71 lines
2.0 KiB
Plaintext
71 lines
2.0 KiB
Plaintext
builtin API
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===========
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Adding a new built-in
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---------------------
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There are 4 things to do to add a built-in command implementation to
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git:
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. Define the implementation of the built-in command `foo` with
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signature:
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int cmd_foo(int argc, const char **argv, const char *prefix);
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. Add the external declaration for the function to `builtin.h`.
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. Add the command to `commands[]` table in `handle_internal_command()`,
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defined in `git.c`. The entry should look like:
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{ "foo", cmd_foo, <options> },
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+
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where options is the bitwise-or of:
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`RUN_SETUP`::
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Make sure there is a git directory to work on, and if there is a
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work tree, chdir to the top of it if the command was invoked
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in a subdirectory. If there is no work tree, no chdir() is
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done.
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`USE_PAGER`::
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If the standard output is connected to a tty, spawn a pager and
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feed our output to it.
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`NEED_WORK_TREE`::
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Make sure there is a work tree, i.e. the command cannot act
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on bare repositories.
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This only makes sense when `RUN_SETUP` is also set.
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. Add `builtin-foo.o` to `BUILTIN_OBJS` in `Makefile`.
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Additionally, if `foo` is a new command, there are 3 more things to do:
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. Add tests to `t/` directory.
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. Write documentation in `Documentation/git-foo.txt`.
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. Add an entry for `git-foo` to `command-list.txt`.
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. Add an entry for `/git-foo` to `.gitignore`.
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How a built-in is called
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------------------------
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The implementation `cmd_foo()` takes three parameters, `argc`, `argv,
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and `prefix`. The first two are similar to what `main()` of a
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standalone command would be called with.
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When `RUN_SETUP` is specified in the `commands[]` table, and when you
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were started from a subdirectory of the work tree, `cmd_foo()` is called
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after chdir(2) to the top of the work tree, and `prefix` gets the path
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to the subdirectory the command started from. This allows you to
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convert a user-supplied pathname (typically relative to that directory)
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to a pathname relative to the top of the work tree.
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The return value from `cmd_foo()` becomes the exit status of the
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command.
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