phobos/std/digest/digest.d

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27 KiB
D

/**
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$(BOOKTABLE ,
$(TR $(TH Category) $(TH Functions)
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$(TR $(TDNW Template API) $(TD $(MYREF isDigest) $(MYREF DigestType) $(MYREF hasPeek)
$(MYREF ExampleDigest) $(MYREF _digest) $(MYREF hexDigest) $(MYREF makeDigest)
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$(TR $(TDNW OOP API) $(TD $(MYREF Digest)
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$(TR $(TDNW Helper functions) $(TD $(MYREF toHexString))
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$(TR $(TDNW Implementation helpers) $(TD $(MYREF digestLength) $(MYREF WrapperDigest))
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* This module describes the digest APIs used in Phobos. All digests follow these APIs.
* Additionally, this module contains useful helper methods which can be used with every _digest type.
*
* APIs:
* There are two APIs for digests: The template API and the OOP API. The template API uses structs
* and template helpers like $(LREF isDigest). The OOP API implements digests as classes inheriting
* the $(LREF Digest) interface. All digests are named so that the template API struct is called "$(B x)"
* and the OOP API class is called "$(B x)Digest". For example we have $(D MD5) <--> $(D MD5Digest),
* $(D CRC32) <--> $(D CRC32Digest), etc.
*
* The template API is slightly more efficient. It does not have to allocate memory dynamically,
* all memory is allocated on the stack. The OOP API has to allocate in the finish method if no
* buffer was provided. If you provide a buffer to the OOP APIs finish function, it doesn't allocate,
* but the $(LREF Digest) classes still have to be created using $(D new) which allocates them using the GC.
*
* The OOP API is useful to change the _digest function and/or _digest backend at 'runtime'. The benefit here
* is that switching e.g. Phobos MD5Digest and an OpenSSLMD5Digest implementation is ABI compatible.
*
* If just one specific _digest type and backend is needed, the template API is usually a good fit.
* In this simplest case, the template API can even be used without templates: Just use the "$(B x)" structs
* directly.
*
* License: $(WEB www.boost.org/LICENSE_1_0.txt, Boost License 1.0).
* Authors:
* Johannes Pfau
*
* Source: $(PHOBOSSRC std/_digest/_digest.d)
*
* Macros:
* MYREF = <font face='Consolas, "Bitstream Vera Sans Mono", "Andale Mono", Monaco, "DejaVu Sans Mono", "Lucida Console", monospace'><a href="#$1">$1</a>&nbsp;</font>
* MYREF2 = <font face='Consolas, "Bitstream Vera Sans Mono", "Andale Mono", Monaco, "DejaVu Sans Mono", "Lucida Console", monospace'><a href="#$2">$1</a>&nbsp;</font>
* MYREF3 = <a href="#$2">$(D $1)</a>
*
* CTFE:
* Digests do not work in CTFE
*
* TODO:
* Digesting single bits (as opposed to bytes) is not implemented. This will be done as another
* template constraint helper (hasBitDigesting!T) and an additional interface (BitDigest)
*/
/* Copyright Johannes Pfau 2012.
* Distributed under the Boost Software License, Version 1.0.
* (See accompanying file LICENSE_1_0.txt or copy at
* http://www.boost.org/LICENSE_1_0.txt)
*/
module std.digest.digest;
import std.range, std.traits;
import std.typetuple : allSatisfy;
public import std.ascii : LetterCase;
///
unittest
{
import std.digest.crc;
//Simple example
char[8] hexHash = hexDigest!CRC32("The quick brown fox jumps over the lazy dog");
assert(hexHash == "39A34F41");
//Simple example, using the API manually
CRC32 context = makeDigest!CRC32();
context.put(cast(ubyte[])"The quick brown fox jumps over the lazy dog");
ubyte[4] hash = context.finish();
assert(toHexString(hash) == "39A34F41");
}
///
unittest
{
//Generating the hashes of a file, idiomatic D way
import std.digest.crc, std.digest.sha, std.digest.md;
import std.stdio;
// Digests a file and prints the result.
void digestFile(Hash)(string filename) if(isDigest!Hash)
{
auto file = File(filename);
auto result = digest!Hash(file.byChunk(4096 * 1024));
writefln("%s (%s) = %s", Hash.stringof, filename, toHexString(result));
}
void main(string[] args)
{
foreach (name; args[1 .. $])
{
digestFile!MD5(name);
digestFile!SHA1(name);
digestFile!CRC32(name);
}
}
}
///
unittest
{
//Generating the hashes of a file using the template API
import std.digest.crc, std.digest.sha, std.digest.md;
import std.stdio;
// Digests a file and prints the result.
