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-rw-r--r--rerere.c360
1 files changed, 360 insertions, 0 deletions
diff --git a/rerere.c b/rerere.c
new file mode 100644
index 0000000..eec2b50
--- /dev/null
+++ b/rerere.c
@@ -0,0 +1,360 @@
+#include "cache.h"
+#include "path-list.h"
+#include "rerere.h"
+#include "xdiff/xdiff.h"
+#include "xdiff-interface.h"
+
+/* if rerere_enabled == -1, fall back to detection of .git/rr-cache */
+static int rerere_enabled = -1;
+
+/* automatically update cleanly resolved paths to the index */
+static int rerere_autoupdate;
+
+static char *merge_rr_path;
+
+static const char *rr_path(const char *name, const char *file)
+{
+ return git_path("rr-cache/%s/%s", name, file);
+}
+
+static int has_resolution(const char *name)
+{
+ struct stat st;
+ return !stat(rr_path(name, "postimage"), &st);
+}
+
+static void read_rr(struct path_list *rr)
+{
+ unsigned char sha1[20];
+ char buf[PATH_MAX];
+ FILE *in = fopen(merge_rr_path, "r");
+ if (!in)
+ return;
+ while (fread(buf, 40, 1, in) == 1) {
+ int i;
+ char *name;
+ if (get_sha1_hex(buf, sha1))
+ die("corrupt MERGE_RR");
+ buf[40] = '\0';
+ name = xstrdup(buf);
+ if (fgetc(in) != '\t')
+ die("corrupt MERGE_RR");
+ for (i = 0; i < sizeof(buf) && (buf[i] = fgetc(in)); i++)
+ ; /* do nothing */
+ if (i == sizeof(buf))
+ die("filename too long");
+ path_list_insert(buf, rr)->util = name;
+ }
+ fclose(in);
+}
+
+static struct lock_file write_lock;
+
+static int write_rr(struct path_list *rr, int out_fd)
+{
+ int i;
+ for (i = 0; i < rr->nr; i++) {
+ const char *path;
+ int length;
+ if (!rr->items[i].util)
+ continue;
+ path = rr->items[i].path;
+ length = strlen(path) + 1;
+ if (write_in_full(out_fd, rr->items[i].util, 40) != 40 ||
+ write_in_full(out_fd, "\t", 1) != 1 ||
+ write_in_full(out_fd, path, length) != length)
+ die("unable to write rerere record");
+ }
+ if (commit_lock_file(&write_lock) != 0)
+ die("unable to write rerere record");
+ return 0;
+}
+
+static int handle_file(const char *path,
+ unsigned char *sha1, const char *output)
+{
+ SHA_CTX ctx;
+ char buf[1024];
+ int hunk = 0, hunk_no = 0;
+ struct strbuf one, two;
+ FILE *f = fopen(path, "r");
+ FILE *out = NULL;
+
+ if (!f)
+ return error("Could not open %s", path);
+
+ if (output) {
+ out = fopen(output, "w");
+ if (!out) {
+ fclose(f);
+ return error("Could not write %s", output);
+ }
+ }
+
+ if (sha1)
+ SHA1_Init(&ctx);
+
+ strbuf_init(&one, 0);
+ strbuf_init(&two, 0);
+ while (fgets(buf, sizeof(buf), f)) {
+ if (!prefixcmp(buf, "<<<<<<< ")) {
+ if (hunk)
+ goto bad;
+ hunk = 1;
+ } else if (!prefixcmp(buf, "=======") && isspace(buf[7])) {
+ if (hunk != 1)
+ goto bad;
+ hunk = 2;
+ } else if (!prefixcmp(buf, ">>>>>>> ")) {
+ if (hunk != 2)
+ goto bad;
+ if (strbuf_cmp(&one, &two) > 0)
+ strbuf_swap(&one, &two);
+ hunk_no++;
+ hunk = 0;
+ if (out) {
+ fputs("<<<<<<<\n", out);
+ fwrite(one.buf, one.len, 1, out);
+ fputs("=======\n", out);
+ fwrite(two.buf, two.len, 1, out);
