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-rw-r--r--libc-top-half/musl/src/aio/aio.c418
1 files changed, 418 insertions, 0 deletions
diff --git a/libc-top-half/musl/src/aio/aio.c b/libc-top-half/musl/src/aio/aio.c
new file mode 100644
index 0000000..a1a3e79
--- /dev/null
+++ b/libc-top-half/musl/src/aio/aio.c
@@ -0,0 +1,418 @@
+#include <aio.h>
+#include <pthread.h>
+#include <semaphore.h>
+#include <limits.h>
+#include <errno.h>
+#include <unistd.h>
+#include <stdlib.h>
+#include <sys/auxv.h>
+#include "syscall.h"
+#include "atomic.h"
+#include "pthread_impl.h"
+#include "aio_impl.h"
+
+#define malloc __libc_malloc
+#define calloc __libc_calloc
+#define realloc __libc_realloc
+#define free __libc_free
+
+/* The following is a threads-based implementation of AIO with minimal
+ * dependence on implementation details. Most synchronization is
+ * performed with pthread primitives, but atomics and futex operations
+ * are used for notification in a couple places where the pthread
+ * primitives would be inefficient or impractical.
+ *
+ * For each fd with outstanding aio operations, an aio_queue structure
+ * is maintained. These are reference-counted and destroyed by the last
+ * aio worker thread to exit. Accessing any member of the aio_queue
+ * structure requires a lock on the aio_queue. Adding and removing aio
+ * queues themselves requires a write lock on the global map object,
+ * a 4-level table mapping file descriptor numbers to aio queues. A
+ * read lock on the map is used to obtain locks on existing queues by
+ * excluding destruction of the queue by a different thread while it is
+ * being locked.
+ *
+ * Each aio queue has a list of active threads/operations. Presently there
+ * is a one to one relationship between threads and operations. The only
+ * members of the aio_thread structure which are accessed by other threads
+ * are the linked list pointers, op (which is immutable), running (which
+ * is updated atomically), and err (which is synchronized via running),
+ * so no locking is necessary. Most of the other other members are used
+ * for sharing data between the main flow of execution and cancellation
+ * cleanup handler.
+ *
+ * Taking any aio locks requires having all signals blocked. This is
+ * necessary because aio_cancel is needed by close, and close is required
+ * to be async-signal safe. All aio worker threads run with all signals
+ * blocked permanently.
+ */
+
+struct aio_thread {
+ pthread_t td;
+ struct aiocb *cb;
+ struct aio_thread *next, *prev;
+ struct aio_queue *q;
+ volatile int running;
+ int err, op;
+ ssize_t ret;
+};
+
+struct aio_queue {
+ int fd, seekable, append, ref, init;
+ pthread_mutex_t lock;
+ pthread_cond_t cond;
+ struct aio_thread *head;
+};
+
+struct aio_args {
+ struct aiocb *cb;
+ struct aio_queue *q;
+ int op;
+ sem_t sem;
+};
+
+static pthread_rwlock_t maplock = PTHREAD_RWLOCK_INITIALIZER;
+static struct aio_queue *****map;
+static volatile int aio_fd_cnt;
+volatile int __aio_fut;
+
+static size_t io_thread_stack_size;
+
+#define MAX(a,b) ((a)>(b) ? (a) : (b))
+
+static struct aio_queue *__aio_get_queue(int fd, int need)
+{
+ if (fd < 0) {
+ errno = EBADF;
+ return 0;
+ }
+ int a=fd>>24;
+ unsigned char b=fd>>16, c=fd>>8, d=fd;
+ struct aio_queue *q = 0;
+ pthread_rwlock_rdlock(&maplock);
+ if ((!map || !map[a] || !map[a][b] || !map[a][b][c] || !(q=map[a][b][c][d])) && need) {
+ pthread_rwlock_unlock(&maplock);
+ if (fcntl(fd, F_GETFD) < 0) return 0;
+ pthread_rwlock_wrlock(&maplock);
+ if (!io_thread_stack_size) {
+ unsigned long val = __getauxval(AT_MINSIGSTKSZ);
+ io_thread_stack_size = MAX(MINSIGSTKSZ+2048, val+512);
