git/environment.c
Elijah Newren ecc7c8841d repo_read_index: add config to expect files outside sparse patterns
Typically with sparse checkouts, we expect files outside the sparsity
patterns to be marked as SKIP_WORKTREE and be missing from the working
tree.  Sometimes this expectation would be violated however; including
in cases such as:
  * users grabbing files from elsewhere and writing them to the worktree
    (perhaps by editing a cached copy in an editor, copying/renaming, or
     even untarring)
  * various git commands having incomplete or no support for the
    SKIP_WORKTREE bit[1,2]
  * users attempting to "abort" a sparse-checkout operation with a
    not-so-early Ctrl+C (updating $GIT_DIR/info/sparse-checkout and the
    working tree is not atomic)[3].
When the SKIP_WORKTREE bit in the index did not reflect the presence of
the file in the working tree, it traditionally caused confusion and was
difficult to detect and recover from.  So, in a sparse checkout, since
af6a51875a (repo_read_index: clear SKIP_WORKTREE bit from files present
in worktree, 2022-01-14), Git automatically clears the SKIP_WORKTREE
bit at index read time for entries corresponding to files that are
present in the working tree.

There is another workflow, however, where it is expected that paths
outside the sparsity patterns appear to exist in the working tree and
that they do not lose the SKIP_WORKTREE bit, at least until they get
modified.  A Git-aware virtual file system[4] takes advantage of its
position as a file system driver to expose all files in the working
tree, fetch them on demand using partial clone on access, and tell Git
to pay attention to them on demand by updating the sparse checkout
pattern on writes.  This means that commands like "git status" only have
to examine files that have potentially been modified, whereas commands
like "ls" are able to show the entire codebase without requiring manual
updates to the sparse checkout pattern.

Thus since af6a51875a, Git with such Git-aware virtual file systems
unsets the SKIP_WORKTREE bit for all files and commands like "git
status" have to fetch and examine them all.

Introduce a configuration setting sparse.expectFilesOutsideOfPatterns to
allow limiting the tracked set of files to a small set once again.  A
Git-aware virtual file system or other application that wants to
maintain files outside of the sparse checkout can set this in a
repository to instruct Git not to check for the presence of
SKIP_WORKTREE files.  The setting defaults to false, so most users of
sparse checkout will still get the benefit of an automatically updating
index to recover from the variety of difficult issues detailed in
af6a51875a for paths with SKIP_WORKTREE set despite the path being
present.

[1] https://lore.kernel.org/git/xmqqbmb1a7ga.fsf@gitster-ct.c.googlers.com/
[2] The three long paragraphs in the middle of
    https://lore.kernel.org/git/CABPp-BH9tju7WVm=QZDOvaMDdZbpNXrVWQdN-jmfN8wC6YVhmw@mail.gmail.com/
[3] https://lore.kernel.org/git/CABPp-BFnFpzwGC11TLoLs8YK5yiisA5D5-fFjXnJsbESVDwZsA@mail.gmail.com/
[4] such as the vfsd described in
https://lore.kernel.org/git/20220207190320.2960362-1-jonathantanmy@google.com/

Signed-off-by: Jonathan Nieder <jrnieder@gmail.com>
Signed-off-by: Elijah Newren <newren@gmail.com>
Reviewed-by: Jonathan Nieder <jrnieder@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2022-03-01 23:37:48 -08:00

