Adding upstream version 14.2.upstream/14.2upstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 1290 insertions, 0 deletions

diff --git a/src/pulsecore/pstream.c b/src/pulsecore/pstream.c
new file mode 100644
index 0000000..eb70508
--- /dev/null
+++ b/src/pulsecore/pstream.c
@@ -0,0 +1,1290 @@
+/***
+  This file is part of PulseAudio.
+
+  Copyright 2004-2006 Lennart Poettering
+  Copyright 2006 Pierre Ossman <ossman@cendio.se> for Cendio AB
+
+  PulseAudio is free software; you can redistribute it and/or modify
+  it under the terms of the GNU Lesser General Public License as
+  published by the Free Software Foundation; either version 2.1 of the
+  License, or (at your option) any later version.
+
+  PulseAudio is distributed in the hope that it will be useful, but
+  WITHOUT ANY WARRANTY; without even the implied warranty of
+  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+  Lesser General Public License for more details.
+
+  You should have received a copy of the GNU Lesser General Public
+  License along with PulseAudio; if not, see <http://www.gnu.org/licenses/>.
+***/
+
+#ifdef HAVE_CONFIG_H
+#include <config.h>
+#endif
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <unistd.h>
+
+#ifdef HAVE_NETINET_IN_H
+#include <netinet/in.h>
+#endif
+
+#include <pulse/xmalloc.h>
+
+#include <pulsecore/idxset.h>
+#include <pulsecore/socket.h>
+#include <pulsecore/queue.h>
+#include <pulsecore/log.h>
+#include <pulsecore/creds.h>
+#include <pulsecore/refcnt.h>
+#include <pulsecore/flist.h>
+#include <pulsecore/macro.h>
+
+#include "pstream.h"
+
+/* We piggyback information if audio data blocks are stored in SHM on the seek mode */
+#define PA_FLAG_SHMDATA     0x80000000LU
+#define PA_FLAG_SHMDATA_MEMFD_BLOCK         0x20000000LU
+#define PA_FLAG_SHMRELEASE  0x40000000LU
+#define PA_FLAG_SHMREVOKE   0xC0000000LU
+#define PA_FLAG_SHMMASK     0xFF000000LU
+#define PA_FLAG_SEEKMASK    0x000000FFLU
+#define PA_FLAG_SHMWRITABLE 0x00800000LU
+
+/* The sequence descriptor header consists of 5 32bit integers: */
+enum {
+    PA_PSTREAM_DESCRIPTOR_LENGTH,
+    PA_PSTREAM_DESCRIPTOR_CHANNEL,
+    PA_PSTREAM_DESCRIPTOR_OFFSET_HI,
+    PA_PSTREAM_DESCRIPTOR_OFFSET_LO,
+    PA_PSTREAM_DESCRIPTOR_FLAGS,
+    PA_PSTREAM_DESCRIPTOR_MAX
+};
+
+/* If we have an SHM block, this info follows the descriptor */
+enum {
+    PA_PSTREAM_SHM_BLOCKID,
+    PA_PSTREAM_SHM_SHMID,
+    PA_PSTREAM_SHM_INDEX,
+    PA_PSTREAM_SHM_LENGTH,
+    PA_PSTREAM_SHM_MAX
+};
+
+typedef uint32_t pa_pstream_descriptor[PA_PSTREAM_DESCRIPTOR_MAX];
+
+#define PA_PSTREAM_DESCRIPTOR_SIZE (PA_PSTREAM_DESCRIPTOR_MAX*sizeof(uint32_t))
+
+#define MINIBUF_SIZE (256)
+
+/* To allow uploading a single sample in one frame, this value should be the
+ * same size (16 MB) as PA_SCACHE_ENTRY_SIZE_MAX from pulsecore/core-scache.h.
+ */
+#define FRAME_SIZE_MAX_ALLOW (1024*1024*16)
+
+PA_STATIC_FLIST_DECLARE(items, 0, pa_xfree);
+
+struct item_info {
+    enum {
+        PA_PSTREAM_ITEM_PACKET,
+        PA_PSTREAM_ITEM_MEMBLOCK,
+        PA_PSTREAM_ITEM_SHMRELEASE,
+        PA_PSTREAM_ITEM_SHMREVOKE
+    } type;
+
+    /* packet info */
+    pa_packet *packet;
+#ifdef HAVE_CREDS
+    bool with_ancil_data;
+    pa_cmsg_ancil_data ancil_data;
+#endif
+
+    /* memblock info */
+    pa_memchunk chunk;
+    uint32_t channel;
+    int64_t offset;
+    pa_seek_mode_t seek_mode;
+
+    /* release/revoke info */
+    uint32_t block_id;
+};
+
+struct pstream_read {
+    pa_pstream_descriptor descriptor;
+    pa_memblock *memblock;
+    pa_packet *packet;
+    uint32_t shm_info[PA_PSTREAM_SHM_MAX];
+    void *data;
+    size_t index;
+};
+
+struct pa_pstream {
+    PA_REFCNT_DECLARE;
+
+    pa_mainloop_api *mainloop;
+    pa_defer_event *defer_event;
+    pa_iochannel *io;
+    pa_srbchannel *srb, *srbpending;
+    bool is_srbpending;
+
+    pa_queue *send_queue;
+
+    bool dead;
+
+    struct {
+        union {
+            uint8_t minibuf[MINIBUF_SIZE];
+            pa_pstream_descriptor descriptor;
+        };
+        struct item_info* current;
+        void *data;
+        size_t index;
+        int minibuf_validsize;
+        pa_memchunk memchunk;
+    } write;
+
+    struct pstream_read readio, readsrb;
+
+    /* @use_shm: beside copying the full audio data to the other
+     * PA end, this pipe supports just sending references of the
+     * same audio data blocks if they reside in a SHM pool.
