mailmap: debug: avoid passing NULL to fprintf() '%s' conversion specification

POSIX does not state the behavior of '%s' conversion when passed a
NULL pointer. Some implementations interpolate literal "(null)";
others may crash.

Callers of debug_mm() often pass NULL as indication of either a
missing name or email address.  Instead, let's always supply a
proper string pointer, and make it a bit more descriptive: "(none)"

Signed-off-by: Eric Sunshine <sunshine@sunshineco.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

diff --git a/mailmap.c b/mailmap.c
index 4cc6e8128f73f74f260cdc66bcbbad56afe573c0..928e6e5d9c55ff2364c27b08c1d78b6850b3a1bc 100644 (file)
--- a/mailmap.c
+++ b/mailmap.c
@@ -5,8 +5,10 @@
 #define DEBUG_MAILMAP 0
 #if DEBUG_MAILMAP
 #define debug_mm(...) fprintf(stderr, __VA_ARGS__)
+#define debug_str(X) ((X) ? (X) : "(none)")
 #else
 static inline void debug_mm(const char *format, ...) {}
+static inline const char *debug_str(const char *s) { return s; }
 #endif
 
 const char *git_mailmap_file;
@@ -29,7 +31,7 @@ struct mailmap_entry {
 static void free_mailmap_info(void *p, const char *s)
 {
        struct mailmap_info *mi = (struct mailmap_info *)p;
-       debug_mm("mailmap: -- complex: '%s' -> '%s' <%s>\n", s, mi->name, mi->email);
+       debug_mm("mailmap: -- complex: '%s' -> '%s' <%s>\n", s, debug_str(mi->name), debug_str(mi->email));
        free(mi->name);
        free(mi->email);
 }
@@ -38,7 +40,8 @@ static void free_mailmap_entry(void *p, const char *s)
 {
        struct mailmap_entry *me = (struct mailmap_entry *)p;
        debug_mm("mailmap: removing entries for <%s>, with %d sub-entries\n", s, me->namemap.nr);
-       debug_mm("mailmap: - simple: '%s' <%s>\n", me->name, me->email);
+       debug_mm("mailmap: - simple: '%s' <%s>\n", debug_str(me->name), debug_str(me->email));
+
        free(me->name);
        free(me->email);
 
@@ -94,7 +97,7 @@ static void add_mapping(struct string_list *map,
        }
 
        debug_mm("mailmap:  '%s' <%s> -> '%s' <%s>\n",
-                old_name, old_email, new_name, new_email);
+                debug_str(old_name), old_email, debug_str(new_name), debug_str(new_email));
 }
 
 static char *parse_name_and_email(char *buffer, char **name,
@@ -309,7 +312,7 @@ int map_user(struct string_list *map,
        struct mailmap_entry *me;
 
        debug_mm("map_user: map '%.*s' <%.*s>\n",
-                (int)*namelen, *name, (int)*emaillen, *email);
+                (int)*namelen, debug_str(*name), (int)*emaillen, debug_str(*email));
 
        item = lookup_prefix(map, *email, *emaillen);
        if (item != NULL) {
@@ -337,8 +340,8 @@ int map_user(struct string_list *map,
                                *name = mi->name;
                                *namelen = strlen(*name);
                }
-               debug_mm("map_user:  to '%.*s' <%.*s>\n", (int)*namelen, *name,
-                                (int)*emaillen, *email);
+               debug_mm("map_user:  to '%.*s' <%.*s>\n", (int)*namelen, debug_str(*name),
+                                (int)*emaillen, debug_str(*email));
                return 1;
        }
        debug_mm("map_user:  --\n");