Adding upstream version 0.37.0.upstream/0.37.0

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

1 files changed, 900 insertions, 0 deletions

diff --git a/stream/stream.c b/stream/stream.c
new file mode 100644
index 0000000..dd67825
--- /dev/null
+++ b/stream/stream.c
@@ -0,0 +1,900 @@
+/*
+ * This file is part of mpv.
+ *
+ * mpv 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.
+ *
+ * mpv 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 mpv.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <limits.h>
+
+#include <strings.h>
+#include <assert.h>
+
+#include "osdep/io.h"
+
+#include "mpv_talloc.h"
+
+#include "config.h"
+
+#include "common/common.h"
+#include "common/global.h"
+#include "demux/demux.h"
+#include "misc/bstr.h"
+#include "misc/thread_tools.h"
+#include "common/msg.h"
+#include "options/m_config.h"
+#include "options/options.h"
+#include "options/path.h"
+#include "osdep/timer.h"
+#include "stream.h"
+
+#include "options/m_option.h"
+#include "options/m_config.h"
+
+extern const stream_info_t stream_info_cdda;
+extern const stream_info_t stream_info_dvb;
+extern const stream_info_t stream_info_null;
+extern const stream_info_t stream_info_memory;
+extern const stream_info_t stream_info_mf;
+extern const stream_info_t stream_info_ffmpeg;
+extern const stream_info_t stream_info_ffmpeg_unsafe;
+extern const stream_info_t stream_info_avdevice;
+extern const stream_info_t stream_info_file;
+extern const stream_info_t stream_info_slice;
+extern const stream_info_t stream_info_fd;
+extern const stream_info_t stream_info_ifo_dvdnav;
+extern const stream_info_t stream_info_dvdnav;
+extern const stream_info_t stream_info_bdmv_dir;
+extern const stream_info_t stream_info_bluray;
+extern const stream_info_t stream_info_bdnav;
+extern const stream_info_t stream_info_edl;
+extern const stream_info_t stream_info_libarchive;
+extern const stream_info_t stream_info_cb;
+
+static const stream_info_t *const stream_list[] = {
+#if HAVE_CDDA
+    &stream_info_cdda,
+#endif
+    &stream_info_ffmpeg,
+    &stream_info_ffmpeg_unsafe,
+    &stream_info_avdevice,
+#if HAVE_DVBIN
+    &stream_info_dvb,
+#endif
+#if HAVE_DVDNAV
+    &stream_info_ifo_dvdnav,
+    &stream_info_dvdnav,
+#endif
+#if HAVE_LIBBLURAY
+    &stream_info_bdmv_dir,
+    &stream_info_bluray,
+    &stream_info_bdnav,
+#endif
+#if HAVE_LIBARCHIVE
+    &stream_info_libarchive,
+#endif
+    &stream_info_memory,
+    &stream_info_null,
+    &stream_info_mf,
+    &stream_info_edl,
+    &stream_info_file,
+    &stream_info_slice,
+    &stream_info_fd,
+    &stream_info_cb,
+};
+
+// Because of guarantees documented on STREAM_BUFFER_SIZE.
+// Half the buffer is used as forward buffer, the other for seek-back.
+#define STREAM_MIN_BUFFER_SIZE (STREAM_BUFFER_SIZE * 2)
+// Sort of arbitrary; keep *2 of it comfortably within integer limits.
+// Must be power of 2.
