file.c

Go to the documentation of this file.

/*
 * buffered file I/O
 * Copyright (c) 2001 Fabrice Bellard
 *
 * 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
 */
 
#include "libavutil/avstring.h"
#include "libavutil/internal.h"
#include "libavutil/opt.h"
#include "avformat.h"
#if HAVE_DIRENT_H
#include <dirent.h>
#endif
#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"
 
/* Some systems may not have S_ISFIFO */
#ifndef S_ISFIFO
#  ifdef S_IFIFO
#    define S_ISFIFO(m) (((m) & S_IFMT) == S_IFIFO)
#  else
#    define S_ISFIFO(m) 0
#  endif
#endif
 
/* Not available in POSIX.1-1996 */
#ifndef S_ISLNK
#  ifdef S_IFLNK
#    define S_ISLNK(m) (((m) & S_IFLNK) == S_IFLNK)
#  else
#    define S_ISLNK(m) 0
#  endif
#endif
 
/* Not available in POSIX.1-1996 */
#ifndef S_ISSOCK
#  ifdef S_IFSOCK
#    define S_ISSOCK(m) (((m) & S_IFMT) == S_IFSOCK)
#  else
#    define S_ISSOCK(m) 0
#  endif
#endif
 
/* standard file protocol */
 
typedef struct FileContext {
    const AVClass *class;
    int fd;
    int trunc;
    int blocksize;
    int follow;
    int seekable;
#if HAVE_DIRENT_H
    DIR *dir;
#endif
} FileContext;
 
static const AVOption file_options[] = {
    { "truncate", "truncate existing files on write", offsetof(FileContext, trunc), AV_OPT_TYPE_BOOL, { .i64 = 1 }, 0, 1, AV_OPT_FLAG_ENCODING_PARAM },
    { "blocksize", "set I/O operation maximum block size", offsetof(FileContext, blocksize), AV_OPT_TYPE_INT, { .i64 = INT_MAX }, 1, INT_MAX, AV_OPT_FLAG_ENCODING_PARAM },
    { "follow", "Follow a file as it is being written", offsetof(FileContext, follow), AV_OPT_TYPE_INT, { .i64 = 0 }, 0, 1, AV_OPT_FLAG_DECODING_PARAM },
    { "seekable", "Sets if the file is seekable", offsetof(FileContext, seekable), AV_OPT_TYPE_INT, { .i64 = -1 }, -1, 0, AV_OPT_FLAG_DECODING_PARAM | AV_OPT_FLAG_ENCODING_PARAM },
    { NULL }
};
 
static const AVOption pipe_options[] = {
    { "blocksize", "set I/O operation maximum block size", offsetof(FileContext, blocksize), AV_OPT_TYPE_INT, { .i64 = INT_MAX }, 1, INT_MAX, AV_OPT_FLAG_ENCODING_PARAM },
    { NULL }
};
 
static const AVClass file_class = {
    .class_name = "file",
    .item_name  = av_default_item_name,
    .option     = file_options,
    .version    = LIBAVUTIL_VERSION_INT,
};
 
static const AVClass pipe_class = {
    .class_name = "pipe",
    .item_name  = av_default_item_name,
    .option     = pipe_options,
    .version    = LIBAVUTIL_VERSION_INT,
};
 
static int file_read(URLContext *h, unsigned char *buf, int size)
{
    FileContext *c = h->priv_data;
    int ret;
    size = FFMIN(size, c->blocksize);
    ret = read(c->fd, buf, size);
    if (ret == 0 && c->follow)
        return AVERROR(EAGAIN);
    if (ret == 0)
        return AVERROR_EOF;
    return (ret == -1) ? AVERROR(errno) : ret;
}
 
static int file_write(URLContext *h, const unsigned char *buf, int size)
{
    FileContext *c = h->priv_data;
    int ret;
    size = FFMIN(size, c->blocksize);
    ret = write(c->fd, buf, size);
    return (ret == -1) ? AVERROR(errno) : ret;
}
 
static int file_get_handle(URLContext *h)
{
    FileContext *c = h->priv_data;
    return c->fd;
}
 
static int file_check(URLContext *h, int mask)
{
    int ret = 0;
    const char *filename = h->filename;
    av_strstart(filename, "file:", &filename);
 
