X-Git-Url: https://git.verplant.org/?a=blobdiff_plain;f=read-tree.c;h=c4ca86f48607cc7f83b88739a539b30315b4cc12;hb=b8f80925e3cdf229f03245f2ebb02323ddd98118;hp=af486ff33f6f66323b25efc5ce9e3540d5f5bab9;hpb=19b2860cba5742ab31fd682b80fefefac19be141;p=git.git diff --git a/read-tree.c b/read-tree.c index af486ff3..c4ca86f4 100644 --- a/read-tree.c +++ b/read-tree.c @@ -5,33 +5,25 @@ */ #include "cache.h" -static void create_directories(const char *path) -{ - int len = strlen(path); - char *buf = malloc(len + 1); - const char *slash = path; - - while ((slash = strchr(slash+1, '/')) != NULL) { - len = slash - path; - memcpy(buf, path, len); - buf[len] = 0; - mkdir(buf, 0700); - } -} +static int stage = 0; -static int create_file(const char *path) +static int read_one_entry(unsigned char *sha1, const char *base, int baselen, const char *pathname, unsigned mode) { - int fd = open(path, O_WRONLY | O_TRUNC | O_CREAT, 0600); - if (fd < 0) { - if (errno == ENOENT) { - create_directories(path); - fd = open(path, O_WRONLY | O_TRUNC | O_CREAT, 0600); - } - } - return fd; + int len = strlen(pathname); + unsigned int size = cache_entry_size(baselen + len); + struct cache_entry *ce = malloc(size); + + memset(ce, 0, size); + + ce->ce_mode = htonl(mode); + ce->ce_flags = create_ce_flags(baselen + len, stage); + memcpy(ce->name, base, baselen); + memcpy(ce->name + baselen, pathname, len+1); + memcpy(ce->sha1, sha1, 20); + return add_cache_entry(ce, 1); } -static int unpack(unsigned char *sha1) +static int read_tree(unsigned char *sha1, const char *base, int baselen) { void *buffer; unsigned long size; @@ -39,49 +31,159 @@ static int unpack(unsigned char *sha1) buffer = read_sha1_file(sha1, type, &size); if (!buffer) - usage("unable to read sha1 file"); + return -1; if (strcmp(type, "tree")) - usage("expected a 'tree' node"); + return -1; while (size) { int len = strlen(buffer)+1; unsigned char *sha1 = buffer + len; char *path = strchr(buffer, ' ')+1; - char *data; - unsigned long filesize; unsigned int mode; - int fd; if (size < len + 20 || sscanf(buffer, "%o", &mode) != 1) - usage("corrupt 'tree' file"); + return -1; + buffer = sha1 + 20; size -= len + 20; - data = read_sha1_file(sha1, type, &filesize); - if (!data || strcmp(type, "blob")) - usage("tree file refers to bad file data"); - fd = create_file(path); - if (fd < 0) - usage("unable to create file"); - if (write(fd, data, filesize) != filesize) - usage("unable to write file"); - fchmod(fd, mode); - close(fd); - free(data); + + if (S_ISDIR(mode)) { + int retval; + int pathlen = strlen(path); + char *newbase = malloc(baselen + 1 + pathlen); + memcpy(newbase, base, baselen); + memcpy(newbase + baselen, path, pathlen); + newbase[baselen + pathlen] = '/'; + retval = read_tree(sha1, newbase, baselen + pathlen + 1); + free(newbase); + if (retval) + return -1; + continue; + } + if (read_one_entry(sha1, base, baselen, path, mode) < 0) + return -1; } return 0; } +static int remove_lock = 0; + +static void remove_lock_file(void) +{ + if (remove_lock) + unlink(".git/index.lock"); +} + +static int same(struct cache_entry *a, struct cache_entry *b) +{ + return a->ce_mode == b->ce_mode && + !memcmp(a->sha1, b->sha1, 20); +} + + +/* + * This removes all trivial merges that don't change the tree + * and collapses them to state 0. + * + * _Any_ other merge is left to user policy. That includes "both + * created the same file", and "both removed the same file" - which are + * trivial, but the user might still want to _note_ it. + */ +static struct cache_entry *merge_entries(struct cache_entry *a, + struct cache_entry *b, + struct cache_entry *c) +{ + int len = ce_namelen(a); + + /* + * Are they all the same filename? We won't do + * any name merging + */ + if (ce_namelen(b) != len || + ce_namelen(c) != len || + memcmp(a->name, b->name, len) || + memcmp(a->name, c->name, len)) + return NULL; + + /* + * Ok, all three entries describe the same + * filename, but maybe the contents or file + * mode have changed? + * + * The trivial cases end up being the ones where two + * out of three files are the same: + * - both destinations the same, trivially take either + * - one of the destination versions hasn't changed, + * take the other. + * + * The "all entries exactly the same" case falls out as + * a special case of any of the "two same" cases. + * + * Here "a" is "original", and "b" and "c" are the two + * trees we are merging. + */ + if (same(b,c)) + return c; + if (same(a,b)) + return c; + if (same(a,c)) + return b; + return NULL; +} + +static void trivially_merge_cache(struct cache_entry **src, int nr) +{ + struct cache_entry **dst = src; + + while (nr) { + struct cache_entry *ce, *result; + + ce = src[0]; + if (nr > 2 && (result = merge_entries(ce, src[1], src[2])) != NULL) { + ce = result; + ce->ce_flags &= ~htons(CE_STAGEMASK); + src += 2; + nr -= 2; + active_nr -= 2; + } + *dst = ce; + src++; + dst++; + nr--; + } +} + int main(int argc, char **argv) { + int i, newfd; unsigned char sha1[20]; - if (argc != 2) - usage("read-tree "); - if (get_sha1_hex(argv[1], sha1) < 0) - usage("read-tree "); - sha1_file_directory = getenv(DB_ENVIRONMENT); - if (!sha1_file_directory) - sha1_file_directory = DEFAULT_DB_ENVIRONMENT; - if (unpack(sha1) < 0) - usage("unpack failed"); + newfd = open(".git/index.lock", O_RDWR | O_CREAT | O_EXCL, 0600); + if (newfd < 0) + die("unable to create new cachefile"); + atexit(remove_lock_file); + remove_lock = 1; + + for (i = 1; i < argc; i++) { + const char *arg = argv[i]; + + /* "-m" stands for "merge", meaning we start in stage 1 */ + if (!strcmp(arg, "-m")) { + stage = 1; + continue; + } + if (get_sha1_hex(arg, sha1) < 0) + usage("read-tree [-m] "); + if (stage > 3) + usage("can't merge more than two trees"); + if (read_tree(sha1, "", 0) < 0) + die("failed to unpack tree object %s", arg); + stage++; + } + if (stage == 4) + trivially_merge_cache(active_cache, active_nr); + if (write_cache(newfd, active_cache, active_nr) || + rename(".git/index.lock", ".git/index")) + die("unable to write new index file"); + remove_lock = 0; return 0; }