rerere forget path: forget recorded resolution

After you find out an earlier resolution you told rerere to use was a
mismerge, there is no easy way to clear it.  A new subcommand "forget" can
be used to tell git to forget a recorded resolution, so that you can redo
the merge from scratch.

Signed-off-by: Junio C Hamano <gitster@pobox.com>

diff --git a/builtin-rerere.c b/builtin-rerere.c
index 2be9ffb77b38ae687537f3599c9d11e3fbc026a9..0253abf9b698ed10a8df5c21ef07c93b8e6460dc 100644 (file)
--- a/builtin-rerere.c
+++ b/builtin-rerere.c
@@ -110,6 +110,8 @@ int cmd_rerere(int argc, const char **argv, const char *prefix)
 
        if (!strcmp(argv[1], "-h"))
                usage(git_rerere_usage);
+       else if (!strcmp(argv[1], "forget"))
+               return rerere_forget(argv + 2);
 
        fd = setup_rerere(&merge_rr);
        if (fd < 0)

diff --git a/rerere.c b/rerere.c
index db1d42f1b61777c0099de01c4e917a57e1f68dca..d92990a6bba01c321bb67bd07287772075f6994a 100644 (file)
--- a/rerere.c
+++ b/rerere.c
@@ -3,6 +3,9 @@
 #include "rerere.h"
 #include "xdiff/xdiff.h"
 #include "xdiff-interface.h"
+#include "dir.h"
+#include "resolve-undo.h"
+#include "ll-merge.h"
 
 /* if rerere_enabled == -1, fall back to detection of .git/rr-cache */
 static int rerere_enabled = -1;
@@ -223,6 +226,87 @@ static int handle_file(const char *path, unsigned char *sha1, const char *output
        return hunk_no;
 }
 
+struct rerere_io_mem {
+       struct rerere_io io;
+       struct strbuf input;
+};
+
+static int rerere_mem_getline(struct strbuf *sb, struct rerere_io *io_)
+{
+       struct rerere_io_mem *io = (struct rerere_io_mem *)io_;
+       char *ep;
+       size_t len;
+
+       strbuf_release(sb);
+       if (!io->input.len)
+               return -1;
+       ep = strchrnul(io->input.buf, '\n');
+       if (*ep == '\n')
+               ep++;
+       len = ep - io->input.buf;
+       strbuf_add(sb, io->input.buf, len);
+       strbuf_remove(&io->input, 0, len);
+       return 0;
+}
+
+static int handle_cache(const char *path, unsigned char *sha1, const char *output)
+{
+       mmfile_t mmfile[3];
+       mmbuffer_t result = {NULL, 0};
+       struct cache_entry *ce;
+       int pos, len, i, hunk_no;
+       struct rerere_io_mem io;
+
+       /*
+        * Reproduce the conflicted merge in-core
+        */
+       len = strlen(path);
+       pos = cache_name_pos(path, len);
+       if (0 <= pos)
+               return -1;
+       pos = -pos - 1;
+
+       for (i = 0; i < 3; i++) {
+               enum object_type type;
+               unsigned long size;
+
+               mmfile[i].size = 0;
+               mmfile[i].ptr = NULL;
+               if (active_nr <= pos)
+                       break;
+               ce = active_cache[pos++];
+               if (ce_namelen(ce) != len || memcmp(ce->name, path, len)
+                   || ce_stage(ce) != i + 1)
+                       break;
+               mmfile[i].ptr = read_sha1_file(ce->sha1, &type, &size);
+               mmfile[i].size = size;
+       }
+       for (i = 0; i < 3; i++) {
+               if (!mmfile[i].ptr && !mmfile[i].size)
+                       mmfile[i].ptr = xstrdup("");
+       }
+       ll_merge(&result, path, &mmfile[0],
+                &mmfile[1], "ours",
+                &mmfile[2], "theirs", 0);
+       for (i = 0; i < 3; i++)
+               free(mmfile[i].ptr);
+
+       memset(&io, 0, sizeof(&io));
+       io.io.getline = rerere_mem_getline;
+       if (output)
+               io.io.output = fopen(output, "w");
+       else
+               io.io.output = NULL;
+       strbuf_init(&io.input, 0);
+       strbuf_attach(&io.input, result.ptr, result.size, result.size);
+
+       hunk_no = handle_path(sha1, (struct rerere_io *)&io);
+       strbuf_release(&io.input);
+       if (io.io.output)
+               fclose(io.io.output);
+       return hunk_no;
+}
+
 static int find_conflict(struct string_list *conflict)
 {
        int i;
@@ -434,3 +518,52 @@ int rerere(void)
                return 0;
        return do_plain_rerere(&merge_rr, fd);
 }
+
+static int rerere_forget_one_path(const char *path, struct string_list *rr)
+{
+       const char *filename;
+       char *hex;
+       unsigned char sha1[20];
+       int ret;
+
+       ret = handle_cache(path, sha1, NULL);
+       if (ret < 1)
+               return error("Could not parse conflict hunks in '%s'", path);
+       hex = xstrdup(sha1_to_hex(sha1));
+       filename = rerere_path(hex, "postimage");
+       if (unlink(filename))
+               return (errno == ENOENT
+                       ? error("no remembered resolution for %s", path)
+                       : error("cannot unlink %s: %s", filename, strerror(errno)));
+
+       handle_cache(path, sha1, rerere_path(hex, "preimage"));
+       fprintf(stderr, "Updated preimage for '%s'\n", path);
+
+
+       string_list_insert(path, rr)->util = hex;
+       fprintf(stderr, "Forgot resolution for %s\n", path);
+       return 0;
+}
+
+int rerere_forget(const char **pathspec)
+{
+       int i, fd;
+       struct string_list conflict = { NULL, 0, 0, 1 };
+       struct string_list merge_rr = { NULL, 0, 0, 1 };
+
+       if (read_cache() < 0)
+               return error("Could not read index");
+
+       fd = setup_rerere(&merge_rr);
+
+       unmerge_cache(pathspec);
+       find_conflict(&conflict);
+       for (i = 0; i < conflict.nr; i++) {
+               struct string_list_item *it = &conflict.items[i];
+               if (!match_pathspec(pathspec, it->string, strlen(it->string),
+                                   0, NULL))
+                       continue;
+               rerere_forget_one_path(it->string, &merge_rr);
+       }
+       return write_rr(&merge_rr, fd);
+}

