/* * Input cache protocol. * Copyright (c) 2011,2014 Michael Niedermayer * * This file is part of FFmpeg. * * FFmpeg 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. * * FFmpeg 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 FFmpeg; if not, write to the Free Software * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA * * Based on file.c by Fabrice Bellard */ /** * @TODO *      support keeping files *      support filling with a background thread */ #include "libavutil/avassert.h"#include "libavutil/avstring.h"#include "libavutil/file_open.h"#include "libavutil/opt.h"#include "libavutil/tree.h"#include "avio.h"#include <fcntl.h>#if HAVE_IO_H#include <io.h>#endif#if HAVE_UNISTD_H#include <unistd.h>#endif#include <sys/stat.h>#include <stdlib.h>#include "os_support.h"#include "url.h" typedef struct CacheEntry {    int64_t logical_pos;    int64_t physical_pos;    int size;} CacheEntry; typedef struct Context {    AVClass *class;    int fd;    char *filename;    struct AVTreeNode *root;    int64_t logical_pos;    int64_t cache_pos;    int64_t inner_pos;    int64_t end;    int is_true_eof;    URLContext *inner;    int64_t cache_hit, cache_miss;    int read_ahead_limit;} Context; static int cmp(const void *key, const void *node){    return FFDIFFSIGN(*(const int64_t *)key, ((const CacheEntry *) node)->logical_pos);} static int cache_open(URLContext *h, const char *arg, int flags, AVDictionary **options){    int ret;    char *buffername;    Context *c= h->priv_data;     av_strstart(arg, "cache:", &arg);     c->fd = avpriv_tempfile("ffcache", &buffername, 0, h);    if (c->fd < 0){        av_log(h, AV_LOG_ERROR, "Failed to create tempfile\n");        return c->fd;    }     ret = unlink(buffername);     if (ret >= 0)        av_freep(&buffername);    else        c->filename = buffername;     return ffurl_open_whitelist(&c->inner, arg, flags, &h->interrupt_callback,                                options, h->protocol_whitelist, h->protocol_blacklist, h);} static int add_entry(URLContext *h, const unsigned char *buf, int size){    Context *c= h->priv_data;    int64_t pos = -1;    int ret;    CacheEntry *entry = NULL, *next[2] = {NULL, NULL};    CacheEntry *entry_ret;    struct AVTreeNode *node = NULL;     //FIXME avoid lseek    pos = lseek(c->fd, 0, SEEK_END);    if (pos < 0) {        ret = AVERROR(errno);        av_log(h, AV_LOG_ERROR, "seek in cache failed\n");        goto fail;    }    c->cache_pos = pos;     ret = write(c->fd, buf, size);    if (ret < 0) {        ret = AVERROR(errno);        av_log(h, AV_LOG_ERROR, "write in cache failed\n");        goto fail;    }    c->cache_pos += ret;     entry = av_tree_find(c->root, &c->logical_pos, cmp, (void**)next);     if (!entry)        entry = next[0];     if (!entry ||        entry->logical_pos  + entry->size != c->logical_pos ||        entry->physical_pos + entry->size != pos    ) {        entry = av_malloc(sizeof(*entry));        node = av_tree_node_alloc();        if (!entry || !node) {            ret = AVERROR(ENOMEM);            goto fail;        }        entry->logical_pos = c->logical_pos;        entry->physical_pos = pos;        entry->size = ret;         entry_ret = av_tree_insert(&c->root, entry, cmp, &node);        if (entry_ret && entry_ret != entry) {            ret = -1;            av_log(h, AV_LOG_ERROR, "av_tree_insert failed\n");            goto fail;        }    } else        entry->size += ret;     return 0;fail:    //we could truncate the file to pos here if pos >=0 but ftruncate isn't available in VS so    //for simplicty we just leave the file a bit larger    av_free(entry);    av_free(node);    return ret;} static int cache_read(URLContext *h, unsigned char *buf, int size){    Context *c= h->priv_data;    CacheEntry *entry, *next[2] = {NULL, NULL};    int64_t r;     entry = av_tree_find(c->root, &c->logical_pos, cmp, (void**)next);     if (!entry)        entry = next[0];     if (entry) {        int64_t in_block_pos = c->logical_pos - entry->logical_pos;        av_assert0(entry->logical_pos <= c->logical_pos);        if (in_block_pos < entry->size) {            int64_t physical_target = entry->physical_pos + in_block_pos;             if (c->cache_pos != physical_target) {                r = lseek(c->fd, physical_target, SEEK_SET);            } else                r = c->cache_pos;             if (r >= 0) {                c->cache_pos = r;                r = read(c->fd, buf, FFMIN(size, entry->size - in_block_pos));            }             if (r > 0) {                c->cache_pos += r;                c->logical_pos += r;                c->cache_hit ++;                return r;            }        }    }     // Cache miss or some kind of fault with the cache     if (c->logical_pos != c->inner_pos) {        r = ffurl_seek(c->inner, c->logical_pos, SEEK_SET);        if (r<0) {            av_log(h, AV_LOG_ERROR, "Failed to perform internal seek\n");            return r;        }        c->inner_pos = r;    }     r = ffurl_read(c->inner, buf, size);    if (r == AVERROR_EOF && size>0) {        c->is_true_eof = 1;        av_assert0(c->end >= c->logical_pos);    }    if (r<=0)        return r;    c->inner_pos += r;     c->cache_miss ++;     add_entry(h, buf, r);    c->logical_pos += r;    c->end = FFMAX(c->end, c->logical_pos);     return r;} static int64_t cache_seek(URLContext *h, int64_t pos, int whence){    Context *c= h->priv_data;    int64_t ret;     if (whence == AVSEEK_SIZE) {        pos= ffurl_seek(c->inner, pos, whence);        if(pos <= 0){            pos= ffurl_seek(c->inner, -1, SEEK_END);            if (ffurl_seek(c->inner, c->inner_pos, SEEK_SET) < 0)                av_log(h, AV_LOG_ERROR, "Inner protocol failed to seekback end : %"PRId64"\n", pos);        }        if (pos > 0)            c->is_true_eof = 1;        c->end = FFMAX(c->end, pos);        return pos;    }     if (whence == SEEK_CUR) {        whence = SEEK_SET;        pos += c->logical_pos;    } else if (whence == SEEK_END && c->is_true_eof) {resolve_eof:        whence = SEEK_SET;        pos += c->end;    }     if (whence == SEEK_SET && pos >= 0 && pos < c->end) {        //Seems within filesize, assume it will not fail.        c->logical_pos = pos;        return pos;    }     //cache miss    ret= ffurl_seek(c->inner, pos, whence);    if ((whence == SEEK_SET && pos >= c->logical_pos ||         whence == SEEK_END && pos <= 0) && ret < 0) {        if (   (whence == SEEK_SET && c->read_ahead_limit >= pos - c->logical_pos)            || c->read_ahead_limit < 0) {            uint8_t tmp[32768];            while (c->logical_pos < pos || whence == SEEK_END) {                int size = sizeof(tmp);                if (whence == SEEK_SET)                    size = FFMIN(sizeof(tmp), pos - c->logical_pos);                ret = cache_read(h, tmp, size);                if (ret == AVERROR_EOF && whence == SEEK_END) {                    av_assert0(c->is_true_eof);                    goto resolve_eof;                }                if (ret < 0) {                    return ret;                }            }            return c->logical_pos;        }    }     if (ret >= 0) {        c->logical_pos = ret;        c->end = FFMAX(c->end, ret);    }     return ret;} static int enu_free(void *opaque, void *elem){    av_free(elem);    return 0;} static int cache_close(URLContext *h){    Context *c= h->priv_data;    int ret;     av_log(h, AV_LOG_INFO, "Statistics, cache hits:%"PRId64" cache misses:%"PRId64"\n",           c->cache_hit, c->cache_miss);     close(c->fd);    if (c->filename) {        ret = unlink(c->filename);        if (ret < 0)            av_log(h, AV_LOG_ERROR, "Could not delete %s.\n", c->filename);        av_freep(&c->filename);    }    ffurl_closep(&c->inner);    av_tree_enumerate(c->root, NULL, NULL, enu_free);    av_tree_destroy(c->root);     return 0;} #define OFFSET(x) offsetof(Context, x)#define D AV_OPT_FLAG_DECODING_PARAM static const AVOption options[] = {    { "read_ahead_limit", "Amount in bytes that may be read ahead when seeking isn't supported, -1 for unlimited", OFFSET(read_ahead_limit), AV_OPT_TYPE_INT, { .i64 = 65536 }, -1, INT_MAX, D },    {NULL},}; static const AVClass cache_context_class = {    .class_name = "cache",    .item_name  = av_default_item_name,    .option     = options,    .version    = LIBAVUTIL_VERSION_INT,}; const URLProtocol ff_cache_protocol = {    .name                = "cache",    .url_open2           = cache_open,    .url_read            = cache_read,    .url_seek            = cache_seek,    .url_close           = cache_close,    .priv_data_size      = sizeof(Context),    .priv_data_class     = &cache_context_class,};