+     *
+     * @use_memfd: pipe supports sending SHM memfd block references
+     *
+     * @registered_memfd_ids: registered memfd pools SHM IDs. Check
+     * pa_pstream_register_memfd_mempool() for more information. */
+    bool use_shm, use_memfd;
+    pa_idxset *registered_memfd_ids;
+
+    pa_memimport *import;
+    pa_memexport *export;
+
+    pa_pstream_packet_cb_t receive_packet_callback;
+    void *receive_packet_callback_userdata;
+
+    pa_pstream_memblock_cb_t receive_memblock_callback;
+    void *receive_memblock_callback_userdata;
+
+    pa_pstream_notify_cb_t drain_callback;
+    void *drain_callback_userdata;
+
+    pa_pstream_notify_cb_t die_callback;
+    void *die_callback_userdata;
+
+    pa_pstream_block_id_cb_t revoke_callback;
+    void *revoke_callback_userdata;
+
+    pa_pstream_block_id_cb_t release_callback;
+    void *release_callback_userdata;
+
+    pa_mempool *mempool;
+
+#ifdef HAVE_CREDS
+    pa_cmsg_ancil_data read_ancil_data, *write_ancil_data;
+    bool send_ancil_data_now;
+#endif
+};
+
+#ifdef HAVE_CREDS
+/*
+ * memfd-backed SHM pools blocks transfer occur without passing the pool's
+ * fd every time, thus minimizing overhead and avoiding fd leaks. A
+ * REGISTER_MEMFD_SHMID command is sent, with the pool's memfd fd, very early
+ * on. This command has an ID that uniquely identifies the pool in question.
+ * Further pool's block references can then be exclusively done using such ID;
+ * the fd can be safely closed – on both ends – afterwards.
+ *
+ * On the sending side of this command, we want to close the passed fds
+ * directly after being sent. Meanwhile we're only allowed to asynchronously
+ * schedule packet writes to the pstream, so the job of closing passed fds is
+ * left to the pstream's actual writing function do_write(): it knows the
+ * exact point in time where the fds are passed to the other end through
+ * iochannels and the sendmsg() system call.
+ *
+ * Nonetheless not all code paths in the system desire their socket-passed
+ * fds to be closed after the send. srbchannel needs the passed fds to still
+ * be open for further communication. System-wide global memfd-backed pools
+ * also require the passed fd to be open: they pass the same fd, with the same
+ * ID registration mechanism, for each newly connected client to the system.
+ *
+ * So from all of the above, never close the ancillary fds by your own and
+ * always call below method instead. It takes care of closing the passed fds
+ * _only if allowed_ by the code paths that originally created them to do so.
+ * Moreover, it is multiple-invocations safe: failure handlers can, and
+ * should, call it for passed fds cleanup without worrying too much about
+ * the system state.
+ */
+void pa_cmsg_ancil_data_close_fds(struct pa_cmsg_ancil_data *ancil) {
+    if (ancil && ancil->nfd > 0 && ancil->close_fds_on_cleanup) {
+        int i;
+
+        pa_assert(ancil->nfd <= MAX_ANCIL_DATA_FDS);
+
+        for (i = 0; i < ancil->nfd; i++)
+            if (ancil->fds[i] != -1) {
+                pa_assert_se(pa_close(ancil->fds[i]) == 0);
+                ancil->fds[i] = -1;
+            }
+
+        ancil->nfd = 0;
+        ancil->close_fds_on_cleanup = false;
+    }
+}
+#endif
+
+static int do_write(pa_pstream *p);
+static int do_read(pa_pstream *p, struct pstream_read *re);
+
+static void do_pstream_read_write(pa_pstream *p) {
+    pa_assert(p);
+    pa_assert(PA_REFCNT_VALUE(p) > 0);
+
+    pa_pstream_ref(p);
+
+    p->mainloop->defer_enable(p->defer_event, 0);
+
+    if (!p->dead && p->srb) {
+        int r = 0;
+
+        if(do_write(p) < 0)
+            goto fail;
+
+        while (!p->dead && r == 0) {
+            r = do_read(p, &p->readsrb);
+            if (r < 0)
+                goto fail;
+        }
+    }
+
+    if (!p->dead && pa_iochannel_is_readable(p->io)) {
+        if (do_read(p, &p->readio) < 0)
+            goto fail;
+    } else if (!p->dead && pa_iochannel_is_hungup(p->io))
+        goto fail;
+
+    while (!p->dead && pa_iochannel_is_writable(p->io)) {
+        int r = do_write(p);
+        if (r < 0)
+            goto fail;
+        if (r == 0)
+            break;
+    }
+
+    pa_pstream_unref(p);
+    return;
+
+fail:
+
+    if (p->die_callback)
+        p->die_callback(p, p->die_callback_userdata);
+
+    pa_pstream_unlink(p);
+    pa_pstream_unref(p);
+}
+
+static bool srb_callback(pa_srbchannel *srb, void *userdata) {
+    bool b;
+    pa_pstream *p = userdata;
+
+    pa_assert(p);
+    pa_assert(PA_REFCNT_VALUE(p) > 0);
+    pa_assert(p->srb == srb);
+
+    pa_pstream_ref(p);
+
+    do_pstream_read_write(p);
+
+    /* If either pstream or the srb is going away, return false.
+       We need to check this before p is destroyed. */
+    b = (PA_REFCNT_VALUE(p) > 1) && (p->srb == srb);
+    pa_pstream_unref(p);
+
+    return b;
+}
+
+static void io_callback(pa_iochannel*io, void *userdata) {
+    pa_pstream *p = userdata;
+
+    pa_assert(p);
+    pa_assert(PA_REFCNT_VALUE(p) > 0);
+    pa_assert(p->io == io);
+
+    do_pstream_read_write(p);
+}
+
+static void defer_callback(pa_mainloop_api *m, pa_defer_event *e, void*userdata) {
+    pa_pstream *p = userdata;
+
+    pa_assert(p);
+    pa_assert(PA_REFCNT_VALUE(p) > 0);
+    pa_assert(p->defer_event == e);
+    pa_assert(p->mainloop == m);
+
+    do_pstream_read_write(p);
+}
+
+static void memimport_release_cb(pa_memimport *i, uint32_t block_id, void *userdata);
+
+pa_pstream *pa_pstream_new(pa_mainloop_api *m, pa_iochannel *io, pa_mempool *pool) {
+    pa_pstream *p;
+
+    pa_assert(m);
+    pa_assert(io);
+    pa_assert(pool);
+
+    p = pa_xnew0(pa_pstream, 1);
+    PA_REFCNT_INIT(p);
+    p->io = io;
+    pa_iochannel_set_callback(io, io_callback, p);
+
+    p->mainloop = m;
+    p->defer_event = m->defer_new(m, defer_callback, p);
+    m->defer_enable(p->defer_event, 0);
+
+    p->send_queue = pa_queue_new();
+
+    p->mempool = pool;
+
+    /* We do importing unconditionally */
+    p->import = pa_memimport_new(p->mempool, memimport_release_cb, p);
+
+    pa_iochannel_socket_set_rcvbuf(io, pa_mempool_block_size_max(p->mempool));
+    pa_iochannel_socket_set_sndbuf(io, pa_mempool_block_size_max(p->mempool));
+
+    return p;
+}
+
+/* Attach memfd<->SHM_ID mapping to given pstream and its memimport.