+ fputs(">>>>>>>\n", out);
+ }
+ if (sha1) {
+ SHA1_Update(&ctx, one.buf ? one.buf : "",
+ one.len + 1);
+ SHA1_Update(&ctx, two.buf ? two.buf : "",
+ two.len + 1);
+ }
+ strbuf_reset(&one);
+ strbuf_reset(&two);
+ } else if (hunk == 1)
+ strbuf_addstr(&one, buf);
+ else if (hunk == 2)
+ strbuf_addstr(&two, buf);
+ else if (out)
+ fputs(buf, out);
+ continue;
+ bad:
+ hunk = 99; /* force error exit */
+ break;
+ }
+ strbuf_release(&one);
+ strbuf_release(&two);
+
+ fclose(f);
+ if (out)
+ fclose(out);
+ if (sha1)
+ SHA1_Final(sha1, &ctx);
+ if (hunk) {
+ if (output)
+ unlink(output);
+ return error("Could not parse conflict hunks in %s", path);
+ }
+ return hunk_no;
+}
+
+static int find_conflict(struct path_list *conflict)
+{
+ int i;
+ if (read_cache() < 0)
+ return error("Could not read index");
+ for (i = 0; i+1 < active_nr; i++) {
+ struct cache_entry *e2 = active_cache[i];
+ struct cache_entry *e3 = active_cache[i+1];
+ if (ce_stage(e2) == 2 &&
+ ce_stage(e3) == 3 &&
+ ce_same_name(e2, e3) &&
+ S_ISREG(e2->ce_mode) &&
+ S_ISREG(e3->ce_mode)) {
+ path_list_insert((const char *)e2->name, conflict);
+ i++; /* skip over both #2 and #3 */
+ }
+ }
+ return 0;
+}
+
+static int merge(const char *name, const char *path)
+{
+ int ret;
+ mmfile_t cur, base, other;
+ mmbuffer_t result = {NULL, 0};
+ xpparam_t xpp = {XDF_NEED_MINIMAL};
+
+ if (handle_file(path, NULL, rr_path(name, "thisimage")) < 0)
+ return 1;
+
+ if (read_mmfile(&cur, rr_path(name, "thisimage")) ||
+ read_mmfile(&base, rr_path(name, "preimage")) ||
+ read_mmfile(&other, rr_path(name, "postimage")))
+ return 1;
+ ret = xdl_merge(&base, &cur, "", &other, "",
+ &xpp, XDL_MERGE_ZEALOUS, &result);
+ if (!ret) {
+ FILE *f = fopen(path, "w");
+ if (!f)
+ return error("Could not write to %s", path);
+ fwrite(result.ptr, result.size, 1, f);
+ fclose(f);
+ }
+
+ free(cur.ptr);
+ free(base.ptr);
+ free(other.ptr);
+ free(result.ptr);
+
+ return ret;
+}
+
+static struct lock_file index_lock;
+
+static int update_paths(struct path_list *update)
+{
+ int i;
+ int fd = hold_locked_index(&index_lock, 0);
+ int status = 0;
+
+ if (fd < 0)
+ return -1;
+
+ for (i = 0; i < update->nr; i++) {
+ struct path_list_item *item = &update->items[i];
+ if (add_file_to_cache(item->path, ADD_CACHE_IGNORE_ERRORS))
+ status = -1;
+ }
+
+ if (!status && active_cache_changed) {
+ if (write_cache(fd, active_cache, active_nr) ||
+ commit_locked_index(&index_lock))
+ die("Unable to write new index file");
+ } else if (fd >= 0)
+ rollback_lock_file(&index_lock);
+ return status;
+}
+
+static int do_plain_rerere(struct path_list *rr, int fd)
+{
+ struct path_list conflict = { NULL, 0, 0, 1 };
+ struct path_list update = { NULL, 0, 0, 1 };
+ int i;
+
+ find_conflict(&conflict);
+
+ /*
+ * MERGE_RR records paths with conflicts immediately after merge
+ * failed. Some of the conflicted paths might have been hand resolved
+ * in the working tree since then, but the initial run would catch all
+ * and register their preimages.
