Explicitly use "." instead of the result of basename(3) when argv[0] is
an empty string in order to avoid a segfault.

Skip suffix treatment if the result of basename(3) is "/", per POSIX.

Fix the suffix check, which was previously checking for a match at any
location in the string.

---
 basename.c | 14 +++++++++-----
 1 file changed, 9 insertions(+), 5 deletions(-)

diff --git a/basename.c b/basename.c
index 402be17..cbfaf70 100644
--- a/basename.c
+++ b/basename.c
@@ -18,6 +18,7 @@ int
 main(int argc, char *argv[])
 {
        char *s, *p;
+       size_t d;
 
        ARGBEGIN {
        default:
@@ -27,11 +28,14 @@ main(int argc, char *argv[])
        if (argc < 1)
                usage();
 
-       s = basename(argv[0]);
-       if (argc == 2) {
-               p = strstr(s, argv[1]);
-               if (p && p[strlen(p)] == '\0')
-                       *p = '\0';
+       s = strlen(argv[0]) ? basename(argv[0]) : ".";
+       if (argc == 2 && *s != '/') {
+               d = strlen(s) - strlen(argv[1]);
+               if (d >= 0) {
+                       p = s + d;
+                       if (strcmp(p, argv[1]) == 0)
+                               *p = '\0';
+               }
        }
        puts(s);
        return 0;
-- 
2.1.3


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