+ * Check pa_pstream_register_memfd_mempool() for further info.
+ *
+ * Caller owns the passed @memfd_fd and must close it down when appropriate. */
+int pa_pstream_attach_memfd_shmid(pa_pstream *p, unsigned shm_id, int memfd_fd) {
+    int err = -1;
+
+    pa_assert(memfd_fd != -1);
+
+    if (!p->use_memfd) {
+        pa_log_warn("Received memfd ID registration request over a pipe "
+                    "that does not support memfds");
+        return err;
+    }
+
+    if (pa_idxset_get_by_data(p->registered_memfd_ids, PA_UINT32_TO_PTR(shm_id), NULL)) {
+        pa_log_warn("previously registered memfd SHM ID = %u", shm_id);
+        return err;
+    }
+
+    if (pa_memimport_attach_memfd(p->import, shm_id, memfd_fd, true)) {
+        pa_log("Failed to create permanent mapping for memfd region with ID = %u", shm_id);
+        return err;
+    }
+
+    pa_assert_se(pa_idxset_put(p->registered_memfd_ids, PA_UINT32_TO_PTR(shm_id), NULL) == 0);
+    return 0;
+}
+
+static void item_free(void *item) {
+    struct item_info *i = item;
+    pa_assert(i);
+
+    if (i->type == PA_PSTREAM_ITEM_MEMBLOCK) {
+        pa_assert(i->chunk.memblock);
+        pa_memblock_unref(i->chunk.memblock);
+    } else if (i->type == PA_PSTREAM_ITEM_PACKET) {
+        pa_assert(i->packet);
+        pa_packet_unref(i->packet);
+    }
+
+#ifdef HAVE_CREDS
+    /* On error recovery paths, there might be lingering items
+     * on the pstream send queue and they are usually freed with
+     * a call to 'pa_queue_free(p->send_queue, item_free)'. Make
+     * sure we do not leak any fds in that case! */
+    if (i->with_ancil_data)
+        pa_cmsg_ancil_data_close_fds(&i->ancil_data);
+#endif
+
+    if (pa_flist_push(PA_STATIC_FLIST_GET(items), i) < 0)
+        pa_xfree(i);
+}
+
+static void pstream_free(pa_pstream *p) {
+    pa_assert(p);
+
+    pa_pstream_unlink(p);
+
+    pa_queue_free(p->send_queue, item_free);
+
+    if (p->write.current)
+        item_free(p->write.current);
+
+    if (p->write.memchunk.memblock)
+        pa_memblock_unref(p->write.memchunk.memblock);
+
+    if (p->readsrb.memblock)
+        pa_memblock_unref(p->readsrb.memblock);
+
+    if (p->readsrb.packet)
+        pa_packet_unref(p->readsrb.packet);
+
+    if (p->readio.memblock)
+        pa_memblock_unref(p->readio.memblock);
+
+    if (p->readio.packet)
+        pa_packet_unref(p->readio.packet);
+
+    if (p->registered_memfd_ids)
+        pa_idxset_free(p->registered_memfd_ids, NULL);
+
+    pa_xfree(p);
+}
+
+void pa_pstream_send_packet(pa_pstream*p, pa_packet *packet, pa_cmsg_ancil_data *ancil_data) {
+    struct item_info *i;
+
+    pa_assert(p);
+    pa_assert(PA_REFCNT_VALUE(p) > 0);
+    pa_assert(packet);
+
+    if (p->dead) {
+#ifdef HAVE_CREDS
+        pa_cmsg_ancil_data_close_fds(ancil_data);
+#endif
+        return;
+    }
+
+    if (!(i = pa_flist_pop(PA_STATIC_FLIST_GET(items))))
+        i = pa_xnew(struct item_info, 1);
+
+    i->type = PA_PSTREAM_ITEM_PACKET;
+    i->packet = pa_packet_ref(packet);
+
+#ifdef HAVE_CREDS
+    if ((i->with_ancil_data = !!ancil_data)) {
+        i->ancil_data = *ancil_data;
+        if (ancil_data->creds_valid)
+            pa_assert(ancil_data->nfd == 0);
+        else
+            pa_assert(ancil_data->nfd > 0);
+    }
+#endif
+
+    pa_queue_push(p->send_queue, i);
+
+    p->mainloop->defer_enable(p->defer_event, 1);
+}
+
+void pa_pstream_send_memblock(pa_pstream*p, uint32_t channel, int64_t offset, pa_seek_mode_t seek_mode, const pa_memchunk *chunk) {
+    size_t length, idx;
+    size_t bsm;
+
+    pa_assert(p);
+    pa_assert(PA_REFCNT_VALUE(p) > 0);
+    pa_assert(channel != (uint32_t) -1);
+    pa_assert(chunk);
+
+    if (p->dead)
+        return;
+
+    idx = 0;
+    length = chunk->length;
+
+    bsm = pa_mempool_block_size_max(p->mempool);
+
+    while (length > 0) {
+        struct item_info *i;
+        size_t n;
+
+        if (!(i = pa_flist_pop(PA_STATIC_FLIST_GET(items))))
+            i = pa_xnew(struct item_info, 1);
+        i->type = PA_PSTREAM_ITEM_MEMBLOCK;
+
+        n = PA_MIN(length, bsm);
+        i->chunk.index = chunk->index + idx;
+        i->chunk.length = n;
+        i->chunk.memblock = pa_memblock_ref(chunk->memblock);
+
+        i->channel = channel;
+        i->offset = offset;
+        i->seek_mode = seek_mode;
+#ifdef HAVE_CREDS
+        i->with_ancil_data = false;
+#endif
+
+        pa_queue_push(p->send_queue, i);
+
+        idx += n;
+        length -= n;
+    }
+
+    p->mainloop->defer_enable(p->defer_event, 1);
+}
+
+void pa_pstream_send_release(pa_pstream *p, uint32_t block_id) {
+    struct item_info *item;
+    pa_assert(p);
+    pa_assert(PA_REFCNT_VALUE(p) > 0);
+
+    if (p->dead)
+        return;
+
+/*     pa_log("Releasing block %u", block_id); */
+
+    if (!(item = pa_flist_pop(PA_STATIC_FLIST_GET(items))))
+        item = pa_xnew(struct item_info, 1);
+    item->type = PA_PSTREAM_ITEM_SHMRELEASE;
