lib/, src/: Use strsep(3) instead of strtok(3)

strsep(3) is stateless, and so is easier to reason about.

It also has a slight difference: strtok(3) jumps over empty fields,
while strsep(3) respects them as empty fields.  In most of the cases
where we were using strtok(3), it makes more sense to respect empty
fields, and this commit probably silently fixes a few bugs.

In other cases (most notably filesystem paths), contiguous delimiters
("//") should be collapsed, so strtok(3) still makes more sense there.
This commit doesn't replace such strtok(3) calls.

While at this, remove some useless variables used by these calls, and
reduce the scope of others.

Signed-off-by: Alejandro Colomar <alx@kernel.org>

lib/addgrps.c

@@ -14,9 +14,10 @@
 #include "prototypes.h"
 #include "defines.h"
 
-#include <stdio.h>
-#include <grp.h>
 #include <errno.h>
+#include <grp.h>
+#include <stdio.h>
+#include <string.h>
 
 #include "alloc/malloc.h"
 #include "alloc/reallocf.h"
@@ -24,19 +25,19 @@
 
 #ident "$Id$"
 
-#define SEP ",:"
 /*
  * Add groups with names from LIST (separated by commas or colons)
  * to the supplementary group set.  Silently ignore groups which are
- * already there.  Warning: uses strtok().
+ * already there.
  */
-int add_groups (const char *list)
+int
+add_groups(const char *list)
 {
 	GETGROUPS_T *grouplist;
 	size_t i;
 	int ngroups;
 	bool added;
-	char *token;
+	char *g, *p;
 	char buf[1024];
 	int ret;
 	FILE *shadow_logfd = log_get_logfd();
@@ -71,13 +72,13 @@ int add_groups (const char *list)
 	}
 
 	added = false;
-	for (token = strtok (buf, SEP); NULL != token; token = strtok (NULL, SEP)) {
+	p = buf;
+	while (NULL != (g = strsep(&p, ",:"))) {
 		struct group *grp;
 
-		grp = getgrnam (token); /* local, no need for xgetgrnam */
+		grp = getgrnam(g); /* local, no need for xgetgrnam */
 		if (NULL == grp) {
-			fprintf (shadow_logfd, _("Warning: unknown group %s\n"),
-				 token);
+			fprintf(shadow_logfd, _("Warning: unknown group %s\n"), g);
 			continue;
 		}
 

lib/console.c

@@ -26,7 +26,8 @@
  * under "cfgin" in config (directly or indirectly). Fallback to default if
  * something is bad.
  */
-static bool is_listed (const char *cfgin, const char *tty, bool def)
+static bool
+is_listed(const char *cfgin, const char *tty, bool def)
 {
 	FILE *fp;
 	char buf[1024], *s;
@@ -49,14 +50,13 @@ static bool is_listed (const char *cfgin, const char *tty, bool def)
 
 	if (*cons != '/') {
 		char *pbuf;
+
 		STRTCPY(buf, cons);
-		pbuf = &buf[0];
-		while ((s = strtok (pbuf, ":")) != NULL) {
+		pbuf = buf;
+		while (NULL != (s = strsep(&pbuf, ":"))) {
 			if (streq(s, tty)) {
 				return true;
 			}
-
-			pbuf = NULL;
 		}
 		return false;
 	}

lib/motd.c

@@ -12,6 +12,7 @@
 #ident "$Id$"
 
 #include <stdio.h>
+#include <string.h>
 
 #include "defines.h"
 #include "getdef.h"
@@ -26,7 +27,8 @@
  * it to the user's terminal at login time.  The MOTD_FILE configuration
  * option is a colon-delimited list of filenames.
  */
-void motd (void)
+void
+motd(void)
 {
 	FILE *fp;
 	char *motdlist;
@@ -41,12 +43,8 @@ void motd (void)
 
 	motdlist = xstrdup (motdfile);
 
-	for (mb = motdlist; ;mb = NULL) {
-		motdfile = strtok (mb, ":");
-		if (NULL == motdfile) {
-			break;
-		}
-
+	mb = motdlist;
+	while (NULL != (motdfile = strsep(&mb, ":"))) {
 		fp = fopen (motdfile, "r");
 		if (NULL != fp) {
 			while ((c = getc (fp)) != EOF) {