Re: [PATCH] compat: introduce stat_to_kilobytes

> Some platforms do not have st_blocks member in "struct stat"; mingw
> already emulates it by rounding it up to closest 512-byte blocks (even
> though it could overcount when a file has holes).
>
> The reason to use the member is only to figure out how many  
> kilobytes the
> file occupies on-disk, so give a helper in git-compat-util.h to help  
> these
> platforms.
>
> Signed-off-by: Junio C Hamano <gitster@pobox.com>
> ---
>
> * I suspect you may be better off building on top of something like
>   this.
>
>   The comment before "struct mingw_stat" suggests that the only reason
>   this compatiblity definition exists is to add st_blocks member, so I
>   suspect we could remove the definition and simplify the  
> compatibility
>   layer a lot more, but I do not know MinGW, so I am CC'ing j6t here.

> diff --git a/Makefile b/Makefile
> index 53ab4b5..8f69f16 100644
> --- a/Makefile
> +++ b/Makefile
> @@ -124,6 +124,9 @@ all::
> # Define USE_STDEV below if you want git to care about the  
> underlying device
> # change being considered an inode change from the update-index  
> perspective.
> #
> +# Define NO_ST_BLOCKS_IN_STRUCT_STAT if your platform does not have  
> st_blocks
> +# field that counts the on-disk footprint in 512-byte blocks.
> +#
> # Define ASCIIDOC8 if you want to format documentation with AsciiDoc 8
> #
> # Define DOCBOOK_XSL_172 if you want to format man pages with  
> DocBook XSL v1.72.
> @@ -749,6 +752,7 @@ ifneq (,$(findstring MINGW,$(uname_S)))
> 	NO_SVN_TESTS = YesPlease
> 	NO_PERL_MAKEMAKER = YesPlease
> 	NO_POSIX_ONLY_PROGRAMS = YesPlease
> +	NO_ST_BLOCKS_IN_STRUCT_STAT = YesPlease
> 	COMPAT_CFLAGS += -D__USE_MINGW_ACCESS -DNOGDI -Icompat
> 	COMPAT_CFLAGS += -DSNPRINTF_SIZE_CORR=1
> 	COMPAT_CFLAGS += -DSTRIP_EXTENSION=\".exe\"

> --- a/git-compat-util.h
> +++ b/git-compat-util.h
> @@ -192,6 +192,12 @@ extern int git_munmap(void *start, size_t  
> length);
>
> #endif /* NO_MMAP */
>
> +#ifdef NO_ST_BLOCKS_IN_STRUCT_STAT
> +#define stat_to_kilobytes(st) ((((st).st_size+511) / 512) / 2)
> +#else
> +#define stat_to_kilobytes(st) ((st).st_blocks / 2)
> +#endif
> +
> #define DEFAULT_PACKED_GIT_LIMIT \
> 	((1024L * 1024L) * (sizeof(void*) >= 8 ? 8192 : 256))