forked from lix-project/lix
f3dc231250
* 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.)
79 lines
1.8 KiB
C++
79 lines
1.8 KiB
C++
#ifndef __HASH_H
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#define __HASH_H
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#include <string>
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#include "util.hh"
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using namespace std;
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typedef enum { htUnknown, htMD5, htSHA1, htSHA256 } HashType;
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const int md5HashSize = 16;
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const int sha1HashSize = 20;
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const int sha256HashSize = 32;
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struct Hash
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{
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static const unsigned int maxHashSize = 32;
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unsigned int hashSize;
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unsigned char hash[maxHashSize];
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HashType type;
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/* Create an unusable hash object. */
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Hash();
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/* Create a zero-filled hash object. */
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Hash(HashType type);
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/* Check whether two hash are equal. */
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bool operator == (const Hash & h2) const;
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/* Check whether two hash are not equal. */
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bool operator != (const Hash & h2) const;
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/* For sorting. */
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bool operator < (const Hash & h) const;
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};
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/* Convert a hash to a hexadecimal representation. */
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string printHash(const Hash & hash);
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/* Parse a hexadecimal representation of a hash code. */
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Hash parseHash(HashType ht, const string & s);
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/* Convert a hash to a base-32 representation. */
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string printHash32(const Hash & hash);
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/* Parse a base-32 representation of a hash code. */
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Hash parseHash32(HashType ht, const string & s);
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/* Verify that the given string is a valid hash code. */
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bool isHash(const string & s);
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/* Compute the hash of the given string. */
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Hash hashString(HashType ht, const string & s);
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/* Compute the hash of the given file. */
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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
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md5(dump(path)). */
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Hash hashPath(HashType ht, const Path & path);
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/* Compress a hash to the specified number of bytes by cyclically
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XORing bytes together. */
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Hash compressHash(const Hash & hash, unsigned int newSize);
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/* Parse a string representing a hash type. */
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HashType parseHashType(const string & s);
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#endif /* !__HASH_H */
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