[hackers] [sbase] Harden parseoffset() even more || FRIGN

[git]

commit 870a75076d969f0ec8e3ccea9b75726612476bab
Author:     FRIGN <d...@frign.de>
AuthorDate: Wed Sep 30 19:14:14 2015 +0200
Commit:     sin <s...@2f30.org>
CommitDate: Wed Sep 30 19:44:10 2015 +0100

    Harden parseoffset() even more
    
    1) Check for NULL.
    2) Check for empty strings.
    3) Clarify error-messages.

diff --git a/libutil/parseoffset.c b/libutil/parseoffset.c
index 9ce0411..d12557f 100644
--- a/libutil/parseoffset.c
+++ b/libutil/parseoffset.c
@@ -14,6 +14,11 @@ parseoffset(const char *str)
        int base = 10;
        char *end;
 
+       if (!str || !*str) {
+               weprintf("parseoffset: empty string\n");
+               return -1;
+       }
+
        /* bases */
        if (!strncasecmp(str, "0x", strlen("0x"))) {
                base = 16;
@@ -24,7 +29,7 @@ parseoffset(const char *str)
 
        res = strtol(str, &end, base);
        if (res < 0) {
-               weprintf("invalid file offset: %s\n", str);
+               weprintf("parseoffset %s: negative value\n", str);
                return -1;
        }
 
@@ -44,14 +49,14 @@ parseoffset(const char *str)
                        scale = 1024L * 1024L * 1024L;
                        break;
                default:
-                       weprintf("invalid file offset suffix: %s\n", str);
+                       weprintf("parseoffset %s: invalid suffix\n", str);
                        return -1;
                }
        }
 
        /* prevent overflow */
        if (res > (SIZE_MAX / scale)) {
-               weprintf("file offset out of range: %s\n", str);
+               weprintf("parseoffset %s: out of range\n", str);
                return -1;
        }