another safety belt

[lyx.git] / src / support / lyxsum.C

diff --git a/src/support/lyxsum.C b/src/support/lyxsum.C
index f74039591ebe0d1825a4577dfb8ad339ba0a0b6c..f7e89fa200544eaa16c086a91650be70487c082e 100644 (file)
--- a/src/support/lyxsum.C
+++ b/src/support/lyxsum.C
@@ -1,23 +1,32 @@
-/* This file is part of
- * ======================================================
- * 
- *           LyX, The Document Processor
- *           Copyright 2001 The LyX Team.
+/**
+ * \file lyxsum.C
+ * This file is part of LyX, the document processor.
+ * Licence details can be found in the file COPYING.
  *
- * ======================================================
+ * \author Lars Gullik Bjønnes
+ *
+ * Full author contact details are available in file CREDITS
  */
 
-
 #include <config.h>
 
-#include <algorithm>
-#include <boost/crc.hpp>
-
 #include "support/lyxlib.h"
 #include "debug.h"
 
+#include <algorithm>
+#include <boost/crc.hpp>
+
 using std::endl;
 
+// OK, this is ugly, but it is the only workaround I found to compile
+// with gcc (any version) on a system which uses a non-GNU toolchain.
+// The problem is that gcc uses a weak symbol for a particular
+// instantiation and that the system linker usually does not
+// understand those weak symbols (seen on HP-UX, tru64, AIX and
+// others). Thus we force an explicit instanciation of this particular
+// template (JMarc)
+template class boost::detail::crc_table_t<32, 0x04C11DB7, true>;
+
 // Various implementations of lyx::sum(), depending on what methods
 // are available. Order is faster to slowest.
 #if defined(HAVE_MMAP) && defined(HAVE_MUNMAP)
@@ -32,25 +41,19 @@ using std::endl;
 #include <unistd.h>
 #include <sys/mman.h>
 
-using std::ifstream;
-using std::for_each;
-using std::istreambuf_iterator;
-using std::istream_iterator;
-using std::ios;
-
 
 unsigned long lyx::sum(string const & file)
 {
        lyxerr[Debug::FILES] << "lyx::sum() using mmap (lightning fast)"
                             << endl;
-       
+
        int fd = open(file.c_str(), O_RDONLY);
        if (!fd)
                return 0;
-       
+
        struct stat info;
        fstat(fd, &info);
-       
+
        void * mm = mmap(0, info.st_size, PROT_READ,
                         MAP_PRIVATE, fd, 0);
        // Some platforms have the wrong type for MAP_FAILED (compaq cxx).
@@ -58,17 +61,17 @@ unsigned long lyx::sum(string const & file)
                close(fd);
                return 0;
        }
-       
+
        char * beg = static_cast<char*>(mm);
        char * end = beg + info.st_size;
-       
+
        boost::crc_32_type crc;
        crc.process_block(beg, end);
        unsigned long result = crc.checksum();
-       
+
        munmap(mm, info.st_size);
        close(fd);
-       
+
        return result;
 }
 #else // No mmap
@@ -76,6 +79,8 @@ unsigned long lyx::sum(string const & file)
 #include <fstream>
 #include <iterator>
 
+using std::for_each;
+
 namespace {
 
 template<typename InputIterator>
@@ -100,26 +105,30 @@ unsigned long lyx::sum(string const & file)
 
        ifstream ifs(file.c_str());
        if (!ifs) return 0;
-       
+
        istreambuf_iterator<char> beg(ifs);
        istreambuf_iterator<char> end;
-       
+
        return do_crc(beg,end);
 }
 #else
+
+using std::istream_iterator;
+using std::ios;
+
 unsigned long lyx::sum(string const & file)
 {
        lyxerr[Debug::FILES]
                << "lyx::sum() using istream_iterator (slow as a snail)"
                << endl;
-       
+
        ifstream ifs(file.c_str());
        if (!ifs) return 0;
-       
+
        ifs.unsetf(ios::skipws);
        istream_iterator<char> beg(ifs);
        istream_iterator<char> end;
-       
+
        return do_crc(beg,end);
 }
 #endif