+ }
+ if (!map) map = calloc(sizeof *map, (-1U/2+1)>>24);
+ if (!map) goto out;
+ if (!map[a]) map[a] = calloc(sizeof **map, 256);
+ if (!map[a]) goto out;
+ if (!map[a][b]) map[a][b] = calloc(sizeof ***map, 256);
+ if (!map[a][b]) goto out;
+ if (!map[a][b][c]) map[a][b][c] = calloc(sizeof ****map, 256);
+ if (!map[a][b][c]) goto out;
+ if (!(q = map[a][b][c][d])) {
+ map[a][b][c][d] = q = calloc(sizeof *****map, 1);
+ if (q) {
+ q->fd = fd;
+ pthread_mutex_init(&q->lock, 0);
+ pthread_cond_init(&q->cond, 0);
+ a_inc(&aio_fd_cnt);
+ }
+ }
+ }
+ if (q) pthread_mutex_lock(&q->lock);
+out:
+ pthread_rwlock_unlock(&maplock);
+ return q;
+}
+
+static void __aio_unref_queue(struct aio_queue *q)
+{
+ if (q->ref > 1) {
+ q->ref--;
+ pthread_mutex_unlock(&q->lock);
+ return;
+ }
+
+ /* This is potentially the last reference, but a new reference
+ * may arrive since we cannot free the queue object without first
+ * taking the maplock, which requires releasing the queue lock. */
+ pthread_mutex_unlock(&q->lock);
+ pthread_rwlock_wrlock(&maplock);
+ pthread_mutex_lock(&q->lock);
+ if (q->ref == 1) {
+ int fd=q->fd;
+ int a=fd>>24;
+ unsigned char b=fd>>16, c=fd>>8, d=fd;
+ map[a][b][c][d] = 0;
+ a_dec(&aio_fd_cnt);
+ pthread_rwlock_unlock(&maplock);
+ pthread_mutex_unlock(&q->lock);
+ free(q);
+ } else {
+ q->ref--;
+ pthread_rwlock_unlock(&maplock);
+ pthread_mutex_unlock(&q->lock);
+ }
+}
+
+static void cleanup(void *ctx)
+{
+ struct aio_thread *at = ctx;
+ struct aio_queue *q = at->q;
+ struct aiocb *cb = at->cb;
+ struct sigevent sev = cb->aio_sigevent;
+
+ /* There are four potential types of waiters we could need to wake:
+ * 1. Callers of aio_cancel/close.
+ * 2. Callers of aio_suspend with a single aiocb.
+ * 3. Callers of aio_suspend with a list.
+ * 4. AIO worker threads waiting for sequenced operations.
+ * Types 1-3 are notified via atomics/futexes, mainly for AS-safety
+ * considerations. Type 4 is notified later via a cond var. */
+
+ cb->__ret = at->ret;
+ if (a_swap(&at->running, 0) < 0)
+ __wake(&at->running, -1, 1);
+ if (a_swap(&cb->__err, at->err) != EINPROGRESS)
+ __wake(&cb->__err, -1, 1);
+ if (a_swap(&__aio_fut, 0))
+ __wake(&__aio_fut, -1, 1);
+
+ pthread_mutex_lock(&q->lock);
+
+ if (at->next) at->next->prev = at->prev;
+ if (at->prev) at->prev->next = at->next;
+ else q->head = at->next;
+
+ /* Signal aio worker threads waiting for sequenced operations. */
+ pthread_cond_broadcast(&q->cond);
+
+ __aio_unref_queue(q);
+
+ if (sev.sigev_notify == SIGEV_SIGNAL) {
+ siginfo_t si = {
+ .si_signo = sev.sigev_signo,
+ .si_value = sev.sigev_value,
+ .si_code = SI_ASYNCIO,
+ .si_pid = getpid(),
+ .si_uid = getuid()
+ };
+ __syscall(SYS_rt_sigqueueinfo, si.si_pid, si.si_signo, &si);
+ }
+ if (sev.sigev_notify == SIGEV_THREAD) {
+ a_store(&__pthread_self()->cancel, 0);
+ sev.sigev_notify_function(sev.sigev_value);
+ }
+}
+
+static void *io_thread_func(void *ctx)
+{
+ struct aio_thread at, *p;
+
+ struct aio_args *args = ctx;
+ struct aiocb *cb = args->cb;
+ int fd = cb->aio_fildes;
+ int op = args->op;
+ void *buf = (void *)cb->aio_buf;
+ size_t len = cb->aio_nbytes;
+ off_t off = cb->aio_offset;
+
+ struct aio_queue *q = args->q;
+ ssize_t ret;
+
+ pthread_mutex_lock(&q->lock);
+ sem_post(&args->sem);
+
+ at.op = op;
+ at.running = 1;
+ at.ret = -1;
+ at.err = ECANCELED;
+ at.q = q;
+ at.td = __pthread_self();
+ at.cb = cb;
+ at.prev = 0;
+ if ((at.next = q->head)) at.next->prev = &at;
+ q->head = &at;
+
+ if (!q->init) {
+ int seekable = lseek(fd, 0, SEEK_CUR) >= 0;
+ q->seekable = seekable;
+ q->append = !seekable || (fcntl(fd, F_GETFL) & O_APPEND);
+ q->init = 1;
+ }
+