diff --git a/rerere.h b/rerere.h
index 13313f3f2b2cc6a8d895305b7ac92c12c1753682..36560ff2f5501105049e2220f959721104fc4922 100644 (file)
--- a/rerere.h
+++ b/rerere.h
@@ -7,5 +7,6 @@ extern int setup_rerere(struct string_list *);
 extern int rerere(void);
 extern const char *rerere_path(const char *hex, const char *file);
 extern int has_rerere_resolution(const char *hex);
+extern int rerere_forget(const char **);
 
 #endif

diff --git a/t/t2030-unresolve-info.sh b/t/t2030-unresolve-info.sh
index 28e2eb1cec4d1fdc7d28c659ee146741e7d4f850..a38bd6df8490e8c54c29a54084f2a5c232f24e15 100755 (executable)
--- a/t/t2030-unresolve-info.sh
+++ b/t/t2030-unresolve-info.sh
@@ -115,4 +115,29 @@ test_expect_success 'unmerge with plumbing' '
        test $(wc -l <actual) = 3
 '
 
+test_expect_success 'rerere and rerere --forget' '
+       mkdir .git/rr-cache &&
+       prime_resolve_undo &&
+       echo record the resolution &&
+       git rerere &&
+       rerere_id=$(cd .git/rr-cache && echo */postimage) &&
+       rerere_id=${rerere_id%/postimage} &&
+       test -f .git/rr-cache/$rerere_id/postimage &&
+       git checkout -m file &&
+       echo resurrect the conflict &&
+       grep "^=======" file &&
+       echo reresolve the conflict &&
+       git rerere &&
+       test "z$(cat file)" = zdifferent &&
+       echo register the resolution again &&
+       git add file &&
+       check_resolve_undo kept file initial:file second:file third:file &&
+       test -z "$(git ls-files -u)" &&
+       git rerere forget file &&
+       ! test -f .git/rr-cache/$rerere_id/postimage &&
+       tr "\0" "\n" <.git/MERGE_RR >actual &&
+       echo "$rerere_id        file" >expect &&
+       test_cmp expect actual
+'
+
 test_done