[hackers] [sbase] Fix segmentation fault in cut(1) || FRIGN

[git]

commit 75aeb36ba2265b480878a29fdfc270eca0621038
Author: FRIGN <d...@frign.de>
Date:   Sat Jan 24 21:25:40 2015 +0100

    Fix segmentation fault in cut(1)
    
    Be stricter while resolving escapes in the delimiter-string and
    error out when it has length 0 or contains an invalid escape.
    
    Thanks to Hiltjo Posthuma's sharp eagle eyes this bug was spotted.

diff --git a/cut.c b/cut.c
index 5515f20..cd43703 100644
--- a/cut.c
+++ b/cut.c
@@ -144,7 +144,7 @@ resolveescapes(char *s, size_t len)
 {
        size_t i, off, m;
 
-       for (i = 0; i < len - 1; i++) {
+       for (i = 0; i < len; i++) {
                if (s[i] != '\\')
                        continue;
                off = 0;
@@ -158,7 +158,8 @@ resolveescapes(char *s, size_t len)
                 case 'r':  s[i] = '\r'; off++; break;
                 case 't':  s[i] = '\t'; off++; break;
                 case 'v':  s[i] = '\v'; off++; break;
-               default:   continue;
+               case '\0': eprintf("cut: null escape sequence in delimiter\n");
+               default: eprintf("cut: invalid escape sequence '\\%c' in 
delimiter\n", s[i + 1]);
                }
 
                for (m = i + 1; m <= len - off; m++)
@@ -191,6 +192,8 @@ main(int argc, char *argv[])
                break;
        case 'd':
                delim = EARGF(usage());
+               if (!*delim)
+                       eprintf("cut: empty delimiter\n");
                delimlen = resolveescapes(delim, strlen(delim));
                break;
        case 'n':