hex.h

   1 #ifndef HEX_H
   2 #define HEX_H
   3
   4 #include "hash-ll.h"
   5
   6 extern const signed char hexval_table[256];
   7 static inline unsigned int hexval(unsigned char c)
   8 {
   9         return hexval_table[c];
  10 }
  11
  12 /*
  13  * Convert two consecutive hexadecimal digits into a char.  Return a
  14  * negative value on error.  Don't run over the end of short strings.
  15  */
  16 static inline int hex2chr(const char *s)
  17 {
  18         unsigned int val = hexval(s[0]);
  19         return (val & ~0xf) ? val : (val << 4) | hexval(s[1]);
  20 }
  21
  22 /*
  23  * Try to read a hash (specified by the_hash_algo) in hexadecimal
  24  * format from the 40 (or whatever length the hash algorithm uses)
  25  * characters starting at hex.  Write the 20-byte (or the length of
  26  * the hash) result to hash in binary form.
  27  * Return 0 on success.  Reading stops if a NUL is encountered in the
  28  * input, so it is safe to pass this function an arbitrary
  29  * null-terminated string.
  30  */
  31 int get_hash_hex(const char *hex, unsigned char *hash);
  32 int get_oid_hex(const char *hex, struct object_id *oid);
  33
  34 /* Like get_oid_hex, but for an arbitrary hash algorithm. */
  35 int get_oid_hex_algop(const char *hex, struct object_id *oid, const struct git_hash_algo *algop);
  36
  37 /*
  38  * Read `len` pairs of hexadecimal digits from `hex` and write the
  39  * values to `binary` as `len` bytes. Return 0 on success, or -1 if
  40  * the input does not consist of hex digits).
  41  */
  42 int hex_to_bytes(unsigned char *binary, const char *hex, size_t len);
  43
  44 /*
  45  * Convert a binary hash in "unsigned char []" or an object name in
  46  * "struct object_id *" to its hex equivalent. The `_r` variant is reentrant,
  47  * and writes the NUL-terminated output to the buffer `out`, which must be at
  48  * least `GIT_MAX_HEXSZ + 1` bytes, and returns a pointer to out for
  49  * convenience.
  50  *
  51  * The non-`_r` variant returns a static buffer, but uses a ring of 4
  52  * buffers, making it safe to make multiple calls for a single statement, like:
  53  *
  54  *   printf("%s -> %s", hash_to_hex(one), hash_to_hex(two));
  55  *   printf("%s -> %s", oid_to_hex(one), oid_to_hex(two));
  56  */
  57 char *hash_to_hex_algop_r(char *buffer, const unsigned char *hash, const struct git_hash_algo *);
  58 char *oid_to_hex_r(char *out, const struct object_id *oid);
  59 char *hash_to_hex_algop(const unsigned char *hash, const struct git_hash_algo *);       /* static buffer result! */
  60 char *hash_to_hex(const unsigned char *hash);                                           /* same static buffer */
  61 char *oid_to_hex(const struct object_id *oid);                                          /* same static buffer */
  62
  63 /*
  64  * Parse a 40-character hexadecimal object ID starting from hex, updating the
  65  * pointer specified by end when parsing stops.  The resulting object ID is
  66  * stored in oid.  Returns 0 on success.  Parsing will stop on the first NUL or
  67  * other invalid character.  end is only updated on success; otherwise, it is
  68  * unmodified.
  69  */
  70 int parse_oid_hex(const char *hex, struct object_id *oid, const char **end);
  71
  72 /* Like parse_oid_hex, but for an arbitrary hash algorithm. */
  73 int parse_oid_hex_algop(const char *hex, struct object_id *oid, const char **end,
  74                         const struct git_hash_algo *algo);
  75
  76
  77 /*
  78  * These functions work like get_oid_hex and parse_oid_hex, but they will parse
  79  * a hex value for any algorithm. The algorithm is detected based on the length
  80  * and the algorithm in use is returned. If this is not a hex object ID in any
  81  * algorithm, returns GIT_HASH_UNKNOWN.
  82  */
  83 int get_oid_hex_any(const char *hex, struct object_id *oid);
  84 int parse_oid_hex_any(const char *hex, struct object_id *oid, const char **end);
  85
  86 #endif