424 lines
11 KiB
C

/*
* We put all the git config variables in this same object
* file, so that programs can link against the config parser
* without having to link against all the rest of git.
*
* In particular, no need to bring in libz etc unless needed,
* even if you might want to know where the git directory etc
* are.
*/
#include "cache.h"
#include "branch.h"
#include "environment.h"
#include "repository.h"
#include "config.h"
#include "refs.h"
#include "fmt-merge-msg.h"
#include "commit.h"
#include "strvec.h"
#include "object-store.h"
#include "tmp-objdir.h"
#include "chdir-notify.h"
#include "shallow.h"
int trust_executable_bit = 1;
int trust_ctime = 1;
int check_stat = 1;
int has_symlinks = 1;
int minimum_abbrev = 4, default_abbrev = -1;
int ignore_case;
int assume_unchanged;
int prefer_symlink_refs;
int is_bare_repository_cfg = -1; /* unspecified */
int warn_ambiguous_refs = 1;
int warn_on_object_refname_ambiguity = 1;
int repository_format_precious_objects;
int repository_format_worktree_config;
const char *git_commit_encoding;
const char *git_log_output_encoding;
char *apply_default_whitespace;
char *apply_default_ignorewhitespace;
const char *git_attributes_file;
const char *git_hooks_path;
int zlib_compression_level = Z_BEST_SPEED;
int pack_compression_level = Z_DEFAULT_COMPRESSION;
int fsync_object_files;
int use_fsync = -1;
size_t packed_git_window_size = DEFAULT_PACKED_GIT_WINDOW_SIZE;
size_t packed_git_limit = DEFAULT_PACKED_GIT_LIMIT;
size_t delta_base_cache_limit = 96 * 1024 * 1024;
unsigned long big_file_threshold = 512 * 1024 * 1024;
int pager_use_color = 1;
const char *editor_program;
const char *askpass_program;
const char *excludes_file;
enum auto_crlf auto_crlf = AUTO_CRLF_FALSE;
int read_replace_refs = 1;
char *git_replace_ref_base;
enum eol core_eol = EOL_UNSET;
int global_conv_flags_eol = CONV_EOL_RNDTRP_WARN;
char *check_roundtrip_encoding = "SHIFT-JIS";
unsigned whitespace_rule_cfg = WS_DEFAULT_RULE;
enum branch_track git_branch_track = BRANCH_TRACK_REMOTE;
enum rebase_setup_type autorebase = AUTOREBASE_NEVER;
enum push_default_type push_default = PUSH_DEFAULT_UNSPECIFIED;
#ifndef OBJECT_CREATION_MODE
#define OBJECT_CREATION_MODE OBJECT_CREATION_USES_HARDLINKS
#endif
enum object_creation_mode object_creation_mode = OBJECT_CREATION_MODE;
char *notes_ref_name;
int grafts_replace_parents = 1;
int core_apply_sparse_checkout;
int core_sparse_checkout_cone;
int sparse_expect_files_outside_of_patterns;
int merge_log_config = -1;
int precomposed_unicode = -1; /* see probe_utf8_pathname_composition() */
unsigned long pack_size_limit_cfg;
enum log_refs_config log_all_ref_updates = LOG_REFS_UNSET;
#ifndef PROTECT_HFS_DEFAULT
#define PROTECT_HFS_DEFAULT 0
#endif
int protect_hfs = PROTECT_HFS_DEFAULT;
#ifndef PROTECT_NTFS_DEFAULT
#define PROTECT_NTFS_DEFAULT 1
#endif
int protect_ntfs = PROTECT_NTFS_DEFAULT;
const char *core_fsmonitor;
/*
* The character that begins a commented line in user-editable file
* that is subject to stripspace.
*/
char comment_line_char = '#';
int auto_comment_line_char;
/* Parallel index stat data preload? */
int core_preload_index = 1;
/* This is set by setup_git_dir_gently() and/or git_default_config() */
char *git_work_tree_cfg;
static char *git_namespace;
static char *super_prefix;
/*
* Repository-local GIT_* environment variables; see cache.h for details.
*/
const char * const local_repo_env[] = {
ALTERNATE_DB_ENVIRONMENT,
CONFIG_ENVIRONMENT,
CONFIG_DATA_ENVIRONMENT,
CONFIG_COUNT_ENVIRONMENT,
DB_ENVIRONMENT,
GIT_DIR_ENVIRONMENT,
GIT_WORK_TREE_ENVIRONMENT,
GIT_IMPLICIT_WORK_TREE_ENVIRONMENT,
GRAFT_ENVIRONMENT,