void digestFile(Hash)(ref Hash hash, string filename) if(isDigest!Hash)
{
File file = File(filename);
//As digests imlement OutputRange, we could use std.algorithm.copy
//Let's do it manually for now
foreach (buffer; file.byChunk(4096 * 1024))
hash.put(buffer);
auto result = hash.finish();
writefln("%s (%s) = %s", Hash.stringof, filename, toHexString(result));
}
void uMain(string[] args)
{
MD5 md5;
SHA1 sha1;
CRC32 crc32;
md5.start();
sha1.start();
crc32.start();
foreach (arg; args[1 .. $])
{
digestFile(md5, arg);
digestFile(sha1, arg);
digestFile(crc32, arg);
}
}
}
///
unittest
{
import std.digest.crc, std.digest.sha, std.digest.md;
import std.stdio;
// Digests a file and prints the result.
void digestFile(Digest hash, string filename)
{
File file = File(filename);
//As digests implement OutputRange, we could use std.algorithm.copy
//Let's do it manually for now
foreach (buffer; file.byChunk(4096 * 1024))
hash.put(buffer);
ubyte[] result = hash.finish();
writefln("%s (%s) = %s", typeid(hash).toString(), filename, toHexString(result));
}
void umain(string[] args)
{
auto md5 = new MD5Digest();
auto sha1 = new SHA1Digest();
auto crc32 = new CRC32Digest();
foreach (arg; args[1 .. $])
{
digestFile(md5, arg);
digestFile(sha1, arg);
digestFile(crc32, arg);
}
}
}
version(StdDdoc)
version = ExampleDigest;
version(ExampleDigest)
{
/**
* This documents the general structure of a Digest in the template API.
* All digest implementations should implement the following members and therefore pass
* the $(LREF isDigest) test.
*
* Note:
* $(UL
* $(LI A digest must be a struct (value type) to pass the $(LREF isDigest) test.)
* $(LI A digest passing the $(LREF isDigest) test is always an $(D OutputRange))
* )
*/
struct ExampleDigest
{
public:
/**
* Use this to feed the digest with data.
* Also implements the $(XREF range, OutputRange) interface for $(D ubyte) and
* $(D const(ubyte)[]).
* The following usages of $(D put) must work for any type which passes $(LREF isDigest):
* Examples:
* ----
* ExampleDigest dig;
* dig.put(cast(ubyte)0); //single ubyte
* dig.put(cast(ubyte)0, cast(ubyte)0); //variadic
* ubyte[10] buf;
* dig.put(buf); //buffer
* ----
*/
@trusted void put(scope const(ubyte)[] data...)
{
}
/**
* This function is used to (re)initialize the digest.
* It must be called before using the digest and it also works as a 'reset' function
* if the digest has already processed data.
*/
@trusted void start()
{
}
/**
* The finish function returns the final hash sum and resets the Digest.
*
* Note:
* The actual type returned by finish depends on the digest implementation.
* $(D ubyte[16]) is just used as an example. It is guaranteed that the type is a
* static array of ubytes.
*
* $(UL
* $(LI Use $(LREF DigestType) to obtain the actual return type.)
* $(LI Use $(LREF digestLength) to obtain the length of the ubyte array.)
* )
*/
@trusted ubyte[16] finish()
{
return (ubyte[16]).init;
}
}
}
///
unittest
{
//Using the OutputRange feature
import std.algorithm : copy;
import std.range : repeat;
import std.digest.md;
auto oneMillionRange = repeat!ubyte(cast(ubyte)'a', 1000000);
auto ctx = makeDigest!MD5();
copy(oneMillionRange, &ctx); //Note: You must pass a pointer to copy!
assert(ctx.finish().toHexString() == "7707D6AE4E027C70EEA2A935C2296F21");
}
/**
* Use this to check if a type is a digest. See $(LREF ExampleDigest) to see what
* a type must provide to pass this check.
*
* Note:
* This is very useful as a template constraint (see examples)
*
* BUGS:
* $(UL
* $(LI Does not yet verify that put takes scope parameters.)
