Better memtoll() error checking.

Related to PR redis#2357.

src/util.c

@@ -38,6 +38,7 @@
 #include <sys/time.h>
 #include <float.h>
 #include <stdint.h>
+#include <errno.h>
 
 #include "util.h"
 #include "sha1.h"
@@ -170,11 +171,12 @@ int stringmatch(const char *pattern, const char *string, int nocase) {
 }
 
 /* Convert a string representing an amount of memory into the number of
- * bytes, so for instance memtoll("1Gi") will return 1073741824 that is
+ * bytes, so for instance memtoll("1Gb") will return 1073741824 that is
  * (1024*1024*1024).
  *
  * On parsing error, if *err is not NULL, it's set to 1, otherwise it's
- * set to 0 */
+ * set to 0. On error the function return value is 0, regardless of the
+ * fact 'err' is NULL or not. */
 long long memtoll(const char *p, int *err) {
     const char *u;
     char buf[128];
@@ -183,6 +185,7 @@ long long memtoll(const char *p, int *err) {
     unsigned int digits;
 
     if (err) *err = 0;
+
     /* Search the first non digit character. */
     u = p;
     if (*u == '-') u++;
@@ -203,16 +206,26 @@ long long memtoll(const char *p, int *err) {
         mul = 1024L*1024*1024;
     } else {
         if (err) *err = 1;
-        mul = 1;
+        return 0;
     }
+
+    /* Copy the digits into a buffer, we'll use strtoll() to convert
+     * the digit (without the unit) into a number. */
     digits = u-p;
     if (digits >= sizeof(buf)) {
         if (err) *err = 1;
-        return LLONG_MAX;
+        return 0;
     }
     memcpy(buf,p,digits);
     buf[digits] = '\0';
-    val = strtoll(buf,NULL,10);
+
+    char *endptr;
+    errno = 0;
+    val = strtoll(buf,&endptr,10);
+    if ((val == 0 && errno == EINVAL) || *endptr != '\0') {
+        if (err) *err = 1;
+        return 0;
+    }
     return val*mul;
 }