From 5da5c8f4cf4fb4e1cbccca4e7cebe70b77cf0b00 Mon Sep 17 00:00:00 2001
From: Junio C Hamano <junkio@cox.net>
Date: Sat, 30 Jul 2005 00:58:28 -0700
Subject: [PATCH] Teach parse_commit_buffer about grafting.
Introduce a new file $GIT_DIR/info/grafts (or $GIT_GRAFT_FILE)
which is a list of "fake commit parent records". Each line of
this file is a commit ID, followed by parent commit IDs, all
40-byte hex SHA1 separated by a single SP in between. The
records override the parent information we would normally read
from the commit objects, allowing both adding "fake" parents
(i.e. grafting), and pretending as if a commit is not a child of
some of its real parents (i.e. cauterizing).
Signed-off-by: Junio C Hamano <junkio@cox.net>
---
cache.h | 2 +
commit.c | 114 +++++++++++++++++++++++++++++++++++++++++++++++++++-
sha1_file.c | 13 +++++-
3 files changed, 127 insertions(+), 2 deletions(-)
diff --git a/cache.h b/cache.h
index d1bdb56355..a3c279d008 100644
--- a/cache.h
+++ b/cache.h
@@ -127,10 +127,12 @@ extern unsigned int active_nr, active_alloc, active_cache_changed;
#define DEFAULT_GIT_DIR_ENVIRONMENT ".git"
#define DB_ENVIRONMENT "GIT_OBJECT_DIRECTORY"
#define INDEX_ENVIRONMENT "GIT_INDEX_FILE"
+#define GRAFT_ENVIRONMENT "GIT_GRAFT_FILE"
extern char *get_object_directory(void);
extern char *get_refs_directory(void);
extern char *get_index_file(void);
+extern char *get_graft_file(void);
#define ALTERNATE_DB_ENVIRONMENT "GIT_ALTERNATE_OBJECT_DIRECTORIES"
diff --git a/commit.c b/commit.c
index d4cd45580d..6db31651c2 100644
--- a/commit.c
+++ b/commit.c
@@ -91,11 +91,108 @@ static unsigned long parse_commit_date(const char *buf)
return date;
}
+static struct commit_graft {
+ unsigned char sha1[20];
+ int nr_parent;
+ unsigned char parent[0][20]; /* more */
+} **commit_graft;
+static int commit_graft_alloc, commit_graft_nr;
+
+static int commit_graft_pos(const unsigned char *sha1)
+{
+ int lo, hi;
+ lo = 0;
+ hi = commit_graft_nr;
+ while (lo < hi) {
+ int mi = (lo + hi) / 2;
+ struct commit_graft *graft = commit_graft[mi];
+ int cmp = memcmp(sha1, graft->sha1, 20);
+ if (!cmp)
+ return mi;
+ if (cmp < 0)
+ hi = mi;
+ else
+ lo = mi + 1;
+ }
+ return -lo - 1;
+}
+
+static void prepare_commit_graft(void)
+{
+ char *graft_file = get_graft_file();
+ FILE *fp = fopen(graft_file, "r");
+ char buf[1024];
+ if (!fp) {
+ commit_graft = (struct commit_graft **) "hack";
+ return;
+ }
+ while (fgets(buf, sizeof(buf), fp)) {
+ /* The format is just "Commit Parent1 Parent2 ...\n" */
+ int len = strlen(buf);
+ int i;
+ struct commit_graft *graft = NULL;
+
+ if (buf[len-1] == '\n')
+ buf[--len] = 0;
+ if (buf[0] == '#')
+ continue;
+ if ((len + 1) % 41) {
+ bad_graft_data:
+ error("bad graft data: %s", buf);
+ free(graft);
+ continue;
+ }
+ i = (len + 1) / 41 - 1;
+ graft = xmalloc(sizeof(*graft) + 20 * i);
+ graft->nr_parent = i;
+ if (get_sha1_hex(buf, graft->sha1))
+ goto bad_graft_data;
+ for (i = 40; i < len; i += 41) {
+ if (buf[i] != ' ')
+ goto bad_graft_data;
+ if (get_sha1_hex(buf + i + 1, graft->parent[i/41]))
