Fixed various signedness issues identified by -Wextra.

The following two issues have been addressed:

 * comparison between signed and unsigned - this was found in several places
   throughout the code and has been fixed by switching to more appropriate
   types or adding appropriate explicit casts.
 * comparison of unsigned expression < 0 is always false - this was found in
   the processes and vserver plugins where a size_t had wrongly been used
   instead of a ssize_t and an int respectively.

src/apache.c

@@ -148,7 +148,7 @@ static int init (void)
 
 		status = ssnprintf (credentials, sizeof (credentials), "%s:%s",
 				user, (pass == NULL) ? "" : pass);
-		if (status >= sizeof (credentials))
+		if ((status < 0) || ((size_t) status >= sizeof (credentials)))
 		{
 			ERROR ("apache plugin: init: Returning an error "
 					"because the credentials have been "

src/ascent.c

@@ -174,7 +174,7 @@ static size_t ascent_curl_callback (void *buf, size_t size, size_t nmemb, /* {{{
 
 static int ascent_submit_players (player_stats_t *ps) /* {{{ */
 {
-  int i;
+  size_t i;
   gauge_t value;
 
   for (i = 0; i < RACES_LIST_LENGTH; i++)
@@ -213,7 +213,7 @@ static int ascent_account_player (player_stats_t *ps, /* {{{ */
 {
   if (pi->race >= 0)
   {
-    if ((pi->race >= RACES_LIST_LENGTH)
+    if (((size_t) pi->race >= RACES_LIST_LENGTH)
         || (races_list[pi->race] == NULL))
       ERROR ("ascent plugin: Ignoring invalid numeric race %i.", pi->race);
     else
@@ -222,7 +222,7 @@ static int ascent_account_player (player_stats_t *ps, /* {{{ */
 
   if (pi->class >= 0)
   {
-    if ((pi->class >= CLASSES_LIST_LENGTH)
+    if (((size_t) pi->class >= CLASSES_LIST_LENGTH)
         || (classes_list[pi->class] == NULL))
       ERROR ("ascent plugin: Ignoring invalid numeric class %i.", pi->class);
     else
@@ -231,7 +231,7 @@ static int ascent_account_player (player_stats_t *ps, /* {{{ */
 
   if (pi->gender >= 0)
   {
-    if ((pi->gender >= GENDERS_LIST_LENGTH)
+    if (((size_t) pi->gender >= GENDERS_LIST_LENGTH)
         || (genders_list[pi->gender] == NULL))
       ERROR ("ascent plugin: Ignoring invalid numeric gender %i.",
           pi->gender);
@@ -549,7 +549,7 @@ static int ascent_init (void) /* {{{ */
 
     status = ssnprintf (credentials, sizeof (credentials), "%s:%s",
         user, (pass == NULL) ? "" : pass);
-    if (status >= sizeof (credentials))
+    if ((status < 0) || ((size_t) status >= sizeof (credentials)))
     {
       ERROR ("ascent plugin: ascent_init: Returning an error because the "
           "credentials have been truncated.");

src/collectd-nagios.c

@@ -165,7 +165,7 @@ static int filter_ds (size_t *values_num,
 		return (RET_UNKNOWN);
 	}
 
-	for (i = 0; i < match_ds_num_g; i++)
+	for (i = 0; i < (size_t) match_ds_num_g; i++)
 	{
 		size_t j;
 
@@ -298,7 +298,7 @@ static int do_check_con_none (size_t values_num,
 	int num_okay = 0;
 	const char *status_str = "UNKNOWN";
 	int status_code = RET_UNKNOWN;
-	int i;
+	size_t i;
 
 	for (i = 0; i < values_num; i++)
 	{
@@ -349,7 +349,7 @@ static int do_check_con_none (size_t values_num,
 static int do_check_con_average (size_t values_num,
 		double *values, char **values_names)
 {
-	int i;
+	size_t i;
 	double total;
 	int total_num;
 	double average;
@@ -402,7 +402,7 @@ static int do_check_con_average (size_t values_num,
 static int do_check_con_sum (size_t values_num,
 		double *values, char **values_names)
 {
-	int i;
+	size_t i;
 	double total;
 	int total_num;
 	const char *status_str = "UNKNOWN";
@@ -452,7 +452,7 @@ static int do_check_con_sum (size_t values_num,
 static int do_check_con_percentage (size_t values_num,
 		double *values, char **values_names)
 {
-	int i;
+	size_t i;
 	double sum = 0.0;
 	double percentage;
 

src/common.c

@@ -411,7 +411,7 @@ int check_create_dir (const char *file_orig)
 	char *saveptr;
 	int   last_is_file = 1;
 	int   path_is_absolute = 0;
-	int   len;
+	size_t len;
 	int   i;
 
