cpio: add support for --ignore-devno like GNU cpio

The --ignore-devno option is used to set device numbers to (0, 0).
This can be useful in verifying whether a CPIO archive is reproducible.

function                                             old     new   delta
cpio_o                                               922     961     +39
.rodata                                            78407   78422     +15
bbconfig_config_bz2                                 6161    6167      +6
packed_usage                                       25770   25764      -6
------------------------------------------------------------------------------
(add/remove: 0/0 grow/shrink: 3/1 up/down: 60/-6)              Total: 54 bytes

Signed-off-by: Ariadne Conill <ariadne@dereferenced.org>
Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>

1 files changed, 20 insertions, 0 deletions

diff --git a/archival/cpio.c b/archival/cpio.c
index f525419b8..daf6cffc9 100644
--- a/archival/cpio.c
+++ b/archival/cpio.c
@@ -38,6 +38,13 @@
 //config:       depends on FEATURE_CPIO_O
 //config:       help
 //config:       Passthrough mode. Rarely used.
+//config:
+//config:config FEATURE_CPIO_IGNORE_DEVNO
+//config:       bool "Support --ignore-devno like GNU cpio"
+//config:       default y
+//config:       depends on FEATURE_CPIO_O && LONG_OPTS
+//config:       help
+//config:       Optionally ignore device numbers when creating archives.
 
 //applet:IF_CPIO(APPLET(cpio, BB_DIR_BIN, BB_SUID_DROP))
 
@@ -75,6 +82,9 @@
 //usage:     "\n        -R USER[:GRP]   Set owner of created files"
 //usage:     "\n        -L      Dereference symlinks"
 //usage:     "\n        -0      NUL terminated input"
+//usage:        IF_FEATURE_CPIO_IGNORE_DEVNO(
+//usage:     "\n        --ignore-devno"
+//usage:        )
 
 /* GNU cpio 2.9 --help (abridged):
 
@@ -162,11 +172,13 @@ enum {
         IF_FEATURE_CPIO_P(OPTBIT_PASSTHROUGH,)
         IF_LONG_OPTS(     OPTBIT_QUIET      ,)
         IF_LONG_OPTS(     OPTBIT_2STDOUT    ,)
+        IF_FEATURE_CPIO_IGNORE_DEVNO(OPTBIT_IGNORE_DEVNO,)
         OPT_CREATE             = IF_FEATURE_CPIO_O((1 << OPTBIT_CREATE     )) + 0,
         OPT_FORMAT             = IF_FEATURE_CPIO_O((1 << OPTBIT_FORMAT     )) + 0,
         OPT_PASSTHROUGH        = IF_FEATURE_CPIO_P((1 << OPTBIT_PASSTHROUGH)) + 0,
         OPT_QUIET              = IF_LONG_OPTS(     (1 << OPTBIT_QUIET      )) + 0,
         OPT_2STDOUT            = IF_LONG_OPTS(     (1 << OPTBIT_2STDOUT    )) + 0,
+        OPT_IGNORE_DEVNO       = IF_FEATURE_CPIO_IGNORE_DEVNO((1 << OPTBIT_IGNORE_DEVNO)) + 0,
 };
 
 #define OPTION_STR "it0uvdmLF:R:"
@@ -304,6 +316,11 @@ static NOINLINE int cpio_o(void)
                         }
                 }
 
+#if ENABLE_FEATURE_CPIO_IGNORE_DEVNO
+                if (option_mask32 & OPT_IGNORE_DEVNO)
+                        st.st_dev = st.st_rdev = 0;
+#endif
+
                 bytes += printf("070701"
                                 "%08X%08X%08X%08X%08X%08X%08X"
                                 "%08X%08X%08X%08X" /* GNU cpio uses uppercase hex */
@@ -379,6 +396,9 @@ int cpio_main(int argc UNUSED_PARAM, char **argv)
                 "null\0"         No_argument       "0"
                 "quiet\0"        No_argument       "\xff"
                 "to-stdout\0"    No_argument       "\xfe"
+#if ENABLE_FEATURE_CPIO_IGNORE_DEVNO
+                "ignore-devno\0" No_argument       "\xfd"
+#endif
                 ;
 #endif