+ goto bad_graft_data;
+ }
+ i = commit_graft_pos(graft->sha1);
+ if (0 <= i) {
+ error("duplicate graft data: %s", buf);
+ free(graft);
+ continue;
+ }
+ i = -i - 1;
+ if (commit_graft_alloc <= ++commit_graft_nr) {
+ commit_graft_alloc = alloc_nr(commit_graft_alloc);
+ commit_graft = xrealloc(commit_graft,
+ sizeof(*commit_graft) *
+ commit_graft_alloc);
+ }
+ if (i < commit_graft_nr)
+ memmove(commit_graft + i + 1,
+ commit_graft + i,
+ (commit_graft_nr - i - 1) *
+ sizeof(*commit_graft));
+ commit_graft[i] = graft;
+ }
+ fclose(fp);
+}
+
+static struct commit_graft *lookup_commit_graft(const unsigned char *sha1)
+{
+ int pos;
+ if (!commit_graft)
+ prepare_commit_graft();
+ pos = commit_graft_pos(sha1);
+ if (pos < 0)
+ return NULL;
+ return commit_graft[pos];
+}
+
int parse_commit_buffer(struct commit *item, void *buffer, unsigned long size)
{
char *bufptr = buffer;
unsigned char parent[20];
struct commit_list **pptr;
+ struct commit_graft *graft;
if (item->object.parsed)
return 0;
@@ -109,17 +206,32 @@ int parse_commit_buffer(struct commit *item, void *buffer, unsigned long size)
add_ref(&item->object, &item->tree->object);
bufptr += 46; /* "tree " + "hex sha1" + "\n" */
pptr = &item->parents;
+
+ graft = lookup_commit_graft(item->object.sha1);
while (!memcmp(bufptr, "parent ", 7)) {
struct commit *new_parent;
if (get_sha1_hex(bufptr + 7, parent) || bufptr[47] != '\n')
return error("bad parents in commit %s", sha1_to_hex(item->object.sha1));
+ bufptr += 48;
+ if (graft)
+ continue;
new_parent = lookup_commit(parent);
if (new_parent) {
pptr = &commit_list_insert(new_parent, pptr)->next;
add_ref(&item->object, &new_parent->object);
}
- bufptr += 48;
+ }
+ if (graft) {
+ int i;
+ struct commit *new_parent;
+ for (i = 0; i < graft->nr_parent; i++) {
+ new_parent = lookup_commit(graft->parent[i]);
+ if (!new_parent)
+ continue;
+ pptr = &commit_list_insert(new_parent, pptr)->next;
+ add_ref(&item->object, &new_parent->object);
+ }
}
item->date = parse_commit_date(bufptr);
return 0;
diff --git a/sha1_file.c b/sha1_file.c
index eba5a36f24..8d3a65f5f8 100644
--- a/sha1_file.c
+++ b/sha1_file.c
@@ -61,7 +61,8 @@ static int get_sha1_file(const char *path, unsigned char *result)
return get_sha1_hex(buffer, result);
}
-static char *git_dir, *git_object_dir, *git_index_file, *git_refs_dir;
+static char *git_dir, *git_object_dir, *git_index_file, *git_refs_dir,
+ *git_graft_file;
static void setup_git_env(void)
{
git_dir = gitenv(GIT_DIR_ENVIRONMENT);
@@ -79,6 +80,9 @@ static void setup_git_env(void)
git_index_file = xmalloc(strlen(git_dir) + 7);
sprintf(git_index_file, "%s/index", git_dir);
}
+ git_graft_file = gitenv(GRAFT_ENVIRONMENT);
+ if (!git_graft_file)
+ git_graft_file = strdup(git_path("info/grafts"));
}
char *get_object_directory(void)
@@ -102,6 +106,13 @@ char *get_index_file(void)
return git_index_file;
}
+char *get_graft_file(void)
+{
+ if (!git_graft_file)
+ setup_git_env();
+ return git_graft_file;
+}
+
int safe_create_leading_directories(char *path)
{
char *pos = path;