the existing file descriptor. Instead, let dup2() atomically close the
old file descriptor when assigning the newly opened file to the same
descriptor. This closes a race in a multithreaded application where a
concurrent open() could allocate the existing file descriptor in between
the calls to close() and dup2().
PR: threads/79887
Submitted by: Dmitrij Tejblum tejblum of yandex-team.ru
Reviewed by: davidxu
MFC after: 1 week
__sFILE. This was supposed to be done in 6.0. Some notes:
- Where possible I restored the various lines to their pre-__sFILEX state.
- Retire INITEXTRA() and just initialize the wchar bits (orientation and
mbstate) explicitly instead. The various places that used INITEXTRA
didn't need the locking fields or _up initialized. (Some places needed
_up to exist and not be off the end of a NULL or garbage pointer, but
they didn't require it to be initialized to a specific value.)
- For now, stdio.h "knows" that pthread_t is a 'struct pthread *' to
avoid namespace pollution of including all the pthread types in stdio.h.
Once we remove all the inlines and make __sFILE private it can go back
to using pthread_t, etc.
- This does not remove any of the inlines currently and does not change
any of the public ABI of 'FILE'.
MFC after: 1 month
Reviewed by: peter
them. Thus, any fd whose value is greater than SHRT_MAX is handled
incorrectly (the short value is sign-extended when converted to an int).
An unpleasant side effect is that if fopen() opens a file and gets a
backing fd that is greater than SHRT_MAX, fclose() will fail and the file
descriptor will be leaked. Better handle this by fixing fopen(), fdopen(),
and freopen() to fail attempts to use a fd greater than SHRT_MAX with
EMFILE.
At some point in the future we should look at expanding the file descriptor
in FILE to an int, but that is a bit complicated due to ABI issues.
MFC after: 1 week
Discussed on: arch
Reviewed by: wollman
Issue __sflush() before possible setting O_APPEND mode or ftruncate(),
write to wrong place may occurse oserwise.
Use simplified _sseek() to the start, if no O_APPEND is set, instead
of _fseeko() (_sseek() to the end, if O_APPEND, occurse later, as for
file != NULL).
Don't check seek error return, as original fopen() and freopen() never
does.
file != NULL:
Add missing _sseek() to the end.
to the initial state when a stream is opened or seeked upon. Use the
stream's conversion state object instead of a freshly-zeroed one in
fgetwc(), fputwc() and ungetwc().
This is only a performance improvement for now, but it would also be
required in order to support state-dependent encodings.
a NULL filename argument allows a stream's mode to be changed. At the
moment it just recycles the old file descriptor instead of storing the
filename somewhere and using that to reopen the file, as the standard
seems to require. Strictly conforming C99 applications probably can't
tell the difference but POSIX ones can.
PR: 46791
Add a lock to FILE. flockfile and friends are now implemented
(for the most part) in libc. flockfile_debug is implemented in
libc_r; I suppose it's about time to kill it but will do it in
a future commit.
Fix a potential deadlock in _fwalk in a threaded environment.
A file flag (__SIGN) was added to stdio.h that, when set, tells
_fwalk to ignore it in its walk. This seemed to be needed in
refill.c because each file needs to be locked when flushing.
Add a stub for pthread_self in libc. This is needed by flockfile
which is allowed by POSIX to be recursive.
Make fgetpos() error return value (-1) match man page.
Remove recursive calls to locked functions (stdio); I think I've
got them all, but I may have missed a couple.
A few K&R -> ANSI conversions along with removal of a few instances
of "register".
$Id$ -> $FreeBSD$ in libc/stdio/rget.c
Not objected to: -arch, a few months ago
adding (weak definitions to) stubs for some of the pthread
functions. If the threads library is linked in, the real
pthread functions will pulled in.
Use the following convention for system calls wrapped by the
threads library:
__sys_foo - actual system call
_foo - weak definition to __sys_foo
foo - weak definition to __sys_foo
Change all libc uses of system calls wrapped by the threads
library from foo to _foo. In order to define the prototypes
for _foo(), we introduce namespace.h and un-namespace.h
(suggested by bde). All files that need to reference these
system calls, should include namespace.h before any standard
includes, then include un-namespace.h after the standard
includes and before any local includes. <db.h> is an exception
and shouldn't be included in between namespace.h and
un-namespace.h namespace.h will define foo to _foo, and
un-namespace.h will undefine foo.
Try to eliminate some of the recursive calls to MT-safe
functions in libc/stdio in preparation for adding a mutex
to FILE. We have recursive mutexes, but would like to avoid
using them if possible.
Remove uneeded includes of <errno.h> from a few files.
Add $FreeBSD$ to a few files in order to pass commitprep.
Approved by: -arch
just use _foo() <-- foo(). In the case of a libpthread that doesn't do
call conversion (such as linuxthreads and our upcoming libpthread), this
is adequate. In the case of libc_r, we still need three names, which are
now _thread_sys_foo() <-- _foo() <-- foo().
Convert all internal libc usage of: aio_suspend(), close(), fsync(), msync(),
nanosleep(), open(), fcntl(), read(), and write() to _foo() instead of foo().
Remove all internal libc usage of: creat(), pause(), sleep(), system(),
tcdrain(), wait(), and waitpid().
Make thread cancellation fully POSIX-compliant.
Suggested by: deischen
points. For library functions, the pattern is __sleep() <--
_libc_sleep() <-- sleep(). The arrows represent weak aliases. For
system calls, the pattern is _read() <-- _libc_read() <-- read().
