Line data    Source code

       1             : #ifndef HEADER_fd_src_discof_restore_utils_fd_zstd_frame_h
       2             : #define HEADER_fd_src_discof_restore_utils_fd_zstd_frame_h
       3             : 
       4             : /* A Zstandard stream is a sequence of independent frames.  A normal
       5             :    frame contains a variable-size header, repeated 3-byte block headers
       6             :    and payloads, and an optional 4-byte checksum.  The last-block bit
       7             :    marks the frame boundary.  A skippable frame contains an 8-byte
       8             :    header followed by a sized payload.
       9             : 
      10             :      stream:
      11             :        +---------- frame 0 ----------+ +---------- frame 1 ----------+
      12             :        | header | blocks | checksum? | | header | blocks | checksum? |
      13             :        +-----------------------------+ +-----------------------------+
      14             : 
      15             :      normal frame:
      16             :        +--------+ +-------------------------+     +-----------+
      17             :        | header | | block header(3) | data | ... | checksum? |
      18             :        +--------+ +-------------------------+     +-----------+
      19             :                          `last` marks the final block
      20             : 
      21             :      skippable frame:
      22             :        +----------+-----------------+---------+
      23             :        | magic(4) | payload size(4) | payload |
      24             :        +----------+-----------------+---------+
      25             : 
      26             :    This scanner accepts fragmented input, keeps only partial headers,
      27             :    skips payload bytes without decompressing them, and returns END at
      28             :    the exact frame boundary. */
      29             : 
      30             : #include "../../../util/fd_util_base.h"
      31             : 
      32        1974 : #define FD_ZSTD_FRAME_MORE (0)  /* Frame end not reached */
      33        1323 : #define FD_ZSTD_FRAME_END  (1)  /* Frame end reached */
      34          30 : #define FD_ZSTD_FRAME_ERR  (-1) /* Frame is invalid */
      35             : 
      36             : #define FD_ZSTD_FRAME_HEADER_MAX      (18UL)
      37        1293 : #define FD_ZSTD_FRAME_BLOCK_HEADER_SZ (3UL)
      38             : 
      39             : struct fd_zstd_frame {
      40             :   uchar header      [ FD_ZSTD_FRAME_HEADER_MAX ];
      41             :   uchar block_header[ FD_ZSTD_FRAME_BLOCK_HEADER_SZ ];
      42             :   ulong bytes_remaining;
      43             :   uint  block_sz_max;
      44             :   uchar header_sz;
      45             :   uchar block_header_sz;
      46             :   uchar state;
      47             :   uchar checksum_sz;
      48             :   uchar last_block;
      49             : };
      50             : 
      51             : typedef struct fd_zstd_frame fd_zstd_frame_t;
      52             : 
      53             : FD_PROTOTYPES_BEGIN
      54             : 
      55             : static inline fd_zstd_frame_t *
      56       26133 : fd_zstd_frame_new( fd_zstd_frame_t * frame ) {
      57       26133 :   if( FD_UNLIKELY( !frame ) ) return NULL;
      58       26133 :   fd_memset( frame, 0, sizeof(fd_zstd_frame_t) );
      59       26133 :   return frame;
      60       26133 : }
      61             : 
      62             : /* fd_zstd_frame_advance assumes frame, data, and consumed are non-NULL.
      63             :    It scans up to data_sz bytes and writes the number used to *consumed.
      64             :    It returns MORE if more input is needed, END at the frame boundary,
      65             :    or ERR for invalid framing. */
      66             : 
      67             : int
      68             : fd_zstd_frame_advance( fd_zstd_frame_t * frame,
      69             :                        void const *      data,
      70             :                        ulong             data_sz,
      71             :                        ulong *           consumed );
      72             : 
      73             : FD_PROTOTYPES_END
      74             : 
      75             : #endif /* HEADER_fd_src_discof_restore_utils_fd_zstd_frame_h */