INDEX_ENVIRONMENT,
NO_REPLACE_OBJECTS_ENVIRONMENT,
GIT_REPLACE_REF_BASE_ENVIRONMENT,
GIT_PREFIX_ENVIRONMENT,
GIT_SUPER_PREFIX_ENVIRONMENT,
GIT_SHALLOW_FILE_ENVIRONMENT,
GIT_COMMON_DIR_ENVIRONMENT,
NULL
};
static char *expand_namespace(const char *raw_namespace)
{
struct strbuf buf = STRBUF_INIT;
struct strbuf **components, **c;
if (!raw_namespace || !*raw_namespace)
return xstrdup("");
strbuf_addstr(&buf, raw_namespace);
components = strbuf_split(&buf, '/');
strbuf_reset(&buf);
for (c = components; *c; c++)
if (strcmp((*c)->buf, "/") != 0)
strbuf_addf(&buf, "refs/namespaces/%s", (*c)->buf);
strbuf_list_free(components);
if (check_refname_format(buf.buf, 0))
die(_("bad git namespace path \"%s\""), raw_namespace);
strbuf_addch(&buf, '/');
return strbuf_detach(&buf, NULL);
}
const char *getenv_safe(struct strvec *argv, const char *name)
{
const char *value = getenv(name);
if (!value)
return NULL;
strvec_push(argv, value);
return argv->v[argv->nr - 1];
}
void setup_git_env(const char *git_dir)
{
const char *shallow_file;
const char *replace_ref_base;
struct set_gitdir_args args = { NULL };
struct strvec to_free = STRVEC_INIT;
args.commondir = getenv_safe(&to_free, GIT_COMMON_DIR_ENVIRONMENT);
args.object_dir = getenv_safe(&to_free, DB_ENVIRONMENT);
args.graft_file = getenv_safe(&to_free, GRAFT_ENVIRONMENT);
args.index_file = getenv_safe(&to_free, INDEX_ENVIRONMENT);
args.alternate_db = getenv_safe(&to_free, ALTERNATE_DB_ENVIRONMENT);
if (getenv(GIT_QUARANTINE_ENVIRONMENT)) {
args.disable_ref_updates = 1;
}
repo_set_gitdir(the_repository, git_dir, &args);
strvec_clear(&to_free);
if (getenv(NO_REPLACE_OBJECTS_ENVIRONMENT))
read_replace_refs = 0;
replace_ref_base = getenv(GIT_REPLACE_REF_BASE_ENVIRONMENT);
free(git_replace_ref_base);
git_replace_ref_base = xstrdup(replace_ref_base ? replace_ref_base
: "refs/replace/");
free(git_namespace);
git_namespace = expand_namespace(getenv(GIT_NAMESPACE_ENVIRONMENT));
shallow_file = getenv(GIT_SHALLOW_FILE_ENVIRONMENT);
if (shallow_file)
set_alternate_shallow_file(the_repository, shallow_file, 0);
}
int is_bare_repository(void)
{
/* if core.bare is not 'false', let's see if there is a work tree */
return is_bare_repository_cfg && !get_git_work_tree();
}
int have_git_dir(void)
{
return startup_info->have_repository
|| the_repository->gitdir;
}
const char *get_git_dir(void)
{
if (!the_repository->gitdir)
BUG("git environment hasn't been setup");
return the_repository->gitdir;
}
const char *get_git_common_dir(void)
{
if (!the_repository->commondir)
BUG("git environment hasn't been setup");
return the_repository->commondir;
}
const char *get_git_namespace(void)
{
if (!git_namespace)
BUG("git environment hasn't been setup");
return git_namespace;
}
const char *strip_namespace(const char *namespaced_ref)
{
const char *out;
if (skip_prefix(namespaced_ref, get_git_namespace(), &out))
return out;
return NULL;
}
const char *get_super_prefix(void)
{
static int initialized;
if (!initialized) {
super_prefix = xstrdup_or_null(getenv(GIT_SUPER_PREFIX_ENVIRONMENT));
initialized = 1;
}
return super_prefix;
}
static int git_work_tree_initialized;
/*
* Note. This works only before you used a work tree. This was added
* primarily to support git-clone to work in a new repository it just
* created, and is not meant to flip between different work trees.
*/
void set_git_work_tree(const char *new_work_tree)
{
if (git_work_tree_initialized) {
struct strbuf realpath = STRBUF_INIT;
strbuf_realpath(&realpath, new_work_tree, 1);
new_work_tree = realpath.buf;
if (strcmp(new_work_tree, the_repository->worktree))
die("internal error: work tree has already been set\n"
