Files
git/lib/sigchain.h
Patrick Steinhardt 9759608622 Move libgit.a sources into separate "lib/" directory
The Git project is not exactly the easiest project to get started in:
it's written in C and POSIX shell, with bits of Perl, Rust and other
languages sprinkled into it. On top of that, the project has grown
somewhat organically over time, making the codebase hard to navigate.

These are problems that we're aware of, and there have been and still
are efforts to clean up some of the technical debt that is natural to
exist an a project that is more than 20 years old. Furthermore, we
provide resources to newcomers that help them out like our coding
guidelines, code of conduct or "MyFirstContribution.adoc".

But there is a rather practical problem: finding your way around in our
project's tree is not easy. Doing a directory listing in the top-level
directory will present you with more than 550 files, which makes it
extremely hard for a newcomer to figure out what files they are even
supposed to look at. This makes the onboarding experience somewhat
harder than it really needs to be. This isn't only a problem for
newcomers though, as I myself struggle to find the files I am looking
for because of the sheer number of files.

Besides the problem of discoverability it also creates a problem of
structure. It is not obvious at all which files are part of "libgit.a"
and which files are only linked into our final executables. So while we
have this split in our build systems, that split is not evident at all
in our tree.

Introduce a new "lib/" directory and move all of our sources for
"libgit.a" into it to fix these issues. It makes the split we have
evident and reduces the number of files in our top-level tree from 550
files to ~80 files.

This is still a lot of files, but it's significantly easier to navigate
already. Furthermore, we can further iterate after this step and think
about introducing a better structure for remaining files, as well.

Signed-off-by: Patrick Steinhardt <ps@pks.im>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2026-06-22 10:58:23 -07:00

58 lines
1.7 KiB
C

#ifndef SIGCHAIN_H
#define SIGCHAIN_H
/**
* Code often wants to set a signal handler to clean up temporary files or
* other work-in-progress when we die unexpectedly. For multiple pieces of
* code to do this without conflicting, each piece of code must remember
* the old value of the handler and restore it either when:
*
* 1. The work-in-progress is finished, and the handler is no longer
* necessary. The handler should revert to the original behavior
* (either another handler, SIG_DFL, or SIG_IGN).
*
* 2. The signal is received. We should then do our cleanup, then chain
* to the next handler (or die if it is SIG_DFL).
*
* Sigchain is a tiny library for keeping a stack of handlers. Your handler
* and installation code should look something like:
*
* ------------------------------------------
* void clean_foo_on_signal(int sig)
* {
* clean_foo();
* sigchain_pop(sig);
* raise(sig);
* }
*
* void other_func()
* {
* sigchain_push_common(clean_foo_on_signal);
* mess_up_foo();
* clean_foo();
* }
* ------------------------------------------
*
*/
/**
* Handlers are given the typedef of sigchain_fun. This is the same type
* that is given to signal() or sigaction(). It is perfectly reasonable to
* push SIG_DFL or SIG_IGN onto the stack.
*/
typedef void (*sigchain_fun)(int);
/* You can sigchain_push and sigchain_pop individual signals. */
int sigchain_push(int sig, sigchain_fun f);
int sigchain_pop(int sig);
/**
* push the handler onto the stack for the common signals:
* SIGINT, SIGHUP, SIGTERM, SIGQUIT and SIGPIPE.
*/
void sigchain_push_common(sigchain_fun f);
void sigchain_pop_common(void);
#endif /* SIGCHAIN_H */