@matheusbsbs / matheus-bagliano / commits / 5b3c650777

config: learn `git_protected_config()`

`uploadpack.packObjectsHook` is the only 'protected configuration only' variable today, but we've noted that `safe.directory` and the upcoming `safe.bareRepository` should also be 'protected configuration only'. So, for consistency, we'd like to have a single implementation for protected configuration. The primary constraints are: 1. Reading from protected configuration should be fast. Nearly all "git" commands inside a bare repository will read both `safe.directory` and `safe.bareRepository`, so we cannot afford to be slow. 2. Protected configuration must be readable when the gitdir is not known. `safe.directory` and `safe.bareRepository` both affect repository discovery and the gitdir is not known at that point [1]. The chosen implementation in this commit is to read protected configuration and cache the values in a global configset. This is similar to the caching behavior we get with the_repository->config. Introduce git_protected_config(), which reads protected configuration and caches them in the global configset protected_config. Then, refactor `uploadpack.packObjectsHook` to use git_protected_config(). The protected configuration functions are named similarly to their non-protected counterparts, e.g. git_protected_config_check_init() vs git_config_check_init(). In light of constraint 1, this implementation can still be improved. git_protected_config() iterates through every variable in protected_config, which is wasteful, but it makes the conversion simple because it matches existing patterns. We will likely implement constant time lookup functions for protected configuration in a future series (such functions already exist for non-protected configuration, i.e. repo_config_get_*()). An alternative that avoids introducing another configset is to continue to read all config using git_config(), but only accept values that have the correct config scope [2]. This technically fulfills constraint 2, because git_config() simply ignores the local and worktree config when the gitdir is not known. However, this would read incomplete config into the_repository->config, which would need to be reset when the gitdir is known and git_config() needs to read the local and worktree config. Resetting the_repository->config might be reasonable while we only have these 'protected configuration only' variables, but it's not clear whether this extends well to future variables. [1] In this case, we do have a candidate gitdir though, so with a little refactoring, it might be possible to provide a gitdir. [2] This is how `uploadpack.packObjectsHook` was implemented prior to this commit. Signed-off-by: Glen Choo <chooglen@google.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>

Glen Choo committed Jul 14, 2022 at 21:27 UTC 5b3c650777547f2274540a036da641651fb866b0

4 files changed +82 -11

config.c

+43

@@ -81,6 +81,17 @@ static enum config_scope current_parsing_scope;

81 static int pack_compression_seen;

82 static int zlib_compression_seen;

84 +/*

85 + * Config that comes from trusted scopes, namely:

86 + * - CONFIG_SCOPE_SYSTEM (e.g. /etc/gitconfig)

87 + * - CONFIG_SCOPE_GLOBAL (e.g. $HOME/.gitconfig, $XDG_CONFIG_HOME/git)

88 + * - CONFIG_SCOPE_COMMAND (e.g. "-c" option, environment variables)

89 + *

90 + * This is declared here for code cleanliness, but unlike the other

91 + * static variables, this does not hold config parser state.

92 + */

93 +static struct config_set protected_config;

94 +

95 static int config_file_fgetc(struct config_source *conf)

96 {

97 return getc_unlocked(conf->u.file);

@@ -2378,6 +2389,11 @@ int git_configset_add_file(struct config_set *cs, const char *filename)

2389 return git_config_from_file(config_set_callback, filename, cs);

2390 }

2391

2392 +int git_configset_add_parameters(struct config_set *cs)

2393 +{

2394 + return git_config_from_parameters(config_set_callback, cs);

2395 +}

2396 +

2397 int git_configset_get_value(struct config_set *cs, const char *key, const char **value)

2398 {

2399 const struct string_list *values = NULL;

@@ -2619,6 +2635,33 @@ int repo_config_get_pathname(struct repository *repo,

2635 return ret;

2636 }

2637

2638 +/* Read values into protected_config. */

2639 +static void read_protected_config(void)

2640 +{

2641 + char *xdg_config = NULL, *user_config = NULL, *system_config = NULL;

2642 +

2643 + git_configset_init(&protected_config);

2644 +

2645 + system_config = git_system_config();

2646 + git_global_config(&user_config, &xdg_config);

2647 +

2648 + git_configset_add_file(&protected_config, system_config);

2649 + git_configset_add_file(&protected_config, xdg_config);

2650 + git_configset_add_file(&protected_config, user_config);

2651 + git_configset_add_parameters(&protected_config);

2652 +

2653 + free(system_config);

2654 + free(xdg_config);

2655 + free(user_config);

