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>

9 files changed, 16 insertions, 16 deletions

diff --git a/util-linux/acpid.c b/util-linux/acpid.c
index fc8151f6a..0f2cb6bdc 100644
--- a/util-linux/acpid.c
+++ b/util-linux/acpid.c
@@ -151,7 +151,7 @@ static const char *find_action(struct input_event *ev, const char *buf)
 		}
 
 		if (buf) {
-			if (strncmp(buf, evt_tab[i].desc, strlen(buf)) == 0) {
+			if (is_prefixed_with(evt_tab[i].desc, buf)) {
 				action = evt_tab[i].desc;
 				break;
 			}
diff --git a/util-linux/fdisk.c b/util-linux/fdisk.c
index 39eb27b47..7fe70fb72 100644
--- a/util-linux/fdisk.c
+++ b/util-linux/fdisk.c
@@ -2781,14 +2781,14 @@ is_ide_cdrom_or_tape(const char *device)
 	   the process hangs on the attempt to read a music CD.
 	   So try to be careful. This only works since 2.1.73. */
 
-	if (strncmp("/dev/hd", device, 7))
+	if (!is_prefixed_with(device, "/dev/hd"))
 		return 0;
 
 	snprintf(buf, sizeof(buf), "/proc/ide/%s/media", device+5);
 	procf = fopen_for_read(buf);
 	if (procf != NULL && fgets(buf, sizeof(buf), procf))
-		is_ide = (!strncmp(buf, "cdrom", 5) ||
-			  !strncmp(buf, "tape", 4));
+		is_ide = (is_prefixed_with(buf, "cdrom") ||
+			  is_prefixed_with(buf, "tape"));
 	else
 		/* Now when this proc file does not exist, skip the
 		   device when it is read-only. */
diff --git a/util-linux/fdisk_osf.c b/util-linux/fdisk_osf.c
index ff16389bd..af04cfcc8 100644
--- a/util-linux/fdisk_osf.c
+++ b/util-linux/fdisk_osf.c
@@ -854,7 +854,7 @@ xbsd_initlabel(struct partition *p)
 
 	d->d_magic = BSD_DISKMAGIC;
 
-	if (strncmp(disk_device, "/dev/sd", 7) == 0)
+	if (is_prefixed_with(disk_device, "/dev/sd"))
 		d->d_type = BSD_DTYPE_SCSI;
 	else
 		d->d_type = BSD_DTYPE_ST506;
diff --git a/util-linux/fdisk_sgi.c b/util-linux/fdisk_sgi.c
index 785fc661b..23ebc56ef 100644
--- a/util-linux/fdisk_sgi.c
+++ b/util-linux/fdisk_sgi.c
@@ -440,7 +440,7 @@ sgi_write_table(void)
 		(unsigned int*)sgilabel, sizeof(*sgilabel)) == 0);
 
 	write_sector(0, sgilabel);
-	if (!strncmp((char*)sgilabel->directory[0].vol_file_name, "sgilabel", 8)) {
+	if (is_prefixed_with((char*)sgilabel->directory[0].vol_file_name, "sgilabel")) {
 		/*
 		 * keep this habit of first writing the "sgilabel".
 		 * I never tested whether it works without (AN 981002).
diff --git a/util-linux/findfs.c b/util-linux/findfs.c
index 49e8979ac..07734f359 100644
--- a/util-linux/findfs.c
+++ b/util-linux/findfs.c
@@ -27,7 +27,7 @@ int findfs_main(int argc UNUSED_PARAM, char **argv)
 	if (!dev)
 		bb_show_usage();
 
-	if (strncmp(dev, "/dev/", 5) == 0) {
+	if (is_prefixed_with(dev, "/dev/")) {
 		/* Just pass any /dev/xxx name right through.
 		 * This might aid in some scripts being able
 		 * to call this unconditionally */
diff --git a/util-linux/mdev.c b/util-linux/mdev.c
index b2d56575f..ccc00d365 100644
--- a/util-linux/mdev.c
+++ b/util-linux/mdev.c
@@ -610,7 +610,7 @@ static void make_device(char *device_name, char *path, int operation)
 	 * We use strstr("/block/") to forestall future surprises.
 	 */
 	type = S_IFCHR;
-	if (strstr(path, "/block/") || (G.subsystem && strncmp(G.subsystem, "block", 5) == 0))
+	if (strstr(path, "/block/") || (G.subsystem && is_prefixed_with(G.subsystem, "block")))
 		type = S_IFBLK;
 
