nix-super/src/libutil/hash.hh

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#ifndef __HASH_H
#define __HASH_H
#include "types.hh"
#include "serialise.hh"
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namespace nix {
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typedef enum { htUnknown, htMD5, htSHA1, htSHA256 } HashType;
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const int md5HashSize = 16;
const int sha1HashSize = 20;
const int sha256HashSize = 32;
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extern const string base32Chars;
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struct Hash
{
static const unsigned int maxHashSize = 32;
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unsigned int hashSize;
unsigned char hash[maxHashSize];
HashType type;
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/* Create an unusable hash object. */
Hash();
/* Create a zero-filled hash object. */
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Hash(HashType type);
/* Check whether two hash are equal. */
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bool operator == (const Hash & h2) const;
/* Check whether two hash are not equal. */
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bool operator != (const Hash & h2) const;
/* For sorting. */
bool operator < (const Hash & h) const;
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};
/* Convert a hash to a hexadecimal representation. */
string printHash(const Hash & hash);
/* Parse a hexadecimal representation of a hash code. */
Hash parseHash(HashType ht, const string & s);
/* Returns the length of a base-32 hash representation. */
unsigned int hashLength32(const Hash & hash);
/* Convert a hash to a base-32 representation. */
string printHash32(const Hash & hash);
/* Parse a base-32 representation of a hash code. */
Hash parseHash32(HashType ht, const string & s);
/* Verify that the given string is a valid hash code. */
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bool isHash(const string & s);
/* Compute the hash of the given string. */
* Removed the `id' attribute hack. * Formalise the notion of fixed-output derivations, i.e., derivations for which a cryptographic hash of the output is known in advance. Changes to such derivations should not propagate upwards through the dependency graph. Previously this was done by specifying the hash component of the output path through the `id' attribute, but this is insecure since you can lie about it (i.e., you can specify any hash and then produce a completely different output). Now the responsibility for checking the output is moved from the builder to Nix itself. A fixed-output derivation can be created by specifying the `outputHash' and `outputHashAlgo' attributes, the latter taking values `md5', `sha1', and `sha256', and the former specifying the actual hash in hexadecimal or in base-32 (auto-detected by looking at the length of the attribute value). MD5 is included for compatibility but should be considered deprecated. * Removed the `drvPath' pseudo-attribute in derivation results. It's no longer necessary. * Cleaned up the support for multiple output paths in derivation store expressions. Each output now has a unique identifier (e.g., `out', `devel', `docs'). Previously there was no way to tell output paths apart at the store expression level. * `nix-hash' now has a flag `--base32' to specify that the hash should be printed in base-32 notation. * `fetchurl' accepts parameters `sha256' and `sha1' in addition to `md5'. * `nix-prefetch-url' now prints out a SHA-1 hash in base-32. (TODO: a flag to specify the hash.)
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Hash hashString(HashType ht, const string & s);
/* Compute the hash of the given file. */
* Removed the `id' attribute hack. * Formalise the notion of fixed-output derivations, i.e., derivations for which a cryptographic hash of the output is known in advance. Changes to such derivations should not propagate upwards through the dependency graph. Previously this was done by specifying the hash component of the output path through the `id' attribute, but this is insecure since you can lie about it (i.e., you can specify any hash and then produce a completely different output). Now the responsibility for checking the output is moved from the builder to Nix itself. A fixed-output derivation can be created by specifying the `outputHash' and `outputHashAlgo' attributes, the latter taking values `md5', `sha1', and `sha256', and the former specifying the actual hash in hexadecimal or in base-32 (auto-detected by looking at the length of the attribute value). MD5 is included for compatibility but should be considered deprecated. * Removed the `drvPath' pseudo-attribute in derivation results. It's no longer necessary. * Cleaned up the support for multiple output paths in derivation store expressions. Each output now has a unique identifier (e.g., `out', `devel', `docs'). Previously there was no way to tell output paths apart at the store expression level. * `nix-hash' now has a flag `--base32' to specify that the hash should be printed in base-32 notation. * `fetchurl' accepts parameters `sha256' and `sha1' in addition to `md5'. * `nix-prefetch-url' now prints out a SHA-1 hash in base-32. (TODO: a flag to specify the hash.)
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Hash hashFile(HashType ht, const Path & path);
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/* Compute the hash of the given path. The hash is defined as
(essentially) hashString(ht, dumpPath(path)). */
struct PathFilter;
extern PathFilter defaultPathFilter;
Hash hashPath(HashType ht, const Path & path,
PathFilter & filter = defaultPathFilter);
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/* Compress a hash to the specified number of bytes by cyclically
XORing bytes together. */
Hash compressHash(const Hash & hash, unsigned int newSize);
* Removed the `id' attribute hack. * Formalise the notion of fixed-output derivations, i.e., derivations for which a cryptographic hash of the output is known in advance. Changes to such derivations should not propagate upwards through the dependency graph. Previously this was done by specifying the hash component of the output path through the `id' attribute, but this is insecure since you can lie about it (i.e., you can specify any hash and then produce a completely different output). Now the responsibility for checking the output is moved from the builder to Nix itself. A fixed-output derivation can be created by specifying the `outputHash' and `outputHashAlgo' attributes, the latter taking values `md5', `sha1', and `sha256', and the former specifying the actual hash in hexadecimal or in base-32 (auto-detected by looking at the length of the attribute value). MD5 is included for compatibility but should be considered deprecated. * Removed the `drvPath' pseudo-attribute in derivation results. It's no longer necessary. * Cleaned up the support for multiple output paths in derivation store expressions. Each output now has a unique identifier (e.g., `out', `devel', `docs'). Previously there was no way to tell output paths apart at the store expression level. * `nix-hash' now has a flag `--base32' to specify that the hash should be printed in base-32 notation. * `fetchurl' accepts parameters `sha256' and `sha1' in addition to `md5'. * `nix-prefetch-url' now prints out a SHA-1 hash in base-32. (TODO: a flag to specify the hash.)
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/* Parse a string representing a hash type. */
HashType parseHashType(const string & s);
union Ctx;
class HashSink : public Sink
{
private:
HashType ht;
Ctx * ctx;
public:
HashSink(HashType ht);
~HashSink();
virtual void operator () (const unsigned char * data, unsigned int len);
Hash finish();
};
}
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#endif /* !__HASH_H */