2656 +}

2657 +

2658 +void git_protected_config(config_fn_t fn, void *data)

2659 +{

2660 + if (!protected_config.hash_initialized)

2661 + read_protected_config();

2662 + configset_iter(&protected_config, fn, data);

2663 +}

2664 +

2665 /* Functions used historically to read configuration from 'the_repository' */

2666 void git_config(config_fn_t fn, void *data)

2667 {

config.h

+16

@@ -446,6 +446,15 @@ void git_configset_init(struct config_set *cs);

446 */

447 int git_configset_add_file(struct config_set *cs, const char *filename);

448

449 +/**

450 + * Parses command line options and environment variables, and adds the

451 + * variable-value pairs to the `config_set`. Returns 0 on success, or -1

452 + * if there is an error in parsing. The caller decides whether to free

453 + * the incomplete configset or continue using it when the function

454 + * returns -1.

455 + */

456 +int git_configset_add_parameters(struct config_set *cs);

457 +

458 /**

459 * Finds and returns the value list, sorted in order of increasing priority

460 * for the configuration variable `key` and config set `cs`. When the

@@ -505,6 +514,13 @@ int repo_config_get_maybe_bool(struct repository *repo,

514 int repo_config_get_pathname(struct repository *repo,

515 const char *key, const char **dest);

516

517 +/*

518 + * Functions for reading protected config. By definition, protected

519 + * config ignores repository config, so these do not take a `struct

520 + * repository` parameter.

521 + */

522 +void git_protected_config(config_fn_t fn, void *data);

523 +

524 /**

525 * Querying For Specific Variables

526 * -------------------------------

t/t5544-pack-objects-hook.sh

+6 -1

@@ -56,7 +56,12 @@ test_expect_success 'hook does not run from repo config' '

56 ! grep "hook running" stderr &&

57 test_path_is_missing .git/hook.args &&

58 test_path_is_missing .git/hook.stdin &&

59 - test_path_is_missing .git/hook.stdout

59 + test_path_is_missing .git/hook.stdout &&

60 +

61 + # check that global config is used instead

62 + test_config_global uploadpack.packObjectsHook ./hook &&

63 + git clone --no-local . dst2.git 2>stderr &&

64 + grep "hook running" stderr

65 '

67 test_expect_success 'hook works with partial clone' '

upload-pack.c

+17 -10

@@ -1321,18 +1321,27 @@ static int upload_pack_config(const char *var, const char *value, void *cb_data)

1321 data->advertise_sid = git_config_bool(var, value);

1322 }

1323

1324 - if (current_config_scope() != CONFIG_SCOPE_LOCAL &&

1325 - current_config_scope() != CONFIG_SCOPE_WORKTREE) {

1326 - if (!strcmp("uploadpack.packobjectshook", var))

1327 - return git_config_string(&data->pack_objects_hook, var, value);

1328 - }

1329 -

1324 if (parse_object_filter_config(var, value, data) < 0)

1325 return -1;

1326

1327 return parse_hide_refs_config(var, value, "uploadpack");

1328 }

1329

1330 +static int upload_pack_protected_config(const char *var, const char *value, void *cb_data)

1331 +{

1332 + struct upload_pack_data *data = cb_data;

1333 +

1334 + if (!strcmp("uploadpack.packobjectshook", var))

1335 + return git_config_string(&data->pack_objects_hook, var, value);

1336 + return 0;

1337 +}

1338 +

1339 +static void get_upload_pack_config(struct upload_pack_data *data)

1340 +{

1341 + git_config(upload_pack_config, data);

1342 + git_protected_config(upload_pack_protected_config, data);

1343 +}

1344 +

1345 void upload_pack(const int advertise_refs, const int stateless_rpc,

1346 const int timeout)

1347 {

@@ -1340,8 +1349,7 @@ void upload_pack(const int advertise_refs, const int stateless_rpc,

1349 struct upload_pack_data data;

1350

1351 upload_pack_data_init(&data);

1343 -

1344 - git_config(upload_pack_config, &data);

1352 + get_upload_pack_config(&data);

1353

1354 data.stateless_rpc = stateless_rpc;

1355 data.timeout = timeout;

@@ -1695,8 +1703,7 @@ int upload_pack_v2(struct repository *r, struct packet_reader *request)

1703

1704 upload_pack_data_init(&data);

1705 data.use_sideband = LARGE_PACKET_MAX;

1698 -

1699 - git_config(upload_pack_config, &data);

1706 + get_upload_pack_config(&data);

1707

1708 while (state != FETCH_DONE) {

1709 switch (state) {