 	/*

src/configfile.c

@@ -555,7 +555,7 @@ static oconfig_item_t *cf_read_dir (const char *dir, int depth)
 
 		status = ssnprintf (name, sizeof (name), "%s/%s",
 				dir, de->d_name);
-		if (status >= sizeof (name))
+		if ((status < 0) || ((size_t) status >= sizeof (name)))
 		{
 			ERROR ("configfile: Not including `%s/%s' because its"
 					" name is too long.",
@@ -630,7 +630,7 @@ static oconfig_item_t *cf_read_generic (const char *path, int depth)
 	int status;
 	const char *path_ptr;
 	wordexp_t we;
-	int i;
+	size_t i;
 
 	if (depth >= CF_MAX_DEPTH)
 	{

src/netlink.c

@@ -246,7 +246,7 @@ static int link_filter (const struct sockaddr_nl __attribute__((unused)) *sa,
 
   /* Update the `iflist'. It's used to know which interfaces exist and query
    * them later for qdiscs and classes. */
-  if (msg->ifi_index >= iflist_len)
+  if ((msg->ifi_index >= 0) && ((size_t) msg->ifi_index >= iflist_len))
   {
     char **temp;
 
@@ -359,7 +359,8 @@ static int qos_filter (const struct sockaddr_nl __attribute__((unused)) *sa,
     return (0);
   }
 
-  if (msg->tcm_ifindex >= iflist_len)
+  if ((msg->tcm_ifindex >= 0)
+      && ((size_t) msg->tcm_ifindex >= iflist_len))
   {
     ERROR ("netlink plugin: qos_filter: msg->tcm_ifindex = %i "
 	">= iflist_len = %zu",
@@ -580,9 +581,9 @@ static int ir_read (void)
 
   /* `link_filter' will update `iflist' which is used here to iterate over all
    * interfaces. */
-  for (ifindex = 0; ifindex < iflist_len; ifindex++)
+  for (ifindex = 0; (size_t) ifindex < iflist_len; ifindex++)
   {
-    int type_index;
+    size_t type_index;
 
     if (iflist[ifindex] == NULL)
       continue;

src/network.c

@@ -498,7 +498,7 @@ static int parse_part_values (void **ret_buffer, int *ret_buffer_len,
 
 	exp_size = 3 * sizeof (uint16_t)
 		+ pkg_numval * (sizeof (uint8_t) + sizeof (value_t));
-	if (buffer_len < exp_size)
+	if ((buffer_len < 0) || ((size_t) buffer_len < exp_size))
 	{
 		WARNING ("network plugin: parse_part_values: "
 				"Packet too short: "
@@ -562,7 +562,7 @@ static int parse_part_number (void **ret_buffer, int *ret_buffer_len,
 	uint16_t pkg_length;
 	uint16_t pkg_type;
 
-	if (buffer_len < exp_size)
+	if ((buffer_len < 0) || ((size_t) buffer_len < exp_size))
 	{
 		WARNING ("network plugin: parse_part_number: "
 				"Packet too short: "
@@ -602,7 +602,7 @@ static int parse_part_string (void **ret_buffer, int *ret_buffer_len,
 	uint16_t pkg_length;
 	uint16_t pkg_type;
 
-	if (buffer_len < header_size)
+	if ((buffer_len < 0) || ((size_t) buffer_len < header_size))
 	{
 		WARNING ("network plugin: parse_part_string: "
 				"Packet too short: "
@@ -644,7 +644,8 @@ static int parse_part_string (void **ret_buffer, int *ret_buffer_len,
 	/* Check that the package data fits into the output buffer.
 	 * The previous if-statement ensures that:
 	 * `pkg_length > header_size' */
-	if ((pkg_length - header_size) > output_len)
+	if ((output_len < 0)
+			|| ((size_t) output_len < ((size_t) pkg_length - header_size)))
 	{
 		WARNING ("network plugin: parse_part_string: "
 				"Output buffer too small.");

