From 4ea82473aa310de7543141f96c2e6b23ef9fcd4c Mon Sep 17 00:00:00 2001 From: Jeff King Date: Mon, 3 Oct 2016 16:34:48 -0400 Subject: [PATCH] link_alt_odb_entry: refactor string handling The string handling in link_alt_odb_entry() is mostly an artifact of the original version, which took the path as a ptr/len combo, and did not have a NUL-terminated string until we created one in the alternate_object_database struct. But since 5bdf0a8 (sha1_file: normalize alt_odb path before comparing and storing, 2011-09-07), the first thing we do is put the path into a strbuf, which gives us some easy opportunities for cleanup. In particular: - we call strlen(pathbuf.buf), which is silly; we can look at pathbuf.len. - even though we have a strbuf, we don't maintain its "len" field when chomping extra slashes from the end, and instead keep a separate "pfxlen" variable. We can fix this and then drop "pfxlen" entirely. - we don't check whether the path is usable until after we allocate the new struct, making extra cleanup work for ourselves. Since we have a NUL-terminated string, we can bump the "is it usable" checks higher in the function. While we're at it, we can move that logic to its own helper, which makes the flow of link_alt_odb_entry() easier to follow. Signed-off-by: Jeff King Signed-off-by: Junio C Hamano --- sha1_file.c | 85 +++++++++++++++++++++++++++++------------------------ 1 file changed, 46 insertions(+), 39 deletions(-) diff --git a/sha1_file.c b/sha1_file.c index 057262d46e..3d8c1e88a5 100644 --- a/sha1_file.c +++ b/sha1_file.c @@ -234,6 +234,36 @@ char *sha1_pack_index_name(const unsigned char *sha1) struct alternate_object_database *alt_odb_list; static struct alternate_object_database **alt_odb_tail; +/* + * Return non-zero iff the path is usable as an alternate object database. + */ +static int alt_odb_usable(struct strbuf *path, const char *normalized_objdir) +{ + struct alternate_object_database *alt; + + /* Detect cases where alternate disappeared */ + if (!is_directory(path->buf)) { + error("object directory %s does not exist; " + "check .git/objects/info/alternates.", + path->buf); + return 0; + } + + /* + * Prevent the common mistake of listing the same + * thing twice, or object directory itself. + */ + for (alt = alt_odb_list; alt; alt = alt->next) { + if (path->len == alt->name - alt->base - 1 && + !memcmp(path->buf, alt->base, path->len)) + return 0; + } + if (!fspathcmp(path->buf, normalized_objdir)) + return 0; + + return 1; +} + /* * Prepare alternate object database registry. * @@ -253,8 +283,7 @@ static int link_alt_odb_entry(const char *entry, const char *relative_base, int depth, const char *normalized_objdir) { struct alternate_object_database *ent; - struct alternate_object_database *alt; - size_t pfxlen, entlen; + size_t entlen; struct strbuf pathbuf = STRBUF_INIT; if (!is_absolute_path(entry) && relative_base) { @@ -270,47 +299,26 @@ static int link_alt_odb_entry(const char *entry, const char *relative_base, return -1; } - pfxlen = strlen(pathbuf.buf); - /* * The trailing slash after the directory name is given by * this function at the end. Remove duplicates. */ - while (pfxlen && pathbuf.buf[pfxlen-1] == '/') - pfxlen -= 1; + while (pathbuf.len && pathbuf.buf[pathbuf.len - 1] == '/') + strbuf_setlen(&pathbuf, pathbuf.len - 1); - entlen = st_add(pfxlen, 43); /* '/' + 2 hex + '/' + 38 hex + NUL */ + if (!alt_odb_usable(&pathbuf, normalized_objdir)) { + strbuf_release(&pathbuf); + return -1; + } + + entlen = st_add(pathbuf.len, 43); /* '/' + 2 hex + '/' + 38 hex + NUL */ ent = xmalloc(st_add(sizeof(*ent), entlen)); - memcpy(ent->base, pathbuf.buf, pfxlen); - strbuf_release(&pathbuf); + memcpy(ent->base, pathbuf.buf, pathbuf.len); - ent->name = ent->base + pfxlen + 1; - ent->base[pfxlen + 3] = '/'; - ent->base[pfxlen] = ent->base[entlen-1] = 0; - - /* Detect cases where alternate disappeared */ - if (!is_directory(ent->base)) { - error("object directory %s does not exist; " - "check .git/objects/info/alternates.", - ent->base); - free(ent); - return -1; - } - - /* Prevent the common mistake of listing the same - * thing twice, or object directory itself. - */ - for (alt = alt_odb_list; alt; alt = alt->next) { - if (pfxlen == alt->name - alt->base - 1 && - !memcmp(ent->base, alt->base, pfxlen)) { - free(ent); - return -1; - } - } - if (!fspathcmp(ent->base, normalized_objdir)) { - free(ent); - return -1; - } + ent->name = ent->base + pathbuf.len + 1; + ent->base[pathbuf.len] = '/'; + ent->base[pathbuf.len + 3] = '/'; + ent->base[entlen-1] = 0; /* add the alternate entry */ *alt_odb_tail = ent; @@ -318,10 +326,9 @@ static int link_alt_odb_entry(const char *entry, const char *relative_base, ent->next = NULL; /* recursively add alternates */ - read_info_alternates(ent->base, depth + 1); - - ent->base[pfxlen] = '/'; + read_info_alternates(pathbuf.buf, depth + 1); + strbuf_release(&pathbuf); return 0; }