+ pthread_cleanup_push(cleanup, &at);
+
+ /* Wait for sequenced operations. */
+ if (op!=LIO_READ && (op!=LIO_WRITE || q->append)) {
+ for (;;) {
+ for (p=at.next; p && p->op!=LIO_WRITE; p=p->next);
+ if (!p) break;
+ pthread_cond_wait(&q->cond, &q->lock);
+ }
+ }
+
+ pthread_mutex_unlock(&q->lock);
+
+ switch (op) {
+ case LIO_WRITE:
+ ret = q->append ? write(fd, buf, len) : pwrite(fd, buf, len, off);
+ break;
+ case LIO_READ:
+ ret = !q->seekable ? read(fd, buf, len) : pread(fd, buf, len, off);
+ break;
+ case O_SYNC:
+ ret = fsync(fd);
+ break;
+ case O_DSYNC:
+ ret = fdatasync(fd);
+ break;
+ }
+ at.ret = ret;
+ at.err = ret<0 ? errno : 0;
+
+ pthread_cleanup_pop(1);
+
+ return 0;
+}
+
+static int submit(struct aiocb *cb, int op)
+{
+ int ret = 0;
+ pthread_attr_t a;
+ sigset_t allmask, origmask;
+ pthread_t td;
+ struct aio_queue *q = __aio_get_queue(cb->aio_fildes, 1);
+ struct aio_args args = { .cb = cb, .op = op, .q = q };
+ sem_init(&args.sem, 0, 0);
+
+ if (!q) {
+ if (errno != EBADF) errno = EAGAIN;
+ cb->__ret = -1;
+ cb->__err = errno;
+ return -1;
+ }
+ q->ref++;
+ pthread_mutex_unlock(&q->lock);
+
+ 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, io_thread_stack_size);
+ pthread_attr_setguardsize(&a, 0);
+ }
+ pthread_attr_setdetachstate(&a, PTHREAD_CREATE_DETACHED);
+ sigfillset(&allmask);
+ pthread_sigmask(SIG_BLOCK, &allmask, &origmask);
+ cb->__err = EINPROGRESS;
+ if (pthread_create(&td, &a, io_thread_func, &args)) {
+ pthread_mutex_lock(&q->lock);
+ __aio_unref_queue(q);
+ cb->__err = errno = EAGAIN;
+ cb->__ret = ret = -1;
+ }
+ pthread_sigmask(SIG_SETMASK, &origmask, 0);
+
+ if (!ret) {
+ while (sem_wait(&args.sem));
+ }
+
+ return ret;
+}
+
+int aio_read(struct aiocb *cb)
+{
+ return submit(cb, LIO_READ);
+}
+
+int aio_write(struct aiocb *cb)
+{
+ return submit(cb, LIO_WRITE);
+}
+
+int aio_fsync(int op, struct aiocb *cb)
+{
+ if (op != O_SYNC && op != O_DSYNC) {
+ errno = EINVAL;
+ return -1;
+ }
+ return submit(cb, op);
+}
+
+ssize_t aio_return(struct aiocb *cb)
+{
+ return cb->__ret;
+}
+
+int aio_error(const struct aiocb *cb)
+{
+ a_barrier();
+ return cb->__err & 0x7fffffff;
+}
+
+int aio_cancel(int fd, struct aiocb *cb)
+{
+ sigset_t allmask, origmask;
+ int ret = AIO_ALLDONE;
+ struct aio_thread *p;
+ struct aio_queue *q;
+
+ /* Unspecified behavior case. Report an error. */
+ if (cb && fd != cb->aio_fildes) {
+ errno = EINVAL;
+ return -1;
+ }
+
+ sigfillset(&allmask);
+ pthread_sigmask(SIG_BLOCK, &allmask, &origmask);
+
+ errno = ENOENT;
+ if (!(q = __aio_get_queue(fd, 0))) {
+ if (errno == EBADF) ret = -1;
+ goto done;
+ }
+
+ for (p = q->head; p; p = p->next) {
+ if (cb && cb != p->cb) continue;
+ /* Transition target from running to running-with-waiters */
+ if (a_cas(&p->running, 1, -1)) {
+ pthread_cancel(p->td);
+ __wait(&p->running, 0, -1, 1);
+ if (p->err == ECANCELED) ret = AIO_CANCELED;
+ }
+ }
+
+ pthread_mutex_unlock(&q->lock);
+done:
+ pthread_sigmask(SIG_SETMASK, &origmask, 0);
+ return ret;
+}
+
+int __aio_close(int fd)
+{
+ a_barrier();
+ if (aio_fd_cnt) aio_cancel(fd, 0);
+ return fd;
+}
+
+void __aio_atfork(int who)
+{
+ if (who<0) {
+ pthread_rwlock_rdlock(&maplock);
+ return;
+ }
+ if (who>0 && map) for (int a=0; a<(-1U/2+1)>>24; a++)
+ if (map[a]) for (int b=0; b<256; b++)
+ if (map[a][b]) for (int c=0; c<256; c++)
+ if (map[a][b][c]) for (int d=0; d<256; d++)
+ map[a][b][c][d] = 0;
+ pthread_rwlock_unlock(&maplock);
+}
+
+weak_alias(aio_cancel, aio_cancel64);
+weak_alias(aio_error, aio_error64);
+weak_alias(aio_fsync, aio_fsync64);
+weak_alias(aio_read, aio_read64);
+weak_alias(aio_write, aio_write64);
+weak_alias(aio_return, aio_return64);