    {
#if HAVE_ACCESS && defined(R_OK)
    if (access(filename, F_OK) < 0)
        return AVERROR(errno);
    if (mask&AVIO_FLAG_READ)
        if (access(filename, R_OK) >= 0)
            ret |= AVIO_FLAG_READ;
    if (mask&AVIO_FLAG_WRITE)
        if (access(filename, W_OK) >= 0)
            ret |= AVIO_FLAG_WRITE;
#else
    struct stat st;
#   ifndef _WIN32
    ret = stat(filename, &st);
#   else
    ret = win32_stat(filename, &st);
#   endif
    if (ret < 0)
        return AVERROR(errno);
 
    ret |= st.st_mode&S_IRUSR ? mask&AVIO_FLAG_READ  : 0;
    ret |= st.st_mode&S_IWUSR ? mask&AVIO_FLAG_WRITE : 0;
#endif
    }
    return ret;
}
 
static int file_delete(URLContext *h)
{
#if HAVE_UNISTD_H
    int ret;
    const char *filename = h->filename;
    av_strstart(filename, "file:", &filename);
 
    ret = rmdir(filename);
    if (ret < 0 && (errno == ENOTDIR
#   ifdef _WIN32
        || errno == EINVAL
#   endif
        ))
        ret = unlink(filename);
    if (ret < 0)
        return AVERROR(errno);
 
    return ret;
#else
    return AVERROR(ENOSYS);
#endif /* HAVE_UNISTD_H */
}
 
static int file_move(URLContext *h_src, URLContext *h_dst)
{
    const char *filename_src = h_src->filename;
    const char *filename_dst = h_dst->filename;
    av_strstart(filename_src, "file:", &filename_src);
    av_strstart(filename_dst, "file:", &filename_dst);
 
    if (rename(filename_src, filename_dst) < 0)
        return AVERROR(errno);
 
    return 0;
}
 
#if CONFIG_FILE_PROTOCOL
 
static int file_open(URLContext *h, const char *filename, int flags)
{
    FileContext *c = h->priv_data;
    int access;
    int fd;
    struct stat st;
 
    av_strstart(filename, "file:", &filename);
 
    if (flags & AVIO_FLAG_WRITE && flags & AVIO_FLAG_READ) {
        access = O_CREAT | O_RDWR;
        if (c->trunc)
            access |= O_TRUNC;
    } else if (flags & AVIO_FLAG_WRITE) {
        access = O_CREAT | O_WRONLY;
        if (c->trunc)
            access |= O_TRUNC;
    } else {
        access = O_RDONLY;
    }
#ifdef O_BINARY
    access |= O_BINARY;
#endif
    fd = avpriv_open(filename, access, 0666);
    if (fd == -1)
        return AVERROR(errno);
    c->fd = fd;
 
    h->is_streamed = !fstat(fd, &st) && S_ISFIFO(st.st_mode);
 
    /* Buffer writes more than the default 32k to improve throughput especially
     * with networked file systems */
    if (!h->is_streamed && flags & AVIO_FLAG_WRITE)
        h->min_packet_size = h->max_packet_size = 262144;
 
    if (c->seekable >= 0)
        h->is_streamed = !c->seekable;
 
    return 0;
}
 
/* XXX: use llseek */
static int64_t file_seek(URLContext *h, int64_t pos, int whence)
{
    FileContext *c = h->priv_data;
    int64_t ret;
 
    if (whence == AVSEEK_SIZE) {
        struct stat st;
        ret = fstat(c->fd, &st);
        return ret < 0 ? AVERROR(errno) : (S_ISFIFO(st.st_mode) ? 0 : st.st_size);
    }
 
    ret = lseek(c->fd, pos, whence);
 
    return ret < 0 ? AVERROR(errno) : ret;
}
 
static int file_close(URLContext *h)
{
    FileContext *c = h->priv_data;
    return close(c->fd);
}
 
static int file_open_dir(URLContext *h)
{
#if HAVE_LSTAT
    FileContext *c = h->priv_data;
 
    c->dir = opendir(h->filename);
    if (!c->dir)
        return AVERROR(errno);
 
    return 0;
#else
    return AVERROR(ENOSYS);
#endif /* HAVE_LSTAT */
}
 
static int file_read_dir(URLContext *h, AVIODirEntry **next)
{
#if HAVE_LSTAT
    FileContext *c = h->priv_data;
    struct dirent *dir;
    char *fullpath = NULL;
 
