From c88f95a2ea1d089501bed84c085acd7312f7dc2a Mon Sep 17 00:00:00 2001 From: Max Kellermann Date: Tue, 29 Dec 2009 23:55:40 +0100 Subject: input/rewind: new input_stream wrapper to allow stream rewinding This replaces the rewinding buffer code from the CURL input plugin. It is more generic, and allows rewinding even when the server sends Icy-Metadata (which would have been too difficult to implement within the CURL plugin). This is a rather complex patch for the stable branch (v0.15.x), but it fixes a serious problem: the "vorbis" decoder plugin was unable to play streams with Icy-Metadata, because it couldn't rewind the stream after detecting the codec (Vorbis vs. FLAC). --- src/input/curl_input_plugin.c | 12 ++ src/input/curl_input_plugin.h | 10 ++ src/input/rewind_input_plugin.c | 238 ++++++++++++++++++++++++++++++++++++++++ src/input/rewind_input_plugin.h | 49 +++++++++ 4 files changed, 309 insertions(+) create mode 100644 src/input/rewind_input_plugin.c create mode 100644 src/input/rewind_input_plugin.h (limited to 'src/input') diff --git a/src/input/curl_input_plugin.c b/src/input/curl_input_plugin.c index 95d269ce5..37d721d58 100644 --- a/src/input/curl_input_plugin.c +++ b/src/input/curl_input_plugin.c @@ -732,6 +732,18 @@ input_curl_easy_init(struct input_stream *is) return true; } +void +input_curl_reinit(struct input_stream *is) +{ + struct input_curl *c = is->data; + + assert(is->plugin == &input_plugin_curl); + assert(c->easy != NULL); + + curl_easy_setopt(c->easy, CURLOPT_WRITEHEADER, is); + curl_easy_setopt(c->easy, CURLOPT_WRITEDATA, is); +} + static bool input_curl_send_request(struct input_curl *c) { diff --git a/src/input/curl_input_plugin.h b/src/input/curl_input_plugin.h index 3816f039b..63ac0dc23 100644 --- a/src/input/curl_input_plugin.h +++ b/src/input/curl_input_plugin.h @@ -20,6 +20,16 @@ #ifndef MPD_INPUT_CURL_H #define MPD_INPUT_CURL_H +struct input_stream; + extern const struct input_plugin input_plugin_curl; +/** + * This is a workaround for an input_stream API deficiency; after + * exchanging the input_stream pointer in input_rewind_open(), this + * function is called to reinitialize CURL's data pointers. + */ +void +input_curl_reinit(struct input_stream *is); + #endif diff --git a/src/input/rewind_input_plugin.c b/src/input/rewind_input_plugin.c new file mode 100644 index 000000000..0a874a29c --- /dev/null +++ b/src/input/rewind_input_plugin.c @@ -0,0 +1,238 @@ +/* + * Copyright (C) 2003-2009 The Music Player Daemon Project + * http://www.musicpd.org + * + * This program is free software; you can redistribute it and/or modify + * it under the terms of the GNU General Public License as published by + * the Free Software Foundation; either version 2 of the License, or + * (at your option) any later version. + * + * This program 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 General Public License for more details. + * + * You should have received a copy of the GNU General Public License along + * with this program; if not, write to the Free Software Foundation, Inc., + * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA. + */ + +#include "config.h" +#include "input/rewind_input_plugin.h" +#include "input/curl_input_plugin.h" +#include "input_plugin.h" +#include "tag.h" + +#include + +#include +#include + +#undef G_LOG_DOMAIN +#define G_LOG_DOMAIN "input_rewind" + +struct input_rewind { + struct input_stream input; + + /** + * The read position within the buffer. Undefined as long as + * reading_from_buffer() returns false. + */ + size_t head; + + /** + * The write/append position within the buffer. + */ + size_t tail; + + /** + * The size of this buffer is the maximum number of bytes + * which can be rewinded cheaply without passing the "seek" + * call to CURL. + * + * The origin of this buffer is always the beginning of the + * stream (offset 0). + */ + char buffer[64 * 1024]; +}; + +/** + * Are we currently reading from the buffer, and does the buffer + * contain more data for the next read operation? + */ +static bool +reading_from_buffer(const struct input_stream *is) +{ + const struct input_rewind *r = is->data; + + return r->tail > 0 && is->offset < r->input.offset; +} + +/** + * Copy public attributes from the underlying input stream to the + * "rewind" input stream. This function is called when a method of + * the underlying stream has returned, which may have modified these + * attributes. + */ +static void +copy_attributes(struct input_stream *dest) +{ + const struct input_rewind *r = dest->data; + const struct input_stream *src = &r->input; + + dest->ready = src->ready; + dest->seekable = src->seekable; + dest->error = src->error; + dest->size = src->size; + dest->offset = src->offset; + + if (dest->mime == NULL && src->mime != NULL) + /* this is set only once, and the duplicated pointer + is freed by input_stream_close() */ + dest->mime = g_strdup(src->mime); +} + +static void +input_rewind_close(struct input_stream *is) +{ + struct input_rewind *r = is->data; + + input_stream_close(&r->input); + + g_free(r); +} + +static struct tag * +input_rewind_tag(struct input_stream *is) +{ + struct input_rewind *r = is->data; + + return input_stream_tag(&r->input); +} + +static int +input_rewind_buffer(struct input_stream *is) +{ + struct input_rewind *r = is->data; + + int ret = input_stream_buffer(&r->input); + if (ret < 0 || !reading_from_buffer(is)) + copy_attributes(is); + + return ret; +} + +static size_t +input_rewind_read(struct input_stream *is, void *ptr, size_t size) +{ + struct input_rewind *r = is->data; + + if (reading_from_buffer(is)) { + /* buffered read */ + + assert(r->head == (size_t)is->offset); + assert(r->tail == (size_t)r->input.offset); + + if (size > r->tail - r->head) + size = r->tail - r->head; + + memcpy(ptr, r->buffer + r->head, size); + r->head += size; + is->offset += size; + + return size; + } else { + /* pass method call to underlying stream */ + + size_t nbytes = input_stream_read(&r->input, ptr, size); + + if (r->input.offset > (off_t)sizeof(r->buffer)) + /* disable buffering */ + r->tail = 0; + else if (r->tail == (size_t)is->offset) { + /* append to buffer */ + + memcpy(r->buffer + r->tail, ptr, nbytes); + r->tail += nbytes; + + assert(r->tail == (size_t)r->input.offset); + } + + copy_attributes(is); + + return nbytes; + } +} + +static bool +input_rewind_eof(G_GNUC_UNUSED struct input_stream *is) +{ + struct input_rewind *r = is->data; + + return !reading_from_buffer(is) && input_stream_eof(&r->input); +} + +static bool +input_rewind_seek(struct input_stream *is, off_t offset, int whence) +{ + struct input_rewind *r = is->data; + + assert(is->ready); + + if (whence == SEEK_SET && r->tail > 0 && offset <= (off_t)r->tail) { + /* buffered seek */ + + assert(!reading_from_buffer(is) || + r->head == (size_t)is->offset); + assert(r->tail == (size_t)r->input.offset); + + r->head = (size_t)offset; + is->offset = offset; + + return true; + } else { + bool success = input_stream_seek(&r->input, offset, whence); + copy_attributes(is); + + /* disable the buffer, because r->input has left the + buffered range now */ + r->tail = 0; + + return success; + } +} + +static const struct input_plugin rewind_input_plugin = { + .close = input_rewind_close, + .tag = input_rewind_tag, + .buffer = input_rewind_buffer, + .read = input_rewind_read, + .eof = input_rewind_eof, + .seek = input_rewind_seek, +}; + +void +input_rewind_open(struct input_stream *is) +{ + struct input_rewind *c; + + assert(is != NULL); + assert(is->offset == 0); + + if (is->plugin != &input_plugin_curl) + /* due to limitations in the input_plugin API, we only + (explicitly) support the CURL input plugin */ + return; + + c = g_new(struct input_rewind, 1); + c->tail = 0; + + /* move the CURL input stream to c->input */ + c->input = *is; + input_curl_reinit(&c->input); + + /* convert the existing input_stream pointer to a "rewind" + input stream */ + is->plugin = &rewind_input_plugin; + is->data = c; +} diff --git a/src/input/rewind_input_plugin.h b/src/input/rewind_input_plugin.h new file mode 100644 index 000000000..33fedf4e1 --- /dev/null +++ b/src/input/rewind_input_plugin.h @@ -0,0 +1,49 @@ +/* + * Copyright (C) 2003-2009 The Music Player Daemon Project + * http://www.musicpd.org + * + * This program is free software; you can redistribute it and/or modify + * it under the terms of the GNU General Public License as published by + * the Free Software Foundation; either version 2 of the License, or + * (at your option) any later version. + * + * This program 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 General Public License for more details. + * + * You should have received a copy of the GNU General Public License along + * with this program; if not, write to the Free Software Foundation, Inc., + * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA. + */ + +/** \file + * + * A wrapper for an input_stream object which allows cheap buffered + * rewinding. This is useful while detecting the stream codec (let + * each decoder plugin peek a portion from the stream). + */ + +#ifndef MPD_INPUT_REWIND_H +#define MPD_INPUT_REWIND_H + +#include "config.h" + +struct input_stream; + +#ifdef HAVE_CURL + +void +input_rewind_open(struct input_stream *is); + +#else + +static inline void +input_rewind_open(struct input_stream *is) +{ + (void)is; +} + +#endif + +#endif -- cgit v1.2.3