Re: First cut at git port to Cygwin

From: H. Peter Anvin <hpa@zytor.com>
Date: Sep 30, 2005, 17:01 UTC
Message-ID: <433D6F62.3030906@zytor.com>
In-Reply-To: <7v4q826ffy.fsf@assigned-by-dhcp.cox.net>

Junio C Hamano wrote:

> 
> Could you do update-server-info there, please?
>

Done...

Show 9 quoted lines

> 
> Knowing nothing about Cygwin environment, here are some
> comments.
> 
>         +# Define NO_IPV6 if you lack IPv6 support and getaddrinfo().
> 
> This part probably is applicable outside Cygwin.  At some point,
> can we have it in the mainline please?
>

Well, I would hope that all the changes could eventually be merged.

Show 25 quoted lines

>          # The ones that do not have to link with lcrypto nor lz.
>          SIMPLE_PROGRAMS = \
>         -	git-get-tar-commit-id git-mailinfo git-mailsplit git-stripspace \
>         -	git-daemon git-var
>         +	git-get-tar-commit-id$(X) git-mailinfo$(X) git-mailsplit$(X) \
>         +	git-stripspace$(X) git-var$(X) git-daemon$(X)
>  
> I have seen these $(X) in other programs' ports and found them
> quite distasteful.  Since I not have immediate suggestions
> for improvements, I do not have rights to complain, though.
> 
> Spelling it $X is a bit less distracting but not that much
> better.  Maybe "SIMPLE_PROGRAM_NAMES = git-foo git-bar" and
> "SIMPLE_PROGRAMS = $(patsubst %,%$X,$(SIMPLE_PROGRAM_NAMES))"...
> but that would not help bits like this:
> 
>         -	PROGRAMS += git-http-fetch
>         +	PROGRAMS += git-http-fetch$(X)
> 
> or this: 
> 
>         -git-%: %.o $(LIB_FILE)
>         +git-%$(X): %.o $(LIB_FILE)
> 
> ... so I'd shut up about this part.

My first cut had PROGRAMS_X and SIMPLE_PROGRAMS_X being patsubst of the original versions, but in the end I decided it was even uglier, because these patterns were needed elsewhere. I'll change them to $X except where the parens are needed.

Show 9 quoted lines

>         diff --git a/daemon.c b/daemon.c
>         --- a/daemon.c
>         +++ b/daemon.c
>         @@ -1,9 +1,11 @@
>          #include "cache.h"
>          #include "pkt-line.h"
>         +#include <alloca.h>
> 
> Why?  I do not see any use of alloca in the added code...

I originally used alloca() before changing my mind and using calloc(); I think there might be platforms without alloca out there.

Show 7 quoted lines

>         +#include <sys/poll.h>
> 
> Is poll preferrable over select in general?  Some may have only
> select available and others may have only poll available,
> perhaps?  In any case, this is probably relevant to wider
> audience than just Cygwin; please give it to mainline at some
> point, perhaps conditionally allowing either/both.

The main reason I switched to poll() is that I believe all platforms that are even remotely relevant have both these days, and forming a poll list is so much cleaner than forming a select set. What makes forming a select set even remotely bearable is the invalid assumption that the number of file descriptors is bounded at compile time and therefore that fdset_t can be statically allocated. We've had problems in the past with that assumption on Linux, and I've tried to avoid select since then.

>         +	*socklist_p = malloc(sizeof(int));
>         +	pfd = calloc(socknum, sizeof(struct pollfd));
> 
> Please use xmalloc and xcalloc just for consistency.

Check.

Show 7 quoted lines

>                 test -x $path/git-$cmd && exec $path/git-$cmd "$@" ;;
>         +
>         +	# In case we're running on Cygwin...
>         +	test -x $path/git-$cmd.exe && exec $path/git-$cmd.exe "$@" ;;
>          esac
>  
> Hmph, I think you forgot to drop double semicolon there.

D'oh!

Show 34 quoted lines

> The git.sh script is munged by Makefile so presumably we could
> fix this part up there, like:
> 
>         git: git.sh Makefile
>                 rm -f $@+ $@
>                 sed -e '1s|#!.*/sh|#!$(SHELL_PATH)|' \
>                     -e 's/@@GIT_VERSION@@/$(GIT_VERSION)/g' \
>                     -e 's/@@X@@/$X/g' <$@.sh >$@+
>                 chmod +x $@+
>                 mv $@+ $@
> 
> And then (a patch on top of your "master"):
> 
> diff --git a/git.sh b/git.sh
> --- a/git.sh
> +++ b/git.sh
> @@ -12,10 +12,14 @@ case "$#" in
>  		exit 0 ;;
>  	esac
>  
> -	test -x $path/git-$cmd && exec $path/git-$cmd "$@" ;;
> +	test -x $path/git-$cmd && exec $path/git-$cmd "$@"
>  
> -	# In case we're running on Cygwin...
> -	test -x $path/git-$cmd.exe && exec $path/git-$cmd.exe "$@" ;;
> +	case '@@X@@' in
> +	'')
> +		;;
> +	*)
> +		test -x $path/git-$cmd@@X@@ && exec $path/git-$cmd@@X@@ "$@" ;;
> +	esac		
>  esac
>  
>  echo "Usage: git COMMAND [OPTIONS] [TARGET]"

That wouldn't work, because the shell scripts don't get the .exe extension. However, I can figure out something equivalent.

	-hpa