src/nginx.c

@@ -123,8 +123,9 @@ static int init (void)
 
   if (user != NULL)
   {
-    if (ssnprintf (credentials, sizeof (credentials),
-	  "%s:%s", user, pass == NULL ? "" : pass) >= sizeof (credentials))
+    int status = ssnprintf (credentials, sizeof (credentials),
+	"%s:%s", user, pass == NULL ? "" : pass);
+    if ((status < 0) || ((size_t) status >= sizeof (credentials)))
     {
       ERROR ("nginx plugin: Credentials would have been truncated.");
       return (-1);

src/plugin.c

@@ -328,6 +328,7 @@ int plugin_load (const char *type)
 	int   ret;
 	struct stat    statbuf;
 	struct dirent *de;
+	int status;
 
 	DEBUG ("type = %s", type);
 
@@ -336,8 +337,8 @@ int plugin_load (const char *type)
 
 	/* `cpu' should not match `cpufreq'. To solve this we add `.so' to the
 	 * type when matching the filename */
-	if (ssnprintf (typename, sizeof (typename),
-			"%s.so", type) >= sizeof (typename))
+	status = ssnprintf (typename, sizeof (typename), "%s.so", type);
+	if ((status < 0) || ((size_t) status >= sizeof (typename)))
 	{
 		WARNING ("snprintf: truncated: `%s.so'", type);
 		return (-1);
@@ -357,8 +358,9 @@ int plugin_load (const char *type)
 		if (strncasecmp (de->d_name, typename, typename_len))
 			continue;
 
-		if (ssnprintf (filename, sizeof (filename),
-				"%s/%s", dir, de->d_name) >= sizeof (filename))
+		status = ssnprintf (filename, sizeof (filename),
+				"%s/%s", dir, de->d_name);
+		if ((status < 0) || ((size_t) status >= sizeof (filename)))
 		{
 			WARNING ("snprintf: truncated: `%s/%s'", dir, de->d_name);
 			continue;

src/processes.c

@@ -821,7 +821,7 @@ static char *ps_get_cmdline (pid_t pid, char *name, char *buf, size_t buf_len)
 	n = 0;
 
 	while (42) {
-		size_t status;
+		ssize_t status;
 
 		status = read (fd, (void *)buf_ptr, len);
 

src/snmp.c

@@ -530,9 +530,9 @@ static int csnmp_config_add_host_interval (host_definition_t *hd, oconfig_item_t
     return (-1);
   }
 
-  hd->interval = (int) ci->values[0].value.number;
-  if (hd->interval < 0)
-    hd->interval = 0;
+  hd->interval = ci->values[0].value.number >= 0
+    ? (uint32_t) ci->values[0].value.number
+    : 0;
 
   return (0);
 } /* int csnmp_config_add_host_interval */
@@ -1138,7 +1138,7 @@ static int csnmp_read_table (host_definition_t *host, data_definition_t *data)
       break;
     }
 
-    for (i = 0; i < oid_list_len; i++)
+    for (i = 0; (uint32_t) i < oid_list_len; i++)
       snmp_add_null_var (req, oid_list[i].oid, oid_list[i].oid_len);
 
     res = NULL;
@@ -1441,7 +1441,7 @@ static int csnmp_read_host (host_definition_t *host)
   time_end = time (NULL);
   DEBUG ("snmp plugin: csnmp_read_host (%s) finished at %u;", host->name,
       (unsigned int) time_end);
-  if ((time_end - time_start) > host->interval)
+  if ((uint32_t) (time_end - time_start) > host->interval)
   {
     WARNING ("snmp plugin: Host `%s' should be queried every %i seconds, "
 	"but reading all values takes %u seconds.",
@@ -1504,7 +1504,7 @@ static int csnmp_init (void)
     {
       host->interval = interval_g;
     }
-    else if (host->interval < interval_g)
+    else if (host->interval < (uint32_t) interval_g)
     {
       host->interval = interval_g;
       WARNING ("snmp plugin: Data for host `%s' will be collected every %i seconds.",

src/tail.c

@@ -305,7 +305,7 @@ static int ctail_init (void)
 static int ctail_read (void)
 {
   int success = 0;
-  int i;
+  size_t i;
 
   for (i = 0; i < tail_match_list_num; i++)
   {
@@ -329,7 +329,7 @@ static int ctail_read (void)
 
 static int ctail_shutdown (void)
 {
-  int i;
+  size_t i;
 
   for (i = 0; i < tail_match_list_num; i++)
   {

src/thermal.c

@@ -71,8 +71,9 @@ static int thermal_sysfs_device_read (const char __attribute__((unused)) *dir,
 	if (device_list && ignorelist_match (device_list, name))
 		return -1;
 
