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>

1 files changed, 4 insertions, 5 deletions

diff --git a/libbb/update_passwd.c b/libbb/update_passwd.c
index dc26ebd1d..a2004f480 100644
--- a/libbb/update_passwd.c
+++ b/libbb/update_passwd.c
@@ -84,7 +84,6 @@ int FAST_FUNC update_passwd(const char *filename,
         char *fnamesfx;
         char *sfx_char;
         char *name_colon;
-        unsigned user_len;
         int old_fd;
         int new_fd;
         int i;
@@ -108,7 +107,6 @@ int FAST_FUNC update_passwd(const char *filename,
         fnamesfx = xasprintf("%s+", filename);
         sfx_char = &fnamesfx[strlen(fnamesfx)-1];
         name_colon = xasprintf("%s:", name ? name : "");
-        user_len = strlen(name_colon);
 
         if (shadow)
                 old_fp = fopen(filename, "r+");
@@ -179,7 +177,7 @@ int FAST_FUNC update_passwd(const char *filename,
                         while (list) {
                                 list++;
  next_list_element:
-                                if (strncmp(list, member, member_len) == 0) {
+                                if (is_prefixed_with(list, member)) {
                                         char c;
                                         changed_lines++;
                                         c = list[member_len];
@@ -201,13 +199,14 @@ int FAST_FUNC update_passwd(const char *filename,
                         goto next;
                 }
 
-                if (strncmp(name_colon, line, user_len) != 0) {
+                cp = is_prefixed_with(line, name_colon);
+                if (!cp) {
                         fprintf(new_fp, "%s\n", line);
                         goto next;
                 }
 
                 /* We have a match with "name:"... */
-                cp = line + user_len; /* move past name: */
+                /* cp points past "name:" */
 
 #if ENABLE_FEATURE_ADDUSER_TO_GROUP || ENABLE_FEATURE_DEL_USER_FROM_GROUP
                 if (member) {