[PATCH v2] initramfs: Use KBUILD_BUILD_TIMESTAMP for generated entries

Michal Marek
2011-04-11T15:06:45Z

gen_init_cpio gets the current time and uses it for each symlink,
special file, and directory. Grab the current time once and make it
possible to override it with the KBUILD_BUILD_TIMESTAMP variable for
reproducible builds.

Signed-off-by: Michal Marek <mmarek@suse.cz>
---
Documentation/kbuild/kbuild.txt | 3 +-
scripts/gen_initramfs_list.sh | 9 ++++++-
usr/gen_init_cpio.c | 53 +++++++++++++++++++++++++++++---------
3 files changed, 50 insertions(+), 15 deletions(-)

diff --git a/Documentation/kbuild/kbuild.txt b/Documentation/kbuild/kbuild.txt
index 27d7928..46e6cb8 100644
--- a/Documentation/kbuild/kbuild.txt
+++ b/Documentation/kbuild/kbuild.txt
@@ -200,7 +200,8 @@ To get all available archs you can also specify all. E.g.:
KBUILD_BUILD_TIMESTAMP
--------------------------------------------------
Setting this to a date string overrides the timestamp used in the
-UTS_VERSION definition (uname -v in the running kernel). The default value
+UTS_VERSION definition (uname -v in the running kernel). The value has to
+be a string that can be passed to date -d. The default value
is the output of the date command at one point during build.

KBUILD_BUILD_USER, KBUILD_BUILD_HOST
diff --git a/scripts/gen_initramfs_list.sh b/scripts/gen_initramfs_list.sh
index 4a43fe1..d44cf67 100644
--- a/scripts/gen_initramfs_list.sh
+++ b/scripts/gen_initramfs_list.sh
@@ -287,8 +287,15 @@ done
# we are carefull to delete tmp files
if [ ! -z ${output_file} ]; then
if [ -z ${cpio_file} ]; then
+ timestamp=
+ if test -n "$KBUILD_BUILD_TIMESTAMP"; then
+ timestamp="$(date -d"$KBUILD_BUILD_TIMESTAMP" +%s || :)"
+ if test -n "$timestamp"; then
+ timestamp="-t $timestamp"
+ fi
+ fi
cpio_tfile="$(mktemp ${TMPDIR:-/tmp}/cpiofile.XXXXXX)"
- usr/gen_init_cpio ${cpio_list} > ${cpio_tfile}
+ usr/gen_init_cpio $timestamp ${cpio_list} > ${cpio_tfile}
else
cpio_tfile=${cpio_file}
fi
diff --git a/usr/gen_init_cpio.c b/usr/gen_init_cpio.c
index 7f06884..af0f22f 100644
--- a/usr/gen_init_cpio.c
+++ b/usr/gen_init_cpio.c
@@ -22,6 +22,7 @@

static unsigned int offset;
static unsigned int ino = 721;
+static time_t default_mtime;

struct file_handler {
const char *type;
@@ -102,7 +103,6 @@ static int cpio_mkslink(const char *name, const char *target,
unsigned int mode, uid_t uid, gid_t gid)
{
char s[256];
- time_t mtime = time(NULL);

if (name[0] == '/')
name++;
@@ -114,7 +114,7 @@ static int cpio_mkslink(const char *name, const char *target,
(long) uid, /* uid */
(long) gid, /* gid */
1, /* nlink */
- (long) mtime, /* mtime */
+ (long) default_mtime, /* mtime */
(unsigned)strlen(target)+1, /* filesize */
3, /* major */
1, /* minor */
@@ -152,7 +152,6 @@ static int cpio_mkgeneric(const char *name, unsigned int mode,
uid_t uid, gid_t gid)
{
char s[256];
- time_t mtime = time(NULL);

if (name[0] == '/')
name++;
@@ -164,7 +163,7 @@ static int cpio_mkgeneric(const char *name, unsigned int mode,
(long) uid, /* uid */
(long) gid, /* gid */
2, /* nlink */
- (long) mtime, /* mtime */
+ (long) default_mtime, /* mtime */
0, /* filesize */
3, /* major */
1, /* minor */
@@ -242,7 +241,6 @@ static int cpio_mknod(const char *name, unsigned int mode,
unsigned int maj, unsigned int min)
{
char s[256];
- time_t mtime = time(NULL);

if (dev_type == 'b')
mode |= S_IFBLK;
@@ -259,7 +257,7 @@ static int cpio_mknod(const char *name, unsigned int mode,
(long) uid, /* uid */
(long) gid, /* gid */
1, /* nlink */
- (long) mtime, /* mtime */
+ (long) default_mtime, /* mtime */
0, /* filesize */
3, /* major */
1, /* minor */
@@ -460,7 +458,7 @@ static int cpio_mkfile_line(const char *line)
static void usage(const char *prog)
{
fprintf(stderr, "Usage:\n"
- "\t%s <cpio_list>\n"
+ "\t%s [-t <timestamp>] <cpio_list>\n"
"\n"
"<cpio_list> is a file containing newline separated entries that\n"
"describe the files to be included in the initramfs archive:\n"
@@ -491,7 +489,11 @@ static void usage(const char *prog)
"nod /dev/console 0600 0 0 c 5 1\n"
"dir /root 0700 0 0\n"
"dir /sbin 0755 0 0\n"
- "file /sbin/kinit /usr/src/klibc/kinit/kinit 0755 0 0\n",
+ "file /sbin/kinit /usr/src/klibc/kinit/kinit 0755 0 0\n"
+ "\n"
+ "<timestamp> is time in seconds since Epoch that will be used\n"
+ "as mtime for symlinks, special files and directories. The default\n"
+ "is to use the current time for these entries.\n",
prog);
}

@@ -529,17 +531,42 @@ int main (int argc, char *argv[])
char *args, *type;
int ec = 0;
int line_nr = 0;
+ const char *filename;
+
+ default_mtime = time(NULL);
+ while (1) {
+ int opt = getopt(argc, argv, "t:h");
+ char *invalid;

- if (2 != argc) {
+ if (opt == -1)
+ break;
+ switch (opt) {
+ case 't':
+ default_mtime = strtol(optarg, &invalid, 10);
+ if (!*optarg || *invalid) {
+ fprintf(stderr, "Invalid timestamp: %s\n",
+ optarg);
+ usage(argv[0]);
+ exit(1);
+ }
+ break;
+ case 'h':
+ case '?':
+ usage(argv[0]);
+ exit(opt == 'h' ? 0 : 1);
+ }
+ }
+
+ if (argc - optind != 1) {
usage(argv[0]);
exit(1);
}
-
- if (!strcmp(argv[1], "-"))
+ filename = argv[optind];
+ if (!strcmp(filename, "-"))
cpio_list = stdin;
- else if (! (cpio_list = fopen(argv[1], "r"))) {
+ else if (!(cpio_list = fopen(filename, "r"))) {
fprintf(stderr, "ERROR: unable to open '%s': %s\n\n",
- argv[1], strerror(errno));
+ filename, strerror(errno));
usage(argv[0]);
exit(1);
}
--
1.7.4.1