chunk-format.h

   1 #ifndef CHUNK_FORMAT_H
   2 #define CHUNK_FORMAT_H
   3
   4 #include "hash-ll.h"
   5
   6 struct hashfile;
   7 struct chunkfile;
   8
   9 #define CHUNK_TOC_ENTRY_SIZE (sizeof(uint32_t) + sizeof(uint64_t))
  10
  11 /*
  12  * Initialize a 'struct chunkfile' for writing _or_ reading a file
  13  * with the chunk format.
  14  *
  15  * If writing a file, supply a non-NULL 'struct hashfile *' that will
  16  * be used to write.
  17  *
  18  * If reading a file, use a NULL 'struct hashfile *' and then call
  19  * read_table_of_contents(). Supply the memory-mapped data to the
  20  * pair_chunk() or read_chunk() methods, as appropriate.
  21  *
  22  * DO NOT MIX THESE MODES. Use different 'struct chunkfile' instances
  23  * for reading and writing.
  24  */
  25 struct chunkfile *init_chunkfile(struct hashfile *f);
  26 void free_chunkfile(struct chunkfile *cf);
  27 int get_num_chunks(struct chunkfile *cf);
  28 typedef int (*chunk_write_fn)(struct hashfile *f, void *data);
  29 void add_chunk(struct chunkfile *cf,
  30                uint32_t id,
  31                size_t size,
  32                chunk_write_fn fn);
  33 int write_chunkfile(struct chunkfile *cf, void *data);
  34
  35 int read_table_of_contents(struct chunkfile *cf,
  36                            const unsigned char *mfile,
  37                            size_t mfile_size,
  38                            uint64_t toc_offset,
  39                            int toc_length,
  40                            unsigned expected_alignment);
  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. Likewise the "size" parameter is filled
  48  * with the size of the chunk.
  49  *
  50  * Returns CHUNK_NOT_FOUND if the chunk does not exist.
  51  */
  52 int pair_chunk(struct chunkfile *cf,
  53                uint32_t chunk_id,
  54                const unsigned char **p,
  55                size_t *size);
  56
  57 /*
  58  * Unsafe version of pair_chunk; it does not return the size,
  59  * meaning that the caller cannot possibly be careful about
  60  * reading out of bounds from the mapped memory.
  61  *
  62  * No new callers should use this function, and old callers should
  63  * be audited and migrated over to using the regular pair_chunk()
  64  * function.
  65  */
  66 int pair_chunk_unsafe(struct chunkfile *cf,
  67                       uint32_t chunk_id,
  68                       const unsigned char **p);
  69
  70 typedef int (*chunk_read_fn)(const unsigned char *chunk_start,
  71                              size_t chunk_size, void *data);
  72 /*
  73  * Find 'chunk_id' in the given chunkfile and call the
  74  * given chunk_read_fn method with the information for
  75  * that chunk.
  76  *
  77  * Returns CHUNK_NOT_FOUND if the chunk does not exist.
  78  */
  79 int read_chunk(struct chunkfile *cf,
  80                uint32_t chunk_id,
  81                chunk_read_fn fn,
  82                void *data);
  83
  84 uint8_t oid_version(const struct git_hash_algo *algop);
  85
  86 #endif