libbb: introduce and use is_prefixed_with()

function                                             old     new   delta
is_prefixed_with                                       -      18     +18
complete_username                                     78      77      -1
man_main                                             737     735      -2
fsck_device                                          429     427      -2
unpack_ar_archive                                     80      76      -4
strip_unsafe_prefix                                  105     101      -4
singlemount                                         1054    1050      -4
rtc_adjtime_is_utc                                    90      86      -4
resolve_mount_spec                                    88      84      -4
parse_one_line                                      1029    1025      -4
parse_conf                                          1460    1456      -4
may_wakeup                                            83      79      -4
loadkmap_main                                        219     215      -4
get_irqs_from_stat                                   103      99      -4
get_header_cpio                                      913     909      -4
findfs_main                                           79      75      -4
fbsplash_main                                       1230    1226      -4
load_crontab                                         776     771      -5
expand_vars_to_list                                 1151    1146      -5
date_main                                            881     876      -5
skip_dev_pfx                                          30      24      -6
make_device                                         2199    2193      -6
complete_cmd_dir_file                                773     767      -6
run_applet_and_exit                                  715     708      -7
uudecode_main                                        321     313      -8
pwdx_main                                            197     189      -8
execute                                              568     560      -8
i2cdetect_main                                      1186    1176     -10
procps_scan                                         1242    1230     -12
procps_read_smaps                                   1017    1005     -12
process_module                                       746     734     -12
patch_main                                          1903    1891     -12
nfsmount                                            3572    3560     -12
stack_machine                                        126     112     -14
process_timer_stats                                  449     435     -14
match_fstype                                         111      97     -14
do_ipaddr                                           1344    1330     -14
open_list_and_close                                  359     343     -16
get_header_tar                                      1795    1779     -16
prepend_new_eth_table                                340     323     -17
fsck_main                                           1811    1794     -17
find_iface_state                                      56      38     -18
dnsd_main                                           1321    1303     -18
base_device                                          179     158     -21
find_keyword                                         104      82     -22
handle_incoming_and_exit                            2785    2762     -23
parse_and_put_prompt                                 774     746     -28
modinfo                                              347     317     -30
find_action                                          204     171     -33
update_passwd                                       1470    1436     -34
------------------------------------------------------------------------------
(add/remove: 1/0 grow/shrink: 0/49 up/down: 18/-540)         Total: -522 bytes

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>

4 files changed, 6 insertions, 6 deletions

diff --git a/archival/libarchive/get_header_cpio.c b/archival/libarchive/get_header_cpio.c
index 1a0058b63..7861d1f6f 100644
--- a/archival/libarchive/get_header_cpio.c
+++ b/archival/libarchive/get_header_cpio.c
@@ -37,7 +37,7 @@ char FAST_FUNC get_header_cpio(archive_handle_t *archive_handle)
         }
         archive_handle->offset += 110;
 
-        if (strncmp(&cpio_header[0], "07070", 5) != 0
+        if (!is_prefixed_with(&cpio_header[0], "07070")
          || (cpio_header[5] != '1' && cpio_header[5] != '2')
         ) {
                 bb_error_msg_and_die("unsupported cpio format, use newc or crc");
diff --git a/archival/libarchive/get_header_tar.c b/archival/libarchive/get_header_tar.c
index 0c663fbd7..2dbcdb50c 100644
--- a/archival/libarchive/get_header_tar.c
+++ b/archival/libarchive/get_header_tar.c
@@ -105,7 +105,7 @@ static void process_pax_hdr(archive_handle_t *archive_handle, unsigned sz, int g
                 value = end + 1;
 
 #if ENABLE_FEATURE_TAR_GNU_EXTENSIONS
-                if (!global && strncmp(value, "path=", sizeof("path=") - 1) == 0) {
+                if (!global && is_prefixed_with(value, "path=")) {
                         value += sizeof("path=") - 1;
                         free(archive_handle->tar__longname);
                         archive_handle->tar__longname = xstrdup(value);
@@ -118,7 +118,7 @@ static void process_pax_hdr(archive_handle_t *archive_handle, unsigned sz, int g
                  * This is what Red Hat's patched version of tar uses.
                  */
 # define SELINUX_CONTEXT_KEYWORD "RHT.security.selinux"
-                if (strncmp(value, SELINUX_CONTEXT_KEYWORD"=", sizeof(SELINUX_CONTEXT_KEYWORD"=") - 1) == 0) {
+                if (is_prefixed_with(value, SELINUX_CONTEXT_KEYWORD"=")) {
                         value += sizeof(SELINUX_CONTEXT_KEYWORD"=") - 1;
                         free(archive_handle->tar__sctx[global]);
                         archive_handle->tar__sctx[global] = xstrdup(value);
@@ -202,7 +202,7 @@ char FAST_FUNC get_header_tar(archive_handle_t *archive_handle)
 
         /* Check header has valid magic, "ustar" is for the proper tar,
          * five NULs are for the old tar format  */
-        if (strncmp(tar.magic, "ustar", 5) != 0
+        if (!is_prefixed_with(tar.magic, "ustar")
          && (!ENABLE_FEATURE_TAR_OLDGNU_COMPATIBILITY
              || memcmp(tar.magic, "\0\0\0\0", 5) != 0)
         ) {
diff --git a/archival/libarchive/unpack_ar_archive.c b/archival/libarchive/unpack_ar_archive.c
index 214d17e23..0bc030349 100644
--- a/archival/libarchive/unpack_ar_archive.c
+++ b/archival/libarchive/unpack_ar_archive.c
@@ -12,7 +12,7 @@ void FAST_FUNC unpack_ar_archive(archive_handle_t *ar_archive)
         char magic[7];
 
         xread(ar_archive->src_fd, magic, AR_MAGIC_LEN);
-        if (strncmp(magic, AR_MAGIC, AR_MAGIC_LEN) != 0) {
+        if (!is_prefixed_with(magic, AR_MAGIC)) {
                 bb_error_msg_and_die("invalid ar magic");
         }
         ar_archive->offset += AR_MAGIC_LEN;
diff --git a/archival/libarchive/unsafe_prefix.c b/archival/libarchive/unsafe_prefix.c
index 826c673bf..9994f4d94 100644
--- a/archival/libarchive/unsafe_prefix.c
+++ b/archival/libarchive/unsafe_prefix.c
@@ -15,7 +15,7 @@ const char* FAST_FUNC strip_unsafe_prefix(const char *str)
                         cp++;
                         continue;
                 }
-                if (strncmp(cp, "/../"+1, 3) == 0) {
+                if (is_prefixed_with(cp, "/../"+1)) {
                         cp += 3;
                         continue;
                 }