detect: Clear errno before strtoul

Per the notes for strtoul, since 0 or ULONG_MAX is a legitimate return
value, errno must be cleared before the call so an error can be checked
after the call by testing errno.

Issue: 7126

src/detect-gid.c

@@ -73,8 +73,9 @@ static int DetectGidSetup (DetectEngineCtx *de_ctx, Signature *s, const char *ra
 {
     unsigned long gid = 0;
     char *endptr = NULL;
+    errno = 0;
     gid = strtoul(rawstr, &endptr, 10);
-    if (endptr == NULL || *endptr != '\0') {
+    if (errno == ERANGE || endptr == NULL || *endptr != '\0') {
         SCLogError("invalid character as arg "
                    "to gid keyword");
         goto error;

src/detect-rev.c

@@ -43,8 +43,9 @@ static int DetectRevSetup (DetectEngineCtx *de_ctx, Signature *s, const char *ra
 {
     unsigned long rev = 0;
     char *endptr = NULL;
+    errno = 0;
     rev = strtoul(rawstr, &endptr, 10);
-    if (endptr == NULL || *endptr != '\0') {
+    if (errno == ERANGE || endptr == NULL || *endptr != '\0') {
         SCLogError("invalid character as arg "
                    "to rev keyword");
         goto error;
@@ -68,4 +69,4 @@ static int DetectRevSetup (DetectEngineCtx *de_ctx, Signature *s, const char *ra
 
  error:
     return -1;
-}
+ }

src/detect-sid.c

@@ -53,8 +53,9 @@ static int DetectSidSetup (DetectEngineCtx *de_ctx, Signature *s, const char *si
 {
     unsigned long id = 0;
     char *endptr = NULL;
+    errno = 0;
     id = strtoul(sidstr, &endptr, 10);
-    if (endptr == NULL || *endptr != '\0') {
+    if (errno == ERANGE || endptr == NULL || *endptr != '\0') {
         SCLogError("invalid character as arg "
                    "to sid keyword");
         goto error;