chunk-format.h

   1 #ifndef CHUNK_FORMAT_H
   2 #define CHUNK_FORMAT_H
   3
   4 #include "git-compat-util.h"
   5 #include "hash.h"
   6
   7 struct hashfile;
   8 struct chunkfile;
   9
  10 #define CHUNK_TOC_ENTRY_SIZE (sizeof(uint32_t) + sizeof(uint64_t))
  11
  12 /*
  13  * Initialize a 'struct chunkfile' for writing _or_ reading a file
  14  * with the chunk format.
  15  *
  16  * If writing a file, supply a non-NULL 'struct hashfile *' that will
  17  * be used to write.
  18  *
  19  * If reading a file, use a NULL 'struct hashfile *' and then call
  20  * read_table_of_contents(). Supply the memory-mapped data to the
  21  * pair_chunk() or read_chunk() methods, as appropriate.
  22  *
  23  * DO NOT MIX THESE MODES. Use different 'struct chunkfile' instances
  24  * for reading and writing.
  25  */
  26 struct chunkfile *init_chunkfile(struct hashfile *f);
  27 void free_chunkfile(struct chunkfile *cf);
  28 int get_num_chunks(struct chunkfile *cf);
  29 typedef int (*chunk_write_fn)(struct hashfile *f, void *data);
  30 void add_chunk(struct chunkfile *cf,
  31                uint32_t id,
  32                size_t size,
  33                chunk_write_fn fn);
  34 int write_chunkfile(struct chunkfile *cf, void *data);
  35
  36 int read_table_of_contents(struct chunkfile *cf,
  37                            const unsigned char *mfile,
  38                            size_t mfile_size,
  39                            uint64_t toc_offset,
  40                            int toc_length);
  41
  42 #define CHUNK_NOT_FOUND (-2)
  43
  44 /*
  45  * Find 'chunk_id' in the given chunkfile and assign the
  46  * given pointer to the position in the mmap'd file where
  47  * that chunk begins.
  48  *
  49  * Returns CHUNK_NOT_FOUND if the chunk does not exist.
  50  */
  51 int pair_chunk(struct chunkfile *cf,
  52                uint32_t chunk_id,
  53                const unsigned char **p);
  54
  55 typedef int (*chunk_read_fn)(const unsigned char *chunk_start,
  56                              size_t chunk_size, void *data);
  57 /*
  58  * Find 'chunk_id' in the given chunkfile and call the
  59  * given chunk_read_fn method with the information for
  60  * that chunk.
  61  *
  62  * Returns CHUNK_NOT_FOUND if the chunk does not exist.
  63  */
  64 int read_chunk(struct chunkfile *cf,
  65                uint32_t chunk_id,
  66                chunk_read_fn fn,
  67                void *data);
  68
  69 uint8_t oid_version(const struct git_hash_algo *algop);
  70
  71 #endif