From 3f2e2297b9c88a6ab5fc4bff02cf2a07ce057589 Mon Sep 17 00:00:00 2001 From: Jeff King Date: Fri, 1 Jul 2016 01:58:58 -0400 Subject: add an extra level of indirection to main() There are certain startup tasks that we expect every git process to do. In some cases this is just to improve the quality of the program (e.g., setting up gettext()). In others it is a requirement for using certain functions in libgit.a (e.g., system_path() expects that you have called git_extract_argv0_path()). Most commands are builtins and are covered by the git.c version of main(). However, there are still a few external commands that use their own main(). Each of these has to remember to include the correct startup sequence, and we are not always consistent. Rather than just fix the inconsistencies, let's make this harder to get wrong by providing a common main() that can run this standard startup. We basically have two options to do this: - the compat/mingw.h file already does something like this by adding a #define that replaces the definition of main with a wrapper that calls mingw_startup(). The upside is that the code in each program doesn't need to be changed at all; it's rewritten on the fly by the preprocessor. The downside is that it may make debugging of the startup sequence a bit more confusing, as the preprocessor is quietly inserting new code. - the builtin functions are all of the form cmd_foo(), and git.c's main() calls them. This is much more explicit, which may make things more obvious to somebody reading the code. It's also more flexible (because of course we have to figure out _which_ cmd_foo() to call). The downside is that each of the builtins must define cmd_foo(), instead of just main(). This patch chooses the latter option, preferring the more explicit approach, even though it is more invasive. We introduce a new file common-main.c, with the "real" main. It expects to call cmd_main() from whatever other objects it is linked against. We link common-main.o against anything that links against libgit.a, since we know that such programs will need to do this setup. Note that common-main.o can't actually go inside libgit.a, as the linker would not pick up its main() function automatically (it has no callers). The rest of the patch is just adjusting all of the various external programs (mostly in t/helper) to use cmd_main(). I've provided a global declaration for cmd_main(), which means that all of the programs also need to match its signature. In particular, many functions need to switch to "const char **" instead of "char **" for argv. This effect ripples out to a few other variables and functions, as well. This makes the patch even more invasive, but the end result is much better. We should be treating argv strings as const anyway, and now all programs conform to the same signature (which also matches the way builtins are defined). Signed-off-by: Jeff King Signed-off-by: Junio C Hamano --- http-backend.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'http-backend.c') diff --git a/http-backend.c b/http-backend.c index 8870a2681..3249652b3 100644 --- a/http-backend.c +++ b/http-backend.c @@ -632,7 +632,7 @@ static struct service_cmd { {"POST", "/git-receive-pack$", service_rpc} }; -int main(int argc, char **argv) +int cmd_main(int argc, const char **argv) { char *method = getenv("REQUEST_METHOD"); char *dir; -- cgit v1.2.1 From 650c449250d7279dcbfe2f7cc23624955d53d339 Mon Sep 17 00:00:00 2001 From: Jeff King Date: Fri, 1 Jul 2016 02:04:04 -0400 Subject: common-main: call git_extract_argv0_path() Every program which links against libgit.a must call this function, or risk hitting an assert() in system_path() that checks whether we have configured argv0_path (though only when RUNTIME_PREFIX is defined, so essentially only on Windows). Looking at the diff, you can see that putting it into the common main() saves us having to do it individually in each of the external commands. But what you can't see are the cases where we _should_ have been doing so, but weren't (e.g., git-credential-store, and all of the t/helper test programs). This has been an accident-waiting-to-happen for a long time, but wasn't triggered until recently because it involves one of those programs actually calling system_path(). That happened with git-credential-store in v2.8.0 with ae5f677 (lazily load core.sharedrepository, 2016-03-11). The program: - takes a lock file, which... - opens a tempfile, which... - calls adjust_shared_perm to fix permissions, which... - lazy-loads the config (as of ae5f677), which... - calls system_path() to find the location of /etc/gitconfig On systems with RUNTIME_PREFIX, this means credential-store reliably hits that assert() and cannot be used. We never noticed in the test suite, because we set GIT_CONFIG_NOSYSTEM there, which skips the system_path() lookup entirely. But if we were to tweak git_config() to find /etc/gitconfig even when we aren't going to open it, then the test suite shows multiple failures (for credential-store, and for some other test helpers). I didn't include that tweak here because it's way too specific to this particular call to be worth carrying around what is essentially dead code. The implementation is fairly straightforward, with one exception: there is exactly one caller (git.c) that actually cares about the result of the function, and not the side-effect of setting up argv0_path. We can accommodate that by simply replacing the value of argv[0] in the array we hand down to cmd_main(). Signed-off-by: Jeff King Signed-off-by: Junio C Hamano --- http-backend.c | 1 - 1 file changed, 1 deletion(-) (limited to 'http-backend.c') diff --git a/http-backend.c b/http-backend.c index 3249652b3..2926d1f9e 100644 --- a/http-backend.c +++ b/http-backend.c @@ -642,7 +642,6 @@ int cmd_main(int argc, const char **argv) git_setup_gettext(); - git_extract_argv0_path(argv[0]); set_die_routine(die_webcgi); set_die_is_recursing_routine(die_webcgi_recursing); -- cgit v1.2.1 From 5ce5f5fa5ad3de3c36fdd00df2d5c045ad1d7f04 Mon Sep 17 00:00:00 2001 From: Jeff King Date: Fri, 1 Jul 2016 02:07:01 -0400 Subject: common-main: call git_setup_gettext() This should be part of every program, as otherwise users do not get translated error messages. However, some external commands forgot to do so (e.g., git-credential-store). This fixes them, and eliminates the repeated code in programs that did remember to use it. Signed-off-by: Jeff King Signed-off-by: Junio C Hamano --- http-backend.c | 2 -- 1 file changed, 2 deletions(-) (limited to 'http-backend.c') diff --git a/http-backend.c b/http-backend.c index 2926d1f9e..5a17bcac8 100644 --- a/http-backend.c +++ b/http-backend.c @@ -640,8 +640,6 @@ int cmd_main(int argc, const char **argv) char *cmd_arg = NULL; int i; - git_setup_gettext(); - set_die_routine(die_webcgi); set_die_is_recursing_routine(die_webcgi_recursing); -- cgit v1.2.1