Fix: Discarded-qualifiers errors in string searching functions

Currently Naemon uses a mix of (char *) and (const char *) as input
for different string functions such as strpbrk() or strchr().
Modern compilers and stricter build flags (-Werror)
throw errors when the result of string searching functions like
strpbrk() or strchr() is assigned to a non-const pointer,
especially when the input was cast to const char*.

This commit adds explicit (char *) casts to the return values of
strpbrk and strchr to ensure compatibility across different
compiler versions and to satisfy -Werror=discarded-qualifiers.

Affected functions:
- strpbrk
- strchr

Issues:
- #530
- #522

Signed-off-by: nook24 <info@nook24.eu>

Author: nook24

lib/nspath.c

@@ -29,7 +29,7 @@ static inline int path_components(const char *path)
 	int comps = 1;
 	if (!path)
 		return 0;
-	for (slash = strchr(path, '/'); slash; slash = strchr(slash + 1, '/'))
+	for (slash = (char *)strchr(path, '/'); slash; slash = strchr(slash + 1, '/'))
 		comps++;
 	return comps;
 }

src/naemon/checks.c

@@ -111,7 +111,7 @@ struct check_output *parse_output(const char *buf, struct check_output *check_ou
 	perf_data_string = g_string_new(NULL);
 	tmp = strtok_r(tmpbuf, "\n", &saveptr);
 	if (tmp != NULL) {
-		p = strpbrk((const char *) tmp, "|");
+		p = (char *)strpbrk((const char *) tmp, "|");
 	}
 	if (p == NULL) {
 		/* No perfdata in first line of output. */
@@ -138,7 +138,7 @@ struct check_output *parse_output(const char *buf, struct check_output *check_ou
 	if ((tmp = strtok_r(NULL, "", &saveptr))) {
 
 		/* Is there a perf data delimiter somewhere in the long output? */
-		p = strpbrk((const char *) tmp, "|");
+		p = (char *)strpbrk((const char *) tmp, "|");
 		if (p == NULL) {
 			/* No more perfdata, rest is long output*/
 			check_output->long_output = nm_strdup(tmp);

src/naemon/objects_command.c

@@ -97,7 +97,7 @@ command *find_bang_command(const char *name)
 	if (!name)
 		return NULL;
 
-	bang = strchr(name, '!');
+	bang = (char *)strchr(name, '!');
 	if (!bang)
 		return find_command(name);
 	*bang = 0;

src/naemon/workers.c

@@ -110,7 +110,7 @@ static struct wproc_list *get_wproc_list(const char *cmd)
 		return &workers;
 
 	/* first, look for a specialized worker for this command */
-	if ((space = strchr(cmd, ' ')) != NULL) {
+	if ((space = (char *)strchr(cmd, ' ')) != NULL) {
 		int namelen = (unsigned long)space - (unsigned long)cmd;
 		cmd_name = nm_calloc(1, namelen + 1);
 		memcpy(cmd_name, cmd, namelen);