forked from lix-project/lix
389 lines
9 KiB
C++
389 lines
9 KiB
C++
#pragma once
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#include <memory>
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#include "types.hh"
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#include "util.hh"
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namespace nix {
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/* Abstract destination of binary data. */
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struct Sink
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{
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virtual ~Sink() { }
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virtual void operator () (const unsigned char * data, size_t len) = 0;
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virtual bool good() { return true; }
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void operator () (const std::string & s)
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{
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(*this)((const unsigned char *) s.data(), s.size());
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}
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};
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/* A buffered abstract sink. */
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struct BufferedSink : virtual Sink
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{
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size_t bufSize, bufPos;
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std::unique_ptr<unsigned char[]> buffer;
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BufferedSink(size_t bufSize = 32 * 1024)
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: bufSize(bufSize), bufPos(0), buffer(nullptr) { }
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void operator () (const unsigned char * data, size_t len) override;
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void operator () (const std::string & s)
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{
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Sink::operator()(s);
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}
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void flush();
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virtual void write(const unsigned char * data, size_t len) = 0;
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};
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/* Abstract source of binary data. */
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struct Source
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{
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virtual ~Source() { }
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/* Store exactly ‘len’ bytes in the buffer pointed to by ‘data’.
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It blocks until all the requested data is available, or throws
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an error if it is not going to be available. */
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void operator () (unsigned char * data, size_t len);
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/* Store up to ‘len’ in the buffer pointed to by ‘data’, and
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return the number of bytes stored. It blocks until at least
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one byte is available. */
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virtual size_t read(unsigned char * data, size_t len) = 0;
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virtual bool good() { return true; }
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std::string drain();
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};
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/* A buffered abstract source. */
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struct BufferedSource : Source
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{
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size_t bufSize, bufPosIn, bufPosOut;
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std::unique_ptr<unsigned char[]> buffer;
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BufferedSource(size_t bufSize = 32 * 1024)
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: bufSize(bufSize), bufPosIn(0), bufPosOut(0), buffer(nullptr) { }
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size_t read(unsigned char * data, size_t len) override;
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bool hasData();
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protected:
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/* Underlying read call, to be overridden. */
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virtual size_t readUnbuffered(unsigned char * data, size_t len) = 0;
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};
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/* A sink that writes data to a file descriptor. */
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struct FdSink : BufferedSink
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{
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int fd;
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bool warn = false;
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size_t written = 0;
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FdSink() : fd(-1) { }
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FdSink(int fd) : fd(fd) { }
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FdSink(FdSink&&) = default;
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FdSink& operator=(FdSink && s)
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{
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flush();
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fd = s.fd;
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s.fd = -1;
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warn = s.warn;
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written = s.written;
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return *this;
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}
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~FdSink();
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void write(const unsigned char * data, size_t len) override;
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bool good() override;
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private:
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bool _good = true;
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};
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/* A source that reads data from a file descriptor. */
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struct FdSource : BufferedSource
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{
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int fd;
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size_t read = 0;
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FdSource() : fd(-1) { }
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FdSource(int fd) : fd(fd) { }
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FdSource(FdSource&&) = default;
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FdSource& operator=(FdSource && s)
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{
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fd = s.fd;
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s.fd = -1;
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read = s.read;
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return *this;
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}
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bool good() override;
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protected:
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size_t readUnbuffered(unsigned char * data, size_t len) override;
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private:
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bool _good = true;
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};
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/* A sink that writes data to a string. */
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struct StringSink : Sink
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{
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ref<std::string> s;
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StringSink() : s(make_ref<std::string>()) { };
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explicit StringSink(const size_t reservedSize) : s(make_ref<std::string>()) {
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s->reserve(reservedSize);
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};
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StringSink(ref<std::string> s) : s(s) { };
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void operator () (const unsigned char * data, size_t len) override;
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};
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/* A source that reads data from a string. */
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struct StringSource : Source
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{
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const string & s;
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size_t pos;
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StringSource(const string & _s) : s(_s), pos(0) { }
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size_t read(unsigned char * data, size_t len) override;
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};
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/* A sink that writes all incoming data to two other sinks. */
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struct TeeSink : Sink
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{
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Sink & sink1, & sink2;
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TeeSink(Sink & sink1, Sink & sink2) : sink1(sink1), sink2(sink2) { }
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virtual void operator () (const unsigned char * data, size_t len)
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{
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sink1(data, len);
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sink2(data, len);
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}
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};
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/* Adapter class of a Source that saves all data read to a sink. */
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struct TeeSource : Source
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{
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Source & orig;
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Sink & sink;
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TeeSource(Source & orig, Sink & sink)
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: orig(orig), sink(sink) { }
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size_t read(unsigned char * data, size_t len)
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{
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size_t n = orig.read(data, len);
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sink(data, n);
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return n;
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}
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};
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/* A reader that consumes the original Source until 'size'. */
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struct SizedSource : Source
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{
