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authorNye Liu <nyet@nyet.org>2008-10-15 22:01:40 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2008-10-16 11:21:31 -0700
commit889d51a10712b6fd6175196626de2116858394f4 (patch)
tree3dc6575a4f2429cdd320c05de209c88a73a9da1e /init/initramfs.c
parent9ba16087d9f996a93ab6f4453a52a4b24bc1f25c (diff)
downloadlinux-linaro-stable-889d51a10712b6fd6175196626de2116858394f4.tar.gz
initramfs: add option to preserve mtime from initramfs cpio images
When unpacking the cpio into the initramfs, mtimes are not preserved by default. This patch adds an INITRAMFS_PRESERVE_MTIME option that allows mtimes stored in the cpio image to be used when constructing the initramfs. For embedded applications that run exclusively out of the initramfs, this is invaluable: When building embedded application initramfs images, its nice to know when the files were actually created during the build process - that makes it easier to see what files were modified when so we can compare the files that are being used on the image with the files used during the build process. This might help (for example) to determine if the target system has all the updated files you expect to see w/o having to check MD5s etc. In our environment, the whole system runs off the initramfs partition, and seeing the modified times of the shared libraries (for example) helps us find bugs that may have been introduced by the build system incorrectly propogating outdated shared libraries into the image. Similarly, many of the initializion/configuration files in /etc might be dynamically built by the build system, and knowing when they were modified helps us sanity check whether the target system has the "latest" files etc. Finally, we might use last modified times to determine whether a hot fix should be applied or not to the running ramfs. Signed-off-by: Nye Liu <nyet@nyet.org> Cc: Al Viro <viro@zeniv.linux.org.uk> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'init/initramfs.c')
-rw-r--r--init/initramfs.c53
1 files changed, 53 insertions, 0 deletions
diff --git a/init/initramfs.c b/init/initramfs.c
index 644fc01ad5f0..4f5ba75aaa7c 100644
--- a/init/initramfs.c
+++ b/init/initramfs.c
@@ -6,6 +6,7 @@
#include <linux/delay.h>
#include <linux/string.h>
#include <linux/syscalls.h>
+#include <linux/utime.h>
static __initdata char *message;
static void __init error(char *x)
@@ -72,6 +73,49 @@ static void __init free_hash(void)
}
}
+static long __init do_utime(char __user *filename, time_t mtime)
+{
+ struct timespec t[2];
+
+ t[0].tv_sec = mtime;
+ t[0].tv_nsec = 0;
+ t[1].tv_sec = mtime;
+ t[1].tv_nsec = 0;
+
+ return do_utimes(AT_FDCWD, filename, t, AT_SYMLINK_NOFOLLOW);
+}
+
+static __initdata LIST_HEAD(dir_list);
+struct dir_entry {
+ struct list_head list;
+ char *name;
+ time_t mtime;
+};
+
+static void __init dir_add(const char *name, time_t mtime)
+{
+ struct dir_entry *de = kmalloc(sizeof(struct dir_entry), GFP_KERNEL);
+ if (!de)
+ panic("can't allocate dir_entry buffer");
+ INIT_LIST_HEAD(&de->list);
+ de->name = kstrdup(name, GFP_KERNEL);
+ de->mtime = mtime;
+ list_add(&de->list, &dir_list);
+}
+
+static void __init dir_utime(void)
+{
+ struct dir_entry *de, *tmp;
+ list_for_each_entry_safe(de, tmp, &dir_list, list) {
+ list_del(&de->list);
+ do_utime(de->name, de->mtime);
+ kfree(de->name);
+ kfree(de);
+ }
+}
+
+static __initdata time_t mtime;
+
/* cpio header parsing */
static __initdata unsigned long ino, major, minor, nlink;
@@ -97,6 +141,7 @@ static void __init parse_header(char *s)
uid = parsed[2];
gid = parsed[3];
nlink = parsed[4];
+ mtime = parsed[5];
body_len = parsed[6];
major = parsed[7];
minor = parsed[8];
@@ -130,6 +175,7 @@ static inline void __init eat(unsigned n)
count -= n;
}
+static __initdata char *vcollected;
static __initdata char *collected;
static __initdata int remains;
static __initdata char *collect;
@@ -271,6 +317,7 @@ static int __init do_name(void)
if (wfd >= 0) {
sys_fchown(wfd, uid, gid);
sys_fchmod(wfd, mode);
+ vcollected = kstrdup(collected, GFP_KERNEL);
state = CopyFile;
}
}
@@ -278,12 +325,14 @@ static int __init do_name(void)
sys_mkdir(collected, mode);
sys_chown(collected, uid, gid);
sys_chmod(collected, mode);
+ dir_add(collected, mtime);
} else if (S_ISBLK(mode) || S_ISCHR(mode) ||
S_ISFIFO(mode) || S_ISSOCK(mode)) {
if (maybe_link() == 0) {
sys_mknod(collected, mode, rdev);
sys_chown(collected, uid, gid);
sys_chmod(collected, mode);
+ do_utime(collected, mtime);
}
}
return 0;
@@ -294,6 +343,8 @@ static int __init do_copy(void)
if (count >= body_len) {
sys_write(wfd, victim, body_len);
sys_close(wfd);
+ do_utime(vcollected, mtime);
+ kfree(vcollected);
eat(body_len);
state = SkipIt;
return 0;
@@ -311,6 +362,7 @@ static int __init do_symlink(void)
clean_path(collected, 0);
sys_symlink(collected + N_ALIGN(name_len), collected);
sys_lchown(collected, uid, gid);
+ do_utime(collected, mtime);
state = SkipIt;
next_state = Reset;
return 0;
@@ -466,6 +518,7 @@ static char * __init unpack_to_rootfs(char *buf, unsigned len, int check_only)
buf += inptr;
len -= inptr;
}
+ dir_utime();
kfree(window);
kfree(name_buf);
kfree(symlink_buf);