Revision 0b6806b9e45c659d25b87fb5713c920a3081eac8 authored by Steffen Prohaska on 20 August 2013, 06:43:54 UTC, committed by Junio C Hamano on 20 August 2013, 18:10:59 UTC
Checking out 2GB or more through an external filter (see test) fails
on Mac OS X 10.8.4 (12E55) for a 64-bit executable with:
error: read from external filter cat failed
error: cannot feed the input to external filter cat
error: cat died of signal 13
error: external filter cat failed 141
error: external filter cat failed
The reason is that read() immediately returns with EINVAL when asked
to read more than 2GB. According to POSIX [1], if the value of
nbyte passed to read() is greater than SSIZE_MAX, the result is
implementation-defined. The write function has the same restriction
[2]. Since OS X still supports running 32-bit executables, the
32-bit limit (SSIZE_MAX = INT_MAX = 2GB - 1) seems to be also
imposed on 64-bit executables under certain conditions. For write,
the problem has been addressed earlier [6c642a].
Address the problem for read() and write() differently, by limiting
size of IO chunks unconditionally on all platforms in xread() and
xwrite(). Large chunks only cause problems, like causing latencies
when killing the process, even if OS X was not buggy. Doing IO in
reasonably sized smaller chunks should have no negative impact on
performance.
The compat wrapper clipped_write() introduced earlier [6c642a] is
not needed anymore. It will be reverted in a separate commit. The
new test catches read and write problems.
Note that 'git add' exits with 0 even if it prints filtering errors
to stderr. The test, therefore, checks stderr. 'git add' should
probably be changed (sometime in another commit) to exit with
nonzero if filtering fails. The test could then be changed to use
test_must_fail.
Thanks to the following people for suggestions and testing:
Johannes Sixt <j6t@kdbg.org>
John Keeping <john@keeping.me.uk>
Jonathan Nieder <jrnieder@gmail.com>
Kyle J. McKay <mackyle@gmail.com>
Linus Torvalds <torvalds@linux-foundation.org>
Torsten Bögershausen <tboegi@web.de>
[1] http://pubs.opengroup.org/onlinepubs/009695399/functions/read.html
[2] http://pubs.opengroup.org/onlinepubs/009695399/functions/write.html
[6c642a] commit 6c642a878688adf46b226903858b53e2d31ac5c3
compate/clipped-write.c: large write(2) fails on Mac OS X/XNU
Signed-off-by: Steffen Prohaska <prohaska@zib.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
1 parent 4d06473
attr.h
#ifndef ATTR_H
#define ATTR_H
/* An attribute is a pointer to this opaque structure */
struct git_attr;
/*
* Given a string, return the gitattribute object that
* corresponds to it.
*/
struct git_attr *git_attr(const char *);
/* Internal use */
extern const char git_attr__true[];
extern const char git_attr__false[];
/* For public to check git_attr_check results */
#define ATTR_TRUE(v) ((v) == git_attr__true)
#define ATTR_FALSE(v) ((v) == git_attr__false)
#define ATTR_UNSET(v) ((v) == NULL)
/*
* Send one or more git_attr_check to git_check_attr(), and
* each 'value' member tells what its value is.
* Unset one is returned as NULL.
*/
struct git_attr_check {
struct git_attr *attr;
const char *value;
};
/*
* Return the name of the attribute represented by the argument. The
* return value is a pointer to a null-delimited string that is part
* of the internal data structure; it should not be modified or freed.
*/
char *git_attr_name(struct git_attr *);
int git_check_attr(const char *path, int, struct git_attr_check *);
/*
* Retrieve all attributes that apply to the specified path. *num
* will be set to the number of attributes on the path; **check will
* be set to point at a newly-allocated array of git_attr_check
* objects describing the attributes and their values. *check must be
* free()ed by the caller.
*/
int git_all_attrs(const char *path, int *num, struct git_attr_check **check);
enum git_attr_direction {
GIT_ATTR_CHECKIN,
GIT_ATTR_CHECKOUT,
GIT_ATTR_INDEX
};
void git_attr_set_direction(enum git_attr_direction, struct index_state *);
#endif /* ATTR_H */
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