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Junio C Hamano3dac5042007-12-15 08:40:541builtin API
2===========
3
4Adding a new built-in
5---------------------
6
Junio C Hamano4224f992008-06-23 07:14:087There are 4 things to do to add a built-in command implementation to
Junio C Hamano3dac5042007-12-15 08:40:548git:
9
10. Define the implementation of the built-in command `foo` with
11 signature:
12
13int cmd_foo(int argc, const char **argv, const char *prefix);
14
15. Add the external declaration for the function to `builtin.h`.
16
17. Add the command to `commands[]` table in `handle_internal_command()`,
18 defined in `git.c`. The entry should look like:
19
20{ "foo", cmd_foo, <options> },
Junio C Hamano4224f992008-06-23 07:14:0821+
22where options is the bitwise-or of:
Junio C Hamano3dac5042007-12-15 08:40:5423
24`RUN_SETUP`::
25
26Make sure there is a git directory to work on, and if there is a
27work tree, chdir to the top of it if the command was invoked
28in a subdirectory. If there is no work tree, no chdir() is
29done.
30
31`USE_PAGER`::
32
33If the standard output is connected to a tty, spawn a pager and
34feed our output to it.
35
Junio C Hamano4224f992008-06-23 07:14:0836`NEED_WORK_TREE`::
37
38Make sure there is a work tree, i.e. the command cannot act
39on bare repositories.
Junio C Hamano301bc7b2009-04-28 09:29:3640This only makes sense when `RUN_SETUP` is also set.
Junio C Hamano4224f992008-06-23 07:14:0841
Junio C Hamano3dac5042007-12-15 08:40:5442. Add `builtin-foo.o` to `BUILTIN_OBJS` in `Makefile`.
43
44Additionally, if `foo` is a new command, there are 3 more things to do:
45
46. Add tests to `t/` directory.
47
48. Write documentation in `Documentation/git-foo.txt`.
49
Junio C Hamano4224f992008-06-23 07:14:0850. Add an entry for `git-foo` to `command-list.txt`.
Junio C Hamano3dac5042007-12-15 08:40:5451
52
53How a built-in is called
54------------------------
55
56The implementation `cmd_foo()` takes three parameters, `argc`, `argv,
57and `prefix`. The first two are similar to what `main()` of a
58standalone command would be called with.
59
60When `RUN_SETUP` is specified in the `commands[]` table, and when you
61were started from a subdirectory of the work tree, `cmd_foo()` is called
62after chdir(2) to the top of the work tree, and `prefix` gets the path
63to the subdirectory the command started from. This allows you to
64convert a user-supplied pathname (typically relative to that directory)
65to a pathname relative to the top of the work tree.
66
67The return value from `cmd_foo()` becomes the exit status of the
68command.