Improve the integer verification function.

2 files changed, 14 insertions, 10 deletions

diff --git a/smenu.c b/smenu.c
index 872221d..69847cd 100644
--- a/smenu.c
+++ b/smenu.c
@@ -886,7 +886,7 @@ check_integer_constraint(int nb_args, char ** args, char * value, char * par)
 {
   if (!is_integer(value))
   {
-    fprintf(stderr, "This argument of %s is not an integer: %s", par, value);
+    fprintf(stderr, "The argument of %s is not an integer: %s", par, value);
     return 0;
   }
   return 1;
diff --git a/utils.c b/utils.c
index 6e8f050..80bba23 100644
--- a/utils.c
+++ b/utils.c
@@ -312,17 +312,21 @@ xwcscasecmp(const wchar_t * s1, const wchar_t * s2)
   return (-*s2);
 }
 
-/* ====================================== */
-/* Returns 1 if s represents an integer   */
-/* else 0.                                */
-/* s != NULL is assumed.                  */
-/* 0 and 0x prefixes are not understood.  */
-/* ====================================== */
+/* ==================================================================== */
+/* Returns 1 if s can be converted into an integer otherwise returns 0. */
+/* ==================================================================== */
 int
 is_integer(const char * const s)
 {
-  char * end;
+  long int n;
 
-  strtol(s, &end, 10);
-  return (*end == '\0');
+  if (!s || (strspn(s, "0123456789 ") != strlen(s)))
+    return 0;
+
+  n = strtol(s, NULL, 10);
+
+  if (errno != ERANGE && n >= INT_MIN && n <= INT_MAX)
+    return 1;
+  else
+    return 0;
 }