git/repository.c
brian m. carlson e26f7f19b6 repository: pre-initialize hash algo pointer
There are various git subcommands (among them, clone) which don't set up
the repository (that is, they lack RUN_SETUP or RUN_SETUP_GENTLY) but
end up needing to have information about the hash algorithm in use.
Because the hash algorithm is part of struct repository and it's only
initialized in repository setup, we can end up dereferencing a NULL
pointer in some cases if we call one of these subcommands and look up
the empty blob or empty tree values.

A "git clone" of a project that has two paths that differ only in
case suffers from this if it is run on a case insensitive platform.
When the command attempts to check out one of these two paths after
checking out the other one, the checkout codepath needs to see if
the version that is already on the filesystem (which should not
happen if the FS were case sensitive) is dirty, and it needs to
exercise the hashing code at that point.

In the future, we can add a command line option for this or read it
from the configuration, but until we're ready to expose that
functionality to the user, simply initialize the repository
structure to use the current hash algorithm, SHA-1.

Signed-off-by: brian m. carlson <sandals@crustytoothpaste.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2018-01-19 14:23:32 -08:00

240 lines
5.6 KiB
C

#include "cache.h"
#include "repository.h"
#include "config.h"
#include "submodule-config.h"
/* The main repository */
static struct repository the_repo = {
NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, &the_index, &hash_algos[GIT_HASH_SHA1], 0, 0
};
struct repository *the_repository = &the_repo;
static char *git_path_from_env(const char *envvar, const char *git_dir,
const char *path, int fromenv)
{
if (fromenv) {
const char *value = getenv(envvar);
if (value)
return xstrdup(value);
}
return xstrfmt("%s/%s", git_dir, path);
}
static int find_common_dir(struct strbuf *sb, const char *gitdir, int fromenv)
{
if (fromenv) {
const char *value = getenv(GIT_COMMON_DIR_ENVIRONMENT);
if (value) {
strbuf_addstr(sb, value);
return 1;
}
}
return get_common_dir_noenv(sb, gitdir);
}
static void repo_setup_env(struct repository *repo)
{
struct strbuf sb = STRBUF_INIT;
repo->different_commondir = find_common_dir(&sb, repo->gitdir,
!repo->ignore_env);
free(repo->commondir);
repo->commondir = strbuf_detach(&sb, NULL);
free(repo->objectdir);
repo->objectdir = git_path_from_env(DB_ENVIRONMENT, repo->commondir,
"objects", !repo->ignore_env);
free(repo->graft_file);
repo->graft_file = git_path_from_env(GRAFT_ENVIRONMENT, repo->commondir,
"info/grafts", !repo->ignore_env);
free(repo->index_file);
repo->index_file = git_path_from_env(INDEX_ENVIRONMENT, repo->gitdir,
"index", !repo->ignore_env);
}
void repo_set_gitdir(struct repository *repo, const char *path)
{
const char *gitfile = read_gitfile(path);
char *old_gitdir = repo->gitdir;
repo->gitdir = xstrdup(gitfile ? gitfile : path);
repo_setup_env(repo);
free(old_gitdir);
}
void repo_set_hash_algo(struct repository *repo, int hash_algo)
{
repo->hash_algo = &hash_algos[hash_algo];
}
/*
* Attempt to resolve and set the provided 'gitdir' for repository 'repo'.
* Return 0 upon success and a non-zero value upon failure.
*/
static int repo_init_gitdir(struct repository *repo, const char *gitdir)
{
int ret = 0;
int error = 0;
char *abspath = NULL;
const char *resolved_gitdir;
abspath = real_pathdup(gitdir, 0);
if (!abspath) {
ret = -1;
goto out;
}
/* 'gitdir' must reference the gitdir directly */
resolved_gitdir = resolve_gitdir_gently(abspath, &error);
if (!resolved_gitdir) {
ret = -1;
goto out;
}
repo_set_gitdir(repo, resolved_gitdir);
out:
free(abspath);
return ret;
}
void repo_set_worktree(struct repository *repo, const char *path)
{
repo->worktree = real_pathdup(path, 1);
}
static int read_and_verify_repository_format(struct repository_format *format,
const char *commondir)
{
int ret = 0;
struct strbuf sb = STRBUF_INIT;
strbuf_addf(&sb, "%s/config", commondir);
read_repository_format(format, sb.buf);
strbuf_reset(&sb);
if (verify_repository_format(format, &sb) < 0) {
warning("%s", sb.buf);
ret = -1;
}
strbuf_release(&sb);
return ret;
}
/*
* Initialize 'repo' based on the provided 'gitdir'.
* Return 0 upon success and a non-zero value upon failure.
*/
int repo_init(struct repository *repo, const char *gitdir, const char *worktree)
{
struct repository_format format;
memset(repo, 0, sizeof(*repo));
repo->ignore_env = 1;
if (repo_init_gitdir(repo, gitdir))
goto error;
if (read_and_verify_repository_format(&format, repo->commondir))
goto error;
repo_set_hash_algo(repo, format.hash_algo);
if (worktree)
repo_set_worktree(repo, worktree);
return 0;
error:
repo_clear(repo);
return -1;
}
/*
* Initialize 'submodule' as the submodule given by 'path' in parent repository
* 'superproject'.
* Return 0 upon success and a non-zero value upon failure.
*/
int repo_submodule_init(struct repository *submodule,
struct repository *superproject,
const char *path)
{
const struct submodule *sub;
struct strbuf gitdir = STRBUF_INIT;
struct strbuf worktree = STRBUF_INIT;
int ret = 0;
sub = submodule_from_cache(superproject, &null_oid, path);
if (!sub) {
ret = -1;
goto out;
}
strbuf_repo_worktree_path(&gitdir, superproject, "%s/.git", path);
strbuf_repo_worktree_path(&worktree, superproject, "%s", path);
if (repo_init(submodule, gitdir.buf, worktree.buf)) {
/*
* If initilization fails then it may be due to the submodule
* not being populated in the superproject's worktree. Instead
* we can try to initilize the submodule by finding it's gitdir
* in the superproject's 'modules' directory. In this case the
* submodule would not have a worktree.
*/
strbuf_reset(&gitdir);
strbuf_repo_git_path(&gitdir, superproject,
"modules/%s", sub->name);
if (repo_init(submodule, gitdir.buf, NULL)) {
ret = -1;
goto out;
}
}
submodule->submodule_prefix = xstrfmt("%s%s/",
superproject->submodule_prefix ?
superproject->submodule_prefix :
"", path);
out:
strbuf_release(&gitdir);
strbuf_release(&worktree);
return ret;
}
void repo_clear(struct repository *repo)
{
FREE_AND_NULL(repo->gitdir);
FREE_AND_NULL(repo->commondir);
FREE_AND_NULL(repo->objectdir);
FREE_AND_NULL(repo->graft_file);
FREE_AND_NULL(repo->index_file);
FREE_AND_NULL(repo->worktree);
FREE_AND_NULL(repo->submodule_prefix);
if (repo->config) {
git_configset_clear(repo->config);
FREE_AND_NULL(repo->config);
}
if (repo->submodule_cache) {
submodule_cache_free(repo->submodule_cache);
repo->submodule_cache = NULL;
}
if (repo->index) {
discard_index(repo->index);
FREE_AND_NULL(repo->index);
}
}
int repo_read_index(struct repository *repo)
{
if (!repo->index)
repo->index = xcalloc(1, sizeof(*repo->index));
return read_index_from(repo->index, repo->index_file);
}