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/* file_wrappers.c
*
* $Id: file_wrappers.c,v 1.2 2000/01/13 07:18:50 guy Exp $
*
* Wiretap Library
* Copyright (c) 1998 by Gilbert Ramirez <gram@verdict.uthscsa.edu>
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License
* as published by the Free Software Foundation; either version 2
* of the License, or (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
*
*/
#ifdef HAVE_CONFIG_H
#include "config.h"
#endif
/*
* OK, now this is tricky.
*
* At least on FreeBSD 3.2, "/usr/include/zlib.h" includes
* "/usr/include/zconf.h", which, if HAVE_UNISTD_H is defined,
* #defines "z_off_t" to be "off_t", and if HAVE_UNISTD_H is
* not defines, #defines "z_off_t" to be "long" if it's not
* already #defined.
*
* In 4.4-Lite-derived systems such as FreeBSD, "off_t" is
* "long long int", not "long int", so the definition of "z_off_t" -
* and therefore the types of the arguments to routines such as
* "gzseek()", as declared, with prototypes, in "zlib.h" - depends
* on whether HAVE_UNISTD_H is defined prior to including "zlib.h"!
*
* It's not defined in the FreeBSD 3.2 "zlib", so if we include "zlib.h"
* after defining HAVE_UNISTD_H, we get a misdeclaration of "gzseek()",
* and, if we're building with "zlib" support, anything that seeks
* on a file may not work.
*
* Other BSDs may have the same problem, if they haven't done something
* such as defining HAVE_UNISTD_H in "zconf.h".
*
* "config.h" defines HAVE_UNISTD_H, on all systems that have it, and all
* 4.4-Lite-derived BSDs have it. Therefore, given that "zlib.h" is included
* by "file_wrappers.h", that means that unless we include "zlib.h" before
* we include "config.h", we get a misdeclaration of "gzseek()".
*
* Unfortunately, it's "config.h" that tells us whether we have "zlib"
* in the first place, so we don't know whether to include "zlib.h"
* until we include "config.h"....
*
* So what we do is *undefine* HAVE_UNISTD_H before including "wtap.h"
* (we need "wtap.h" to get the WTAP_ERR_ZLIB values, and it also includes
* "zlib.h" if HAVE_ZLIB" is defined), and make "file_seek()" a subroutine,
* so that the only call to "gzseek()" is in this file, which, by dint of
* the hackery described above, manages to correctly declare "gzseek()".
*
* DO NOT, UNDER ANY CIRCUMSTANCES, REMOVE THE FOLLOWING LINE, OR MOVE
* IT AFTER THE INCLUDE OF "wtap.h"! Doing so will cause any program
* using Wiretap to read capture files to fail miserably on a FreeBSD
* 3.2 or 3.3 system - and possibly other BSD systems - if zlib is
* installed. If you *must* include <unistd.h> here, do so *before*
* including "wtap.h", and before undefining HAVE_UNISTD_H. If you
* *must* have HAVE_UNISTD_H defined before including "wtap.h", put
* "file_error()" into a file by itself, which can cheerfully include
* "wtap.h" and get "gzseek()" misdeclared, and include just "zlib.h"
* in this file - *after* undefining HAVE_UNISTD_H.
*/
#undef HAVE_UNISTD_H
#include <errno.h>
#include <stdio.h>
#include "wtap.h"
#include "file_wrappers.h"
#ifdef HAVE_LIBZ
int
file_seek(void *stream, long offset, int whence)
{
return gzseek(stream, offset, whence);
}
#else /* HAVE_LIBZ */
int
file_seek(FILE *stream, long offset, int whence)
{
return fseek(stream, offset, whence);
}
#endif /* HAVE_LIBZ */
/*
* Routine to return a Wiretap error code (0 for no error, an errno
* for a file error, or a WTAP_ERR_ code for other errors) for an
* I/O stream.
*/
#ifdef HAVE_LIBZ
int
file_error(void *fh)
{
int errnum;
gzerror(fh, &errnum);
switch (errnum) {
case Z_OK: /* no error */
return 0;
case Z_STREAM_END: /* EOF - not an error */
return 0;
case Z_ERRNO: /* file I/O error */
return errno;
default:
return WTAP_ERR_ZLIB + errnum;
}
}
#else /* HAVE_LIBZ */
int
file_error(FILE *fh)
{
if (ferror(fh))
return errno;
else
return 0;
}
#endif /* HAVE_LIBZ */
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