* $(LI Should check that finish() returns a ubyte[num] array)
* )
*/
template isDigest(T)
{
enum bool isDigest = isOutputRange!(T, const(ubyte)[]) && isOutputRange!(T, ubyte) &&
is(T == struct) &&
is(typeof(
{
T dig = void; //Can define
dig.put(cast(ubyte)0, cast(ubyte)0); //varags
dig.start(); //has start
auto value = dig.finish(); //has finish
}));
}
///
unittest
{
import std.digest.crc;
static assert(isDigest!CRC32);
}
///
unittest
{
import std.digest.crc;
void myFunction(T)() if(isDigest!T)
{
T dig;
dig.start();
auto result = dig.finish();
}
myFunction!CRC32();
}
/**
* Use this template to get the type which is returned by a digest's $(LREF finish) method.
*/
template DigestType(T)
{
static if(isDigest!T)
{
alias DigestType =
ReturnType!(typeof(
{
T dig = void;
return dig.finish();
}));
}
else
static assert(false, T.stringof ~ " is not a digest! (fails isDigest!T)");
}
///
unittest
{
import std.digest.crc;
assert(is(DigestType!(CRC32) == ubyte[4]));
}
///
unittest
{
import std.digest.crc;
CRC32 dig;
dig.start();
DigestType!CRC32 result = dig.finish();
}
/**
* Used to check if a digest supports the $(D peek) method.
* Peek has exactly the same function signatures as finish, but it doesn't reset
* the digest's internal state.
*
* Note:
* $(UL
* $(LI This is very useful as a template constraint (see examples))
* $(LI This also checks if T passes $(LREF isDigest))
* )
*/
template hasPeek(T)
{
enum bool hasPeek = isDigest!T &&
is(typeof(
{
T dig = void; //Can define
DigestType!T val = dig.peek();
}));
}
///
unittest
{
import std.digest.crc, std.digest.md;
assert(!hasPeek!(MD5));
assert(hasPeek!CRC32);
}
///
unittest
{
import std.digest.crc;
void myFunction(T)() if(hasPeek!T)
{
T dig;
dig.start();
auto result = dig.peek();
}
myFunction!CRC32();
}
private template isDigestibleRange(Range)
{
import std.digest.md;
enum bool isDigestibleRange = isInputRange!Range && is(typeof(
{
MD5 ha; //Could use any conformant hash
ElementType!Range val;
ha.put(val);
}));
}
/**
* This is a convenience function to calculate a hash using the template API.
* Every digest passing the $(LREF isDigest) test can be used with this function.
*
* Params:
* range= an $(D InputRange) with $(D ElementType) $(D ubyte), $(D ubyte[]) or $(D ubyte[num])
*/
DigestType!Hash digest(Hash, Range)(auto ref Range range) if(!isArray!Range
&& isDigestibleRange!Range)
{
import std.algorithm : copy;
Hash hash;
hash.start();
copy(range, &hash);
return hash.finish();
}
///
unittest
{
import std.digest.md;
auto testRange = repeat!ubyte(cast(ubyte)'a', 100);
auto md5 = digest!MD5(testRange);
}
/**
* This overload of the digest function handles arrays.
*
* Params:
* data= one or more arrays of any type
*/
DigestType!Hash digest(Hash, T...)(scope const T data) if(allSatisfy!(isArray, typeof(data)))
{
Hash hash;
hash.start();
foreach(datum; data)
hash.put(cast(const(ubyte[]))datum);
return hash.finish();
}
///
unittest
{
import std.digest.md, std.digest.sha, std.digest.crc;
auto md5 = digest!MD5( "The quick brown fox jumps over the lazy dog");
auto sha1 = digest!SHA1( "The quick brown fox jumps over the lazy dog");
auto crc32 = digest!CRC32("The quick brown fox jumps over the lazy dog");
assert(toHexString(crc32) == "39A34F41");
}
///
unittest
{
import std.digest.crc;
auto crc32 = digest!CRC32("The quick ", "brown ", "fox jumps over the lazy dog");
assert(toHexString(crc32) == "39A34F41");
}
/**
* This is a convenience function similar to $(LREF digest), but it returns the string
* representation of the hash. Every digest passing the $(LREF isDigest) test can be used with this
* function.
*
* Params:
* order= the order in which the bytes are processed (see $(LREF toHexString))
* range= an $(D InputRange) with $(D ElementType) $(D ubyte), $(D ubyte[]) or $(D ubyte[num])
*/
char[digestLength!(Hash)*2] hexDigest(Hash, Order order = Order.increasing, Range)(ref Range range)
if(!isArray!Range && isDigestibleRange!Range)
{
return toHexString!order(digest!Hash(range));
}
///
unittest
{
import std.digest.md;
auto testRange = repeat!ubyte(cast(ubyte)'a', 100);
assert(hexDigest!MD5(testRange) == "36A92CC94A9E0FA21F625F8BFB007ADF");
}
/**
* This overload of the hexDigest function handles arrays.
