From f1de981e8b6dedccf915095792c9afbe3c989591 Mon Sep 17 00:00:00 2001 From: Jeff King Date: Fri, 14 Aug 2020 12:17:36 -0400 Subject: config: fix leaks from git_config_get_string_const() There are two functions to get a single config string: - git_config_get_string() - git_config_get_string_const() One might naively think that the first one allocates a new string and the second one just points us to the internal configset storage. But in fact they both allocate a new copy; the second one exists only to avoid having to cast when using it with a const global which we never intend to free. The documentation for the function explains that clearly, but it seems I'm not alone in being surprised by this. Of 17 calls to the function, 13 of them leak the resulting value. We could obviously fix these by adding the appropriate free(). But it would be simpler still if we actually had a non-allocating way to get the string. There's git_config_get_value() but that doesn't quite do what we want. If the config key is present but is a boolean with no value (e.g., "[foo]bar" in the file), then we'll get NULL (whereas the string versions will print an error and die). So let's introduce a new variant, git_config_get_string_tmp(), that behaves as these callers expect. We need a new name because we have new semantics but the same function signature (so even if we converted the four remaining callers, topics in flight might be surprised). The "tmp" is because this value should only be held onto for a short time. In practice it's rare for us to clear and refresh the configset, invalidating the pointer, but hopefully the "tmp" makes callers think about the lifetime. In each of the converted cases here the value only needs to last within the local function or its immediate caller. Signed-off-by: Jeff King Signed-off-by: Junio C Hamano diff --git a/builtin/fetch.c b/builtin/fetch.c index 82ac4be..5c0e3ab 100644 --- a/builtin/fetch.c +++ b/builtin/fetch.c @@ -645,7 +645,7 @@ static void prepare_format_display(struct ref *ref_map) struct ref *rm; const char *format = "full"; - git_config_get_string_const("fetch.output", &format); + git_config_get_string_tmp("fetch.output", &format); if (!strcasecmp(format, "full")) compact_format = 0; else if (!strcasecmp(format, "compact")) diff --git a/builtin/submodule--helper.c b/builtin/submodule--helper.c index 7f90770..acee0be 100644 --- a/builtin/submodule--helper.c +++ b/builtin/submodule--helper.c @@ -1511,7 +1511,7 @@ static void determine_submodule_update_strategy(struct repository *r, if (parse_submodule_update_strategy(update, out) < 0) die(_("Invalid update mode '%s' for submodule path '%s'"), update, path); - } else if (!repo_config_get_string_const(r, key, &val)) { + } else if (!repo_config_get_string_tmp(r, key, &val)) { if (parse_submodule_update_strategy(val, out) < 0) die(_("Invalid update mode '%s' configured for submodule path '%s'"), val, path); @@ -1667,7 +1667,7 @@ static int prepare_to_clone_next_submodule(const struct cache_entry *ce, } key = xstrfmt("submodule.%s.update", sub->name); - if (!repo_config_get_string_const(the_repository, key, &update_string)) { + if (!repo_config_get_string_tmp(the_repository, key, &update_string)) { update_type = parse_submodule_update_type(update_string); } else { update_type = sub->update_strategy.type; @@ -1690,7 +1690,7 @@ static int prepare_to_clone_next_submodule(const struct cache_entry *ce, strbuf_reset(&sb); strbuf_addf(&sb, "submodule.%s.url", sub->name); - if (repo_config_get_string_const(the_repository, sb.buf, &url)) { + if (repo_config_get_string_tmp(the_repository, sb.buf, &url)) { if (starts_with_dot_slash(sub->url) || starts_with_dot_dot_slash(sub->url)) { url = compute_submodule_clone_url(sub->url); @@ -1976,7 +1976,7 @@ static const char *remote_submodule_branch(const char *path) return NULL; key = xstrfmt("submodule.%s.branch", sub->name); - if (repo_config_get_string_const(the_repository, key, &branch)) + if (repo_config_get_string_tmp(the_repository, key, &branch)) branch = sub->branch; free(key); diff --git a/config.c b/config.c index 8db9c77..facd73d 100644 --- a/config.c +++ b/config.c @@ -2020,6 +2020,20 @@ int git_configset_get_string(struct config_set *cs, const char *key, char **dest return git_configset_get_string_const(cs, key, (const char **)dest); } +int git_configset_get_string_tmp(struct config_set *cs, const char *key, + const char **dest) +{ + const char *value; + if (!git_configset_get_value(cs, key, &value)) { + if (!value) + return config_error_nonbool(key); + *dest = value; + return 0; + } else { + return 1; + } +} + int git_configset_get_int(struct config_set *cs, const char *key, int *dest) { const char *value; @@ -2165,6 +2179,17 @@ int repo_config_get_string(struct repository *repo, return repo_config_get_string_const(repo, key, (const char **)dest); } +int repo_config_get_string_tmp(struct repository *repo, + const char *key, const char **dest) +{ + int ret; + git_config_check_init(repo); + ret = git_configset_get_string_tmp(repo->config, key, dest); + if (ret < 0) + git_die_config(key, NULL); + return ret; +} + int repo_config_get_int(struct repository *repo, const char *key, int *dest) { @@ -2242,6 +2267,11 @@ int git_config_get_string(const char *key, char **dest) return