Since d1c5f2a (Add git-am, applymbox replacement., 2005-10-07),
git-am.sh supported the --3way option, and if set, would attempt to do a
3-way merge if the initial patch application fails.
Since d96a275 (git-am: add am.threeWay config variable, 2015-06-04), the
setting am.threeWay configures if the --3way option is set by default.
Since 5d86861 (am -3: list the paths that needed 3-way fallback,
2012-03-28), in a 3-way merge git-am.sh would list the paths that needed
3-way fallback, so that the user can review them more carefully to spot
mismerges.
Re-implement the above in builtin/am.c.
Signed-off-by: Paul Tan <pyokagan@xxxxxxxxx>
---
Notes:
v5
* s/a index/an index/
builtin/am.c | 157 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++--
1 file changed, 153 insertions(+), 4 deletions(-)
diff --git a/builtin/am.c b/builtin/am.c
index 511e4dd..af22c35 100644
--- a/builtin/am.c
+++ b/builtin/am.c
@@ -19,6 +19,8 @@
#include "unpack-trees.h"
#include "branch.h"
#include "sequencer.h"
+#include "revision.h"
+#include "merge-recursive.h"
/**
* Returns 1 if the file is empty or does not exist, 0 otherwise.
@@ -82,6 +84,8 @@ struct am_state {
/* number of digits in patch filename */
int prec;
+ int threeway;
+
int quiet;
int append_signoff;
@@ -102,6 +106,8 @@ static void am_state_init(struct am_state *state, const char *dir)
state->dir = xstrdup(dir);
state->prec = 4;
+
+ git_config_get_bool("am.threeway", &state->threeway);
}
/**
@@ -371,6 +377,9 @@ static void am_load(struct am_state *state)
read_commit_msg(state);
+ read_state_file(&sb, state, "threeway", 1);
+ state->threeway = !strcmp(sb.buf, "t");
+
read_state_file(&sb, state, "quiet", 1);
state->quiet = !strcmp(sb.buf, "t");
@@ -555,6 +564,8 @@ static void am_setup(struct am_state *state, enum patch_format patch_format,
die(_("Failed to split patches."));
}
+ write_file(am_path(state, "threeway"), 1, state->threeway ? "t" : "f");
+
write_file(am_path(state, "quiet"), 1, state->quiet ? "t" : "f");
write_file(am_path(state, "sign"), 1, state->append_signoff ? "t" : "f");
@@ -790,16 +801,34 @@ finish:
}
/**
- * Applies current patch with git-apply. Returns 0 on success, -1 otherwise.
+ * Applies current patch with git-apply. Returns 0 on success, -1 otherwise. If
+ * `index_file` is not NULL, the patch will be applied to that index.
*/
-static int run_apply(const struct am_state *state)
+static int run_apply(const struct am_state *state, const char *index_file)
{
struct child_process cp = CHILD_PROCESS_INIT;
cp.git_cmd = 1;
+ if (index_file)
+ argv_array_pushf(&cp.env_array, "GIT_INDEX_FILE=%s", index_file);
+
+ /*
+ * If we are allowed to fall back on 3-way merge, don't give false
+ * errors during the initial attempt.
+ */
+ if (state->threeway && !index_file) {
+ cp.no_stdout = 1;
+ cp.no_stderr = 1;
+ }
+
argv_array_push(&cp.args, "apply");
- argv_array_push(&cp.args, "--index");
+
+ if (index_file)
+ argv_array_push(&cp.args, "--cached");
+ else
+ argv_array_push(&cp.args, "--index");
+
argv_array_push(&cp.args, am_path(state, "patch"));
if (run_command(&cp))
@@ -807,8 +836,106 @@ static int run_apply(const struct am_state *state)
/* Reload index as git-apply will have modified it. */
discard_cache();
+ read_cache_from(index_file ? index_file : get_index_file());
+
+ return 0;
+}
+
+/**
+ * Builds an index that contains just the blobs needed for a 3way merge.
+ */
+static int build_fake_ancestor(const struct am_state *state, const char *index_file)
+{
+ struct child_process cp = CHILD_PROCESS_INIT;
+
+ cp.git_cmd = 1;
+ argv_array_push(&cp.args, "apply");
+ argv_array_pushf(&cp.args, "--build-fake-ancestor=%s", index_file);
+ argv_array_push(&cp.args, am_path(state, "patch"));
+
+ if (run_command(&cp))
+ return -1;
+
+ return 0;
+}
+
+/**
+ * Attempt a threeway merge, using index_path as the temporary index.
