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/* This file is part of dvi2bitmap; see README for copyrights and licence */
#include <config.h>
#include <FileByteStream.h>
#include <iostream>
//#include <fcntl.h>
#include <sys/stat.h>
#include <unistd.h>
#ifdef HAVE_CSTD_INCLUDE
#include <cstdio>
#include <cerrno>
#include <cassert>
#include <cstring> // for strerror
#else
#include <stdio.h>
#include <errno.h>
#include <assert.h>
#include <string.h>
#endif
using STD::cerr;
using STD::endl;
/**
* Opens the requested file. If preload is true, then open the file
* and read it entire into memory (possibly helpful if the client will
* be seeking a lot). If the file can't be opened, then try adding
* <code>tryext</code> to the end of it.
*
* <p>The file to be opened must be a seekable object -- that is, it
* must be a regular file, rather than a named pipe or a socket. The
* constructor checks this, and throws an exception if this is not the
* case. If you wish to open a named pipe, you can do so using {@link
* InputByteStream#InputByteStream(string)}.
*
* @param filename the file to be opened
* @param tryext a file extension, including any dot, which should be
* added to the end of <code>filename</code> if that cannot be opened;
* default <code>""</code> suppresses this
* @param preload if true, then the file is read entirely into memory
*
* @throws InputByteStreamError if there is a problem opening the
* file, including the discovery that it is not a seekable object
*/
FileByteStream::FileByteStream(string& filename,
string tryext,
bool preload)
throw (InputByteStreamError)
{
if (getVerbosity() > normal)
cerr << "FileByteStream(name=" << filename
<< ",ext=" << tryext
<< ",preload=" << (preload?"yes":"no") << ")" << endl;
int newfd = -1;
try {
newfd = openSourceSpec("<osfile>" + filename);
} catch (InputByteStreamError& e) {
newfd = -1;
}
if (newfd < 0) {
newfd = openSourceSpec("<osfile>" + filename + tryext);
// Let it throw the exception, this time
// If it succeeds, modify the argument
filename += tryext;
}
assert(newfd >= 0);
// ermm, we should test for HAVE_SYS_STAT_H, here, but (a) are
// there really any platforms which don't have stat?, and (b) we
// need the filesize information, and I don't know how else to
// get it. Deal with this if we really do find such a wierd
// platform.
#ifndef HAVE_SYS_STAT_H
#error "Come on -- you _must_ have stat(2)!"
#endif
struct stat S;
if (fstat (newfd, &S))
{
string errstr = STD::strerror (errno);
throw InputByteStreamError ("Can't stat open file (" + errstr + ")");
}
filesize_ = S.st_size;
bindToFileDescriptor(newfd,
filename,
(preload ? filesize_ : 0),
preload,
true); // assert is seekable
}
FileByteStream::~FileByteStream()
{
// nothing
}
/**
* Sets the position of the file pointer.
*
* @param pos if positive, the offset from the beginning of the file;
* if negative, the offset from the end of the file
*
* @throws InputByteStreamError if the offset is larger
* than the size of the file
*/
void FileByteStream::seek(int pos)
throw (InputByteStreamError)
{
int fd = getFD();
int offset = (pos >= 0 ? pos : filesize_ + pos);
if (offset < 0 || offset > filesize_)
throw InputByteStreamError("FileByteStream: seek out of bounds");
if (fd < 0) {
// preloaded
bufferSeek(offset);
// no need to reload buffer
} else {
if (lseek(fd, offset, SEEK_SET) < 0) {
string errmsg = STD::strerror(errno);
throw InputByteStreamError("Can't seek (" + errmsg + ")");
}
if (getVerbosity() > normal)
cerr << "FileByteStream::seek(" << pos << "=>" << offset
<< ") ok" << endl;
reloadBuffer();
}
}
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