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https://git.lyx.org/repos/lyx.git
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a654de29ea
git-svn-id: svn://svn.lyx.org/lyx/lyx-devel/trunk@3802 a592a061-630c-0410-9148-cb99ea01b6c8
127 lines
2.5 KiB
C
127 lines
2.5 KiB
C
/* This file is part of
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* ======================================================
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*
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* LyX, The Document Processor
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* Copyright 2001 The LyX Team.
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*
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* ======================================================
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*/
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#include <config.h>
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#include <algorithm>
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#include <boost/crc.hpp>
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#include "support/lyxlib.h"
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#include "debug.h"
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using std::endl;
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// Various implementations of lyx::sum(), depending on what methods
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// are available. Order is faster to slowest.
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#if defined(HAVE_MMAP) && defined(HAVE_MUNMAP)
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// Make sure we get modern version of mmap and friends with void*,
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// not `compatibility' version with caddr_t.
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#define _POSIX_C_SOURCE 199506L
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#include <sys/types.h>
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#include <sys/stat.h>
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#include <fcntl.h>
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#include <unistd.h>
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#include <sys/mman.h>
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using std::ifstream;
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using std::for_each;
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using std::istreambuf_iterator;
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using std::istream_iterator;
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using std::ios;
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unsigned long lyx::sum(string const & file)
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{
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lyxerr[Debug::FILES] << "lyx::sum() using mmap (lightning fast)"
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<< endl;
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int fd = open(file.c_str(), O_RDONLY);
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if (!fd)
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return 0;
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struct stat info;
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fstat(fd, &info);
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void * mm = mmap(0, info.st_size, PROT_READ,
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MAP_PRIVATE, fd, 0);
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// Some platforms have the wrong type for MAP_FAILED (compaq cxx).
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if (mm == reinterpret_cast<void*>(MAP_FAILED)) {
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close(fd);
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return 0;
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}
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char * beg = static_cast<char*>(mm);
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char * end = beg + info.st_size;
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boost::crc_32_type crc;
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crc.process_block(beg, end);
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unsigned long result = crc.checksum();
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munmap(mm, info.st_size);
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close(fd);
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return result;
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}
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#else // No mmap
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#include <fstream>
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#include <iterator>
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namespace {
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template<typename InputIterator>
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inline
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unsigned long do_crc(InputIterator first, InputIterator last)
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{
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boost::crc_32_type crc;
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crc = for_each(first, last, crc);
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return crc.checksum();
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}
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} // namespace
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#if HAVE_DECL_ISTREAMBUF_ITERATOR
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using std::ifstream;
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using std::istreambuf_iterator;
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unsigned long lyx::sum(string const & file)
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{
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lyxerr[Debug::FILES] << "lyx::sum() using istreambuf_iterator (fast)"
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<< endl;
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ifstream ifs(file.c_str());
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if (!ifs) return 0;
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istreambuf_iterator<char> beg(ifs);
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istreambuf_iterator<char> end;
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return do_crc(beg,end);
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}
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#else
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unsigned long lyx::sum(string const & file)
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{
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lyxerr[Debug::FILES]
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<< "lyx::sum() using istream_iterator (slow as a snail)"
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<< endl;
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ifstream ifs(file.c_str());
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if (!ifs) return 0;
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ifs.unsetf(ios::skipws);
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istream_iterator<char> beg(ifs);
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istream_iterator<char> end;
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return do_crc(beg,end);
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}
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#endif
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#endif // mmap
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