+ */
+static int fall_back_threeway(const struct am_state *state, const char *index_path)
+{
+ unsigned char orig_tree[GIT_SHA1_RAWSZ], his_tree[GIT_SHA1_RAWSZ],
+ our_tree[GIT_SHA1_RAWSZ];
+ const unsigned char *bases[1] = {orig_tree};
+ struct merge_options o;
+ struct commit *result;
+ char *his_tree_name;
+
+ if (get_sha1("HEAD", our_tree) < 0)
+ hashcpy(our_tree, EMPTY_TREE_SHA1_BIN);
+
+ if (build_fake_ancestor(state, index_path))
+ return error("could not build fake ancestor");
+
+ discard_cache();
+ read_cache_from(index_path);
+
+ if (write_index_as_tree(orig_tree, &the_index, index_path, 0, NULL))
+ return error(_("Repository lacks necessary blobs to fall back on 3-way merge."));
+
+ say(state, stdout, _("Using index info to reconstruct a base tree..."));
+
+ if (!state->quiet) {
+ /*
+ * List paths that needed 3-way fallback, so that the user can
+ * review them with extra care to spot mismerges.
+ */
+ struct rev_info rev_info;
+ const char *diff_filter_str = "--diff-filter=AM";
+
+ init_revisions(&rev_info, NULL);
+ rev_info.diffopt.output_format = DIFF_FORMAT_NAME_STATUS;
+ diff_opt_parse(&rev_info.diffopt, &diff_filter_str, 1);
+ add_pending_sha1(&rev_info, "HEAD", our_tree, 0);
+ diff_setup_done(&rev_info.diffopt);
+ run_diff_index(&rev_info, 1);
+ }
+
+ if (run_apply(state, index_path))
+ return error(_("Did you hand edit your patch?\n"
+ "It does not apply to blobs recorded in its index."));
+
+ if (write_index_as_tree(his_tree, &the_index, index_path, 0, NULL))
+ return error("could not write tree");
+
+ say(state, stdout, _("Falling back to patching base and 3-way merge..."));
+
+ discard_cache();
read_cache();
+ /*
+ * This is not so wrong. Depending on which base we picked, orig_tree
+ * may be wildly different from ours, but his_tree has the same set of
+ * wildly different changes in parts the patch did not touch, so
+ * recursive ends up canceling them, saying that we reverted all those
+ * changes.
+ */
+
+ init_merge_options(&o);
+
+ o.branch1 = "HEAD";
+ his_tree_name = xstrfmt("%.*s", linelen(state->msg), state->msg);
+ o.branch2 = his_tree_name;
+
+ if (state->quiet)
+ o.verbosity = 0;
+
+ if (merge_recursive_generic(&o, our_tree, his_tree, 1, bases, &result)) {
+ free(his_tree_name);
+ return error(_("Failed to merge in the changes."));
+ }
+
+ free(his_tree_name);
return 0;
}
@@ -877,6 +1004,7 @@ static void am_run(struct am_state *state)
while (state->cur <= state->last) {
const char *mail = am_path(state, msgnum(state));
+ int apply_status;
if (!file_exists(mail))
goto next;
@@ -889,7 +1017,26 @@ static void am_run(struct am_state *state)
say(state, stdout, _("Applying: %.*s"), linelen(state->msg), state->msg);
- if (run_apply(state) < 0) {
+ apply_status = run_apply(state, NULL);
+
+ if (apply_status && state->threeway) {
+ struct strbuf sb = STRBUF_INIT;
+
+ strbuf_addstr(&sb, am_path(state, "patch-merge-index"));
+ apply_status = fall_back_threeway(state, sb.buf);
+ strbuf_release(&sb);
+
+ /*
+ * Applying the patch to an earlier tree and merging
+ * the result may have produced the same tree as ours.
+ */
+ if (!apply_status && !index_has_changes(NULL)) {
+ say(state, stdout, _("No changes -- Patch already applied."));
+ goto next;
+ }
+ }
+
+ if (apply_status) {
int advice_amworkdir = 1;
printf_ln(_("Patch failed at %s %.*s"), msgnum(state),
@@ -1161,6 +1308,8 @@ int cmd_am(int argc, const char **argv, const char *prefix)
};
struct option options[] = {
+ OPT_BOOL('3', "3way", &state.threeway,
+ N_("allow fall back on 3way merging if needed")),
OPT__QUIET(&state.quiet, N_("be quiet")),
OPT_BOOL('s', "signoff", &state.append_signoff,
N_("add a Signed-off-by line to the commit message")),
--
2.5.0.rc1.76.gf60a929
--
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