diff options
Diffstat (limited to 'nix/libutil/serialise.cc')
| -rw-r--r-- | nix/libutil/serialise.cc | 259 |
1 files changed, 259 insertions, 0 deletions
diff --git a/nix/libutil/serialise.cc b/nix/libutil/serialise.cc new file mode 100644 index 0000000000..6b71f52c15 --- /dev/null +++ b/nix/libutil/serialise.cc @@ -0,0 +1,259 @@ +#include "serialise.hh" +#include "util.hh" + +#include <cstring> +#include <cerrno> + + +namespace nix { + + +BufferedSink::~BufferedSink() +{ + /* We can't call flush() here, because C++ for some insane reason + doesn't allow you to call virtual methods from a destructor. */ + assert(!bufPos); + delete[] buffer; +} + + +void BufferedSink::operator () (const unsigned char * data, size_t len) +{ + if (!buffer) buffer = new unsigned char[bufSize]; + + while (len) { + /* Optimisation: bypass the buffer if the data exceeds the + buffer size. */ + if (bufPos + len >= bufSize) { + flush(); + write(data, len); + break; + } + /* Otherwise, copy the bytes to the buffer. Flush the buffer + when it's full. */ + size_t n = bufPos + len > bufSize ? bufSize - bufPos : len; + memcpy(buffer + bufPos, data, n); + data += n; bufPos += n; len -= n; + if (bufPos == bufSize) flush(); + } +} + + +void BufferedSink::flush() +{ + if (bufPos == 0) return; + size_t n = bufPos; + bufPos = 0; // don't trigger the assert() in ~BufferedSink() + write(buffer, n); +} + + +FdSink::~FdSink() +{ + try { flush(); } catch (...) { ignoreException(); } +} + + +void FdSink::write(const unsigned char * data, size_t len) +{ + writeFull(fd, data, len); +} + + +void Source::operator () (unsigned char * data, size_t len) +{ + while (len) { + size_t n = read(data, len); + data += n; len -= n; + } +} + + +BufferedSource::~BufferedSource() +{ + delete[] buffer; +} + + +size_t BufferedSource::read(unsigned char * data, size_t len) +{ + if (!buffer) buffer = new unsigned char[bufSize]; + + if (!bufPosIn) bufPosIn = readUnbuffered(buffer, bufSize); + + /* Copy out the data in the buffer. */ + size_t n = len > bufPosIn - bufPosOut ? bufPosIn - bufPosOut : len; + memcpy(data, buffer + bufPosOut, n); + bufPosOut += n; + if (bufPosIn == bufPosOut) bufPosIn = bufPosOut = 0; + return n; +} + + +bool BufferedSource::hasData() +{ + return bufPosOut < bufPosIn; +} + + +size_t FdSource::readUnbuffered(unsigned char * data, size_t len) +{ + ssize_t n; + do { + checkInterrupt(); + n = ::read(fd, (char *) data, bufSize); + } while (n == -1 && errno == EINTR); + if (n == -1) throw SysError("reading from file"); + if (n == 0) throw EndOfFile("unexpected end-of-file"); + return n; +} + + +size_t StringSource::read(unsigned char * data, size_t len) +{ + if (pos == s.size()) throw EndOfFile("end of string reached"); + size_t n = s.copy((char *) data, len, pos); + pos += n; + return n; +} + + +void writePadding(size_t len, Sink & sink) +{ + if (len % 8) { + unsigned char zero[8]; + memset(zero, 0, sizeof(zero)); + sink(zero, 8 - (len % 8)); + } +} + + +void writeInt(unsigned int n, Sink & sink) +{ + unsigned char buf[8]; + memset(buf, 0, sizeof(buf)); + buf[0] = n & 0xff; + buf[1] = (n >> 8) & 0xff; + buf[2] = (n >> 16) & 0xff; + buf[3] = (n >> 24) & 0xff; + sink(buf, sizeof(buf)); +} + + +void writeLongLong(unsigned long long n, Sink & sink) +{ + unsigned char buf[8]; + buf[0] = n & 0xff; + buf[1] = (n >> 8) & 0xff; + buf[2] = (n >> 16) & 0xff; + buf[3] = (n >> 24) & 0xff; + buf[4] = (n >> 32) & 0xff; + buf[5] = (n >> 40) & 0xff; + buf[6] = (n >> 48) & 0xff; + buf[7] = (n >> 56) & 0xff; + sink(buf, sizeof(buf)); +} + + +void writeString(const unsigned char * buf, size_t len, Sink & sink) +{ + writeInt(len, sink); + sink(buf, len); + writePadding(len, sink); +} + + +void writeString(const string & s, Sink & sink) +{ + writeString((const unsigned char *) s.data(), s.size(), sink); +} + + +template<class T> void writeStrings(const T & ss, Sink & sink) +{ + writeInt(ss.size(), sink); + foreach (typename T::const_iterator, i, ss) + writeString(*i, sink); +} + +template void writeStrings(const Paths & ss, Sink & sink); +template void writeStrings(const PathSet & ss, Sink & sink); + + +void readPadding(size_t len, Source & source) +{ + if (len % 8) { + unsigned char zero[8]; + size_t n = 8 - (len % 8); + source(zero, n); + for (unsigned int i = 0; i < n; i++) + if (zero[i]) throw SerialisationError("non-zero padding"); + } +} + + +unsigned int readInt(Source & source) +{ + unsigned char buf[8]; + source(buf, sizeof(buf)); + if (buf[4] || buf[5] || buf[6] || buf[7]) + throw SerialisationError("implementation cannot deal with > 32-bit integers"); + return + buf[0] | + (buf[1] << 8) | + (buf[2] << 16) | + (buf[3] << 24); +} + + +unsigned long long readLongLong(Source & source) +{ + unsigned char buf[8]; + source(buf, sizeof(buf)); + return + ((unsigned long long) buf[0]) | + ((unsigned long long) buf[1] << 8) | + ((unsigned long long) buf[2] << 16) | + ((unsigned long long) buf[3] << 24) | + ((unsigned long long) buf[4] << 32) | + ((unsigned long long) buf[5] << 40) | + ((unsigned long long) buf[6] << 48) | + ((unsigned long long) buf[7] << 56); +} + + +size_t readString(unsigned char * buf, size_t max, Source & source) +{ + size_t len = readInt(source); + if (len > max) throw Error("string is too long"); + source(buf, len); + readPadding(len, source); + return len; +} + + +string readString(Source & source) +{ + size_t len = readInt(source); + unsigned char * buf = new unsigned char[len]; + AutoDeleteArray<unsigned char> d(buf); + source(buf, len); + readPadding(len, source); + return string((char *) buf, len); +} + + +template<class T> T readStrings(Source & source) +{ + unsigned int count = readInt(source); + T ss; + while (count--) + ss.insert(ss.end(), readString(source)); + return ss; +} + +template Paths readStrings(Source & source); +template PathSet readStrings(Source & source); + + +} |