+#define STREAM_MAX_BUFFER_SIZE (512 * 1024 * 1024)
+
+struct stream_opts {
+    int64_t buffer_size;
+    bool load_unsafe_playlists;
+};
+
+#define OPT_BASE_STRUCT struct stream_opts
+
+const struct m_sub_options stream_conf = {
+    .opts = (const struct m_option[]){
+        {"stream-buffer-size", OPT_BYTE_SIZE(buffer_size),
+            M_RANGE(STREAM_MIN_BUFFER_SIZE, STREAM_MAX_BUFFER_SIZE)},
+        {"load-unsafe-playlists", OPT_BOOL(load_unsafe_playlists)},
+        {0}
+    },
+    .size = sizeof(struct stream_opts),
+    .defaults = &(const struct stream_opts){
+        .buffer_size = 128 * 1024,
+    },
+};
+
+// return -1 if not hex char
+static int hex2dec(char c)
+{
+    if (c >= '0' && c <= '9')
+        return c - '0';
+    if (c >= 'A' && c <= 'F')
+        return 10 + c - 'A';
+    if (c >= 'a' && c <= 'f')
+        return 10 + c - 'a';
+    return -1;
+}
+
+// Replace escape sequences in an URL (or a part of an URL)
+void mp_url_unescape_inplace(char *url)
+{
+    for (int len = strlen(url), i = 0, o = 0; i <= len;) {
+        if ((url[i] != '%') || (i > len - 3)) {  // %NN can't start after len-3
+            url[o++] = url[i++];
+            continue;
+        }
+
+        int msd = hex2dec(url[i + 1]),
+            lsd = hex2dec(url[i + 2]);
+
+        if (msd >= 0 && lsd >= 0) {
+            url[o++] = 16 * msd + lsd;
+            i += 3;
+        } else {
+            url[o++] = url[i++];
+            url[o++] = url[i++];
+            url[o++] = url[i++];
+        }
+    }
+}
+
+static const char hex_digits[] = "0123456789ABCDEF";
+
+
+static const char url_default_ok[] = "abcdefghijklmnopqrstuvwxyz"
+                                     "ABCDEFGHIJKLMNOPQRSTUVWXYZ"
+                                     "0123456789"
+                                     "-._~";
+
+// Escape according to http://tools.ietf.org/html/rfc3986#section-2.1
+// Only unreserved characters are not escaped.
+// The argument ok (if not NULL) is as follows:
+//      ok[0] != '~': additional characters that are not escaped
+//      ok[0] == '~': do not escape anything but these characters
+//                    (can't override the unreserved characters, which are
+//                     never escaped)
+char *mp_url_escape(void *talloc_ctx, const char *url, const char *ok)
+{
+    char *rv = talloc_size(talloc_ctx, strlen(url) * 3 + 1);
+    char *out = rv;
+    bool negate = ok && ok[0] == '~';
+
+    for (char c; (c = *url); url++) {
+        bool as_is = negate ? !strchr(ok + 1, c)
+                            : (strchr(url_default_ok, c) || (ok && strchr(ok, c)));
+        if (as_is) {
+            *out++ = c;
+        } else {
+            unsigned char v = c;
+            *out++ = '%';
+            *out++ = hex_digits[v / 16];
+            *out++ = hex_digits[v % 16];
+        }
+    }
+
+    *out = 0;
+    return rv;
+}
+
+static const char *match_proto(const char *url, const char *proto)
+{
+    int l = strlen(proto);
+    if (l > 0) {
+        if (strncasecmp(url, proto, l) == 0 && strncmp("://", url + l, 3) == 0)
+            return url + l + 3;
+    } else if (!mp_is_url(bstr0(url))) {
+        return url; // pure filenames
+    }
+    return NULL;
+}
+
+// src and new are both STREAM_ORIGIN_* values. This checks whether a stream
+// with flags "new" can be opened from the "src". On success, return
+// new origin, on incompatibility return 0.
+static int check_origin(int src, int new)
+{
+    switch (src) {
+    case STREAM_ORIGIN_DIRECT:
+    case STREAM_ORIGIN_UNSAFE:
+        // Allow anything, but constrain it to the new origin.
+        return new;
+    case STREAM_ORIGIN_FS:
+        // From unix FS, allow all but unsafe.
+        if (new == STREAM_ORIGIN_FS || new == STREAM_ORIGIN_NET)
+            return new;
+        break;
+    case STREAM_ORIGIN_NET:
+        // Allow only other network links.