 #if ENABLE_FEATURE_MDEV_CONF
diff --git a/util-linux/mount.c b/util-linux/mount.c
index fbc89c862..cb40c802d 100644
--- a/util-linux/mount.c
+++ b/util-linux/mount.c
@@ -641,7 +641,7 @@ static llist_t *get_block_backed_filesystems(void)
 		if (!f) continue;
 
 		while ((buf = xmalloc_fgetline(f)) != NULL) {
-			if (strncmp(buf, "nodev", 5) == 0 && isspace(buf[5]))
+			if (is_prefixed_with(buf, "nodev") && isspace(buf[5]))
 				goto next;
 			fs = skip_whitespace(buf);
 			if (*fs == '#' || *fs == '*' || !*fs)
@@ -1364,9 +1364,9 @@ static NOINLINE int nfsmount(struct mntent *mp, unsigned long vfsflags, char *fi
 						strcspn(opteq, " \t\n\r,"));
 				continue;
 			case 18: // "proto"
-				if (!strncmp(opteq, "tcp", 3))
+				if (is_prefixed_with(opteq, "tcp"))
 					tcp = 1;
-				else if (!strncmp(opteq, "udp", 3))
+				else if (is_prefixed_with(opteq, "udp"))
 					tcp = 0;
 				else
 					bb_error_msg("warning: unrecognized proto= option");
@@ -1459,7 +1459,7 @@ static NOINLINE int nfsmount(struct mntent *mp, unsigned long vfsflags, char *fi
 				"rdirplus\0"
 				"acl\0";
 			int val = 1;
-			if (!strncmp(opt, "no", 2)) {
+			if (is_prefixed_with(opt, "no")) {
 				val = 0;
 				opt += 2;
 			}
@@ -1979,7 +1979,7 @@ static int singlemount(struct mntent *mp, int ignore_busy)
 	}
 
 	// Might this be an NFS filesystem?
-	if ((!mp->mnt_type || strncmp(mp->mnt_type, "nfs", 3) == 0)
+	if ((!mp->mnt_type || is_prefixed_with(mp->mnt_type, "nfs"))
 	 && strchr(mp->mnt_fsname, ':') != NULL
 	) {
 		if (!mp->mnt_type)
diff --git a/util-linux/rtcwake.c b/util-linux/rtcwake.c
index 53d9384db..8aee0cfcb 100644
--- a/util-linux/rtcwake.c
+++ b/util-linux/rtcwake.c
@@ -66,7 +66,7 @@ static NOINLINE bool may_wakeup(const char *rtcname)
 		return false;
 
 	/* wakeup events could be disabled or not supported */
-	return strncmp(buf, "enabled\n", 8) == 0;
+	return is_prefixed_with(buf, "enabled\n") != NULL;
 }
 
 static NOINLINE void setup_alarm(int fd, time_t *wakeup, time_t rtc_time)
diff --git a/util-linux/volume_id/get_devname.c b/util-linux/volume_id/get_devname.c
index 0c6bdfddf..53bdbdf09 100644
--- a/util-linux/volume_id/get_devname.c
+++ b/util-linux/volume_id/get_devname.c
@@ -302,9 +302,9 @@ int resolve_mount_spec(char **fsname)
 {
 	char *tmp = *fsname;
 
-	if (strncmp(*fsname, "UUID=", 5) == 0)
+	if (is_prefixed_with(*fsname, "UUID="))
 		tmp = get_devname_from_uuid(*fsname + 5);
-	else if (strncmp(*fsname, "LABEL=", 6) == 0)
+	else if (is_prefixed_with(*fsname, "LABEL=") == 0)
 		tmp = get_devname_from_label(*fsname + 6);
 
 	if (tmp == *fsname)