implement POSIX asynchronous io

some features are not yet supported, and only minimal testing has been
performed. should be considered experimental at this point.

1 files changed, 104 insertions, 0 deletions

diff --git a/src/aio/aio_readwrite.c b/src/aio/aio_readwrite.c
new file mode 100644
index 00000000..27168f25
--- /dev/null
+++ b/src/aio/aio_readwrite.c
@@ -0,0 +1,104 @@
+#include <aio.h>
+#include <fcntl.h>
+#include "pthread_impl.h"
+
+static void dummy(void)
+{
+}
+
+weak_alias(dummy, __aio_wake);
+
+static void notify_signal(struct sigevent *sev)
+{
+	siginfo_t si = {
+		.si_signo = sev->sigev_signo,
+		.si_value = sev->sigev_value,
+		.si_code = SI_ASYNCIO,
+		.si_pid = __pthread_self()->pid,
+		.si_uid = getuid()
+	};
+	__syscall(SYS_rt_sigqueueinfo, si.si_pid, si.si_signo, &si);
+}
+
+static void *io_thread(void *p)
+{
+	struct aiocb *cb = p;
+	int fd = cb->aio_filedes;
+	void *buf = (void *)cb->aio_buf;
+	size_t len = cb->aio_nbytes;
+	off_t off = cb->aio_offset;
+	int op = cb->aio_lio_opcode;
+	struct sigevent sev = cb->aio_sigevent;
+	ssize_t ret;
+
+	if (op == LIO_WRITE) {
+		if (  (fcntl(fd, F_GETFL) & O_APPEND)
+		    ||((ret = pwrite(fd, buf, len, off))<0 && errno==ESPIPE) )
+			ret = write(fd, buf, len);
+	} else if (op == LIO_READ) {
+		if ( (ret = pread(fd, buf, len, off))<0 && errno==ESPIPE )
+			ret = read(fd, buf, len);
+	} else {
+		ret = 0;
+	}
+	cb->__ret = ret;
+
+	if (ret < 0) a_store(&cb->__err, errno);
+	else a_store(&cb->__err, 0);
+
+	__aio_wake();
+
+	switch (cb->aio_sigevent.sigev_notify) {
+	case SIGEV_SIGNAL:
+		notify_signal(&sev);
+		break;
+	case SIGEV_THREAD:
+		sev.sigev_notify_function(sev.sigev_value);
+		break;
+	}
+
+	return 0;
+}
+
+static int new_req(struct aiocb *cb)
+{
+	int ret = 0;
+	pthread_attr_t a;
+	sigset_t set;
+	pthread_t td;
+
+	if (cb->aio_sigevent.sigev_notify == SIGEV_THREAD) {
+		if (cb->aio_sigevent.sigev_notify_attributes)
+			a = *cb->aio_sigevent.sigev_notify_attributes;
+		else
+			pthread_attr_init(&a);
+	} else {
+		pthread_attr_init(&a);
+		pthread_attr_setstacksize(&a, PAGE_SIZE);
+		pthread_attr_setguardsize(&a, 0);
+	}
+	pthread_attr_setdetachstate(&a, PTHREAD_CREATE_DETACHED);
+	sigfillset(&set);
+	pthread_sigmask(SIG_BLOCK, &set, &set);
+	cb->__err = EINPROGRESS;
+	if (pthread_create(&td, &a, io_thread, cb)) {
+		errno = EAGAIN;
+		ret = -1;
+	}
+	pthread_sigmask(SIG_SETMASK, &set, 0);
+	cb->__td = td;
+
+	return ret;
+}
+
+ssize_t aio_read(struct aiocb *cb)
+{
+	cb->aio_lio_opcode = LIO_READ;
+	return new_req(cb);
+}
+
+ssize_t aio_write(struct aiocb *cb)
+{
+	cb->aio_lio_opcode = LIO_WRITE;
+	return new_req(cb);
+}