Teach "git apply" to prepend a prefix with "--root=<root>"

diff --git a/builtin-apply.c b/builtin-apply.c
index c4978893122bbcfd80201fe937eb8433b29e1aa0..bf528966cabd23d844add6dcc6e414a7ca32be7c 100644 (file)
--- a/builtin-apply.c
+++ b/builtin-apply.c
@@ -57,6 +57,8 @@ static int whitespace_error;
 static int squelch_whitespace_errors = 5;
 static int applied_after_fixing_ws;
 static const char *patch_input_file;
+static const char *root;
+static int root_len;
 
 static void parse_whitespace_option(const char *option)
 {
@@ -331,6 +333,8 @@ static char *find_name(const char *line, char *def, int p_value, int terminate)
                                 */
                                strbuf_remove(&name, 0, cp - name.buf);
                                free(def);
+                               if (root)
+                                       strbuf_insert(&name, 0, root, root_len);
                                return strbuf_detach(&name, NULL);
                        }
                }
@@ -369,6 +373,14 @@ static char *find_name(const char *line, char *def, int p_value, int terminate)
                free(def);
        }
 
+       if (root) {
+               char *ret = xmalloc(root_len + len + 1);
+               strcpy(ret, root);
+               memcpy(ret + root_len, start, len);
+               ret[root_len + len] = '\0';
+               return ret;
+       }
+
        return xmemdupz(start, len);
 }
 
@@ -3118,6 +3130,18 @@ int cmd_apply(int argc, const char **argv, const char *unused_prefix)
                        inaccurate_eof = 1;
                        continue;
                }
+               if (!strncmp(arg, "--root=", strlen("--root="))) {
+                       arg += strlen("--root=");
+                       root_len = strlen(arg);
+                       if (root_len && arg[root_len + 1] != '/') {
+                               char *new_root;
+                               root = new_root = xmalloc(root_len + 2);
+                               strcpy(new_root, arg);
+                               strcpy(new_root + root_len++, "/");
+                       } else
+                               root = arg;
+                       continue;
+               }
                if (0 < prefix_length)
                        arg = prefix_filename(prefix, prefix_length, arg);