+/*     $NetBSD: shm.c,v 1.1.6.1 2016/03/22 09:04:19 snj Exp $  */
 
 /*-
  * Copyright (c) 2013 The NetBSD Foundation, Inc.
@@ -34,7 +34,7 @@
  */
 
 #include <sys/cdefs.h>
-__RCSID("$NetBSD: shm.c,v 1.1 2013/12/19 19:11:50 rmind Exp $");
+__RCSID("$NetBSD: shm.c,v 1.1.6.1 2016/03/22 09:04:19 snj Exp $");
 
 #include <sys/mman.h>
 #include <sys/mount.h>
@@ -57,31 +57,36 @@
 
 #define        MOUNT_SHMFS             MOUNT_TMPFS
 
-static const char *            _shmfs_path = NULL;
+static bool                    shm_ok = false;
 
 static bool
 _shm_check_fs(void)
 {
-       const char *shmfs = SHMFS_DIR_PATH;
+       int fd;
        struct statvfs sv;
        struct stat st;
 
-       if (statvfs1(shmfs, &sv, ST_NOWAIT) == -1) {
+       fd = open(SHMFS_DIR_PATH, O_DIRECTORY|O_RDONLY);
+       if (fd == -1)
                return false;
-       }
-       if (strncmp(sv.f_fstypename, MOUNT_SHMFS, sizeof(sv.f_fstypename))) {
-               return false;
-       }
+
+       if (fstatvfs1(fd, &sv, ST_NOWAIT) == -1)
+               goto out;
+
+       if (strncmp(sv.f_fstypename, MOUNT_SHMFS, sizeof(sv.f_fstypename)))
+               goto out;
 
-       if (lstat(shmfs, &st) == -1) {
-               return false;
-       }
-       if ((st.st_mode & SHMFS_DIR_MODE) != SHMFS_DIR_MODE) {
-               return false;
-       }
+       if (fstat(fd, &st) == -1)
+               goto out;
+
+       if ((st.st_mode & SHMFS_DIR_MODE) != SHMFS_DIR_MODE)
+               goto out;
 
-       _shmfs_path = shmfs;
-       return true;
+       shm_ok = true;
+
+out:
+       close(fd);
+       return shm_ok;
 }
 
 static bool
@@ -89,7 +94,7 @@
 {
        int ret;
 
-       if (__predict_false(!_shmfs_path) && !_shm_check_fs()) {
+       if (__predict_false(!shm_ok) && !_shm_check_fs()) {
                errno = ENOTSUP;
                return false;
        }
@@ -103,10 +108,10 @@
                return false;
        }
 
-       ret = snprintf(buf, len, "%s/%s%s",
-           _shmfs_path, SHMFS_OBJ_PREFIX, name);
+       ret = snprintf(buf, len, SHMFS_DIR_PATH "/" SHMFS_OBJ_PREFIX "%s",
+           name);
 
-       if ((size_t)ret >= PATH_MAX) {
+       if ((size_t)ret >= len) {
                errno = ENAMETOOLONG;
                return false;
        }
@@ -116,7 +121,7 @@
 int
 shm_open(const char *name, int oflag, mode_t mode)
 {
-       char path[PATH_MAX + 1];
+       char path[PATH_MAX];
 
        if (!_shm_get_path(path, sizeof(path), name)) {
                return -1;
@@ -127,7 +132,7 @@
 int
 shm_unlink(const char *name)
 {
-       char path[PATH_MAX + 1];
+       char path[PATH_MAX];
 
        if (!_shm_get_path(path, sizeof(path), name)) {
                return -1;