+        if (new == STREAM_ORIGIN_NET)
+            return new;
+        break;
+    }
+    return 0;
+}
+
+// Read len bytes from the start position, and wrap around as needed. Limit the
+// actually read data to the size of the buffer. Return amount of copied bytes.
+//  len: max bytes to copy to dst
+//  pos: index into s->buffer[], e.g. s->buf_start is byte 0
+//  returns: bytes copied to dst (limited by len and available buffered data)
+static int ring_copy(struct stream *s, void *dst, int len, int pos)
+{
+    assert(len >= 0);
+
+    if (pos < s->buf_start || pos > s->buf_end)
+        return 0;
+
+    int copied = 0;
+    len = MPMIN(len, s->buf_end - pos);
+
+    if (len && pos <= s->buffer_mask) {
+        int copy = MPMIN(len, s->buffer_mask + 1 - pos);
+        memcpy(dst, &s->buffer[pos], copy);
+        copied += copy;
+        len -= copy;
+        pos += copy;
+    }
+
+    if (len) {
+        memcpy((char *)dst + copied, &s->buffer[pos & s->buffer_mask], len);
+        copied += len;
+    }
+
+    return copied;
+}
+
+// Resize the current stream buffer. Uses a larger size if needed to keep data.
+// Does nothing if the size is adequate. Calling this with 0 ensures it uses the
+// default buffer size if possible.
+// The caller must check whether enough data was really allocated.
+//  keep: keep at least [buf_end-keep, buf_end] (used for assert()s only)
+//  new: new total size of buffer
+//  returns: false if buffer allocation failed, true if reallocated or size ok
+static bool stream_resize_buffer(struct stream *s, int keep, int new)
+{
+    assert(keep >= s->buf_end - s->buf_cur);
+    assert(keep <= new);
+
+    new = MPMAX(new, s->requested_buffer_size);
+    new = MPMIN(new, STREAM_MAX_BUFFER_SIZE);
+    new = mp_round_next_power_of_2(new);
+
+    assert(keep <= new); // can't fail (if old buffer size was valid)
+
+    if (new == s->buffer_mask + 1)
+        return true;
+
+    int old_pos = s->buf_cur - s->buf_start;
+    int old_used_len = s->buf_end - s->buf_start;
+    int skip = old_used_len > new ? old_used_len - new : 0;
+
+    MP_DBG(s, "resize stream to %d bytes, drop %d bytes\n", new, skip);
+
+    void *nbuf = ta_alloc_size(s, new);
+    if (!nbuf)
+        return false; // oom; tolerate it, caller needs to check if required
+
+    int new_len = 0;
+    if (s->buffer)
+        new_len = ring_copy(s, nbuf, new, s->buf_start + skip);
+    assert(new_len == old_used_len - skip);
+    assert(old_pos >= skip); // "keep" too low
+    assert(old_pos - skip <= new_len);
+    s->buf_start = 0;
+    s->buf_cur = old_pos - skip;
+    s->buf_end = new_len;
+
+    ta_free(s->buffer);
+
+    s->buffer = nbuf;
+    s->buffer_mask = new - 1;
+
+    return true;
+}
+
+static int stream_create_instance(const stream_info_t *sinfo,
+                                  struct stream_open_args *args,
+                                  struct stream **ret)
+{
+    const char *url = args->url;
+    int flags = args->flags;
+
+    *ret = NULL;
+
+    const char *path = url;
+
+    if (flags & STREAM_LOCAL_FS_ONLY) {
+        if (!sinfo->local_fs)
+            return STREAM_NO_MATCH;
+    } else {
+        for (int n = 0; sinfo->protocols && sinfo->protocols[n]; n++) {
+            path = match_proto(url, sinfo->protocols[n]);
+            if (path)
+                break;
+        }
+
+        if (!path)
+            return STREAM_NO_MATCH;
+    }
+
+    stream_t *s = talloc_zero(NULL, stream_t);
+    s->global = args->global;
+    struct stream_opts *opts = mp_get_config_group(s, s->global, &stream_conf);
+    if (flags & STREAM_SILENT) {
+        s->log = mp_null_log;
+    } else {
+        s->log = mp_log_new(s, s->global->log, sinfo->name);
+    }
+    s->info = sinfo;
+    s->cancel = args->cancel;
+    s->url = talloc_strdup(s, url);
+    s->path = talloc_strdup(s, path);
