summaryrefslogtreecommitdiff
path: root/Documentation/technical/api-builtin.txt
blob: 150a02a5586bf62bddfc15ee8c8e9039330fb791 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
builtin API
===========
 
Adding a new built-in
---------------------
 
There are 4 things to do to add a built-in command implementation to
Git:
 
. Define the implementation of the built-in command `foo` with
  signature:
 
	int cmd_foo(int argc, const char **argv, const char *prefix);
 
. Add the external declaration for the function to `builtin.h`.
 
. Add the command to `commands[]` table in `handle_builtin()`,
  defined in `git.c`.  The entry should look like:
 
	{ "foo", cmd_foo, <options> },
+
where options is the bitwise-or of:
 
`RUN_SETUP`::
 
	Make sure there is a Git directory to work on, and if there is a
	work tree, chdir to the top of it if the command was invoked
	in a subdirectory.  If there is no work tree, no chdir() is
	done.
 
`USE_PAGER`::
 
	If the standard output is connected to a tty, spawn a pager and
	feed our output to it.
 
`NEED_WORK_TREE`::
 
	Make sure there is a work tree, i.e. the command cannot act
	on bare repositories.
	This only makes sense when `RUN_SETUP` is also set.
 
. Add `builtin/foo.o` to `BUILTIN_OBJS` in `Makefile`.
 
Additionally, if `foo` is a new command, there are 3 more things to do:
 
. Add tests to `t/` directory.
 
. Write documentation in `Documentation/git-foo.txt`.
 
. Add an entry for `git-foo` to `command-list.txt`.
 
. Add an entry for `/git-foo` to `.gitignore`.
 
 
How a built-in is called
------------------------
 
The implementation `cmd_foo()` takes three parameters, `argc`, `argv,
and `prefix`.  The first two are similar to what `main()` of a
standalone command would be called with.
 
When `RUN_SETUP` is specified in the `commands[]` table, and when you
were started from a subdirectory of the work tree, `cmd_foo()` is called
after chdir(2) to the top of the work tree, and `prefix` gets the path
to the subdirectory the command started from.  This allows you to
convert a user-supplied pathname (typically relative to that directory)
to a pathname relative to the top of the work tree.
 
The return value from `cmd_foo()` becomes the exit status of the
command.