libbb: [x]fopen_for_{read,write} introduced and used.

 (by Valdimir)

function                                             old     new   delta
config_open2                                           -      41     +41
config_read                                          507     542     +35
find_pair                                            169     187     +18
fopen_for_write                                        -      14     +14
fopen_for_read                                         -      14     +14
find_main                                            406     418     +12
xfopen_for_write                                       -      10     +10
xfopen_for_read                                        -      10     +10
popstring                                            134     140      +6
parse_inittab                                        396     401      +5
next_token                                           923     928      +5
pack_gzip                                           1659    1661      +2
bb__parsespent                                       117     119      +2
fallbackSort                                        1719    1717      -2
evalvar                                             1376    1374      -2
qrealloc                                              36      33      -3
...
...
...
...
singlemount                                         4579    4569     -10
process_stdin                                        443     433     -10
patch_main                                          1111    1101     -10
ifupdown_main                                       2175    2165     -10
file_action_grep                                      90      80     -10
uuidcache_init                                       649     637     -12
hush_main                                            797     785     -12
read_config                                          230     217     -13
dpkg_main                                           3835    3820     -15
read_line_input                                     3134    3110     -24
sysctl_main                                          232     203     -29
config_open                                           40      10     -30
WARN_BAD_LINE                                         44       -     -44
login_main                                          1714    1575    -139
------------------------------------------------------------------------------
(add/remove: 5/1 grow/shrink: 8/74 up/down: 174/-737)        Total: -563 bytes

2 files changed, 13 insertions, 23 deletions

diff --git a/loginutils/getty.c b/loginutils/getty.c
index 7d4fe4d..358a45c 100644
--- a/loginutils/getty.c
+++ b/loginutils/getty.c
@@ -668,7 +668,7 @@ int getty_main(int argc UNUSED_PARAM, char **argv)
 	logmode = LOGMODE_BOTH;
 
 #ifdef DEBUGGING
-	dbf = xfopen(DEBUGTERM, "w");
+	dbf = xfopen_for_write(DEBUGTERM);
 	for (n = 1; argv[n]; n++) {
 		debug(argv[n]);
 		debug("\n");
diff --git a/loginutils/login.c b/loginutils/login.c
index 9c7941e..5a75ed2 100644
--- a/loginutils/login.c
+++ b/loginutils/login.c
@@ -122,7 +122,7 @@ static void die_if_nologin(void)
 	if (access("/etc/nologin", F_OK))
 		return;
 
-	fp = fopen("/etc/nologin", "r");
+	fp = fopen_for_read("/etc/nologin");
 	if (fp) {
 		while ((c = getc(fp)) != EOF)
 			bb_putchar((c=='\n') ? '\r' : c);
@@ -139,30 +139,20 @@ static ALWAYS_INLINE void die_if_nologin(void) {}
 #if ENABLE_FEATURE_SECURETTY && !ENABLE_PAM
 static int check_securetty(void)
 {
-	FILE *fp;
-	int i;
-	char buf[256];
-
-	fp = fopen("/etc/securetty", "r");
-	if (!fp) {
-		/* A missing securetty file is not an error. */
-		return 1;
-	}
-	while (fgets(buf, sizeof(buf)-1, fp)) {
-		for (i = strlen(buf)-1; i >= 0; --i) {
-			if (!isspace(buf[i]))
+	char *buf;
+	int ret = 1;
+	parser_t *parser = config_open2("/etc/securetty", fopen_for_read);
+	/* N.B. A missing securetty file is not an error. */
+	if (parser) {
+		while (config_read(parser, &buf, 1, 1, "# \t", 0)) {
+			if (strcmp(buf, short_tty) == 0)
 				break;
 		}
-		buf[++i] = '\0';
-		if (!buf[0] || (buf[0] == '#'))
-			continue;
-		if (strcmp(buf, short_tty) == 0) {
-			fclose(fp);
-			return 1;
-		}
+		config_close(parser);
+		// buf != NULL here iff config file was empty (OK) or buf equals short_tty (OK)
+		ret = buf != NULL;
 	}
-	fclose(fp);
-	return 0;
+	return ret;
 }
 #else
 static ALWAYS_INLINE int check_securetty(void) { return 1; }