Subject: Re: [PATCH v2] Makefile: add OPEN_RETURNS_EINTR knob

From: Junio C Hamano <[email-masked]>
Date: Fri, 26 Feb 2021 14:17:53 -0800

Jeff King <[email-masked]> writes:

> However, note that we must not enable this on Windows. It doesn't do
> anything there, and the macro overrides the existing mingw_open()
> redirection. I've added a preemptive #undef here in the mingw header
> (which is processed first) to just quietly disable it (we could also
> make it an #error, but there is little point in being so aggressive).
> ...
> diff --git a/compat/open.c b/compat/open.c
> new file mode 100644
> index 0000000000..eb3754a23b
> --- /dev/null
> +++ b/compat/open.c
> @@ -0,0 +1,25 @@
> +#include "git-compat-util.h"
> +
> +#undef open
> +int git_open_with_retry(const char *path, int flags, ...)
> +{
> +	mode_t mode = 0;
> +	int ret;
> +
> +	/*
> +	 * Also O_TMPFILE would take a mode, but it isn't defined everywhere.
> +	 * And anyway, we don't use it in our code base.
> +	 */

That is being extra careful---I like it very much.

> +	if (flags & O_CREAT) {
> +		va_list ap;
> +		va_start(ap, flags);
> +		mode = va_arg(ap, int);
> +		va_end(ap);
> +	}
> +
> +	do {
> +		ret = open(path, flags, mode);
> +	} while (ret < 0 && errno == EINTR);
> +
> +	return ret;
> +}

Thanks.

> diff --git a/git-compat-util.h b/git-compat-util.h
> index 838246289c..551cc9f22f 100644
> --- a/git-compat-util.h
> +++ b/git-compat-util.h
> @@ -788,6 +788,12 @@ int git_vsnprintf(char *str, size_t maxsize,
>  		  const char *format, va_list ap);
>  #endif
>  
> +#ifdef OPEN_RETURNS_EINTR
> +#undef open
> +#define open git_open_with_retry
> +int git_open_with_retry(const char *path, int flag, ...);
> +#endif
> +
>  #ifdef __GLIBC_PREREQ
>  #if __GLIBC_PREREQ(2, 1)
>  #define HAVE_STRCHRNUL