Paul Kelly wrote:
In some recent enhancements to the iostream library,
include/iostream/ami_stream.h had a call to fseek() changed to fseeko().
This now doesn't compile on Windows; a sample error is:
sh-2.04$ make
make OBJ.i686-pc-mingw32
make[1]: Entering directory `/c/grass/grass7/lib/iostream'
make[1]: `OBJ.i686-pc-mingw32' is up to date.
make[1]: Leaving directory `/c/grass/grass7/lib/iostream'
c++ -I/c/grass/grass7/dist.i686-pc-mingw32/include
-I/c/grass/extra/include -O2 -s -I/c/grass/extra/include
-D_FILE_OFFSET_BITS=64 -DPACKAGE=\""grasslibs"\"
-I/c/grass/grass7/dist.i686-pc-mingw32/include -o
OBJ.i686-pc-mingw32/ami_stream.o -c ami_stream.cc
In file included from ami_stream.cc:47:
c:/grass/grass7/dist.i686-pc-mingw32/include/grass/iostream/ami_stream.h:
In member function `AMI_err AMI_STREAM<T>::seek(off_t)':
c:/grass/grass7/dist.i686-pc-mingw32/include/grass/iostream/ami_stream.h:432:
error: there are no arguments to `fseeko' that depend on a template
parameter, so a declaration of `fseeko' must be available
c:/grass/grass7/dist.i686-pc-mingw32/include/grass/iostream/ami_stream.h:432:
error: (if you use `-fpermissive', G++ will accept your code, but
allowing the use of an undeclared name is deprecated)
make: *** [OBJ.i686-pc-mingw32/ami_stream.o] Error 1
sh-2.04$
Am I right in thinking that if large file support is configured properly
there should be no need to use fseeko() to seek in large files, and
fseek() should be fine? I looked in r.in.xyz which only uses fseek() and
ISTR discussion about it handling huge files recently, although perhaps
that involved reading from stdin.
Paul
fseek is not the same as fseeko.
int fseek(FILE *stream, long offset, int whence);
int fseeko(FILE *stream, off_t offset, int whence);
If large file support is enabled, fseeko will convert off_t to a 64 bit
type even on a 32-bit OS. I'm not sure if long will be 64 bit on a
64-bit OS for fseek.
r.in.xyz may work with large files using plain old fseek as long as
r.in.xyz doesn't make long seeks. ami_stream.h could potentially make
long seeks (e.g., skip the first 8GB of a 30GB file), though in
practice, I'm not sure that code that uses ami_stream (r.terraflow)
actually uses this kind of fseek. Still the interface is designed to
potentially use long seeks and I would be reluctant to simply replace
fseeko with fseek in ami_stream.h.
you may to add a #define to check the compiler type and use fseek only
if fseeko does not exist.
-Andy
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