*
* Params:
* order= the order in which the bytes are processed (see $(LREF toHexString))
* data= one or more arrays of any type
*/
char[digestLength!(Hash)*2] hexDigest(Hash, Order order = Order.increasing, T...)(scope const T data)
if(allSatisfy!(isArray, typeof(data)))
{
return toHexString!order(digest!Hash(data));
}
///
unittest
{
import std.digest.crc;
assert(hexDigest!(CRC32, Order.decreasing)("The quick brown fox jumps over the lazy dog") == "414FA339");
}
///
unittest
{
import std.digest.crc;
assert(hexDigest!(CRC32, Order.decreasing)("The quick ", "brown ", "fox jumps over the lazy dog") == "414FA339");
}
/**
* This is a convenience function which returns an initialized digest, so it's not necessary to call
* start manually.
*/
Hash makeDigest(Hash)()
{
Hash hash;
hash.start();
return hash;
}
///
unittest
{
import std.digest.md;
auto md5 = makeDigest!MD5();
md5.put(0);
assert(toHexString(md5.finish()) == "93B885ADFE0DA089CDF634904FD59F71");
}
/*+*************************** End of template part, welcome to OOP land **************************/
/**
* This describes the OOP API. To understand when to use the template API and when to use the OOP API,
* see the module documentation at the top of this page.
*
* The Digest interface is the base interface which is implemented by all digests.
*
* Note:
* A Digest implementation is always an $(D OutputRange)
*/
interface Digest
{
public:
/**
* Use this to feed the digest with data.
* Also implements the $(XREF range, OutputRange) interface for $(D ubyte) and
* $(D const(ubyte)[]).
*
* Examples:
* ----
* void test(Digest dig)
* {
* dig.put(cast(ubyte)0); //single ubyte
* dig.put(cast(ubyte)0, cast(ubyte)0); //variadic
* ubyte[10] buf;
* dig.put(buf); //buffer
* }
* ----
*/
@trusted nothrow void put(scope const(ubyte)[] data...);
/**
* Resets the internal state of the digest.
* Note:
* $(LREF finish) calls this internally, so it's not necessary to call
* $(D reset) manually after a call to $(LREF finish).
*/
@trusted nothrow void reset();
/**
* This is the length in bytes of the hash value which is returned by $(LREF finish).
* It's also the required size of a buffer passed to $(LREF finish).
*/
@trusted nothrow @property size_t length() const;
/**
* The finish function returns the hash value. It takes an optional buffer to copy the data
* into. If a buffer is passed, it must be at least $(LREF length) bytes big.
*/
@trusted nothrow ubyte[] finish();
///ditto
nothrow ubyte[] finish(scope ubyte[] buf);
//@@@BUG@@@ http://d.puremagic.com/issues/show_bug.cgi?id=6549
/*in
{
assert(buf.length >= this.length);
}*/
/**
* This is a convenience function to calculate the hash of a value using the OOP API.
*/
final @trusted nothrow ubyte[] digest(scope const(void[])[] data...)
{
this.reset();
foreach(datum; data)
this.put(cast(ubyte[])datum);
return this.finish();
}
}
///
unittest
{
//Using the OutputRange feature
import std.algorithm : copy;
import std.range : repeat;
import std.digest.md;
auto oneMillionRange = repeat!ubyte(cast(ubyte)'a', 1000000);
auto ctx = new MD5Digest();
copy(oneMillionRange, ctx);
assert(ctx.finish().toHexString() == "7707D6AE4E027C70EEA2A935C2296F21");
}
///
unittest
{
import std.digest.md, std.digest.sha, std.digest.crc;
ubyte[] md5 = (new MD5Digest()).digest("The quick brown fox jumps over the lazy dog");
ubyte[] sha1 = (new SHA1Digest()).digest("The quick brown fox jumps over the lazy dog");
ubyte[] crc32 = (new CRC32Digest()).digest("The quick brown fox jumps over the lazy dog");
assert(crcHexString(crc32) == "414FA339");
}
///
unittest
{
import std.digest.crc;
ubyte[] crc32 = (new CRC32Digest()).digest("The quick ", "brown ", "fox jumps over the lazy dog");
assert(crcHexString(crc32) == "414FA339");
}
unittest
{
assert(!isDigest!(Digest));
assert(isOutputRange!(Digest, ubyte));
}
///
unittest
{
void test(Digest dig)
{
dig.put(cast(ubyte)0); //single ubyte
dig.put(cast(ubyte)0, cast(ubyte)0); //variadic
ubyte[10] buf;
dig.put(buf); //buffer
}
}
/*+*************************** End of OOP part, helper functions follow ***************************/
/**
* See $(LREF toHexString)
*/
enum Order : bool
{
increasing, ///
decreasing ///
}
/**
* Used to convert a hash value (a static or dynamic array of ubytes) to a string.
