ffmpeg/libavformat/avio.h

/*
 * unbuffered io for ffmpeg system
 * 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
 */
#ifndef AVIO_H
#define AVIO_H

/* output byte stream handling */

typedef int64_t offset_t;

/* unbuffered I/O */

struct URLContext {
    struct URLProtocol *prot;
    int flags;
    int is_streamed;  /* true if streamed (no seek possible), default = false */
    int max_packet_size;  /* if non zero, the stream is packetized with this max packet size */
    void *priv_data;
#if LIBAVFORMAT_VERSION_INT >= (52<<16)
    char *filename; /* specified filename */
#else
    char filename[1]; /* specified filename */
#endif
};

typedef struct URLContext URLContext;

typedef struct URLPollEntry {
    URLContext *handle;
    int events;
    int revents;
} URLPollEntry;

#define URL_RDONLY 0
#define URL_WRONLY 1
#define URL_RDWR   2

typedef int URLInterruptCB(void);

int url_open(URLContext **h, const char *filename, int flags);
int url_read(URLContext *h, unsigned char *buf, int size);
int url_write(URLContext *h, unsigned char *buf, int size);
offset_t url_seek(URLContext *h, offset_t pos, int whence);
int url_close(URLContext *h);
int url_exist(const char *filename);
offset_t url_filesize(URLContext *h);
int url_get_max_packet_size(URLContext *h);
void url_get_filename(URLContext *h, char *buf, int buf_size);

/* the callback is called in blocking functions to test regulary if
   asynchronous interruption is needed. AVERROR(EINTR) is returned
   in this case by the interrupted function. 'NULL' means no interrupt
   callback is given. */
void url_set_interrupt_cb(URLInterruptCB *interrupt_cb);

/* not implemented */
int url_poll(URLPollEntry *poll_table, int n, int timeout);

/**
 * passing this as the "whence" parameter to a seek function causes it to
 * return the filesize without seeking anywhere, supporting this is optional
 * if its not supprted then the seek function will return <0
 */
#define AVSEEK_SIZE 0x10000

typedef struct URLProtocol {
    const char *name;
    int (*url_open)(URLContext *h, const char *filename, int flags);
    int (*url_read)(URLContext *h, unsigned char *buf, int size);
    int (*url_write)(URLContext *h, unsigned char *buf, int size);
    offset_t (*url_seek)(URLContext *h, offset_t pos, int whence);
    int (*url_close)(URLContext *h);
    struct URLProtocol *next;
} URLProtocol;

extern URLProtocol *first_protocol;
extern URLInterruptCB *url_interrupt_cb;

int register_protocol(URLProtocol *protocol);

typedef struct {
    unsigned char *buffer;
    int buffer_size;
    unsigned char *buf_ptr, *buf_end;
    void *opaque;
    int (*read_packet)(void *opaque, uint8_t *buf, int buf_size);
    int (*write_packet)(void *opaque, uint8_t *buf, int buf_size);
    offset_t (*seek)(void *opaque, offset_t offset, int whence);
    offset_t pos; /* position in the file of the current buffer */
    int must_flush; /* true if the next seek should flush */
    int eof_reached; /* true if eof reached */
    int write_flag;  /* true if open for writing */
    int is_streamed;
    int max_packet_size;
    unsigned long checksum;
    unsigned char *checksum_ptr;
    unsigned long (*update_checksum)(unsigned long checksum, const uint8_t *buf, unsigned int size);
    int error;         ///< contains the error code or 0 if no error happened
} ByteIOContext;

int init_put_byte(ByteIOContext *s,
                  unsigned char *buffer,
                  int buffer_size,
                  int write_flag,
                  void *opaque,
                  int (*read_packet)(void *opaque, uint8_t *buf, int buf_size),
                  int (*write_packet)(void *opaque, uint8_t *buf, int buf_size),
                  offset_t (*seek)(void *opaque, offset_t offset, int whence));

void put_byte(ByteIOContext *s, int b);
void put_buffer(ByteIOContext *s, const unsigned char *buf, int size);
void put_le64(ByteIOContext *s, uint64_t val);
void put_be64(ByteIOContext *s, uint64_t val);
void put_le32(ByteIOContext *s, unsigned int val);
void put_be32(ByteIOContext *s, unsigned int val);
void put_le24(ByteIOContext *s, unsigned int val);
void put_be24(ByteIOContext *s, unsigned int val);
void put_le16(ByteIOContext *s, unsigned int val);
void put_be16(ByteIOContext *s, unsigned int val);
void put_tag(ByteIOContext *s, const char *tag);

void put_strz(ByteIOContext *s, const char *buf);

offset_t url_fseek(ByteIOContext *s, offset_t offset, int whence);
void url_fskip(ByteIOContext *s, offset_t offset);
offset_t url_ftell(ByteIOContext *s);
offset_t url_fsize(ByteIOContext *s);
int url_feof(ByteIOContext *s);
int url_ferror(ByteIOContext *s);

