Initial commit

1 files changed, 69 insertions, 0 deletions

diff --git a/sys/fio/seek.x b/sys/fio/seek.x
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+++ b/sys/fio/seek.x
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+# Copyright(c) 1986 Association of Universities for Research in Astronomy Inc.
+
+include	<config.h>
+include	<syserr.h>
+include	<fio.h>
+
+# SEEK -- Position the i/o pointer (file offset at which the next i/o transfer
+# will occur) for a file.  Note that ITOP may have to be adjusted before
+# performing the seek, to make newly written data readable (as when writing at
+# EOF, seeking backward within the same buffer, and reading).  A physical seek
+# is performed for text files.  For binary files, a logical seek is performed,
+# adjusting the i/o pointer.  Physical seeks on binary files are initiated
+# by FFAULT, when filling or flushing a file buffer.
+
+procedure seek (fd, offset)
+
+int	fd			# file
+long	offset			# offset == BOF,EOF, or char offset
+
+pointer	bp
+long	file_offset
+int	status
+long	ffilsz()
+errchk	filerr, syserr, ffilsz
+include	<fio.com>
+
+begin
+	fp = fiodes[fd]
+	if (fd <= 0 || fp == NULL)
+	    call syserr (SYS_FILENOTOPEN)
+
+	call fcanpb (fd)	# cancel any pushback
+	UPDATE_IOP(fd)		# make newly written data readable
+
+	if (FTYPE(fp) == TEXT_FILE) {
+	    # General seeks only permitted on text files opened for reading.
+	    if (FMODE(fp) != READ_ONLY)
+		if (offset != BOF && offset != EOF)
+		    call filerr (FNAME(fp), SYS_FSEEKNTXF)
+
+	    bp = bufptr[fd]
+	    if (BUF_MODIFIED(fd)) {		# flush buffer?
+		call fputtx (fd, Memc[bp], otop[fd] - bp, status)
+		if (status != ERR)
+		    call zcall2 (ZFLSTX(fp), FCHAN(fp), status)
+		if (status == ERR)
+		    call filerr (FNAME(fp), SYS_FWRITE)
+	    }
+
+	    iop[fd] = bp
+	    itop[fd] = bp
+	    otop[fd] = bp
+
+	    call zcall3 (ZSEKTX(fp), FCHAN(fp), offset, status)
+	    if (status == ERR)
+		call filerr (FNAME(fp), SYS_FSEEK)
+
+	} else {				# logical seek (binary files)
+	    switch (offset) {
+	    case BOF:
+		file_offset = 1
+	    case EOF:
+		file_offset = ffilsz (fd) + 1
+	    default:
+		file_offset = offset
+	    }
+	    iop[fd] = file_offset - boffset[fd] + bufptr[fd]
+	}
+end