+    item->block_id = block_id;
+#ifdef HAVE_CREDS
+    item->with_ancil_data = false;
+#endif
+
+    pa_queue_push(p->send_queue, item);
+    p->mainloop->defer_enable(p->defer_event, 1);
+}
+
+/* might be called from thread context */
+static void memimport_release_cb(pa_memimport *i, uint32_t block_id, void *userdata) {
+    pa_pstream *p = userdata;
+
+    pa_assert(p);
+    pa_assert(PA_REFCNT_VALUE(p) > 0);
+
+    if (p->dead)
+        return;
+
+    if (p->release_callback)
+        p->release_callback(p, block_id, p->release_callback_userdata);
+    else
+        pa_pstream_send_release(p, block_id);
+}
+
+void pa_pstream_send_revoke(pa_pstream *p, uint32_t block_id) {
+    struct item_info *item;
+    pa_assert(p);
+    pa_assert(PA_REFCNT_VALUE(p) > 0);
+
+    if (p->dead)
+        return;
+/*     pa_log("Revoking block %u", block_id); */
+
+    if (!(item = pa_flist_pop(PA_STATIC_FLIST_GET(items))))
+        item = pa_xnew(struct item_info, 1);
+    item->type = PA_PSTREAM_ITEM_SHMREVOKE;
+    item->block_id = block_id;
+#ifdef HAVE_CREDS
+    item->with_ancil_data = false;
+#endif
+
+    pa_queue_push(p->send_queue, item);
+    p->mainloop->defer_enable(p->defer_event, 1);
+}
+
+/* might be called from thread context */
+static void memexport_revoke_cb(pa_memexport *e, uint32_t block_id, void *userdata) {
+    pa_pstream *p = userdata;
+
+    pa_assert(p);
+    pa_assert(PA_REFCNT_VALUE(p) > 0);
+
+    if (p->revoke_callback)
+        p->revoke_callback(p, block_id, p->revoke_callback_userdata);
+    else
+        pa_pstream_send_revoke(p, block_id);
+}
+
+static void prepare_next_write_item(pa_pstream *p) {
+    pa_assert(p);
+    pa_assert(PA_REFCNT_VALUE(p) > 0);
+
+    p->write.current = pa_queue_pop(p->send_queue);
+
+    if (!p->write.current)
+        return;
+    p->write.index = 0;
+    p->write.data = NULL;
+    p->write.minibuf_validsize = 0;
+    pa_memchunk_reset(&p->write.memchunk);
+
+    p->write.descriptor[PA_PSTREAM_DESCRIPTOR_LENGTH] = 0;
+    p->write.descriptor[PA_PSTREAM_DESCRIPTOR_CHANNEL] = htonl((uint32_t) -1);
+    p->write.descriptor[PA_PSTREAM_DESCRIPTOR_OFFSET_HI] = 0;
+    p->write.descriptor[PA_PSTREAM_DESCRIPTOR_OFFSET_LO] = 0;
+    p->write.descriptor[PA_PSTREAM_DESCRIPTOR_FLAGS] = 0;
+
+    if (p->write.current->type == PA_PSTREAM_ITEM_PACKET) {
+        size_t plen;
+
+        pa_assert(p->write.current->packet);
+
+        p->write.data = (void *) pa_packet_data(p->write.current->packet, &plen);
+        p->write.descriptor[PA_PSTREAM_DESCRIPTOR_LENGTH] = htonl((uint32_t) plen);
+
+        if (plen <= MINIBUF_SIZE - PA_PSTREAM_DESCRIPTOR_SIZE) {
+            memcpy(&p->write.minibuf[PA_PSTREAM_DESCRIPTOR_SIZE], p->write.data, plen);
+            p->write.minibuf_validsize = PA_PSTREAM_DESCRIPTOR_SIZE + plen;
+        }
+
+    } else if (p->write.current->type == PA_PSTREAM_ITEM_SHMRELEASE) {
+
+        p->write.descriptor[PA_PSTREAM_DESCRIPTOR_FLAGS] = htonl(PA_FLAG_SHMRELEASE);
+        p->write.descriptor[PA_PSTREAM_DESCRIPTOR_OFFSET_HI] = htonl(p->write.current->block_id);
+
+    } else if (p->write.current->type == PA_PSTREAM_ITEM_SHMREVOKE) {
+
+        p->write.descriptor[PA_PSTREAM_DESCRIPTOR_FLAGS] = htonl(PA_FLAG_SHMREVOKE);
+        p->write.descriptor[PA_PSTREAM_DESCRIPTOR_OFFSET_HI] = htonl(p->write.current->block_id);
+
+    } else {
+        uint32_t flags;
+        bool send_payload = true;
+
+        pa_assert(p->write.current->type == PA_PSTREAM_ITEM_MEMBLOCK);
+        pa_assert(p->write.current->chunk.memblock);
+
+        p->write.descriptor[PA_PSTREAM_DESCRIPTOR_CHANNEL] = htonl(p->write.current->channel);
+        p->write.descriptor[PA_PSTREAM_DESCRIPTOR_OFFSET_HI] = htonl((uint32_t) (((uint64_t) p->write.current->offset) >> 32));
+        p->write.descriptor[PA_PSTREAM_DESCRIPTOR_OFFSET_LO] = htonl((uint32_t) ((uint64_t) p->write.current->offset));
+
+        flags = (uint32_t) (p->write.current->seek_mode & PA_FLAG_SEEKMASK);
+
+        if (p->use_shm) {
+            pa_mem_type_t type;
+            uint32_t block_id, shm_id;
+            size_t offset, length;
+            uint32_t *shm_info = (uint32_t *) &p->write.minibuf[PA_PSTREAM_DESCRIPTOR_SIZE];
+            size_t shm_size = sizeof(uint32_t) * PA_PSTREAM_SHM_MAX;
+            pa_mempool *current_pool = pa_memblock_get_pool(p->write.current->chunk.memblock);
+            pa_memexport *current_export;
+
+            if (p->mempool == current_pool)
+                pa_assert_se(current_export = p->export);
+            else
+                pa_assert_se(current_export = pa_memexport_new(current_pool, memexport_revoke_cb, p));
+
+            if (pa_memexport_put(current_export,
+                                 p->write.current->chunk.memblock,
+                                 &type,
+                                 &block_id,
+                                 &shm_id,
+                                 &offset,
+                                 &length) >= 0) {