-	len = snprintf (filename, sizeof (filename), "%s/%s/temp", dirname_sysfs, name);
-	if ((len < 0) || ((unsigned int)len >= sizeof (filename)))
+	len = snprintf (filename, sizeof (filename),
+			"%s/%s/temp", dirname_sysfs, name);
+	if ((len < 0) || ((size_t) len >= sizeof (filename)))
 		return -1;
 
 	len = read_file_contents (filename, data, sizeof(data));
@@ -90,8 +91,9 @@ static int thermal_sysfs_device_read (const char __attribute__((unused)) *dir,
 		}
 	}
 
-	len = snprintf (filename, sizeof (filename), "%s/%s/cur_state", dirname_sysfs, name);
-	if ((len < 0) || ((unsigned int)len >= sizeof (filename)))
+	len = snprintf (filename, sizeof (filename),
+			"%s/%s/cur_state", dirname_sysfs, name);
+	if ((len < 0) || ((size_t) len >= sizeof (filename)))
 		return -1;
 
 	len = read_file_contents (filename, data, sizeof(data));
@@ -128,12 +130,15 @@ static int thermal_procfs_device_read (const char __attribute__((unused)) *dir,
 	 * temperature:             55 C
 	 */
 
-	len = snprintf (filename, sizeof (filename), "%s/%s/temperature", dirname_procfs, name);
-	if ((len < 0) || ((unsigned int)len >= sizeof (filename)))
+	len = snprintf (filename, sizeof (filename),
+			"%s/%s/temperature", dirname_procfs, name);
+	if ((len < 0) || ((size_t) len >= sizeof (filename)))
 		return -1;
 
 	len = read_file_contents (filename, data, sizeof(data));
-	if (len > sizeof(str_temp) && data[--len] == '\n' && !strncmp(data, str_temp, sizeof(str_temp)-1)) {
+	if ((len > 0) && ((size_t) len > sizeof(str_temp))
+			&& (data[--len] == '\n')
+			&& (! strncmp(data, str_temp, sizeof(str_temp)-1))) {
 		char *endptr = NULL;
 		double temp;
 		double celsius, add;

src/utils_cache.c

@@ -522,7 +522,7 @@ gauge_t *uc_get_rate (const data_set_t *ds, const value_list_t *vl)
 
   /* This is important - the caller has no other way of knowing how many
    * values are returned. */
-  if (ret_num != ds->ds_num)
+  if (ret_num != (size_t) ds->ds_num)
   {
     ERROR ("utils_cache: uc_get_rate: ds[%s] has %i values, "
 	"but uc_get_rate_by_name returned %zu.",

src/utils_cmd_getval.c

@@ -51,7 +51,7 @@ int handle_getval (FILE *fh, char *buffer)
   const data_set_t *ds;
 
   int   status;
-  int   i;
+  size_t i;
 
   if ((fh == NULL) || (buffer == NULL))
     return (-1);
@@ -123,7 +123,7 @@ int handle_getval (FILE *fh, char *buffer)
     return (-1);
   }
 
-  if (ds->ds_num != values_num)
+  if ((size_t) ds->ds_num != values_num)
   {
     ERROR ("ds[%s]->ds_num = %i, "
 	"but uc_get_rate_by_name returned %u values.",

src/utils_match.c

@@ -50,7 +50,7 @@ static char *match_substr (const char *str, int begin, int end)
 
   if ((begin < 0) || (end < 0) || (begin >= end))
     return (NULL);
-  if (end > (strlen (str) + 1))
+  if ((size_t) end > (strlen (str) + 1))
   {
     ERROR ("utils_match: match_substr: `end' points after end of string.");
     return (NULL);
@@ -228,7 +228,7 @@ int match_apply (cu_match_t *obj, const char *str)
   regmatch_t re_match[32];
   char *matches[32];
   size_t matches_num;
-  int i;
+  size_t i;
 
   if ((obj == NULL) || (str == NULL))
     return (-1);