1 files changed, 258 insertions, 0 deletions

diff --git a/private/crt32/stdio/fseek.c b/private/crt32/stdio/fseek.c
new file mode 100644
index 000000000..79a975870
--- /dev/null
+++ b/private/crt32/stdio/fseek.c
@@ -0,0 +1,258 @@
+/***
+*fseek.c - reposition file pointer on a stream
+*
+*	Copyright (c) 1985-1992, Microsoft Corporation. All rights reserved.
+*
+*Purpose:
+*	defines fseek() - move the file pointer to new place in file
+*
+*Revision History:
+*	10-13-83  RN	initial version
+*	06-26-85  TC	added code to allow variable buffer lengths
+*	02-10-87  BCM	fixed '%' mistakenly used for '/'
+*	03-04-87  JCR	added errno settings
+*	04-16-87  JCR	added _IOUNGETC support for bug fix and changes whence
+*			from unsigned int to int (ANSI conformance)
+*	04-17-87  JCR	fseek() now clears end-of-file indicator flag _IOEOF
+*			(for ANSI conformance)
+*	04-21-87  JCR	be smart about lseek'ing to the end of the file and
+*			back
+*	09-17-87  SKS	handle case of '\n' at beginning of buffer (FCRLF flag)
+*	09-24-87  JCR	fixed an incorrect access to flag _IOEOF
+*	09-28-87  JCR	Corrected _iob2 indexing (now uses _iob_index() macro).
+*	09-30-87  JCR	Fixed buffer allocation bug, now use _getbuf()
+*	11-04-87  JCR	Multi-thread support
+*	12-11-87  JCR	Added "_LOAD_DS" to declaration
+*	01-13-88  JCR	Removed unnecessary calls to mthread fileno/feof/ferror
+*	03-04-88  JCR	Return value from read() must be treated as unsigned
+*			value
+*	05-27-88  PHG	Merged DLL and normal versions
+*	06-06-88  JCR	Optimized _iob2[] references
+*	06-15-88  JCR	Near reference to _iob[] entries; improve REG variables
+*	08-25-88  GJF	Don't use FP_OFF() macro for the 386
+*	12-02-88  JCR	Added _IOCTRLZ support (fixes bug pertaining to ^Z at
+*			eof)
+*	04-12-89  JCR	Ripped out all of the special read-only code.  See the
+*			comments in the routine header for more information.
+*	08-17-89  GJF	Clean up, now specific to OS/2 2.0 (i.e., 386 flat
+*			model). Also fixed copyright and indents.
+*	02-15-90  GJF	Fixed copyright
+*	03-19-90  GJF	Made calling type _CALLTYPE1, added #include
+*			<cruntime.h> and removed #include <register.h>.
+*	05-29-90  SBM   Use _flush, not [_]fflush[_lk]
+*	07-23-90  SBM	Replaced <assertm.h> by <assert.h>
+*	10-02-90  GJF	New-style function declarators.
+*	01-21-91  GJF	ANSI naming.
+*	03-27-92  DJM	POSIX support.
+*	08-08-92  GJF	Use seek method constants!
+*	08-26-92  GJF	Include unistd.h for POSIX build.
+*
+*******************************************************************************/
+
+#include <cruntime.h>
+#include <stdio.h>
+#include <file2.h>
+#include <assert.h>
+#ifdef	_POSIX_
+#include <unistd.h>
+#else
+#include <msdos.h>
+#endif
+#include <errno.h>
+#include <malloc.h>
+#include <io.h>
+#include <stddef.h>
+#include <internal.h>
+#ifndef _POSIX_
+#include <os2dll.h>
+#endif
+
+/***
+*int fseek(stream, offset, whence) - reposition file pointer
+*
+*Purpose:
+*
+*	Reposition file pointer to the desired location.  The new location
+*	is calculated as follows:
+*				 { whence=0, beginning of file }
+*		<offset> bytes + { whence=1, current position  }
+*				 { whence=2, end of file       }
+*
+*	Be careful to coordinate with buffering.
+*
+*			- - - - - - - - - - - - -
+*
+*	[NOTE: We used to bend over backwards to try and preserve the current
+*	buffer and maintain disk block alignment.  This ended up making our
+*	code big and slow and complicated, and slowed us down quite a bit.
+*	Some of the things pertinent to the old implimentation:
+*
+*	(1) Read-only: We only did the special code path if the file was
+*	opened read-only (_IOREAD).  If the file was writable, we didn't
+*	try to optimize.
+*
+*	(2) Buffering:	We'd assign a buffer, if necessary, since the
+*	later code might need it (i.e., call _getbuf).
+*
+*	(3) Ungetc: Fseek had to be careful NOT to save the buffer if
+*	an ungetc had ever been done on the buffer (flag _IOUNGETC).
