forked from lix-project/lix
a3e0656cbb
significantly cuts down the number of syscalls (e.g., for "nix-store -qR /var/run/current-system" via the daemon, it reduced the number of syscalls in the client from 29134 to 4766 and in the daemon from 44266 to 20666).
123 lines
2.8 KiB
C++
123 lines
2.8 KiB
C++
#ifndef __SERIALISE_H
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#define __SERIALISE_H
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#include "types.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, unsigned int 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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/* The callee should store exactly *len bytes in the buffer
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pointed to by data. It should block if that much data is not
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yet available, or throw an error if it is not going to be
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available. */
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virtual void operator () (unsigned char * data, unsigned int len) = 0;
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};
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/* A sink that writes data to a file descriptor (using a buffer). */
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struct FdSink : Sink
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{
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int fd;
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unsigned int bufSize, bufPos;
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unsigned char * buffer;
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FdSink() : fd(-1), bufSize(32 * 1024), bufPos(0), buffer(0) { }
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FdSink(int fd, unsigned int bufSize = 32 * 1024)
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: fd(fd), bufSize(bufSize), bufPos(0), buffer(0) { }
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~FdSink()
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{
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flush();
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if (buffer) delete[] buffer;
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}
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void operator () (const unsigned char * data, unsigned int len);
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void flush();
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};
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/* A source that reads data from a file descriptor. */
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struct FdSource : Source
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{
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int fd;
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unsigned int bufSize, bufPosIn, bufPosOut;
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unsigned char * buffer;
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FdSource() : fd(-1), bufSize(32 * 1024), bufPosIn(0), bufPosOut(0), buffer(0) { }
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FdSource(int fd, unsigned int bufSize = 32 * 1024)
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: fd(fd), bufSize(bufSize), bufPosIn(0), bufPosOut(0), buffer(0) { }
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~FdSource()
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{
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if (buffer) delete[] buffer;
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}
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void operator () (unsigned char * data, unsigned int len);
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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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string s;
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virtual void operator () (const unsigned char * data, unsigned int len)
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{
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s.append((const char *) data, len);
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}
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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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unsigned int pos;
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StringSource(const string & _s) : s(_s), pos(0) { }
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virtual void operator () (unsigned char * data, unsigned int len)
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{
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s.copy((char *) data, len, pos);
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pos += len;
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if (pos > s.size())
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throw Error("end of string reached");
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}
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};
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void writePadding(unsigned int len, Sink & sink);
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void writeInt(unsigned int n, Sink & sink);
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void writeLongLong(unsigned long long n, Sink & sink);
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void writeString(const string & s, Sink & sink);
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void writeStringSet(const StringSet & ss, Sink & sink);
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void readPadding(unsigned int len, Source & source);
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unsigned int readInt(Source & source);
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unsigned long long readLongLong(Source & source);
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string readString(Source & source);
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StringSet readStringSet(Source & source);
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MakeError(SerialisationError, Error)
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}
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#endif /* !__SERIALISE_H */
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