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On POSIX systems, system calls can be interrupted by signals. In this
case, they'll return EINTR, indicating that the system call needs to
be restarted.
(The situation is a little more complicated than this with SA_RESTART,
but you can read man 7 signal if you like.)
The short of it is that you need to catch EINTR and restart the call
for these system calls:
* read, readv, write, writev, ioctl
* open() when dealing with a fifo
* wait*
* Anything socket based (send*, recv*, connect, accept etc)
* flock and lock control with fcntl
* mq_ functions which can block
* futex
* sem_wait (and timed wait)
* pause, sigsuspend, sigtimedwait, sigwaitinfo
* poll, epoll_wait, select and 'p' versions of the same
* msgrcv, msgsnd, semop, semtimedop
* close (although, on Linux, EINTR won't happen here)
* any sleep functions (careful, you need to handle this are restart
with different arguments)
We've been a little sloppy with this until now. This patch adds a
macro for dealing with this and corrects every case of these system
calls (that I found).
The macro is HANDLE_EINTR in base/eintr_wrapper.h. It's safe to
include on Windows and is a no-op there.
On POSIX, it uses GCC magic to return the correct type based on the
expression and restarts the system call if it throws EINTR.
And you can use it like:
HANDLE_EINTR(close(fd));
Or:
ssize_t bytes_read = HANDLE_EINTR(read(fd, buffer, len));
*BEWARE* that it will evaluate the argument multiple times, so this is
not safe:
HANDLE_EINTR(close(FireMissiles()));
http://groups.google.com/group/chromium-dev/browse_thread/thread/41a35b2a457d73a0
http://codereview.chromium.org/100225
git-svn-id: svn://svn.chromium.org/chrome/trunk/src@15102 0039d316-1c4b-4281-b951-d872f2087c98
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