+ */
+
+ for (i = 0; i < conflict.nr; i++) {
+ const char *path = conflict.items[i].path;
+ if (!path_list_has_path(rr, path)) {
+ unsigned char sha1[20];
+ char *hex;
+ int ret;
+ ret = handle_file(path, sha1, NULL);
+ if (ret < 1)
+ continue;
+ hex = xstrdup(sha1_to_hex(sha1));
+ path_list_insert(path, rr)->util = hex;
+ if (mkdir(git_path("rr-cache/%s", hex), 0755))
+ continue;;
+ handle_file(path, NULL, rr_path(hex, "preimage"));
+ fprintf(stderr, "Recorded preimage for '%s'\n", path);
+ }
+ }
+
+ /*
+ * Now some of the paths that had conflicts earlier might have been
+ * hand resolved. Others may be similar to a conflict already that
+ * was resolved before.
+ */
+
+ for (i = 0; i < rr->nr; i++) {
+ int ret;
+ const char *path = rr->items[i].path;
+ const char *name = (const char *)rr->items[i].util;
+
+ if (has_resolution(name)) {
+ if (!merge(name, path)) {
+ fprintf(stderr, "Resolved '%s' using "
+ "previous resolution.\n", path);
+ if (rerere_autoupdate)
+ path_list_insert(path, &update);
+ goto mark_resolved;
+ }
+ }
+
+ /* Let's see if we have resolved it. */
+ ret = handle_file(path, NULL, NULL);
+ if (ret)
+ continue;
+
+ fprintf(stderr, "Recorded resolution for '%s'.\n", path);
+ copy_file(rr_path(name, "postimage"), path, 0666);
+ mark_resolved:
+ rr->items[i].util = NULL;
+ }
+
+ if (update.nr)
+ update_paths(&update);
+
+ return write_rr(rr, fd);
+}
+
+static int git_rerere_config(const char *var, const char *value, void *cb)
+{
+ if (!strcmp(var, "rerere.enabled"))
+ rerere_enabled = git_config_bool(var, value);
+ else if (!strcmp(var, "rerere.autoupdate"))
+ rerere_autoupdate = git_config_bool(var, value);
+ else
+ return git_default_config(var, value, cb);
+ return 0;
+}
+
+static int is_rerere_enabled(void)
+{
+ struct stat st;
+ const char *rr_cache;
+ int rr_cache_exists;
+
+ if (!rerere_enabled)
+ return 0;
+
+ rr_cache = git_path("rr-cache");
+ rr_cache_exists = !stat(rr_cache, &st) && S_ISDIR(st.st_mode);
+ if (rerere_enabled < 0)
+ return rr_cache_exists;
+
+ if (!rr_cache_exists &&
+ (mkdir(rr_cache, 0777) || adjust_shared_perm(rr_cache)))
+ die("Could not create directory %s", rr_cache);
+ return 1;
+}
+
+int setup_rerere(struct path_list *merge_rr)
+{
+ int fd;
+
+ git_config(git_rerere_config, NULL);
+ if (!is_rerere_enabled())
+ return -1;
+
+ merge_rr_path = xstrdup(git_path("rr-cache/MERGE_RR"));
+ fd = hold_lock_file_for_update(&write_lock, merge_rr_path, 1);
+ read_rr(merge_rr);
+ return fd;
+}
+
+int rerere(void)
+{
+ struct path_list merge_rr = { NULL, 0, 0, 1 };
+ int fd;
+
+ fd = setup_rerere(&merge_rr);
+ if (fd < 0)
+ return 0;
+ return do_plain_rerere(&merge_rr, fd);
+}