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systemd/0004-implement-a-union-to-pad-out-file_handle.patch

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From 370c860f748d149097710dc7952a64f627db9de7 Mon Sep 17 00:00:00 2001
From: Dave Reisner <dreisner@archlinux.org>
Date: Sat, 19 Apr 2014 13:22:35 -0400
Subject: [PATCH] implement a union to pad out file_handle
Cases where name_to_handle_at is used allocated the full struct to be
MAX_HANDLE_SZ, and assigned this size to handle_bytes. This is wrong
since handle_bytes should describe the length of the flexible array
member and not the whole struct.
Define a union type which includes sufficient padding to allow
assignment of MAX_HANDLE_SZ to be correct.
---
src/libudev/libudev-monitor.c | 6 ++----
src/readahead/readahead-common.c | 6 ++----
src/shared/util.h | 6 ++++++
src/tmpfiles/tmpfiles.c | 11 ++++-------
4 files changed, 14 insertions(+), 15 deletions(-)
diff --git src/libudev/libudev-monitor.c src/libudev/libudev-monitor.c
index 3f7436b..0a2ab82 100644
--- src/libudev/libudev-monitor.c
+++ src/libudev/libudev-monitor.c
@@ -108,15 +108,13 @@ static struct udev_monitor *udev_monitor_new(struct udev *udev)
/* we consider udev running when /dev is on devtmpfs */
static bool udev_has_devtmpfs(struct udev *udev) {
- struct file_handle *h;
+ union file_handle_union h = { .handle.handle_bytes = MAX_HANDLE_SZ, };
int mount_id;
_cleanup_fclose_ FILE *f = NULL;
char line[LINE_MAX], *e;
int r;
- h = alloca(MAX_HANDLE_SZ);
- h->handle_bytes = MAX_HANDLE_SZ;
- r = name_to_handle_at(AT_FDCWD, "/dev", h, &mount_id, 0);
+ r = name_to_handle_at(AT_FDCWD, "/dev", &h.handle, &mount_id, 0);
if (r < 0)
return false;
diff --git src/readahead/readahead-common.c src/readahead/readahead-common.c
index 5ffa88b..49679fc 100644
--- src/readahead/readahead-common.c
+++ src/readahead/readahead-common.c
@@ -75,7 +75,7 @@ int fs_on_ssd(const char *p) {
if (major(st.st_dev) == 0) {
_cleanup_fclose_ FILE *f = NULL;
int mount_id;
- struct file_handle *h;
+ union file_handle_union h = { .handle.handle_bytes = MAX_HANDLE_SZ, };
/* Might be btrfs, which exposes "ssd" as mount flag if it is on ssd.
*
@@ -83,9 +83,7 @@ int fs_on_ssd(const char *p) {
* and then lookup the mount ID in mountinfo to find
* the mount options. */
- h = alloca(MAX_HANDLE_SZ);
- h->handle_bytes = MAX_HANDLE_SZ;
- r = name_to_handle_at(AT_FDCWD, p, h, &mount_id, AT_SYMLINK_FOLLOW);
+ r = name_to_handle_at(AT_FDCWD, p, &h.handle, &mount_id, AT_SYMLINK_FOLLOW);
if (r < 0)
return false;
diff --git src/shared/util.h src/shared/util.h
index 900f1cf..891848a 100644
--- src/shared/util.h
+++ src/shared/util.h
@@ -22,6 +22,7 @@
***/
#include <alloca.h>
+#include <fcntl.h>
#include <inttypes.h>
#include <time.h>
#include <sys/time.h>
@@ -883,3 +884,8 @@ int fd_warn_permissions(const char *path
unsigned long personality_from_string(const char *p);
const char *personality_to_string(unsigned long);
+
+union file_handle_union {
+ struct file_handle handle;
+ char padding[sizeof(struct file_handle) + MAX_HANDLE_SZ];
+};
diff --git src/tmpfiles/tmpfiles.c src/tmpfiles/tmpfiles.c
index 33e7cbc..04b472d 100644
--- src/tmpfiles/tmpfiles.c
+++ src/tmpfiles/tmpfiles.c
@@ -217,19 +217,16 @@ static bool unix_socket_alive(const char *fn) {
}
static int dir_is_mount_point(DIR *d, const char *subdir) {
- struct file_handle *h;
+ union file_handle_union h = { .handle.handle_bytes = MAX_HANDLE_SZ };
int mount_id_parent, mount_id;
int r_p, r;
- h = alloca(MAX_HANDLE_SZ);
-
- h->handle_bytes = MAX_HANDLE_SZ;
- r_p = name_to_handle_at(dirfd(d), ".", h, &mount_id_parent, 0);
+ r_p = name_to_handle_at(dirfd(d), ".", &h.handle, &mount_id_parent, 0);
if (r_p < 0)
r_p = -errno;
- h->handle_bytes = MAX_HANDLE_SZ;
- r = name_to_handle_at(dirfd(d), subdir, h, &mount_id, 0);
+ h.handle.handle_bytes = MAX_HANDLE_SZ;
+ r = name_to_handle_at(dirfd(d), subdir, &h.handle, &mount_id, 0);
if (r < 0)
r = -errno;
--
1.7.9.2