+
+                if (type == PA_MEM_TYPE_SHARED_POSIX)
+                    send_payload = false;
+
+                if (type == PA_MEM_TYPE_SHARED_MEMFD && p->use_memfd) {
+                    if (pa_idxset_get_by_data(p->registered_memfd_ids, PA_UINT32_TO_PTR(shm_id), NULL)) {
+                        flags |= PA_FLAG_SHMDATA_MEMFD_BLOCK;
+                        send_payload = false;
+                    } else {
+                        if (pa_log_ratelimit(PA_LOG_ERROR)) {
+                            pa_log("Cannot send block reference with non-registered memfd ID = %u", shm_id);
+                            pa_log("Fallig back to copying full block data over socket");
+                        }
+                    }
+                }
+
+                if (send_payload) {
+                    pa_assert_se(pa_memexport_process_release(current_export, block_id) == 0);
+                } else {
+                    flags |= PA_FLAG_SHMDATA;
+                    if (pa_mempool_is_remote_writable(current_pool))
+                        flags |= PA_FLAG_SHMWRITABLE;
+
+                    shm_info[PA_PSTREAM_SHM_BLOCKID] = htonl(block_id);
+                    shm_info[PA_PSTREAM_SHM_SHMID] = htonl(shm_id);
+                    shm_info[PA_PSTREAM_SHM_INDEX] = htonl((uint32_t) (offset + p->write.current->chunk.index));
+                    shm_info[PA_PSTREAM_SHM_LENGTH] = htonl((uint32_t) p->write.current->chunk.length);
+
+                    p->write.descriptor[PA_PSTREAM_DESCRIPTOR_LENGTH] = htonl(shm_size);
+                    p->write.minibuf_validsize = PA_PSTREAM_DESCRIPTOR_SIZE + shm_size;
+                }
+            }
+/*             else */
+/*                 FIXME: Avoid memexport slot leaks. Call pa_memexport_process_release() */
+/*                 pa_log_warn("Failed to export memory block."); */
+
+            if (current_export != p->export)
+                pa_memexport_free(current_export);
+            pa_mempool_unref(current_pool);
+        }
+
+        if (send_payload) {
+            p->write.descriptor[PA_PSTREAM_DESCRIPTOR_LENGTH] = htonl((uint32_t) p->write.current->chunk.length);
+            p->write.memchunk = p->write.current->chunk;
+            pa_memblock_ref(p->write.memchunk.memblock);
+        }
+
+        p->write.descriptor[PA_PSTREAM_DESCRIPTOR_FLAGS] = htonl(flags);
+    }
+
+#ifdef HAVE_CREDS
+    if ((p->send_ancil_data_now = p->write.current->with_ancil_data))
+        p->write_ancil_data = &p->write.current->ancil_data;
+#endif
+}
+
+static void check_srbpending(pa_pstream *p) {
+    if (!p->is_srbpending)
+        return;
+
+    if (p->srb)
+        pa_srbchannel_free(p->srb);
+
+    p->srb = p->srbpending;
+    p->is_srbpending = false;
+
+    if (p->srb)
+        pa_srbchannel_set_callback(p->srb, srb_callback, p);
+}
+
+static int do_write(pa_pstream *p) {
+    void *d;
+    size_t l;
+    ssize_t r;
+    pa_memblock *release_memblock = NULL;
+
+    pa_assert(p);
+    pa_assert(PA_REFCNT_VALUE(p) > 0);
+
+    if (!p->write.current)
+        prepare_next_write_item(p);
+
+    if (!p->write.current) {
+        /* The out queue is empty, so switching channels is safe */
+        check_srbpending(p);
+        return 0;
+    }
+
+    if (p->write.minibuf_validsize > 0) {
+        d = p->write.minibuf + p->write.index;
+        l = p->write.minibuf_validsize - p->write.index;
+    } else if (p->write.index < PA_PSTREAM_DESCRIPTOR_SIZE) {
+        d = (uint8_t*) p->write.descriptor + p->write.index;
+        l = PA_PSTREAM_DESCRIPTOR_SIZE - p->write.index;
+    } else {
+        pa_assert(p->write.data || p->write.memchunk.memblock);
+
+        if (p->write.data)
+            d = p->write.data;
+        else {
+            d = pa_memblock_acquire_chunk(&p->write.memchunk);
+            release_memblock = p->write.memchunk.memblock;
+        }
+
+        d = (uint8_t*) d + p->write.index - PA_PSTREAM_DESCRIPTOR_SIZE;
+        l = ntohl(p->write.descriptor[PA_PSTREAM_DESCRIPTOR_LENGTH]) - (p->write.index - PA_PSTREAM_DESCRIPTOR_SIZE);
+    }
+
+    pa_assert(l > 0);
+
+#ifdef HAVE_CREDS
+    if (p->send_ancil_data_now) {
+        if (p->write_ancil_data->creds_valid) {
+            pa_assert(p->write_ancil_data->nfd == 0);
+            if ((r = pa_iochannel_write_with_creds(p->io, d, l, &p->write_ancil_data->creds)) < 0)
+                goto fail;
+        }
+        else
+            if ((r = pa_iochannel_write_with_fds(p->io, d, l, p->write_ancil_data->nfd, p->write_ancil_data->fds)) < 0)
+                goto fail;
+
+        pa_cmsg_ancil_data_close_fds(p->write_ancil_data);
+        p->send_ancil_data_now = false;
+    } else
+#endif
+    if (p->srb)
+        r = pa_srbchannel_write(p->srb, d, l);
+    else if ((r = pa_iochannel_write(p->io, d, l)) < 0)
+        goto fail;
+
+    if (release_memblock)
+        pa_memblock_release(release_memblock);
+
+    p->write.index += (size_t) r;