+    s->mode = flags & (STREAM_READ | STREAM_WRITE);
+    s->requested_buffer_size = opts->buffer_size;
+
+    if (flags & STREAM_LESS_NOISE)
+        mp_msg_set_max_level(s->log, MSGL_WARN);
+
+    struct demux_opts *demux_opts = mp_get_config_group(s, s->global, &demux_conf);
+    s->access_references = demux_opts->access_references;
+    talloc_free(demux_opts);
+
+    MP_VERBOSE(s, "Opening %s\n", url);
+
+    if (strlen(url) > INT_MAX / 8) {
+        MP_ERR(s, "URL too large.\n");
+        talloc_free(s);
+        return STREAM_ERROR;
+    }
+
+    if ((s->mode & STREAM_WRITE) && !sinfo->can_write) {
+        MP_DBG(s, "No write access implemented.\n");
+        talloc_free(s);
+        return STREAM_NO_MATCH;
+    }
+
+    s->stream_origin = flags & STREAM_ORIGIN_MASK; // pass through by default
+    if (opts->load_unsafe_playlists) {
+        s->stream_origin = STREAM_ORIGIN_DIRECT;
+    } else if (sinfo->stream_origin) {
+        s->stream_origin = check_origin(s->stream_origin, sinfo->stream_origin);
+    }
+
+    if (!s->stream_origin) {
+        talloc_free(s);
+        return STREAM_UNSAFE;
+    }
+
+    int r = STREAM_UNSUPPORTED;
+    if (sinfo->open2) {
+        r = sinfo->open2(s, args);
+    } else if (!args->special_arg) {
+        r = (sinfo->open)(s);
+    }
+    if (r != STREAM_OK) {
+        talloc_free(s);
+        return r;
+    }
+
+    if (!stream_resize_buffer(s, 0, 0)) {
+        free_stream(s);
+        return STREAM_ERROR;
+    }
+
+    assert(s->seekable == !!s->seek);
+
+    if (s->mime_type)
+        MP_VERBOSE(s, "Mime-type: '%s'\n", s->mime_type);
+
+    MP_DBG(s, "Stream opened successfully.\n");
+
+    *ret = s;
+    return STREAM_OK;
+}
+
+int stream_create_with_args(struct stream_open_args *args, struct stream **ret)
+
+{
+    assert(args->url);
+
+    int r = STREAM_NO_MATCH;
+    *ret = NULL;
+
+    // Open stream proper
+    if (args->sinfo) {
+        r = stream_create_instance(args->sinfo, args, ret);
+    } else {
+        for (int i = 0; i < MP_ARRAY_SIZE(stream_list); i++) {
+            r = stream_create_instance(stream_list[i], args, ret);
+            if (r == STREAM_OK)
+                break;
+            if (r == STREAM_NO_MATCH || r == STREAM_UNSUPPORTED)
+                continue;
+            if (r == STREAM_UNSAFE)
+                continue;
+            break;
+        }
+    }
+
+    if (!*ret && !(args->flags & STREAM_SILENT) && !mp_cancel_test(args->cancel))
+    {
+        struct mp_log *log = mp_log_new(NULL, args->global->log, "!stream");
+
+        if (r == STREAM_UNSAFE) {
+            mp_err(log, "\nRefusing to load potentially unsafe URL from a playlist.\n"
+                   "Use the --load-unsafe-playlists option to load it anyway.\n\n");
+        } else if (r == STREAM_NO_MATCH || r == STREAM_UNSUPPORTED) {
+            mp_err(log, "No protocol handler found to open URL %s\n", args->url);
+            mp_err(log, "The protocol is either unsupported, or was disabled "
+                        "at compile-time.\n");
+        } else {
+            mp_err(log, "Failed to open %s.\n", args->url);
+        }
+
+        talloc_free(log);
+    }
+
+    return r;
+}
+
+struct stream *stream_create(const char *url, int flags,
+                             struct mp_cancel *c, struct mpv_global *global)
+{
+    struct stream_open_args args = {
+        .global = global,
+        .cancel = c,
+        .flags = flags,
+        .url = url,
+    };
+    struct stream *s;
+    stream_create_with_args(&args, &s);
+    return s;
+}
+
+stream_t *open_output_stream(const char *filename, struct mpv_global *global)
+{
+    return stream_create(filename, STREAM_ORIGIN_DIRECT | STREAM_WRITE,
+                         NULL, global);
+}
+
+// Read function bypassing the local stream buffer. This will not write into
+// s->buffer, but into buf[0..len] instead.