repo_config_get_string(the_repository, key, dest); } +int git_config_get_string_tmp(const char *key, const char **dest) +{ + return repo_config_get_string_tmp(the_repository, key, dest); +} + int git_config_get_int(const char *key, int *dest) { return repo_config_get_int(the_repository, key, dest); diff --git a/config.h b/config.h index 0608744..a75b22e 100644 --- a/config.h +++ b/config.h @@ -460,6 +460,7 @@ int git_configset_get_value(struct config_set *cs, const char *key, const char * int git_configset_get_string_const(struct config_set *cs, const char *key, const char **dest); int git_configset_get_string(struct config_set *cs, const char *key, char **dest); +int git_configset_get_string_tmp(struct config_set *cs, const char *key, const char **dest); int git_configset_get_int(struct config_set *cs, const char *key, int *dest); int git_configset_get_ulong(struct config_set *cs, const char *key, unsigned long *dest); int git_configset_get_bool(struct config_set *cs, const char *key, int *dest); @@ -478,6 +479,8 @@ int repo_config_get_string_const(struct repository *repo, const char *key, const char **dest); int repo_config_get_string(struct repository *repo, const char *key, char **dest); +int repo_config_get_string_tmp(struct repository *repo, + const char *key, const char **dest); int repo_config_get_int(struct repository *repo, const char *key, int *dest); int repo_config_get_ulong(struct repository *repo, @@ -538,6 +541,13 @@ int git_config_get_string_const(const char *key, const char **dest); int git_config_get_string(const char *key, char **dest); /** + * Similar to `git_config_get_string_const`, but does not allocate any new + * memory; on success `dest` will point to memory owned by the config + * machinery, which could be invalidated if it is discarded and reloaded. + */ +int git_config_get_string_tmp(const char *key, const char **dest); + +/** * Finds and parses the value to an integer for the configuration variable * `key`. Dies on error; otherwise, stores the value of the parsed integer in * `dest` and returns 0. When the configuration variable `key` is not found, diff --git a/connect.c b/connect.c index e0d5b9f..3a55561 100644 --- a/connect.c +++ b/connect.c @@ -1052,7 +1052,7 @@ static const char *get_ssh_command(void) if ((ssh = getenv("GIT_SSH_COMMAND"))) return ssh; - if (!git_config_get_string_const("core.sshcommand", &ssh)) + if (!git_config_get_string_tmp("core.sshcommand", &ssh)) return ssh; return NULL; @@ -1071,7 +1071,7 @@ static void override_ssh_variant(enum ssh_variant *ssh_variant) { const char *variant = getenv("GIT_SSH_VARIANT"); - if (!variant && git_config_get_string_const("ssh.variant", &variant)) + if (!variant && git_config_get_string_tmp("ssh.variant", &variant)) return; if (!strcmp(variant, "auto")) diff --git a/editor.c b/editor.c index 91989ee..6303ae0 100644 --- a/editor.c +++ b/editor.c @@ -40,7 +40,7 @@ const char *git_sequence_editor(void) const char *editor = getenv("GIT_SEQUENCE_EDITOR"); if (!editor) - git_config_get_string_const("sequence.editor", &editor); + git_config_get_string_tmp("sequence.editor", &editor); if (!editor) editor = git_editor(); diff --git a/help.c b/help.c index 44cee69..d41c36a 100644 --- a/help.c +++ b/help.c @@ -375,7 +375,7 @@ void list_cmds_by_config(struct string_list *list) { const char *cmd_list; - if (git_config_get_string_const("completion.commands", &cmd_list)) + if (git_config_get_string_tmp("completion.commands", &cmd_list)) return; string_list_sort(list); diff --git a/protocol.c b/protocol.c index d1dd342..8d964fc 100644 --- a/protocol.c +++ b/protocol.c @@ -21,7 +21,7 @@ enum protocol_version get_protocol_version_config(void) const char *git_test_k = "GIT_TEST_PROTOCOL_VERSION"; const char *git_test_v; - if (!git_config_get_string_const("protocol.version", &value)) { + if (!git_config_get_string_tmp("protocol.version", &value)) { enum protocol_version version = parse_protocol_version(value); if (version == protocol_unknown_version) diff --git a/submodule.c b/submodule.c index e2ef569..842903c 100644 --- a/submodule.c +++ b/submodule.c @@ -194,7 +194,7 @@ void set_diffopt_flags_from_submodule_config(struct diff_options *diffopt, char *key; key = xstrfmt("submodule.%s.ignore", submodule->name); - if (repo_config_get_string_const(the_repository, key, &ignore)) + if (repo_config_get_string_tmp(the_repository, key, &ignore)) ignore = submodule->ignore; free(key); @@ -1299,7 +1299,7 @@ static int get_fetch_recurse_config(const struct submodule *submodule, int fetch_recurse = submodule->fetch_recurse; key = xstrfmt("submodule.%s.fetchRecurseSubmodules", submodule->name); - if (!repo_config_get_string_const(spf->r, key, &value)) { + if (!repo_config_get_string_tmp(spf->r, key, &value)) { fetch_recurse = parse_fetch_recurse_submodules_arg(key, value); } free(key); diff --git a/t/helper/test-config.c b/t/helper/test-config.c index 234c722..a6e9367 100644 --- a/t/helper/test-config.c +++ b/t/helper/test-config.c @@ -126,7 +126,7 @@ int cmd__config(int argc, const char **argv) goto exit1; } } else if (argc == 3 && !strcmp(argv[1], "get_string")) { - if (!git_config_get_string_const(argv[2], &v)) { + if (!git_config_get_string_tmp(argv[2], &v)) { printf("%s\n", v); goto exit0; } else { -- cgit v0.10.2-6-g49f6