"Current worktree: %s\nNew worktree: %s",
the_repository->worktree, new_work_tree);
strbuf_release(&realpath);
return;
}
git_work_tree_initialized = 1;
repo_set_worktree(the_repository, new_work_tree);
}
const char *get_git_work_tree(void)
{
return the_repository->worktree;
}
char *get_object_directory(void)
{
if (!the_repository->objects->odb)
BUG("git environment hasn't been setup");
return the_repository->objects->odb->path;
}
int odb_mkstemp(struct strbuf *temp_filename, const char *pattern)
{
int fd;
/*
* we let the umask do its job, don't try to be more
* restrictive except to remove write permission.
*/
int mode = 0444;
git_path_buf(temp_filename, "objects/%s", pattern);
fd = git_mkstemp_mode(temp_filename->buf, mode);
if (0 <= fd)
return fd;
/* slow path */
/* some mkstemp implementations erase temp_filename on failure */
git_path_buf(temp_filename, "objects/%s", pattern);
safe_create_leading_directories(temp_filename->buf);
return xmkstemp_mode(temp_filename->buf, mode);
}
int odb_pack_keep(const char *name)
{
int fd;
fd = open(name, O_RDWR|O_CREAT|O_EXCL, 0600);
if (0 <= fd)
return fd;
/* slow path */
safe_create_leading_directories_const(name);
return open(name, O_RDWR|O_CREAT|O_EXCL, 0600);
}
char *get_index_file(void)
{
if (!the_repository->index_file)
BUG("git environment hasn't been setup");
return the_repository->index_file;
}
char *get_graft_file(struct repository *r)
{
if (!r->graft_file)
BUG("git environment hasn't been setup");
return r->graft_file;
}
static void set_git_dir_1(const char *path)
{
xsetenv(GIT_DIR_ENVIRONMENT, path, 1);
setup_git_env(path);
}
static void update_relative_gitdir(const char *name,
const char *old_cwd,
const char *new_cwd,
void *data)
{
char *path = reparent_relative_path(old_cwd, new_cwd, get_git_dir());
struct tmp_objdir *tmp_objdir = tmp_objdir_unapply_primary_odb();
trace_printf_key(&trace_setup_key,
"setup: move $GIT_DIR to '%s'",
path);
set_git_dir_1(path);
if (tmp_objdir)
tmp_objdir_reapply_primary_odb(tmp_objdir, old_cwd, new_cwd);
free(path);
}
void set_git_dir(const char *path, int make_realpath)
{
struct strbuf realpath = STRBUF_INIT;
if (make_realpath) {
strbuf_realpath(&realpath, path, 1);
path = realpath.buf;
}
set_git_dir_1(path);
if (!is_absolute_path(path))
chdir_notify_register(NULL, update_relative_gitdir, NULL);
strbuf_release(&realpath);
}
const char *get_log_output_encoding(void)
{
return git_log_output_encoding ? git_log_output_encoding
: get_commit_output_encoding();
}
const char *get_commit_output_encoding(void)
{
return git_commit_encoding ? git_commit_encoding : "UTF-8";
}
static int the_shared_repository = PERM_UMASK;
static int need_shared_repository_from_config = 1;
void set_shared_repository(int value)
{
the_shared_repository = value;
need_shared_repository_from_config = 0;
}
int get_shared_repository(void)
{
if (need_shared_repository_from_config) {
const char *var = "core.sharedrepository";
const char *value;
if (!git_config_get_value(var, &value))
the_shared_repository = git_config_perm(var, value);
need_shared_repository_from_config = 0;
}
return the_shared_repository;
}
void reset_shared_repository(void)
{
need_shared_repository_from_config = 1;
}
int use_optional_locks(void)
{
return git_env_bool(GIT_OPTIONAL_LOCKS_ENVIRONMENT, 1);
}
int print_sha1_ellipsis(void)
{
/*
* Determine if the calling environment contains the variable
* GIT_PRINT_SHA1_ELLIPSIS set to "yes".
*/
static int cached_result = -1; /* unknown */
if (cached_result < 0) {
const char *v = getenv("GIT_PRINT_SHA1_ELLIPSIS");
cached_result = (v && !strcasecmp(v, "yes"));
}
return cached_result;
}