From 5da5c8f4cf4fb4e1cbccca4e7cebe70b77cf0b00 Mon Sep 17 00:00:00 2001 From: Junio C Hamano 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 --- 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 d1bdb5635..a3c279d00 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 d4cd45580..6db31651c 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 eba5a36f2..8d3a65f5f 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; -- 2.30.2