+// Returns 0 on error or EOF, and length of bytes read on success.
+// Partial reads are possible, even if EOF is not reached.
+static int stream_read_unbuffered(stream_t *s, void *buf, int len)
+{
+    assert(len >= 0);
+    if (len <= 0)
+        return 0;
+
+    int res = 0;
+    // we will retry even if we already reached EOF previously.
+    if (s->fill_buffer && !mp_cancel_test(s->cancel))
+        res = s->fill_buffer(s, buf, len);
+    if (res <= 0) {
+        s->eof = 1;
+        return 0;
+    }
+    assert(res <= len);
+    // When reading succeeded we are obviously not at eof.
+    s->eof = 0;
+    s->pos += res;
+    s->total_unbuffered_read_bytes += res;
+    return res;
+}
+
+// Ask for having at most "forward" bytes ready to read in the buffer.
+// To read everything, you may have to call this in a loop.
+//  forward: desired amount of bytes in buffer after s->cur_pos
+//  returns: progress (false on EOF or on OOM or if enough data was available)
+static bool stream_read_more(struct stream *s, int forward)
+{
+    assert(forward >= 0);
+
+    int forward_avail = s->buf_end - s->buf_cur;
+    if (forward_avail >= forward)
+        return false;
+
+    // Avoid that many small reads will lead to many low-level read calls.
+    forward = MPMAX(forward, s->requested_buffer_size / 2);
+    assert(forward_avail < forward);
+
+    // Keep guaranteed seek-back.
+    int buf_old = MPMIN(s->buf_cur - s->buf_start, s->requested_buffer_size / 2);
+
+    if (!stream_resize_buffer(s, buf_old + forward_avail, buf_old + forward))
+        return false;
+
+    int buf_alloc = s->buffer_mask + 1;
+
+    assert(s->buf_start <= s->buf_cur);
+    assert(s->buf_cur <= s->buf_end);
+    assert(s->buf_cur < buf_alloc * 2);
+    assert(s->buf_end < buf_alloc * 2);
+    assert(s->buf_start < buf_alloc);
+
+    // Note: read as much as possible, even if forward is much smaller. Do
+    // this because the stream buffer is supposed to set an approx. minimum
+    // read size on it.
+    int read = buf_alloc - (buf_old + forward_avail); // free buffer past end
+
+    int pos = s->buf_end & s->buffer_mask;
+    read = MPMIN(read, buf_alloc - pos);
+
+    // Note: if wrap-around happens, we need to make two calls. This may
+    // affect latency (e.g. waiting for new data on a socket), so do only
+    // 1 read call always.
+    read = stream_read_unbuffered(s, &s->buffer[pos], read);
+
+    s->buf_end += read;
+
+    // May have overwritten old data.
