lib/utils_base.c: Stop dumping core on bad args to check_snmp

Since the state patch introduction, we've been freeing uninitialized
memory in lib/utils_base.c::np_cleanup(), which caused coredumps
with check_snmp when illegal threshold ranges (for example) were
passed, or when we called 'die' without having read any state.

This patch fixes it by replacing the malloc() calls in there (all of
them, since using malloc() is almost always an error) with calloc().

malloc() either doesn't initialize the memory at all, or taints it
with a special marker so it can tell us when we're free()'ing memory
that hasn't been initialized. calloc() explicitly initializes the
allocated memory to nul bytes, which is a zero-cost operation when
we get the memory from the kernel (which alread does that) and almost
always desirable everywhere else.

Signed-off-by: Andreas Ericsson <ae@op5.se>

lib/utils_base.c

@@ -35,7 +35,7 @@ nagios_plugin *this_nagios_plugin=NULL;
 
 void np_init( char *plugin_name, int argc, char **argv ) {
 	if (this_nagios_plugin==NULL) {
-		this_nagios_plugin = malloc(sizeof(nagios_plugin));
+		this_nagios_plugin = calloc(1, sizeof(nagios_plugin));
 		if (this_nagios_plugin==NULL) {
 			die(STATE_UNKNOWN, _("Cannot allocate memory: %s"),
 			    strerror(errno));
@@ -108,7 +108,7 @@ range
 	double end;
 	char *end_str;
 
-	temp_range = (range *) malloc(sizeof(range));
+	temp_range = (range *) calloc(1, sizeof(range));
 
 	/* Set defaults */
 	temp_range->start = 0;
@@ -154,7 +154,7 @@ _set_thresholds(thresholds **my_thresholds, char *warn_string, char *critical_st
 {
 	thresholds *temp_thresholds = NULL;
 
-	if ((temp_thresholds = malloc(sizeof(thresholds))) == NULL)
+	if ((temp_thresholds = calloc(1, sizeof(thresholds))) == NULL)
 		die(STATE_UNKNOWN, _("Cannot allocate memory: %s"),
 		    strerror(errno));
 
@@ -335,13 +335,13 @@ char *np_extract_value(const char *varlist, const char *name, char sep) {
 				if (tmp = index(varlist, sep)) {
 					/* Value is delimited by a comma */
 					if (tmp-varlist == 0) continue;
-					value = (char *)malloc(tmp-varlist+1);
+					value = (char *)calloc(1, tmp-varlist+1);
 					strncpy(value, varlist, tmp-varlist);
 					value[tmp-varlist] = '\0';
 				} else {
 					/* Value is delimited by a \0 */
 					if (strlen(varlist) == 0) continue;
-					value = (char *)malloc(strlen(varlist) + 1);
+					value = (char *)calloc(1, strlen(varlist) + 1);
 					strncpy(value, varlist, strlen(varlist));
 					value[strlen(varlist)] = '\0';
 				}
@@ -431,7 +431,7 @@ void np_enable_state(char *keyname, int expected_data_version) {
 	if(this_nagios_plugin==NULL)
 		die(STATE_UNKNOWN, _("This requires np_init to be called"));
 
-	this_state = (state_key *) malloc(sizeof(state_key));
+	this_state = (state_key *) calloc(1, sizeof(state_key));
 	if(this_state==NULL)
 		die(STATE_UNKNOWN, _("Cannot allocate memory: %s"),
 		    strerror(errno));
@@ -482,7 +482,7 @@ state_data *np_state_read() {
 	statefile = fopen( this_nagios_plugin->state->_filename, "r" );
 	if(statefile!=NULL) {
 
-		this_state_data = (state_data *) malloc(sizeof(state_data));
+		this_state_data = (state_data *) calloc(1, sizeof(state_data));
 		if(this_state_data==NULL)
 			die(STATE_UNKNOWN, _("Cannot allocate memory: %s"),
 			    strerror(errno));
@@ -517,7 +517,7 @@ int _np_state_read_file(FILE *f) {
 	time(&current_time);
 
 	/* Note: This introduces a limit of 1024 bytes in the string data */
-	line = (char *) malloc(1024);
+	line = (char *) calloc(1, 1024);
 	if(line==NULL)
 		die(STATE_UNKNOWN, _("Cannot allocate memory: %s"),
 		    strerror(errno));