| Message ID | 20231220-gen_init_cpio-reproducible-v1-1-d40da0b2c15c@arista.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | gen_init_cpio: Apply mtime supplied by user to all file types | expand |
On Wed, Dec 20, 2023 at 9:33 AM Dmitry Safonov <dima@arista.com> wrote: > > Currently gen_init_cpio -d <timestamp> is applied to symlinks, > directories and special files. These files are created by > gen_init_cpio from their description. Without <timestamp> option > current time(NULL) is used. And regular files that go in initramfs > are created before cpio generation, so their mtime(s) are preserved. > > This is usually not an issue as reproducible builds should rebuild > everything in the distribution, including binaries, configs and whatever > other regular files may find their way into kernel's initramfs. > > On the other hand, gen_initramfs.sh usage claims: > > -d <date> Use date for all file mtime values > > Ar Arista initramfs files are managed with version control system > that preserves mtime. Those are configs, boot parameters, init scripts, > version files, platform-specific files, probably some others, too. > > While it's certainly possible to work this around by copying the file > into temp directory and adjusting mtime prior to gen_init_cpio call, > I don't see why it needs workarounds. > > The intended user of -d <date> option is the one that needs to create > a reproducible build, see commit a8b8017c34fe ("initramfs: Use > KBUILD_BUILD_TIMESTAMP for generated entries"). If a user wants > the build reproduction, they use -d <date>, which can be set on all > types of files, without surprising exceptions and workarounds. > Let's KISS here and just apply the time that user specified > with -d option. > > Based-on-a-patch-by: Baptiste Covolato <baptiste@arista.com> > Link: https://lore.kernel.org/lkml/20181025215133.20138-1-baptiste@arista.com/ > Signed-off-by: Dmitry Safonov <dima@arista.com> Applied to linux-kbuild. Thanks. > --- > usr/gen_init_cpio.c | 33 +++++++++++++++++++++------------ > 1 file changed, 21 insertions(+), 12 deletions(-) > > diff --git a/usr/gen_init_cpio.c b/usr/gen_init_cpio.c > index 61230532fef1..edcdb8abfa31 100644 > --- a/usr/gen_init_cpio.c > +++ b/usr/gen_init_cpio.c > @@ -27,6 +27,7 @@ > static unsigned int offset; > static unsigned int ino = 721; > static time_t default_mtime; > +static bool do_file_mtime; > static bool do_csum = false; > > struct file_handler { > @@ -329,6 +330,7 @@ static int cpio_mkfile(const char *name, const char *location, > int file; > int retval; > int rc = -1; > + time_t mtime; > int namesize; > unsigned int i; > uint32_t csum = 0; > @@ -347,16 +349,21 @@ static int cpio_mkfile(const char *name, const char *location, > goto error; > } > > - if (buf.st_mtime > 0xffffffff) { > - fprintf(stderr, "%s: Timestamp exceeds maximum cpio timestamp, clipping.\n", > - location); > - buf.st_mtime = 0xffffffff; > - } > + if (do_file_mtime) { > + mtime = default_mtime; > + } else { > + mtime = buf.st_mtime; > + if (mtime > 0xffffffff) { > + fprintf(stderr, "%s: Timestamp exceeds maximum cpio timestamp, clipping.\n", > + location); > + mtime = 0xffffffff; > + } > > - if (buf.st_mtime < 0) { > - fprintf(stderr, "%s: Timestamp negative, clipping.\n", > - location); > - buf.st_mtime = 0; > + if (mtime < 0) { > + fprintf(stderr, "%s: Timestamp negative, clipping.\n", > + location); > + mtime = 0; > + } > } > > if (buf.st_size > 0xffffffff) { > @@ -387,7 +394,7 @@ static int cpio_mkfile(const char *name, const char *location, > (long) uid, /* uid */ > (long) gid, /* gid */ > nlinks, /* nlink */ > - (long) buf.st_mtime, /* mtime */ > + (long) mtime, /* mtime */ > size, /* filesize */ > 3, /* major */ > 1, /* minor */ > @@ -536,8 +543,9 @@ static void usage(const char *prog) > "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" > + "as mtime for symlinks, directories, regular and special files.\n" > + "The default is to use the current time for all files, but\n" > + "preserve modification time for regular files.\n" > "-c: calculate and store 32-bit checksums for file data.\n", > prog); > } > @@ -594,6 +602,7 @@ int main (int argc, char *argv[]) > usage(argv[0]); > exit(1); > } > + do_file_mtime = true; > break; > case 'c': > do_csum = true; > > --- > base-commit: 55cb5f43689d7a9ea5bf35ef050f12334f197347 > change-id: 20231219-gen_init_cpio-reproducible-99c707d8e66c > > Best regards, > -- > Dmitry Safonov <dima@arista.com> >
diff --git a/usr/gen_init_cpio.c b/usr/gen_init_cpio.c index 61230532fef1..edcdb8abfa31 100644 --- a/usr/gen_init_cpio.c +++ b/usr/gen_init_cpio.c @@ -27,6 +27,7 @@ static unsigned int offset; static unsigned int ino = 721; static time_t default_mtime; +static bool do_file_mtime; static bool do_csum = false; struct file_handler { @@ -329,6 +330,7 @@ static int cpio_mkfile(const char *name, const char *location, int file; int retval; int rc = -1; + time_t mtime; int namesize; unsigned int i; uint32_t csum = 0; @@ -347,16 +349,21 @@ static int cpio_mkfile(const char *name, const char *location, goto error; } - if (buf.st_mtime > 0xffffffff) { - fprintf(stderr, "%s: Timestamp exceeds maximum cpio timestamp, clipping.\n", - location); - buf.st_mtime = 0xffffffff; - } + if (do_file_mtime) { + mtime = default_mtime; + } else { + mtime = buf.st_mtime; + if (mtime > 0xffffffff) { + fprintf(stderr, "%s: Timestamp exceeds maximum cpio timestamp, clipping.\n", + location); + mtime = 0xffffffff; + } - if (buf.st_mtime < 0) { - fprintf(stderr, "%s: Timestamp negative, clipping.\n", - location); - buf.st_mtime = 0; + if (mtime < 0) { + fprintf(stderr, "%s: Timestamp negative, clipping.\n", + location); + mtime = 0; + } } if (buf.st_size > 0xffffffff) { @@ -387,7 +394,7 @@ static int cpio_mkfile(const char *name, const char *location, (long) uid, /* uid */ (long) gid, /* gid */ nlinks, /* nlink */ - (long) buf.st_mtime, /* mtime */ + (long) mtime, /* mtime */ size, /* filesize */ 3, /* major */ 1, /* minor */ @@ -536,8 +543,9 @@ static void usage(const char *prog) "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" + "as mtime for symlinks, directories, regular and special files.\n" + "The default is to use the current time for all files, but\n" + "preserve modification time for regular files.\n" "-c: calculate and store 32-bit checksums for file data.\n", prog); } @@ -594,6 +602,7 @@ int main (int argc, char *argv[]) usage(argv[0]); exit(1); } + do_file_mtime = true; break; case 'c': do_csum = true;