+
+    if (p->write.index >= PA_PSTREAM_DESCRIPTOR_SIZE + ntohl(p->write.descriptor[PA_PSTREAM_DESCRIPTOR_LENGTH])) {
+        pa_assert(p->write.current);
+        item_free(p->write.current);
+        p->write.current = NULL;
+
+        if (p->write.memchunk.memblock)
+            pa_memblock_unref(p->write.memchunk.memblock);
+
+        pa_memchunk_reset(&p->write.memchunk);
+
+        if (p->drain_callback && !pa_pstream_is_pending(p))
+            p->drain_callback(p, p->drain_callback_userdata);
+    }
+
+    return (size_t) r == l ? 1 : 0;
+
+fail:
+#ifdef HAVE_CREDS
+    if (p->send_ancil_data_now)
+        pa_cmsg_ancil_data_close_fds(p->write_ancil_data);
+#endif
+
+    if (release_memblock)
+        pa_memblock_release(release_memblock);
+
+    return -1;
+}
+
+static void memblock_complete(pa_pstream *p, struct pstream_read *re) {
+    pa_memchunk chunk;
+    int64_t offset;
+
+    if (!p->receive_memblock_callback)
+        return;
+
+    chunk.memblock = re->memblock;
+    chunk.index = 0;
+    chunk.length = re->index - PA_PSTREAM_DESCRIPTOR_SIZE;
+
+    offset = (int64_t) (
+             (((uint64_t) ntohl(re->descriptor[PA_PSTREAM_DESCRIPTOR_OFFSET_HI])) << 32) |
+             (((uint64_t) ntohl(re->descriptor[PA_PSTREAM_DESCRIPTOR_OFFSET_LO]))));
+
+    p->receive_memblock_callback(
+        p,
+        ntohl(re->descriptor[PA_PSTREAM_DESCRIPTOR_CHANNEL]),
+        offset,
+        ntohl(re->descriptor[PA_PSTREAM_DESCRIPTOR_FLAGS]) & PA_FLAG_SEEKMASK,
+        &chunk,
+        p->receive_memblock_callback_userdata);
+}
+
+static int do_read(pa_pstream *p, struct pstream_read *re) {
+    void *d;
+    size_t l;
+    ssize_t r;
+    pa_memblock *release_memblock = NULL;
+    pa_assert(p);
+    pa_assert(PA_REFCNT_VALUE(p) > 0);
+
+    if (re->index < PA_PSTREAM_DESCRIPTOR_SIZE) {
+        d = (uint8_t*) re->descriptor + re->index;
+        l = PA_PSTREAM_DESCRIPTOR_SIZE - re->index;
+    } else {
+        pa_assert(re->data || re->memblock);
+
+        if (re->data)
+            d = re->data;
+        else {
+            d = pa_memblock_acquire(re->memblock);
+            release_memblock = re->memblock;
+        }
+
+        d = (uint8_t*) d + re->index - PA_PSTREAM_DESCRIPTOR_SIZE;
+        l = ntohl(re->descriptor[PA_PSTREAM_DESCRIPTOR_LENGTH]) - (re->index - PA_PSTREAM_DESCRIPTOR_SIZE);
+    }
+
+    if (re == &p->readsrb) {
+        r = pa_srbchannel_read(p->srb, d, l);
+        if (r == 0) {
+            if (release_memblock)
+                pa_memblock_release(release_memblock);
+            return 1;
+        }
+    }
+    else
+#ifdef HAVE_CREDS
+    {
+        pa_cmsg_ancil_data b;
+
+        if ((r = pa_iochannel_read_with_ancil_data(p->io, d, l, &b)) <= 0)
+            goto fail;
+
+        if (b.creds_valid) {
+            p->read_ancil_data.creds_valid = true;
+            p->read_ancil_data.creds = b.creds;
+        }
+        if (b.nfd > 0) {
+            pa_assert(b.nfd <= MAX_ANCIL_DATA_FDS);
+            p->read_ancil_data.nfd = b.nfd;
+            memcpy(p->read_ancil_data.fds, b.fds, sizeof(int) * b.nfd);
+            p->read_ancil_data.close_fds_on_cleanup = b.close_fds_on_cleanup;
+        }
+    }
+#else
+    if ((r = pa_iochannel_read(p->io, d, l)) <= 0)
+        goto fail;
+#endif
+
+    if (release_memblock)
+        pa_memblock_release(release_memblock);
+
+    re->index += (size_t) r;
+
+    if (re->index == PA_PSTREAM_DESCRIPTOR_SIZE) {
+        uint32_t flags, length, channel;
+        /* Reading of frame descriptor complete */
+
+        flags = ntohl(re->descriptor[PA_PSTREAM_DESCRIPTOR_FLAGS]);
+
+        if (!p->use_shm && (flags & PA_FLAG_SHMMASK) != 0) {
+            pa_log_warn("Received SHM frame on a socket where SHM is disabled.");
+            return -1;
+        }
+
+        if (flags == PA_FLAG_SHMRELEASE) {
+
+            /* This is a SHM memblock release frame with no payload */
+
+/*             pa_log("Got release frame for %u", ntohl(re->descriptor[PA_PSTREAM_DESCRIPTOR_OFFSET_HI])); */
+
+            pa_assert(p->export);
+            pa_memexport_process_release(p->export, ntohl(re->descriptor[PA_PSTREAM_DESCRIPTOR_OFFSET_HI]));
+
+            goto frame_done;
+
+        } else if (flags == PA_FLAG_SHMREVOKE) {
+
+            /* This is a SHM memblock revoke frame with no payload */
+
+/*             pa_log("Got revoke frame for %u", ntohl(re->descriptor[PA_PSTREAM_DESCRIPTOR_OFFSET_HI])); */
+
+            pa_assert(p->import);
+            pa_memimport_process_revoke(p->import, ntohl(re->descriptor[PA_PSTREAM_DESCRIPTOR_OFFSET_HI]));
+
+            goto frame_done;
+        }
+
+        length = ntohl(re->descriptor[PA_PSTREAM_DESCRIPTOR_LENGTH]);
+
+        if (length > FRAME_SIZE_MAX_ALLOW || length <= 0) {
+            pa_log_warn("Received invalid frame size: %lu", (unsigned long) length);
+            return -1;
+        }
+
+        pa_assert(!re->packet && !re->memblock);
+
