difftool: handle unmerged files in dir-diff mode

diff --git a/compat/setenv.c b/compat/setenv.c
index fc1439a6439393ff5224e98ab126607ceaa4994d..7849f258d20195ac27c9be921fb8b65ac094a408 100644 (file)
--- a/compat/setenv.c
+++ b/compat/setenv.c
@@ -18,7 +18,7 @@ int gitsetenv(const char *name, const char *value, int replace)
 
        namelen = strlen(name);
        valuelen = strlen(value);
-       envstr = malloc((namelen + valuelen + 2));
+       envstr = malloc(st_add3(namelen, valuelen, 2));
        if (!envstr) {
                errno = ENOMEM;
                return -1;