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🎥 Command line media player
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C
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#include <errno.h>#include <fcntl.h>#include <stdlib.h>#include <sys/stat.h>#include <sys/types.h>#include <unistd.h>
#include "cache.h"#include "common/msg.h"#include "common/av_common.h"#include "demux.h"#include "options/path.h"#include "options/m_config.h"#include "options/m_option.h"#include "osdep/io.h"
struct demux_cache_opts { char *cache_dir; int unlink_files;};
#define OPT_BASE_STRUCT struct demux_cache_opts
const struct m_sub_options demux_cache_conf = { .opts = (const struct m_option[]){ OPT_STRING("cache-dir", cache_dir, M_OPT_FILE), OPT_CHOICE("cache-unlink-files", unlink_files, 0, ({"immediate", 2}, {"whendone", 1}, {"no", 0})), {0} }, .size = sizeof(struct demux_cache_opts), .defaults = &(const struct demux_cache_opts){ .unlink_files = 2, },};
struct demux_cache { struct mp_log *log; struct demux_cache_opts *opts;
char *filename; bool need_unlink; int fd; int64_t file_pos; uint64_t file_size;};
struct pkt_header { uint32_t data_len; uint32_t av_flags; uint32_t num_sd;};
struct sd_header { uint32_t av_type; uint32_t len;};
static void cache_destroy(void *p){ struct demux_cache *cache = p;
if (cache->fd >= 0) close(cache->fd);
if (cache->need_unlink && cache->opts->unlink_files >= 1) { if (unlink(cache->filename)) MP_ERR(cache, "Failed to delete cache temporary file.\n"); }}
// Create a cache. This also initializes the cache file from the options. The// log parameter must stay valid until demux_cache is destroyed.// Free with talloc_free().struct demux_cache *demux_cache_create(struct mpv_global *global, struct mp_log *log){ struct demux_cache *cache = talloc_zero(NULL, struct demux_cache); talloc_set_destructor(cache, cache_destroy); cache->opts = mp_get_config_group(cache, global, &demux_cache_conf); cache->log = log; cache->fd = -1;
char *cache_dir = cache->opts->cache_dir; if (!(cache_dir && cache_dir[0])) { MP_ERR(cache, "No cache data directory supplied.\n"); goto fail; }
cache->filename = mp_path_join(cache, cache_dir, "mpv-cache-XXXXXX.dat"); cache->fd = mp_mkostemps(cache->filename, 4, O_CLOEXEC); if (cache->fd < 0) { MP_ERR(cache, "Failed to create cache temporary file.\n"); goto fail; } cache->need_unlink = true; if (cache->opts->unlink_files >= 2) { if (unlink(cache->filename)) { MP_ERR(cache, "Failed to unlink cache temporary file after creation.\n"); } else { cache->need_unlink = false; } }
return cache;fail: talloc_free(cache); return NULL;}
uint64_t demux_cache_get_size(struct demux_cache *cache){ return cache->file_size;}
static bool do_seek(struct demux_cache *cache, uint64_t pos){ if (cache->file_pos == pos) return true;
off_t res = lseek(cache->fd, pos, SEEK_SET);
if (res == (off_t)-1) { MP_ERR(cache, "Failed to seek in cache file.\n"); cache->file_pos = -1; } else { cache->file_pos = res; }
return cache->file_pos >= 0;}
static bool write_raw(struct demux_cache *cache, void *ptr, size_t len){ ssize_t res = write(cache->fd, ptr, len);
if (res < 0) { MP_ERR(cache, "Failed to write to cache file: %s\n", mp_strerror(errno)); return false; }
cache->file_pos += res; cache->file_size = MPMAX(cache->file_size, cache->file_pos);
// Should never happen, unless the disk is full, or someone succeeded to // trick us to write into a pipe or a socket. if (res != len) { MP_ERR(cache, "Could not write all data.\n"); return false; }
return true;}
static bool read_raw(struct demux_cache *cache, void *ptr, size_t len){ ssize_t res = read(cache->fd, ptr, len);
if (res < 0) { MP_ERR(cache, "Failed to read cache file: %s\n", mp_strerror(errno)); return false; }
cache->file_pos += res;
// Should never happen, unless the file was cut short, or someone succeeded // to rick us to write into a pipe or a socket. if (res != len) { MP_ERR(cache, "Could not read all data.\n"); return false; }