+    if (s->buf_end - s->buf_start >= buf_alloc) {
+        assert(s->buf_end >= buf_alloc);
+
+        s->buf_start = s->buf_end - buf_alloc;
+
+        assert(s->buf_start <= s->buf_cur);
+        assert(s->buf_cur <= s->buf_end);
+
+        if (s->buf_start >= buf_alloc) {
+            s->buf_start -= buf_alloc;
+            s->buf_cur -= buf_alloc;
+            s->buf_end -= buf_alloc;
+        }
+    }
+
+    // Must not have overwritten guaranteed old data.
+    assert(s->buf_cur - s->buf_start >= buf_old);
+
+    if (s->buf_cur < s->buf_end)
+        s->eof = 0;
+
+    return !!read;
+}
+
+// Read between 1..buf_size bytes of data, return how much data has been read.
+// Return 0 on EOF, error, or if buf_size was 0.
+int stream_read_partial(stream_t *s, void *buf, int buf_size)
+{
+    assert(s->buf_cur <= s->buf_end);
+    assert(buf_size >= 0);
+    if (s->buf_cur == s->buf_end && buf_size > 0) {
+        if (buf_size > (s->buffer_mask + 1) / 2) {
+            // Direct read if the buffer is too small anyway.
+            stream_drop_buffers(s);
+            return stream_read_unbuffered(s, buf, buf_size);
+        }
+        stream_read_more(s, 1);
+    }
+    int res = ring_copy(s, buf, buf_size, s->buf_cur);
+    s->buf_cur += res;
+    return res;
+}
+
+// Slow version of stream_read_char(); called by it if the buffer is empty.
+int stream_read_char_fallback(stream_t *s)
+{
+    uint8_t c;
+    return stream_read_partial(s, &c, 1) ? c : -256;
+}
+
+int stream_read(stream_t *s, void *mem, int total)
+{
+    int len = total;
+    while (len > 0) {
+        int read = stream_read_partial(s, mem, len);
+        if (read <= 0)
+            break; // EOF
+        mem = (char *)mem + read;
+        len -= read;
+    }
+    total -= len;
+    return total;
+}
+
+// Read ahead so that at least forward_size bytes are readable ahead. Returns
+// the actual forward amount available (restricted by EOF or buffer limits).
+int stream_peek(stream_t *s, int forward_size)
+{
+    while (stream_read_more(s, forward_size)) {}
+    return s->buf_end - s->buf_cur;
+}
+
+// Like stream_read(), but do not advance the current position. This may resize
+// the buffer to satisfy the read request.
+int stream_read_peek(stream_t *s, void *buf, int buf_size)
+{
+    stream_peek(s, buf_size);
+    return ring_copy(s, buf, buf_size, s->buf_cur);
+}
+
+int stream_write_buffer(stream_t *s, void *buf, int len)
+{
+    if (!s->write_buffer)
+        return -1;
+    int orig_len = len;
+    while (len) {
+        int w = s->write_buffer(s, buf, len);
+        if (w <= 0)
+            return -1;
+        s->pos += w;
+        buf = (char *)buf + w;
+        len -= w;
+    }
+    return orig_len;
+}
+
+// Drop len bytes form input, possibly reading more until all is skipped. If
+// EOF or an error was encountered before all could be skipped, return false,
+// otherwise return true.
+static bool stream_skip_read(struct stream *s, int64_t len)
+{
+    while (len > 0) {
+        unsigned int left = s->buf_end - s->buf_cur;
+        if (!left) {
+            if (!stream_read_more(s, 1))
+                return false;
+            continue;
+        }
+        unsigned skip = MPMIN(len, left);
+        s->buf_cur += skip;
+        len -= skip;
+    }
+    return true;
+}
+
+// Drop the internal buffer. Note that this will advance the stream position
+// (as seen by stream_tell()), because the real stream position is ahead of the
+// logical stream position by the amount of buffered but not yet read data.
+void stream_drop_buffers(stream_t *s)
+{
+    s->pos = stream_tell(s);
+    s->buf_start = s->buf_cur = s->buf_end = 0;
+    s->eof = 0;
+    stream_resize_buffer(s, 0, 0);
+}
+
+// Seek function bypassing the local stream buffer.
