prefix_filename(): safely handle the case where pfx_len=0

Current prefix_filename() is proofed against the case where the prefix
'pfx' is NULL or a 0-length string, _except on Windows_.

Change the behaviour to work the same on both platforms, and only
check pfx_len so that callers passing a NULL prefix with a nonzero
pfx_len segfault early on both.

Signed-off-by: Thomas Rast <trast@student.ethz.ch>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

diff --git a/setup.c b/setup.c
index a3b76de2bb1c18e2f3b8cdf5799c3c650b16d027..346ef2eb2d678b742280c0816a09b8ca174ca799 100644 (file)
--- a/setup.c
+++ b/setup.c
@@ -46,7 +46,7 @@ const char *prefix_filename(const char *pfx, int pfx_len, const char *arg)
 {
        static char path[PATH_MAX];
 #ifndef WIN32
-       if (!pfx || !*pfx || is_absolute_path(arg))
+       if (!pfx_len || is_absolute_path(arg))
                return arg;
        memcpy(path, pfx, pfx_len);
        strcpy(path + pfx_len, arg);
@@ -55,7 +55,7 @@ const char *prefix_filename(const char *pfx, int pfx_len, const char *arg)
        /* don't add prefix to absolute paths, but still replace '\' by '/' */
        if (is_absolute_path(arg))
                pfx_len = 0;
-       else
+       else if (pfx_len)
                memcpy(path, pfx, pfx_len);
        strcpy(path + pfx_len, arg);
        for (p = path + pfx_len; *p; p++)