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70 lines
2.0 KiB
70 lines
2.0 KiB
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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