Merge branch 'ar/maint-mksnpath' into HEAD

* ar/maint-mksnpath:
  Fix potentially dangerous uses of mkpath and git_path
  Fix mkpath abuse in dwim_ref and dwim_log of sha1_name.c
  Add mksnpath which allows you to specify the output buffer

builtin-apply.c

@@ -2841,8 +2841,8 @@ static void create_one_file(char *path, unsigned mode, const char *buf, unsigned
 		unsigned int nr = getpid();
 
 		for (;;) {
-			const char *newpath;
-			newpath = mkpath("%s~%u", path, nr);
+			char newpath[PATH_MAX];
+			mksnpath(newpath, sizeof(newpath), "%s~%u", path, nr);
 			if (!try_create_file(newpath, mode, buf, size)) {
 				if (!rename(newpath, path))
 					return;

cache.h

@@ -495,6 +495,9 @@ extern int check_repository_format(void);
 #define DATA_CHANGED    0x0020
 #define TYPE_CHANGED    0x0040
 
+extern char *mksnpath(char *buf, size_t n, const char *fmt, ...)
+	__attribute__((format (printf, 3, 4)));
+
 /* Return a statically allocated filename matching the sha1 signature */
 extern char *mkpath(const char *fmt, ...) __attribute__((format (printf, 1, 2)));
 extern char *git_path(const char *fmt, ...) __attribute__((format (printf, 1, 2)));

path.c

@@ -32,6 +32,21 @@ static char *cleanup_path(char *path)
 	return path;
 }
 
+char *mksnpath(char *buf, size_t n, const char *fmt, ...)
+{
+	va_list args;
+	unsigned len;
+
+	va_start(args, fmt);
+	len = vsnprintf(buf, n, fmt, args);
+	va_end(args);
+	if (len >= n) {
+		snprintf(buf, n, bad_path);
+		return buf;
+	}
+	return cleanup_path(buf);
+}
+
 char *mkpath(const char *fmt, ...)
 {
 	va_list args;

sha1_name.c

@@ -245,11 +245,13 @@ int dwim_ref(const char *str, int len, unsigned char *sha1, char **ref)
 
 	*ref = NULL;
 	for (p = ref_rev_parse_rules; *p; p++) {
+		char fullref[PATH_MAX];
 		unsigned char sha1_from_ref[20];
 		unsigned char *this_result;
 
 		this_result = refs_found ? sha1_from_ref : sha1;
-		r = resolve_ref(mkpath(*p, len, str), this_result, 1, NULL);
+		mksnpath(fullref, sizeof(fullref), *p, len, str);
+		r = resolve_ref(fullref, this_result, 1, NULL);
 		if (r) {
 			if (!refs_found++)
 				*ref = xstrdup(r);
@@ -272,7 +274,7 @@ int dwim_log(const char *str, int len, unsigned char *sha1, char **log)
 		char path[PATH_MAX];
 		const char *ref, *it;
 
-		strcpy(path, mkpath(*p, len, str));
+		mksnpath(path, sizeof(path), *p, len, str);
 		ref = resolve_ref(path, hash, 1, NULL);
 		if (!ref)
 			continue;