+static bool stream_seek_unbuffered(stream_t *s, int64_t newpos)
+{
+    if (newpos != s->pos) {
+        MP_VERBOSE(s, "stream level seek from %" PRId64 " to %" PRId64 "\n",
+                   s->pos, newpos);
+
+        s->total_stream_seeks++;
+
+        if (newpos > s->pos && !s->seekable) {
+            MP_ERR(s, "Cannot seek forward in this stream\n");
+            return false;
+        }
+        if (newpos < s->pos && !s->seekable) {
+            MP_ERR(s, "Cannot seek backward in linear streams!\n");
+            return false;
+        }
+        if (s->seek(s, newpos) <= 0) {
+            int level = mp_cancel_test(s->cancel) ? MSGL_V : MSGL_ERR;
+            MP_MSG(s, level, "Seek failed (to %lld, size %lld)\n",
+                   (long long)newpos, (long long)stream_get_size(s));
+            return false;
+        }
+        stream_drop_buffers(s);
+        s->pos = newpos;
+    }
+    return true;
+}
+
+bool stream_seek(stream_t *s, int64_t pos)
+{
+    MP_TRACE(s, "seek request from %" PRId64 " to %" PRId64 "\n",
+             stream_tell(s), pos);
+
+    s->eof = 0; // eof should be set only on read; seeking always clears it
+
+    if (pos < 0) {
+        MP_ERR(s, "Invalid seek to negative position %lld!\n", (long long)pos);
+        pos = 0;
+    }
+
+    if (pos <= s->pos) {
+        int64_t x = pos - (s->pos - (int)s->buf_end);
+        if (x >= (int)s->buf_start) {
+            s->buf_cur = x;
+            assert(s->buf_cur >= s->buf_start);
+            assert(s->buf_cur <= s->buf_end);
+            return true;
+        }
+    }
+
+    if (s->mode == STREAM_WRITE)
+        return s->seekable && s->seek(s, pos);
+
+    // Skip data instead of performing a seek in some cases.
+    if (pos >= s->pos &&
+        ((!s->seekable && s->fast_skip) ||
+         pos - s->pos <= s->requested_buffer_size))
+    {
+        return stream_skip_read(s, pos - stream_tell(s));
+    }
+
+    return stream_seek_unbuffered(s, pos);
+}
+
+// Like stream_seek(), but strictly prefer skipping data instead of failing, if
+// it's a forward-seek.
+bool stream_seek_skip(stream_t *s, int64_t pos)
+{
+    uint64_t cur_pos = stream_tell(s);
+
+    if (cur_pos == pos)
+        return true;
+
+    return !s->seekable && pos > cur_pos
+        ? stream_skip_read(s, pos - cur_pos)
+        : stream_seek(s, pos);
+}
+
+int stream_control(stream_t *s, int cmd, void *arg)
+{
+    return s->control ? s->control(s, cmd, arg) : STREAM_UNSUPPORTED;
+}
+
+// Return the current size of the stream, or a negative value if unknown.
+int64_t stream_get_size(stream_t *s)
+{
+    return s->get_size ? s->get_size(s) : -1;
+}
+
+void free_stream(stream_t *s)
+{
+    if (!s)
+        return;
+
+    if (s->close)
+        s->close(s);
+    talloc_free(s);
+}
+
+static const char *const bom[3] = {"\xEF\xBB\xBF", "\xFF\xFE", "\xFE\xFF"};
+
+// Return utf16 argument for stream_read_line
+int stream_skip_bom(struct stream *s)
+{
+    char buf[4];
+    int len = stream_read_peek(s, buf, sizeof(buf));
+    bstr data = {buf, len};
+    for (int n = 0; n < 3; n++) {
+        if (bstr_startswith0(data, bom[n])) {
+            stream_seek_skip(s, stream_tell(s) + strlen(bom[n]));
+            return n;
+        }
+    }
+    return -1; // default to 8 bit codepages
+}
+
+// Read the rest of the stream into memory (current pos to EOF), and return it.
