• Jeff King's avatar
    add an extra level of indirection to main() · 3f2e2297
    Jeff King authored
    There are certain startup tasks that we expect every git
    process to do. In some cases this is just to improve the
    quality of the program (e.g., setting up gettext()). In
    others it is a requirement for using certain functions in
    libgit.a (e.g., system_path() expects that you have called
    git_extract_argv0_path()).
    
    Most commands are builtins and are covered by the git.c
    version of main(). However, there are still a few external
    commands that use their own main(). Each of these has to
    remember to include the correct startup sequence, and we are
    not always consistent.
    
    Rather than just fix the inconsistencies, let's make this
    harder to get wrong by providing a common main() that can
    run this standard startup.
    
    We basically have two options to do this:
    
     - the compat/mingw.h file already does something like this by
       adding a #define that replaces the definition of main with a
       wrapper that calls mingw_startup().
    
       The upside is that the code in each program doesn't need
       to be changed at all; it's rewritten on the fly by the
       preprocessor.
    
       The downside is that it may make debugging of the startup
       sequence a bit more confusing, as the preprocessor is
       quietly inserting new code.
    
     - the builtin functions are all of the form cmd_foo(),
       and git.c's main() calls them.
    
       This is much more explicit, which may make things more
       obvious to somebody reading the code. It's also more
       flexible (because of course we have to figure out _which_
       cmd_foo() to call).
    
       The downside is that each of the builtins must define
       cmd_foo(), instead of just main().
    
    This patch chooses the latter option, preferring the more
    explicit approach, even though it is more invasive. We
    introduce a new file common-main.c, with the "real" main. It
    expects to call cmd_main() from whatever other objects it is
    linked against.
    
    We link common-main.o against anything that links against
    libgit.a, since we know that such programs will need to do
    this setup. Note that common-main.o can't actually go inside
    libgit.a, as the linker would not pick up its main()
    function automatically (it has no callers).
    
    The rest of the patch is just adjusting all of the various
    external programs (mostly in t/helper) to use cmd_main().
    I've provided a global declaration for cmd_main(), which
    means that all of the programs also need to match its
    signature. In particular, many functions need to switch to
    "const char **" instead of "char **" for argv. This effect
    ripples out to a few other variables and functions, as well.
    
    This makes the patch even more invasive, but the end result
    is much better. We should be treating argv strings as const
    anyway, and now all programs conform to the same signature
    (which also matches the way builtins are defined).
    Signed-off-by: default avatarJeff King <peff@peff.net>
    Signed-off-by: default avatarJunio C Hamano <gitster@pobox.com>
    3f2e2297
common-main.c 229 Bytes