+*
+*	(4) Control ^Z: Fseek had to deal with ^Z after reading a
+*	new buffer's worth of data (flag _IOCTRLZ).
+*
+*	(5) Seek-to-end-and-back: To determine if the new seek was within
+*	the current buffer, we had to 'normalize' the desired location.
+*	This means that we sometimes had to seek to the end of the file
+*	and back to determine what the 0-relative offset was.  Two extra
+*	lseek() calls hurt performance.
+*
+*	(6) CR/LF accounting - When trying to seek within a buffer that
+*	is in text mode, we had to go account for CR/LF expansion.  This
+*	required us to look at every character up to the new offset and
+*	see if it was '\n' or not.  In addition, we had to check the
+*	FCRLF flag to see if the new buffer started with '\n'.
+*
+*	Again, all of these notes are for the OLD implimentation just to
+*	remind folks of some of the issues involving seeking within a buffer
+*	and maintaining buffer alignment.  As an aside, I think this may have
+*	been a big win in the 'old days' on floppy-based systems but on newer
+*	fast hard disks, the extra code/complexity overwhelmed any gain.
+*
+*			- - - - - - - - - - - - -
+*
+*Entry:
+*	FILE *stream - file to reposition file pointer on
+*	long offset - offset to seek to
+*	int whence - origin offset is measured from (0=beg, 1=current pos,
+*		     2=end)
+*
+*Exit:
+*	returns 0 if succeeds
+*	returns -1 and sets errno if fails
+*	fields of FILE struct will be changed
+*
+*Exceptions:
+*
+*******************************************************************************/
+
+#ifdef MTHREAD	/* multi-thread; define both fseek() and _lk_fseek() */
+
+int _CALLTYPE1 fseek (
+	FILE *stream,
+	long offset,
+	int whence
+	)
+{
+	int retval;
+#ifdef MTHREAD
+	int index;
+#endif
+
+	assert(stream != NULL);
+
+#ifdef MTHREAD
+	index = _iob_index(stream);
+#endif
+
+	_lock_str(index);
+
+	retval = _fseek_lk (stream, offset, whence);
+
+	_unlock_str(index);
+
+	return(retval);
+}
+
+
+/***
+*_fseek_lk() - Core fseek() routine (stream is locked)
+*
+*Purpose:
+*	Core fseek() routine; assumes that caller has the stream locked.
+*
+*	[See fseek() for more info.]
+*
+*Entry: [See fseek()]
+*
+*Exit:	[See fseek()]
+*
+*Exceptions:
+*
+*******************************************************************************/
+
+int _CALLTYPE1 _fseek_lk (
+
+#else	/* non multi-thread; just define fseek() */
+
+int _CALLTYPE1 fseek (
+
+#endif	/* rejoin common code */
+
+	FILE *str,
+	long offset,
+	int whence
+	)
+{
+
+
+	REG1 FILE *stream;
+
+	assert(str != NULL);
+
+	/* Init stream pointer */
+	stream = str;
+
+	if ( !inuse(stream) || ((whence != SEEK_SET) && (whence != SEEK_CUR) &&
+	    (whence != SEEK_END)) ) {
+		errno=EINVAL;
+		return(-1);
+	}
+
+	/* Clear EOF flag */
+
+	stream->_flag &= ~_IOEOF;
+
+	/* If seeking relative to current location, then convert to
+	   a seek relative to beginning of file.  This accounts for
+	   buffering, etc. by letting fseek() tell us where we are. */
+
+	if (whence == SEEK_CUR) {
+		offset += _ftell_lk(stream);
+		whence = SEEK_SET;
+	}
+
+	/* Flush buffer as necessary */
+
+#ifdef _POSIX_
+	/*
+	 * If the stream was last read, we throw away the buffer so
+	 * that a possible subsequent write will encounter a clean
+	 * buffer.  (The Win32 version of fflush() throws away the
+	 * buffer if it's read.)  Write buffers must be flushed.
+	 */
+	
+	if ((stream->_flag & (_IOREAD | _IOWRT)) == _IOREAD) {
+		stream->_ptr = stream->_base;
+		stream->_cnt = 0;
+	} else {
+		_flush(stream);
+	}
+#else
+	_flush(stream);
+#endif
+
+
+	/* If file opened for read/write, clear flags since we don't know
+	what the user is going to do next. */
+
+	if (stream->_flag & _IORW)
+		stream->_flag &= ~(_IOWRT|_IOREAD);
+
+	/* Seek to the desired locale and return. */
+
+#ifdef _POSIX_
+	return(lseek(fileno(stream), offset, whence) == -1L ? -1 : 0);
+#else
+	return(_lseek(_fileno(stream), offset, whence) == -1L ? -1 : 0);
+#endif
+}