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initramfs: Use KBUILD_BUILD_TIMESTAMP for generated entries
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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 <[email protected]>
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michal42 committed Apr 18, 2011
1 parent 53e6892 commit a8b8017
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Showing 3 changed files with 50 additions and 15 deletions.
3 changes: 2 additions & 1 deletion Documentation/kbuild/kbuild.txt
Original file line number Diff line number Diff line change
Expand Up @@ -205,7 +205,8 @@ gcc -W... options for more extensive build-time checking.
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
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9 changes: 8 additions & 1 deletion scripts/gen_initramfs_list.sh
Original file line number Diff line number Diff line change
Expand Up @@ -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
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53 changes: 40 additions & 13 deletions usr/gen_init_cpio.c
Original file line number Diff line number Diff line change
Expand Up @@ -22,6 +22,7 @@

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

struct file_handler {
const char *type;
Expand Down Expand Up @@ -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++;
Expand All @@ -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 */
Expand Down Expand Up @@ -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++;
Expand All @@ -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 */
Expand Down Expand Up @@ -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;
Expand All @@ -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 */
Expand Down Expand Up @@ -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"
Expand Down Expand Up @@ -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);
}

Expand Down Expand Up @@ -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);
}
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