nix-super/src/libutil/hash.hh
Eelco Dolstra 451ebf24ce Cache path info lookups in SQLite
This re-implements the binary cache database in C++, allowing it to be
used by other Store backends, in particular the S3 backend.
2016-04-20 14:12:38 +02:00

133 lines
3.1 KiB
C++

#pragma once
#include "types.hh"
#include "serialise.hh"
namespace nix {
MakeError(BadHash, Error);
enum HashType : char { htUnknown, htMD5, htSHA1, htSHA256, htSHA512 };
const int md5HashSize = 16;
const int sha1HashSize = 20;
const int sha256HashSize = 32;
const int sha512HashSize = 64;
extern const string base32Chars;
struct Hash
{
static const unsigned int maxHashSize = 64;
unsigned int hashSize;
unsigned char hash[maxHashSize];
HashType type;
/* Create an unset hash object. */
Hash();
/* Create a zero-filled hash object. */
Hash(HashType type);
/* Check whether a hash is set. */
operator bool () const { return type != htUnknown; }
/* Check whether two hash are equal. */
bool operator == (const Hash & h2) const;
/* Check whether two hash are not equal. */
bool operator != (const Hash & h2) const;
/* For sorting. */
bool operator < (const Hash & h) const;
/* Returns the length of a base-16 representation of this hash. */
size_t base16Len() const
{
return hashSize * 2;
}
/* Returns the length of a base-32 representation of this hash. */
size_t base32Len() const
{
return (hashSize * 8 - 1) / 5 + 1;
}
std::string to_string(bool base32 = true) const;
};
/* Convert a hash to a hexadecimal representation. */
string printHash(const Hash & hash);
Hash parseHash(const string & s);
/* Parse a hexadecimal representation of a hash code. */
Hash parseHash(HashType ht, const string & s);
/* Convert a hash to a base-32 representation. */
string printHash32(const Hash & hash);
/* Print a hash in base-16 if it's MD5, or base-32 otherwise. */
string printHash16or32(const Hash & hash);
/* Parse a base-32 representation of a hash code. */
Hash parseHash32(HashType ht, const string & s);
/* Parse a base-16 or base-32 representation of a hash code. */
Hash parseHash16or32(HashType ht, const string & s);
/* Verify that the given string is a valid hash code. */
bool isHash(const string & s);
/* Compute the hash of the given string. */
Hash hashString(HashType ht, const string & s);
/* Compute the hash of the given file. */
Hash hashFile(HashType ht, const Path & path);
/* Compute the hash of the given path. The hash is defined as
(essentially) hashString(ht, dumpPath(path)). */
struct PathFilter;
extern PathFilter defaultPathFilter;
typedef std::pair<Hash, unsigned long long> HashResult;
HashResult hashPath(HashType ht, const Path & path,
PathFilter & filter = defaultPathFilter);
/* Compress a hash to the specified number of bytes by cyclically
XORing bytes together. */
Hash compressHash(const Hash & hash, unsigned int newSize);
/* Parse a string representing a hash type. */
HashType parseHashType(const string & s);
/* And the reverse. */
string printHashType(HashType ht);
union Ctx;
class HashSink : public BufferedSink
{
private:
HashType ht;
Ctx * ctx;
unsigned long long bytes;
public:
HashSink(HashType ht);
HashSink(const HashSink & h);
~HashSink();
void write(const unsigned char * data, size_t len);
HashResult finish();
HashResult currentHash();
};
}