+        channel = ntohl(re->descriptor[PA_PSTREAM_DESCRIPTOR_CHANNEL]);
+
+        if (channel == (uint32_t) -1) {
+            size_t plen;
+
+            if (flags != 0) {
+                pa_log_warn("Received packet frame with invalid flags value.");
+                return -1;
+            }
+
+            /* Frame is a packet frame */
+            re->packet = pa_packet_new(length);
+            re->data = (void *) pa_packet_data(re->packet, &plen);
+
+        } else {
+
+            if ((flags & PA_FLAG_SEEKMASK) > PA_SEEK_RELATIVE_END) {
+                pa_log_warn("Received memblock frame with invalid seek mode.");
+                return -1;
+            }
+
+            if (((flags & PA_FLAG_SHMMASK) & PA_FLAG_SHMDATA) != 0) {
+
+                if (length != sizeof(re->shm_info)) {
+                    pa_log_warn("Received SHM memblock frame with invalid frame length.");
+                    return -1;
+                }
+
+                /* Frame is a memblock frame referencing an SHM memblock */
+                re->data = re->shm_info;
+
+            } else if ((flags & PA_FLAG_SHMMASK) == 0) {
+
+                /* Frame is a memblock frame */
+
+                re->memblock = pa_memblock_new(p->mempool, length);
+                re->data = NULL;
+            } else {
+
+                pa_log_warn("Received memblock frame with invalid flags value.");
+                return -1;
+            }
+        }
+
+    } else if (re->index >= ntohl(re->descriptor[PA_PSTREAM_DESCRIPTOR_LENGTH]) + PA_PSTREAM_DESCRIPTOR_SIZE) {
+        /* Frame complete */
+
+        if (re->memblock) {
+            memblock_complete(p, re);
+
+            /* This was a memblock frame. We can unref the memblock now */
+            pa_memblock_unref(re->memblock);
+
+        } else if (re->packet) {
+
+            if (p->receive_packet_callback)
+#ifdef HAVE_CREDS
+                p->receive_packet_callback(p, re->packet, &p->read_ancil_data, p->receive_packet_callback_userdata);
+#else
+                p->receive_packet_callback(p, re->packet, NULL, p->receive_packet_callback_userdata);
+#endif
+
+            pa_packet_unref(re->packet);
+        } else {
+            pa_memblock *b = NULL;
+            uint32_t flags = ntohl(re->descriptor[PA_PSTREAM_DESCRIPTOR_FLAGS]);
+            uint32_t shm_id = ntohl(re->shm_info[PA_PSTREAM_SHM_SHMID]);
+            pa_mem_type_t type = (flags & PA_FLAG_SHMDATA_MEMFD_BLOCK) ?
+                                 PA_MEM_TYPE_SHARED_MEMFD : PA_MEM_TYPE_SHARED_POSIX;
+
+            pa_assert(((flags & PA_FLAG_SHMMASK) & PA_FLAG_SHMDATA) != 0);
+            pa_assert(p->import);
+
+            if (type == PA_MEM_TYPE_SHARED_MEMFD && p->use_memfd &&
+                !pa_idxset_get_by_data(p->registered_memfd_ids, PA_UINT32_TO_PTR(shm_id), NULL)) {
+
+                if (pa_log_ratelimit(PA_LOG_ERROR))
+                    pa_log("Ignoring received block reference with non-registered memfd ID = %u", shm_id);
+
+            } else if (!(b = pa_memimport_get(p->import,
+                                              type,
+                                              ntohl(re->shm_info[PA_PSTREAM_SHM_BLOCKID]),
+                                              shm_id,
+                                              ntohl(re->shm_info[PA_PSTREAM_SHM_INDEX]),
+                                              ntohl(re->shm_info[PA_PSTREAM_SHM_LENGTH]),
+                                              !!(flags & PA_FLAG_SHMWRITABLE)))) {
+
+                if (pa_log_ratelimit(PA_LOG_DEBUG))
+                    pa_log_debug("Failed to import memory block.");
+            }
+
+            if (p->receive_memblock_callback) {
+                int64_t offset;
+                pa_memchunk chunk;
+
+                chunk.memblock = b;
+                chunk.index = 0;
+                chunk.length = b ? pa_memblock_get_length(b) : ntohl(re->shm_info[PA_PSTREAM_SHM_LENGTH]);
+
+                offset = (int64_t) (
+                        (((uint64_t) ntohl(re->descriptor[PA_PSTREAM_DESCRIPTOR_OFFSET_HI])) << 32) |
+                        (((uint64_t) ntohl(re->descriptor[PA_PSTREAM_DESCRIPTOR_OFFSET_LO]))));
+
+                p->receive_memblock_callback(
+                        p,
+                        ntohl(re->descriptor[PA_PSTREAM_DESCRIPTOR_CHANNEL]),
+                        offset,
+                        ntohl(re->descriptor[PA_PSTREAM_DESCRIPTOR_FLAGS]) & PA_FLAG_SEEKMASK,
+                        &chunk,
+                        p->receive_memblock_callback_userdata);
+            }
+
+            if (b)
+                pa_memblock_unref(b);
+        }
+
+        goto frame_done;
+    }
+
+    return 0;
+
+frame_done:
+    re->memblock = NULL;
+    re->packet = NULL;
+    re->index = 0;
+    re->data = NULL;
+
+#ifdef HAVE_CREDS
+    /* FIXME: Close received ancillary data fds if the pstream's
+     * receive_packet_callback did not do so.
