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compate/clipped-write.c: large write(2) fails on Mac OS X/XNU

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Due to a bug in the Darwin kernel, write(2) calls have a maximum size
of INT_MAX bytes.

Introduce a new compat function, clipped_write(), that only writes
at most INT_MAX bytes and returns the number of bytes written, as
a substitute for write(2), and allow platforms that need this to
enable it from the build mechanism with NEEDS_CLIPPED_WRITE.

Set it for Mac OS X by default.  It may be necessary to include this
function on Windows, too.

Signed-off-by: Filipe Cabecinhas <filcab+git@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
This commit is contained in:
Filipe Cabecinhas 2013-05-10 15:24:57 -07:00 committed by Junio C Hamano
parent 239222f587
commit 6c642a8786
4 changed files with 27 additions and 0 deletions
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8
Makefile
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@ -69,6 +69,9 @@ all::
# Define NO_MSGFMT_EXTENDED_OPTIONS if your implementation of msgfmt
# doesn't support GNU extensions like --check and --statistics
#
# Define NEEDS_CLIPPED_WRITE if your write(2) cannot write more than
# INT_MAX bytes at once (e.g. MacOS X).
#
# Define HAVE_PATHS_H if you have paths.h and want to use the default PATH
# it specifies.
#
@ -1463,6 +1466,11 @@ ifndef NO_MSGFMT_EXTENDED_OPTIONS
MSGFMT += --check --statistics
endif
ifdef NEEDS_CLIPPED_WRITE
BASIC_CFLAGS += -DNEEDS_CLIPPED_WRITE
COMPAT_OBJS += compat/clipped-write.o
endif
ifneq (,$(XDL_FAST_HASH))
BASIC_CFLAGS += -DXDL_FAST_HASH
endif

13
compat/clipped-write.c Normal file
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@ -0,0 +1,13 @@
#include "../git-compat-util.h"
#undef write
/*
* Version of write that will write at most INT_MAX bytes.
* Workaround a xnu bug on Mac OS X
*/
ssize_t clipped_write(int fildes, const void *buf, size_t nbyte)
{
if (nbyte > INT_MAX)
nbyte = INT_MAX;
return write(fildes, buf, nbyte);
}

1
config.mak.uname
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@ -95,6 +95,7 @@ ifeq ($(uname_S),Darwin)
NO_MEMMEM = YesPlease
USE_ST_TIMESPEC = YesPlease
HAVE_DEV_TTY = YesPlease
NEEDS_CLIPPED_WRITE = YesPlease
COMPAT_OBJS += compat/precompose_utf8.o
BASIC_CFLAGS += -DPRECOMPOSE_UNICODE
endif

5
git-compat-util.h
View File

@ -181,6 +181,11 @@ typedef unsigned long uintptr_t;
#define probe_utf8_pathname_composition(a,b)
#endif
#ifdef NEEDS_CLIPPED_WRITE
ssize_t clipped_write(int fildes, const void *buf, size_t nbyte);
#define write(x,y,z) clipped_write((x),(y),(z))
#endif
#ifdef MKDIR_WO_TRAILING_SLASH
#define mkdir(a,b) compat_mkdir_wo_trailing_slash((a),(b))
extern int compat_mkdir_wo_trailing_slash(const char*, mode_t);