* Can be used with the OOP and with the template API.
*
* The additional order parameter can be used to specify the order of the input data.
* By default the data is processed in increasing order, starting at index 0. To process it in the
* opposite order, pass Order.decreasing as a parameter.
*
* The additional letterCase parameter can be used to specify the case of the output data.
* By default the output is in upper case. To change it to the lower case
* pass LetterCase.lower as a parameter.
*/
char[num*2] toHexString(Order order = Order.increasing, size_t num, LetterCase letterCase = LetterCase.upper)
(in ubyte[num] digest)
{
static if (letterCase == LetterCase.upper)
{
import std.ascii : hexDigits = hexDigits;
}
else
{
import std.ascii : hexDigits = lowerHexDigits;
}
char[num*2] result;
size_t i;
static if(order == Order.increasing)
{
foreach(u; digest)
{
result[i++] = hexDigits[u >> 4];
result[i++] = hexDigits[u & 15];
}
}
else
{
size_t j = num - 1;
while(i < num*2)
{
result[i++] = hexDigits[digest[j] >> 4];
result[i++] = hexDigits[digest[j] & 15];
j--;
}
}
return result;
}
///ditto
auto toHexString(LetterCase letterCase, Order order = Order.increasing, size_t num)(in ubyte[num] digest)
{
return toHexString!(order, num, letterCase)(digest);
}
///ditto
string toHexString(Order order = Order.increasing, LetterCase letterCase = LetterCase.upper)
(in ubyte[] digest)
{
static if (letterCase == LetterCase.upper)
{
import std.ascii : hexDigits = hexDigits;
}
else
{
import std.ascii : hexDigits = lowerHexDigits;
}
auto result = new char[digest.length*2];
size_t i;
static if(order == Order.increasing)
{
foreach(u; digest)
{
result[i++] = hexDigits[u >> 4];
result[i++] = hexDigits[u & 15];
}
}
else
{
foreach(u; retro(digest))
{
result[i++] = hexDigits[u >> 4];
result[i++] = hexDigits[u & 15];
}
}
import std.exception : assumeUnique;
return assumeUnique(result);
}
///ditto
auto toHexString(LetterCase letterCase, Order order = Order.increasing)(in ubyte[] digest)
{
return toHexString!(order, letterCase)(digest);
}
//For more example unittests, see Digest.digest, digest
///
unittest
{
import std.digest.crc;
//Test with template API:
auto crc32 = digest!CRC32("The quick ", "brown ", "fox jumps over the lazy dog");
//Lower case variant:
assert(toHexString!(LetterCase.lower)(crc32) == "39a34f41");
//Usually CRCs are printed in this order, though:
assert(toHexString!(Order.decreasing)(crc32) == "414FA339");
assert(toHexString!(LetterCase.lower, Order.decreasing)(crc32) == "414fa339");
}
///
unittest
{
import std.digest.crc;
// With OOP API
auto crc32 = (new CRC32Digest()).digest("The quick ", "brown ", "fox jumps over the lazy dog");
//Usually CRCs are printed in this order, though:
assert(toHexString!(Order.decreasing)(crc32) == "414FA339");
}
unittest
{
ubyte[16] data;
assert(toHexString(data) == "00000000000000000000000000000000");
assert(toHexString(cast(ubyte[4])[42, 43, 44, 45]) == "2A2B2C2D");
assert(toHexString(cast(ubyte[])[42, 43, 44, 45]) == "2A2B2C2D");
assert(toHexString!(Order.decreasing)(cast(ubyte[4])[42, 43, 44, 45]) == "2D2C2B2A");
assert(toHexString!(Order.decreasing, LetterCase.lower)(cast(ubyte[4])[42, 43, 44, 45]) == "2d2c2b2a");
assert(toHexString!(Order.decreasing)(cast(ubyte[])[42, 43, 44, 45]) == "2D2C2B2A");
}
/*+*********************** End of public helper part, private helpers follow ***********************/
/*
* Used to convert from a ubyte[] slice to a ref ubyte[N].