    *next = ff_alloc_dir_entry();
    if (!*next)
        return AVERROR(ENOMEM);
    do {
        errno = 0;
        dir = readdir(c->dir);
        if (!dir) {
            av_freep(next);
            return AVERROR(errno);
        }
    } while (!strcmp(dir->d_name, ".") || !strcmp(dir->d_name, ".."));
 
    fullpath = av_append_path_component(h->filename, dir->d_name);
    if (fullpath) {
        struct stat st;
        if (!lstat(fullpath, &st)) {
            if (S_ISDIR(st.st_mode))
                (*next)->type = AVIO_ENTRY_DIRECTORY;
            else if (S_ISFIFO(st.st_mode))
                (*next)->type = AVIO_ENTRY_NAMED_PIPE;
            else if (S_ISCHR(st.st_mode))
                (*next)->type = AVIO_ENTRY_CHARACTER_DEVICE;
            else if (S_ISBLK(st.st_mode))
                (*next)->type = AVIO_ENTRY_BLOCK_DEVICE;
            else if (S_ISLNK(st.st_mode))
                (*next)->type = AVIO_ENTRY_SYMBOLIC_LINK;
            else if (S_ISSOCK(st.st_mode))
                (*next)->type = AVIO_ENTRY_SOCKET;
            else if (S_ISREG(st.st_mode))
                (*next)->type = AVIO_ENTRY_FILE;
            else
                (*next)->type = AVIO_ENTRY_UNKNOWN;
 
            (*next)->group_id = st.st_gid;
            (*next)->user_id = st.st_uid;
            (*next)->size = st.st_size;
            (*next)->filemode = st.st_mode & 0777;
            (*next)->modification_timestamp = INT64_C(1000000) * st.st_mtime;
            (*next)->access_timestamp =  INT64_C(1000000) * st.st_atime;
            (*next)->status_change_timestamp = INT64_C(1000000) * st.st_ctime;
        }
        av_free(fullpath);
    }
 
    (*next)->name = av_strdup(dir->d_name);
    return 0;
#else
    return AVERROR(ENOSYS);
#endif /* HAVE_LSTAT */
}
 
static int file_close_dir(URLContext *h)
{
#if HAVE_LSTAT
    FileContext *c = h->priv_data;
    closedir(c->dir);
    return 0;
#else
    return AVERROR(ENOSYS);
#endif /* HAVE_LSTAT */
}
 
const URLProtocol ff_file_protocol = {
    .name                = "file",
    .url_open            = file_open,
    .url_read            = file_read,
    .url_write           = file_write,
    .url_seek            = file_seek,
    .url_close           = file_close,
    .url_get_file_handle = file_get_handle,
    .url_check           = file_check,
    .url_delete          = file_delete,
    .url_move            = file_move,
    .priv_data_size      = sizeof(FileContext),
    .priv_data_class     = &file_class,
    .url_open_dir        = file_open_dir,
    .url_read_dir        = file_read_dir,
    .url_close_dir       = file_close_dir,
    .default_whitelist   = "file,crypto,data"
};
 
#endif /* CONFIG_FILE_PROTOCOL */
 
#if CONFIG_PIPE_PROTOCOL
 
static int pipe_open(URLContext *h, const char *filename, int flags)
{
    FileContext *c = h->priv_data;
    int fd;
    char *final;
    av_strstart(filename, "pipe:", &filename);
 
    fd = strtol(filename, &final, 10);
    if((filename == final) || *final ) {/* No digits found, or something like 10ab */
        if (flags & AVIO_FLAG_WRITE) {
            fd = 1;
        } else {
            fd = 0;
        }
    }
#if HAVE_SETMODE
    setmode(fd, O_BINARY);
#endif
    c->fd = fd;
    h->is_streamed = 1;
    return 0;
}
 
const URLProtocol ff_pipe_protocol = {
    .name                = "pipe",
    .url_open            = pipe_open,
    .url_read            = file_read,
    .url_write           = file_write,
    .url_get_file_handle = file_get_handle,
    .url_check           = file_check,
    .priv_data_size      = sizeof(FileContext),
    .priv_data_class     = &pipe_class,
    .default_whitelist   = "crypto,data"
};
 
#endif /* CONFIG_PIPE_PROTOCOL */