+     *
+     * Malicious clients can attach fds to unknown commands, or attach them
+     * to commands that does not expect fds. By doing so, server will reach
+     * its open fd limit and future clients' SHM transfers will always fail.
+     */
+    p->read_ancil_data.creds_valid = false;
+    p->read_ancil_data.nfd = 0;
+#endif
+
+    return 0;
+
+fail:
+    if (release_memblock)
+        pa_memblock_release(release_memblock);
+
+    return -1;
+}
+
+void pa_pstream_set_die_callback(pa_pstream *p, pa_pstream_notify_cb_t cb, void *userdata) {
+    pa_assert(p);
+    pa_assert(PA_REFCNT_VALUE(p) > 0);
+
+    p->die_callback = cb;
+    p->die_callback_userdata = userdata;
+}
+
+void pa_pstream_set_drain_callback(pa_pstream *p, pa_pstream_notify_cb_t cb, void *userdata) {
+    pa_assert(p);
+    pa_assert(PA_REFCNT_VALUE(p) > 0);
+
+    p->drain_callback = cb;
+    p->drain_callback_userdata = userdata;
+}
+
+void pa_pstream_set_receive_packet_callback(pa_pstream *p, pa_pstream_packet_cb_t cb, void *userdata) {
+    pa_assert(p);
+    pa_assert(PA_REFCNT_VALUE(p) > 0);
+
+    p->receive_packet_callback = cb;
+    p->receive_packet_callback_userdata = userdata;
+}
+
+void pa_pstream_set_receive_memblock_callback(pa_pstream *p, pa_pstream_memblock_cb_t cb, void *userdata) {
+    pa_assert(p);
+    pa_assert(PA_REFCNT_VALUE(p) > 0);
+
+    p->receive_memblock_callback = cb;
+    p->receive_memblock_callback_userdata = userdata;
+}
+
+void pa_pstream_set_release_callback(pa_pstream *p, pa_pstream_block_id_cb_t cb, void *userdata) {
+    pa_assert(p);
+    pa_assert(PA_REFCNT_VALUE(p) > 0);
+
+    p->release_callback = cb;
+    p->release_callback_userdata = userdata;
+}
+
+void pa_pstream_set_revoke_callback(pa_pstream *p, pa_pstream_block_id_cb_t cb, void *userdata) {
+    pa_assert(p);
+    pa_assert(PA_REFCNT_VALUE(p) > 0);
+
+    p->revoke_callback = cb;
+    p->revoke_callback_userdata = userdata;
+}
+
+bool pa_pstream_is_pending(pa_pstream *p) {
+    bool b;
+
+    pa_assert(p);
+    pa_assert(PA_REFCNT_VALUE(p) > 0);
+
+    if (p->dead)
+        b = false;
+    else
+        b = p->write.current || !pa_queue_isempty(p->send_queue);
+
+    return b;
+}
+
+void pa_pstream_unref(pa_pstream*p) {
+    pa_assert(p);
+    pa_assert(PA_REFCNT_VALUE(p) > 0);
+
+    if (PA_REFCNT_DEC(p) <= 0)
+        pstream_free(p);
+}
+
+pa_pstream* pa_pstream_ref(pa_pstream*p) {
+    pa_assert(p);
+    pa_assert(PA_REFCNT_VALUE(p) > 0);
+
+    PA_REFCNT_INC(p);
+    return p;
+}
+
+void pa_pstream_unlink(pa_pstream *p) {
+    pa_assert(p);
+
+    if (p->dead)
+        return;
+
+    p->dead = true;
+
+    while (p->srb || p->is_srbpending) /* In theory there could be one active and one pending */
+        pa_pstream_set_srbchannel(p, NULL);
+
+    if (p->import) {
+        pa_memimport_free(p->import);
+        p->import = NULL;
+    }
+
+    if (p->export) {
+        pa_memexport_free(p->export);
+        p->export = NULL;
+    }
+
+    if (p->io) {
+        pa_iochannel_free(p->io);
+        p->io = NULL;
+    }
+
+    if (p->defer_event) {
+        p->mainloop->defer_free(p->defer_event);
+        p->defer_event = NULL;
+    }
+
+    p->die_callback = NULL;
+    p->drain_callback = NULL;
+    p->receive_packet_callback = NULL;
+    p->receive_memblock_callback = NULL;
+}
+
+void pa_pstream_enable_shm(pa_pstream *p, bool enable) {
+    pa_assert(p);
+    pa_assert(PA_REFCNT_VALUE(p) > 0);
+
+    p->use_shm = enable;
+
+    if (enable) {
+
+        if (!p->export)
+            p->export = pa_memexport_new(p->mempool, memexport_revoke_cb, p);
+
+    } else {
+
+        if (p->export) {
+            pa_memexport_free(p->export);
+            p->export = NULL;
+        }
+    }
+}
+
+void pa_pstream_enable_memfd(pa_pstream *p) {
+    pa_assert(p);
+    pa_assert(PA_REFCNT_VALUE(p) > 0);
+    pa_assert(p->use_shm);
+
+    p->use_memfd = true;
+
+    if (!p->registered_memfd_ids) {
+        p->registered_memfd_ids = pa_idxset_new(NULL, NULL);
+    }
+}
+
+bool pa_pstream_get_shm(pa_pstream *p) {
+    pa_assert(p);
+    pa_assert(PA_REFCNT_VALUE(p) > 0);
+
+    return p->use_shm;
+}
+
+bool pa_pstream_get_memfd(pa_pstream *p) {
+    pa_assert(p);
+    pa_assert(PA_REFCNT_VALUE(p) > 0);
+
+    return p->use_memfd;
+}
+
+void pa_pstream_set_srbchannel(pa_pstream *p, pa_srbchannel *srb) {
+    pa_assert(p);
+    pa_assert(PA_REFCNT_VALUE(p) > 0 || srb == NULL);
+
+    if (srb == p->srb)
+        return;
+
+    /* We can't handle quick switches between srbchannels. */
+    pa_assert(!p->is_srbpending);
+
+    p->srbpending = srb;
+    p->is_srbpending = true;
+
+    /* Switch immediately, if possible. */
+    if (p->dead)
+        check_srbpending(p);
+    else
+        do_write(p);
+}