* This helper is used internally in the WrapperDigest template to wrap the template API's
* finish function.
*/
ref T[N] asArray(size_t N, T)(ref T[] source, string errorMsg = "")
{
assert(source.length >= N, errorMsg);
return *cast(T[N]*)source.ptr;
}
/**
* This helper is used internally in the WrapperDigest template, but it might be
* useful for other purposes as well. It returns the length (in bytes) of the hash value
* produced by T.
*/
template digestLength(T) if(isDigest!T)
{
enum size_t digestLength = (ReturnType!(T.finish)).length;
}
/**
* Wraps a template API hash struct into a Digest interface.
* Modules providing digest implementations will usually provide
* an alias for this template (e.g. MD5Digest, SHA1Digest, ...).
*/
class WrapperDigest(T) if(isDigest!T) : Digest
{
protected:
T _digest;
public final:
/**
* Initializes the digest.
*/
this()
{
_digest.start();
}
/**
* Use this to feed the digest with data.
* Also implements the $(XREF range, OutputRange) interface for $(D ubyte) and
* $(D const(ubyte)[]).
*/
@trusted nothrow void put(scope const(ubyte)[] data...)
{
_digest.put(data);
}
/**
* Resets the internal state of the digest.
* Note:
* $(LREF finish) calls this internally, so it's not necessary to call
* $(D reset) manually after a call to $(LREF finish).
*/
@trusted nothrow void reset()
{
_digest.start();
}
/**
* This is the length in bytes of the hash value which is returned by $(LREF finish).
* It's also the required size of a buffer passed to $(LREF finish).
*/
@trusted nothrow @property size_t length() const pure
{
return digestLength!T;
}
/**
* The finish function returns the hash value. It takes an optional buffer to copy the data
* into. If a buffer is passed, it must have a length at least $(LREF length) bytes.
*
* Examples:
* --------
*
* import std.digest.md;
* ubyte[16] buf;
* auto hash = new WrapperDigest!MD5();
* hash.put(cast(ubyte)0);
* auto result = hash.finish(buf[]);
* //The result is now in result (and in buf). If you pass a buffer which is bigger than
* //necessary, result will have the correct length, but buf will still have it's original
* //length
* --------
*/
nothrow ubyte[] finish(scope ubyte[] buf)
in
{
assert(buf.length >= this.length);
}
body
{
enum string msg = "Buffer needs to be at least " ~ digestLength!(T).stringof ~ " bytes " ~
"big, check " ~ typeof(this).stringof ~ ".length!";
asArray!(digestLength!T)(buf, msg) = _digest.finish();
return buf[0 .. digestLength!T];
}
///ditto
@trusted nothrow ubyte[] finish()
{
enum len = digestLength!T;
auto buf = new ubyte[len];
asArray!(digestLength!T)(buf) = _digest.finish();
return buf;
}
version(StdDdoc)
{
/**
* Works like $(D finish) but does not reset the internal state, so it's possible
* to continue putting data into this WrapperDigest after a call to peek.
*
* These functions are only available if $(D hasPeek!T) is true.
*/
@trusted ubyte[] peek(scope ubyte[] buf) const;
///ditto
@trusted ubyte[] peek() const;
}
else static if(hasPeek!T)
{
@trusted ubyte[] peek(scope ubyte[] buf) const
in
{
assert(buf.length >= this.length);
}
body
{
enum string msg = "Buffer needs to be at least " ~ digestLength!(T).stringof ~ " bytes " ~
"big, check " ~ typeof(this).stringof ~ ".length!";
asArray!(digestLength!T)(buf, msg) = _digest.peek();
return buf[0 .. digestLength!T];
}
@trusted ubyte[] peek() const
{
enum len = digestLength!T;
auto buf = new ubyte[len];
asArray!(digestLength!T)(buf) = _digest.peek();
return buf;
}
}
}
///
unittest
{
import std.digest.md;
//Simple example
auto hash = new WrapperDigest!MD5();
hash.put(cast(ubyte)0);
auto result = hash.finish();
}
///
unittest
{
//using a supplied buffer
import std.digest.md;
ubyte[16] buf;
auto hash = new WrapperDigest!MD5();
hash.put(cast(ubyte)0);
auto result = hash.finish(buf[]);
//The result is now in result (and in buf). If you pass a buffer which is bigger than
//necessary, result will have the correct length, but buf will still have it's original
//length
}