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Source & orig;
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size_t remain;
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SizedSource(Source & orig, size_t size)
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: orig(orig), remain(size) { }
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size_t read(unsigned char * data, size_t len)
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{
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if (this->remain <= 0) {
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throw EndOfFile("sized: unexpected end-of-file");
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}
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len = std::min(len, this->remain);
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size_t n = this->orig.read(data, len);
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this->remain -= n;
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return n;
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}
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/* Consume the original source until no remain data is left to consume. */
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size_t drainAll()
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{
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std::vector<unsigned char> buf(8192);
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size_t sum = 0;
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while (this->remain > 0) {
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size_t n = read(buf.data(), buf.size());
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sum += n;
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}
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return sum;
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}
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};
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/* Convert a function into a sink. */
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struct LambdaSink : Sink
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{
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typedef std::function<void(const unsigned char *, size_t)> lambda_t;
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lambda_t lambda;
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LambdaSink(const lambda_t & lambda) : lambda(lambda) { }
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virtual void operator () (const unsigned char * data, size_t len)
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{
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lambda(data, len);
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}
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};
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/* Convert a function into a source. */
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struct LambdaSource : Source
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{
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typedef std::function<size_t(unsigned char *, size_t)> lambda_t;
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lambda_t lambda;
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LambdaSource(const lambda_t & lambda) : lambda(lambda) { }
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size_t read(unsigned char * data, size_t len) override
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{
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return lambda(data, len);
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}
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};
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/* Chain two sources together so after the first is exhausted, the second is
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used */
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struct ChainSource : Source
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{
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Source & source1, & source2;
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bool useSecond = false;
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ChainSource(Source & s1, Source & s2)
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: source1(s1), source2(s2)
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{ }
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size_t read(unsigned char * data, size_t len) override;
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};
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/* Convert a function that feeds data into a Sink into a Source. The
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Source executes the function as a coroutine. */
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std::unique_ptr<Source> sinkToSource(
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std::function<void(Sink &)> fun,
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std::function<void()> eof = []() {
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throw EndOfFile("coroutine has finished");
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});
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void writePadding(size_t len, Sink & sink);
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void writeString(const unsigned char * buf, size_t len, Sink & sink);
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inline Sink & operator << (Sink & sink, uint64_t n)
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{
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unsigned char buf[8];
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buf[0] = n & 0xff;
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buf[1] = (n >> 8) & 0xff;
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buf[2] = (n >> 16) & 0xff;
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buf[3] = (n >> 24) & 0xff;
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buf[4] = (n >> 32) & 0xff;
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buf[5] = (n >> 40) & 0xff;
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buf[6] = (n >> 48) & 0xff;
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buf[7] = (unsigned char) (n >> 56) & 0xff;
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sink(buf, sizeof(buf));
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return sink;
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}
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Sink & operator << (Sink & sink, const string & s);
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Sink & operator << (Sink & sink, const Strings & s);
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Sink & operator << (Sink & sink, const StringSet & s);
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MakeError(SerialisationError, Error);
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template<typename T>
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T readNum(Source & source)
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{
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unsigned char buf[8];
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source(buf, sizeof(buf));
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uint64_t n =
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((uint64_t) buf[0]) |
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((uint64_t) buf[1] << 8) |
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((uint64_t) buf[2] << 16) |
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((uint64_t) buf[3] << 24) |
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((uint64_t) buf[4] << 32) |
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((uint64_t) buf[5] << 40) |
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((uint64_t) buf[6] << 48) |
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((uint64_t) buf[7] << 56);
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if (n > std::numeric_limits<T>::max())
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throw SerialisationError("serialised integer %d is too large for type '%s'", n, typeid(T).name());
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return (T) n;
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}
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inline unsigned int readInt(Source & source)
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{
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return readNum<unsigned int>(source);
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}
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inline uint64_t readLongLong(Source & source)
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{
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return readNum<uint64_t>(source);
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}
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void readPadding(size_t len, Source & source);
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size_t readString(unsigned char * buf, size_t max, Source & source);
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string readString(Source & source, size_t max = std::numeric_limits<size_t>::max());
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template<class T> T readStrings(Source & source);
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Source & operator >> (Source & in, string & s);
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template<typename T>
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Source & operator >> (Source & in, T & n)
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{
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n = readNum<T>(in);
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return in;
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}
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template<typename T>
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Source & operator >> (Source & in, bool & b)
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{
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b = readNum<uint64_t>(in);
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return in;
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}
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/* An adapter that converts a std::basic_istream into a source. */
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struct StreamToSourceAdapter : Source
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{
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std::shared_ptr<std::basic_istream<char>> istream;
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StreamToSourceAdapter(std::shared_ptr<std::basic_istream<char>> istream)
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: istream(istream)
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{ }
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size_t read(unsigned char * data, size_t len) override
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{
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if (!istream->read((char *) data, len)) {
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if (istream->eof()) {
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if (istream->gcount() == 0)
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throw EndOfFile("end of file");
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} else
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throw Error("I/O error in StreamToSourceAdapter");
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}
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return istream->gcount();
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}
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};
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}
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