+//  talloc_ctx: used as talloc parent for the returned allocation
+//  max_size: must be set to >0. If the file is larger than that, it is treated
+//            as error. This is a minor robustness measure.
+//  returns: stream contents, or .start/.len set to NULL on error
+// If the file was empty, but no error happened, .start will be non-NULL and
+// .len will be 0.
+// For convenience, the returned buffer is padded with a 0 byte. The padding
+// is not included in the returned length.
+struct bstr stream_read_complete(struct stream *s, void *talloc_ctx,
+                                 int max_size)
+{
+    if (max_size > 1000000000)
+        abort();
+
+    int bufsize;
+    int total_read = 0;
+    int padding = 1;
+    char *buf = NULL;
+    int64_t size = stream_get_size(s) - stream_tell(s);
+    if (size > max_size)
+        return (struct bstr){NULL, 0};
+    if (size > 0)
+        bufsize = size + padding;
+    else
+        bufsize = 1000;
+    while (1) {
+        buf = talloc_realloc_size(talloc_ctx, buf, bufsize);
+        int readsize = stream_read(s, buf + total_read, bufsize - total_read);
+        total_read += readsize;
+        if (total_read < bufsize)
+            break;
+        if (bufsize > max_size) {
+            talloc_free(buf);
+            return (struct bstr){NULL, 0};
+        }
+        bufsize = MPMIN(bufsize + (bufsize >> 1), max_size + padding);
+    }
+    buf = talloc_realloc_size(talloc_ctx, buf, total_read + padding);
+    memset(&buf[total_read], 0, padding);
+    return (struct bstr){buf, total_read};
+}
+
+struct bstr stream_read_file(const char *filename, void *talloc_ctx,
+                             struct mpv_global *global, int max_size)
+{
+    struct bstr res = {0};
+    int flags = STREAM_ORIGIN_DIRECT | STREAM_READ | STREAM_LOCAL_FS_ONLY |
+                STREAM_LESS_NOISE;
+    stream_t *s = stream_create(filename, flags, NULL, global);
+    if (s) {
+        res = stream_read_complete(s, talloc_ctx, max_size);
+        free_stream(s);
+    }
+    return res;
+}
+
+char **stream_get_proto_list(void)
+{
+    char **list = NULL;
+    int num = 0;
+    for (int i = 0; i < MP_ARRAY_SIZE(stream_list); i++) {
+        const stream_info_t *stream_info = stream_list[i];
+
+        if (!stream_info->protocols)
+            continue;
+
+        for (int j = 0; stream_info->protocols[j]; j++) {
+            if (*stream_info->protocols[j] == '\0')
+               continue;
+
+            MP_TARRAY_APPEND(NULL, list, num,
+                                talloc_strdup(NULL, stream_info->protocols[j]));
+        }
+    }
+    MP_TARRAY_APPEND(NULL, list, num, NULL);
+    return list;
+}
+
+void stream_print_proto_list(struct mp_log *log)
+{
+    int count = 0;
+
+    mp_info(log, "Protocols:\n\n");
+    char **list = stream_get_proto_list();
+    for (int i = 0; list[i]; i++) {
+        mp_info(log, " %s://\n", list[i]);
+        count++;
+        talloc_free(list[i]);
+    }
+    talloc_free(list);
+    mp_info(log, "\nTotal: %d protocols\n", count);
+}
+
+bool stream_has_proto(const char *proto)
+{
+    for (int i = 0; i < MP_ARRAY_SIZE(stream_list); i++) {
+        const stream_info_t *stream_info = stream_list[i];
+
+        for (int j = 0; stream_info->protocols && stream_info->protocols[j]; j++) {
+            if (strcmp(stream_info->protocols[j], proto) == 0)
+                return true;
+        }
+    }
+
+    return false;
+}