return true;}
// Serialize a packet to the cache file. Returns the packet position, which can// be passed to demux_cache_read() to read the packet again.// Returns a negative value on errors, i.e. writing the file failed.int64_t demux_cache_write(struct demux_cache *cache, struct demux_packet *dp){ assert(dp->avpacket);
// AV_PKT_FLAG_TRUSTED usually means there are embedded pointers and such // in the packet data. The pointer will become invalid if the packet is // unreferenced. if (dp->avpacket->flags & AV_PKT_FLAG_TRUSTED) { MP_ERR(cache, "Cannot serialize this packet to cache file.\n"); return -1; }
assert(!dp->is_cached); assert(dp->len >= 0 && dp->len <= INT32_MAX); assert(dp->avpacket->flags >= 0 && dp->avpacket->flags <= INT32_MAX); assert(dp->avpacket->side_data_elems >= 0 && dp->avpacket->side_data_elems <= INT32_MAX);
if (!do_seek(cache, cache->file_size)) return -1;
uint64_t pos = cache->file_pos;
struct pkt_header hd = { .data_len = dp->len, .av_flags = dp->avpacket->flags, .num_sd = dp->avpacket->side_data_elems, };
if (!write_raw(cache, &hd, sizeof(hd))) goto fail;
if (!write_raw(cache, dp->buffer, dp->len)) goto fail;
// The handling of FFmpeg side data requires an extra long comment to // explain why this code is fragile and insane. // FFmpeg packet side data is per-packet out of band data, that contains // further information for the decoder (extra metadata and such), which is // not part of the codec itself and thus isn't contained in the packet // payload. All types use a flat byte array. The format of this byte array // is non-standard and FFmpeg-specific, and depends on the side data type // field. The side data type is of course a FFmpeg ABI artifact. // In some cases, the format is described as fixed byte layout. In others, // it contains a struct, i.e. is bound to FFmpeg ABI. Some newer types make // the format explicitly internal (and _not_ part of the ABI), and you need // to use separate accessors to turn it into complex data structures. // As of now, FFmpeg fortunately adheres to the idea that side data can not // contain embedded pointers (due to API rules, but also because they forgot // adding a refcount field, and can't change this until they break ABI). // We rely on this. We hope that FFmpeg won't silently change their // semantics, and add refcounting and embedded pointers. This way we can // for example dump the data in a disk cache, even though we can't use the // data from another process or if this process is restarted (unless we're // absolutely sure the FFmpeg internals didn't change). The data has to be // treated as a memory dump. for (int n = 0; n < dp->avpacket->side_data_elems; n++) { AVPacketSideData *sd = &dp->avpacket->side_data[n];
assert(sd->size >= 0 && sd->size <= INT32_MAX); assert(sd->type >= 0 && sd->type <= INT32_MAX);
struct sd_header sd_hd = { .av_type = sd->type, .len = sd->size, };
if (!write_raw(cache, &sd_hd, sizeof(sd_hd))) goto fail; if (!write_raw(cache, sd->data, sd->size)) goto fail; }
return pos;
fail: // Reset file_size (try not to append crap forever). do_seek(cache, pos); cache->file_size = cache->file_pos; return -1;}
struct demux_packet *demux_cache_read(struct demux_cache *cache, uint64_t pos){ if (!do_seek(cache, pos)) return NULL;
struct pkt_header hd;
if (!read_raw(cache, &hd, sizeof(hd))) return NULL;
if (hd.data_len >= (size_t)-1) return NULL;
struct demux_packet *dp = new_demux_packet(hd.data_len); if (!dp) goto fail;
if (!read_raw(cache, dp->buffer, dp->len)) goto fail;
dp->avpacket->flags = hd.av_flags;
for (uint32_t n = 0; n < hd.num_sd; n++) { struct sd_header sd_hd;
if (!read_raw(cache, &sd_hd, sizeof(sd_hd))) goto fail;
if (sd_hd.len > INT_MAX) goto fail;
uint8_t *sd = av_packet_new_side_data(dp->avpacket, sd_hd.av_type, sd_hd.len); if (!sd) goto fail;
if (!read_raw(cache, sd, sd_hd.len)) goto fail; }
return dp;
fail: talloc_free(dp); return NULL;}