#define URL_EOF (-1)
/* NOTE: return URL_EOF (-1) if EOF */
int url_fgetc(ByteIOContext *s);

/* XXX: currently size is limited */
#ifdef __GNUC__
int url_fprintf(ByteIOContext *s, const char *fmt, ...) __attribute__ ((__format__ (__printf__, 2, 3)));
#else
int url_fprintf(ByteIOContext *s, const char *fmt, ...);
#endif

/* note: unlike fgets, the EOL character is not returned and a whole
   line is parsed. return NULL if first char read was EOF */
char *url_fgets(ByteIOContext *s, char *buf, int buf_size);

void put_flush_packet(ByteIOContext *s);

int get_buffer(ByteIOContext *s, unsigned char *buf, int size);
int get_partial_buffer(ByteIOContext *s, unsigned char *buf, int size);

/* NOTE: return 0 if EOF, so you cannot use it if EOF handling is
   necessary */
int get_byte(ByteIOContext *s);
unsigned int get_le24(ByteIOContext *s);
unsigned int get_le32(ByteIOContext *s);
uint64_t get_le64(ByteIOContext *s);
unsigned int get_le16(ByteIOContext *s);

char *get_strz(ByteIOContext *s, char *buf, int maxlen);
unsigned int get_be16(ByteIOContext *s);
unsigned int get_be24(ByteIOContext *s);
unsigned int get_be32(ByteIOContext *s);
uint64_t get_be64(ByteIOContext *s);

static inline int url_is_streamed(ByteIOContext *s)
{
    return s->is_streamed;
}

int url_fdopen(ByteIOContext *s, URLContext *h);

/* XXX: must be called before any I/O */
int url_setbufsize(ByteIOContext *s, int buf_size);

/* NOTE: when opened as read/write, the buffers are only used for
   reading */
int url_fopen(ByteIOContext *s, const char *filename, int flags);
int url_fclose(ByteIOContext *s);
URLContext *url_fileno(ByteIOContext *s);

/*
 * Return the maximum packet size associated to packetized buffered file
 * handle. If the file is not packetized (stream like http or file on
 * disk), then 0 is returned.
 *
 * @param h buffered file handle
 * @return maximum packet size in bytes
 */
int url_fget_max_packet_size(ByteIOContext *s);

int url_open_buf(ByteIOContext *s, uint8_t *buf, int buf_size, int flags);

/* return the written or read size */
int url_close_buf(ByteIOContext *s);

/*
 * Open a write only memory stream.
 *
 * @param s new IO context
 * @return zero if no error.
 */
int url_open_dyn_buf(ByteIOContext *s);

/*
 * Open a write only packetized memory stream with a maximum packet
 * size of 'max_packet_size'.  The stream is stored in a memory buffer
 * with a big endian 4 byte header giving the packet size in bytes.
 *
 * @param s new IO context
 * @param max_packet_size maximum packet size (must be > 0)
 * @return zero if no error.
 */
int url_open_dyn_packet_buf(ByteIOContext *s, int max_packet_size);

/*
 * Return the written size and a pointer to the buffer. The buffer
 *  must be freed with av_free().
 * @param s IO context
 * @param pointer to a byte buffer
 * @return the length of the byte buffer
 */
int url_close_dyn_buf(ByteIOContext *s, uint8_t **pbuffer);

unsigned long get_checksum(ByteIOContext *s);
void init_checksum(ByteIOContext *s, unsigned long (*update_checksum)(unsigned long c, const uint8_t *p, unsigned int len), unsigned long checksum);

/* file.c */
extern URLProtocol file_protocol;
extern URLProtocol pipe_protocol;

/* udp.c */
extern URLProtocol udp_protocol;
int udp_set_remote_url(URLContext *h, const char *uri);
int udp_get_local_port(URLContext *h);
int udp_get_file_handle(URLContext *h);

/* tcp.c  */
extern URLProtocol tcp_protocol;

/* http.c */
extern URLProtocol http_protocol;

#endif