From: Linus Torvalds Date: Sun, 19 Jun 2005 03:21:34 +0000 (-0700) Subject: Re-implement "check_file_directory_conflict()" X-Git-Tag: v0.99~251 X-Git-Url: https://git.verplant.org/?a=commitdiff_plain;h=12676608fefd6b148bd9fd4cbd4eb6c2ff3e15e9;p=git.git Re-implement "check_file_directory_conflict()" This is (imho) more readable, and is also a lot faster. The expense of looking up sub-directory beginnings was killing us on things like "git-diff-cache", even though that one didn't even care at all about the file vs directory conflicts. We really only care when somebody tries to add a conflicting name to stage 0. We should go through the conflict rules more carefully some day. --- diff --git a/read-cache.c b/read-cache.c index e9618f09..4b8348ca 100644 --- a/read-cache.c +++ b/read-cache.c @@ -171,107 +171,106 @@ int ce_same_name(struct cache_entry *a, struct cache_entry *b) return ce_namelen(b) == len && !memcmp(a->name, b->name, len); } -/* We may be in a situation where we already have path/file and path - * is being added, or we already have path and path/file is being - * added. Either one would result in a nonsense tree that has path - * twice when git-write-tree tries to write it out. Prevent it. - * - * If ok-to-replace is specified, we remove the conflicting entries - * from the cache so the caller should recompute the insert position. - * When this happens, we return non-zero. +/* + * Do we have another file that has the beginning components being a + * proper superset of the name we're trying to add? */ -static int check_file_directory_conflict(const struct cache_entry *ce, - int ok_to_replace) +static int has_file_name(const struct cache_entry *ce, int pos, int ok_to_replace) { - int pos, replaced = 0; - const char *path = ce->name; - int namelen = strlen(path); - int stage = ce_stage(ce); - char *pathbuf = xmalloc(namelen + 1); - char *cp; + int retval = 0; + int len = ce_namelen(ce); + const char *name = ce->name; - memcpy(pathbuf, path, namelen + 1); + while (pos < active_nr) { + struct cache_entry *p = active_cache[pos++]; - /* - * We are inserting path/file. Do they have path registered at - * the same stage? We need to do this for all the levels of our - * subpath. - */ - cp = pathbuf; - while (1) { - char *ep = strchr(cp, '/'); - int len; - if (!ep) + if (len >= ce_namelen(p)) break; - *ep = 0; /* first cut it at slash */ - len = ep - pathbuf; - pos = cache_name_pos(pathbuf, - ntohs(create_ce_flags(len, stage))); - if (0 <= pos) { - /* Our leading path component is registered as a file, - * and we are trying to make it a directory. This is - * bad. - */ - if (!ok_to_replace) { - free(pathbuf); - return -1; - } - fprintf(stderr, "removing file '%s' to replace it with a directory to create '%s'.\n", pathbuf, path); - remove_cache_entry_at(pos); - replaced = 1; - } - *ep = '/'; /* then restore it and go downwards */ - cp = ep + 1; + if (memcmp(name, p->name, len)) + break; + if (p->name[len] != '/') + continue; +fprintf(stderr, "conflict: %s %s\n", ce->name, p->name); + retval = -1; + if (!ok_to_replace) + break; + remove_cache_entry_at(--pos); } - free(pathbuf); + return retval; +} - /* Do we have an entry in the cache that makes our path a prefix - * of it? That is, are we creating a file where they already expect - * a directory there? - */ - pos = cache_name_pos(path, - ntohs(create_ce_flags(namelen, stage))); +/* + * Do we have another file with a pathname that is a proper + * subset of the name we're trying to add? + */ +static int has_dir_name(const struct cache_entry *ce, int pos, int ok_to_replace) +{ + int retval = 0; + const char *name = ce->name; + const char *slash = name + ce_namelen(ce); - /* (0 <= pos) cannot happen because add_cache_entry() - * should have taken care of that case. - */ - pos = -pos-1; + for (;;) { + int len; - /* pos would point at an existing entry that would come immediately - * after our path. It could be the same as our path in higher stage, - * or different path but in a lower stage. - * - * E.g. when we are inserting path at stage 2, - * - * 1 path - * pos-> 3 path - * 2 path/file1 - * 3 path/file1 - * 2 path/file2 - * 2 patho - * - * We need to examine pos, ignore it because it is at different - * stage, examine next to find the path/file at stage 2, and - * complain. We need to do this until we are not the leading - * path of an existing entry anymore. - */ + for (;;) { + if (*--slash == '/') + break; + if (slash <= ce->name) + return retval; + } + len = slash - name; - while (pos < active_nr) { - struct cache_entry *other = active_cache[pos]; - if (strncmp(other->name, path, namelen)) - break; /* it is not our "subdirectory" anymore */ - if ((ce_stage(other) == stage) && - other->name[namelen] == '/') { - if (!ok_to_replace) - return -1; - fprintf(stderr, "removing file '%s' under '%s' to be replaced with a file\n", other->name, path); + pos = cache_name_pos(name, len); + if (pos >= 0) { + retval = -1; + if (ok_to_replace) + break; remove_cache_entry_at(pos); - replaced = 1; - continue; /* cycle without updating pos */ + continue; + } + + /* + * Trivial optimization: if we find an entry that + * already matches the sub-directory, then we know + * we're ok, and we can exit + */ + pos = -pos-1; + if (pos < active_nr) { + struct cache_entry *p = active_cache[pos]; + if (ce_namelen(p) <= len) + continue; + if (p->name[len] != '/') + continue; + if (memcmp(p->name, name, len)) + continue; + break; } - pos++; } - return replaced; + return retval; +} + +/* We may be in a situation where we already have path/file and path + * is being added, or we already have path and path/file is being + * added. Either one would result in a nonsense tree that has path + * twice when git-write-tree tries to write it out. Prevent it. + * + * If ok-to-replace is specified, we remove the conflicting entries + * from the cache so the caller should recompute the insert position. + * When this happens, we return non-zero. + */ +static int check_file_directory_conflict(const struct cache_entry *ce, int pos, int ok_to_replace) +{ + /* + * We check if the path is a sub-path of a subsequent pathname + * first, since removing those will not change the position + * in the array + */ + int retval = has_file_name(ce, pos, ok_to_replace); + /* + * Then check if the path might have a clashing sub-directory + * before it. + */ + return retval + has_dir_name(ce, pos, ok_to_replace); } int add_cache_entry(struct cache_entry *ce, int option) @@ -304,7 +303,7 @@ int add_cache_entry(struct cache_entry *ce, int option) if (!ok_to_add) return -1; - if (check_file_directory_conflict(ce, ok_to_replace)) { + if (!ce_stage(ce) && check_file_directory_conflict(ce, pos, ok_to_replace)) { if (!ok_to_replace) return -1; pos = cache_name_pos(ce->name, ntohs(ce->ce_flags));