nix/libutil/hash.hh

   1 #pragma once
   2
   3 #include "types.hh"
   4 #include "serialise.hh"
   5
   6
   7 namespace nix {
   8
   9
  10 typedef enum { htUnknown, htMD5, htSHA1, htSHA256, htSHA512 } HashType;
  11
  12
  13 const int md5HashSize = 16;
  14 const int sha1HashSize = 20;
  15 const int sha256HashSize = 32;
  16 const int sha512HashSize = 64;
  17
  18 extern const string base32Chars;
  19
  20
  21 struct Hash
  22 {
  23     static const unsigned int maxHashSize = 64;
  24     unsigned int hashSize;
  25     unsigned char hash[maxHashSize];
  26
  27     HashType type;
  28
  29     /* Create an unusable hash object. */
  30     Hash();
  31
  32     /* Create a zero-filled hash object. */
  33     Hash(HashType type);
  34
  35     /* Check whether two hash are equal. */
  36     bool operator == (const Hash & h2) const;
  37
  38     /* Check whether two hash are not equal. */
  39     bool operator != (const Hash & h2) const;
  40
  41     /* For sorting. */
  42     bool operator < (const Hash & h) const;
  43 };
  44
  45
  46 /* Convert a hash to a hexadecimal representation. */
  47 string printHash(const Hash & hash);
  48
  49 /* Parse a hexadecimal representation of a hash code. */
  50 Hash parseHash(HashType ht, const string & s);
  51
  52 /* Returns the length of a base-32 hash representation. */
  53 unsigned int hashLength32(const Hash & hash);
  54
  55 /* Convert a hash to a base-32 representation. */
  56 string printHash32(const Hash & hash);
  57
  58 /* Print a hash in base-16 if it's MD5, or base-32 otherwise. */
  59 string printHash16or32(const Hash & hash);
  60
  61 /* Parse a base-32 representation of a hash code. */
  62 Hash parseHash32(HashType ht, const string & s);
  63
  64 /* Parse a base-16 or base-32 representation of a hash code. */
  65 Hash parseHash16or32(HashType ht, const string & s);
  66
  67 /* Verify that the given string is a valid hash code. */
  68 bool isHash(const string & s);
  69
  70 /* Compute the hash of the given string. */
  71 Hash hashString(HashType ht, const string & s);
  72
  73 /* Compute the hash of the given file. */
  74 Hash hashFile(HashType ht, const Path & path);
  75
  76 /* Compute the hash of the given path.  The hash is defined as
  77    (essentially) hashString(ht, dumpPath(path)). */
  78 struct PathFilter;
  79 extern PathFilter defaultPathFilter;
  80 typedef std::pair<Hash, unsigned long long> HashResult;
  81 HashResult hashPath(HashType ht, const Path & path,
  82     PathFilter & filter = defaultPathFilter);
  83
  84 /* Compress a hash to the specified number of bytes by cyclically
  85    XORing bytes together. */
  86 Hash compressHash(const Hash & hash, unsigned int newSize);
  87
  88 /* Parse a string representing a hash type. */
  89 HashType parseHashType(const string & s);
  90
  91 /* And the reverse. */
  92 string printHashType(HashType ht);
  93
  94
  95 struct Ctx;
  96
  97 class HashSink : public BufferedSink
  98 {
  99 private:
 100     HashType ht;
 101     Ctx * ctx;
 102     unsigned long long bytes;
 103
 104 public:
 105     HashSink(HashType ht);
 106     HashSink(const HashSink & h);
 107     ~HashSink();
 108     void write(const unsigned char * data, size_t len);
 109     HashResult finish();
 110     HashResult currentHash();
 111 };
 112
 113
 114 }