From fa080de7afc95aa1c19a6e6fc0e0708ced2eadc4 Mon Sep 17 00:00:00 2001
From: Joseph Hunkeler <jhunkeler@gmail.com>
Date: Wed, 8 Jul 2015 20:46:52 -0400
Subject: Initial commit

---
 sys/libc/fseek.c | 93 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 93 insertions(+)
 create mode 100644 sys/libc/fseek.c

(limited to 'sys/libc/fseek.c')

diff --git a/sys/libc/fseek.c b/sys/libc/fseek.c
new file mode 100644
index 00000000..fa32466c
--- /dev/null
+++ b/sys/libc/fseek.c
@@ -0,0 +1,93 @@
+/* Copyright(c) 1986 Association of Universities for Research in Astronomy Inc.
+*/
+
+#define	import_spp
+#define	import_libc
+#define	import_stdio
+#define	import_fset
+#include <iraf.h>
+
+
+/* FSEEK -- Seek on a file opened under stdio.  The seek functions do not
+** completely emulate the UNIX seek functions.  The following restrictions
+** apply:
+**
+**	- It is only permissible to seek to the beginning of a line if the
+**	  actual file is a text file.  The seek offset must have been
+**	  obtained by a prior call to FTELL, which returns the seek offset
+**	  of the next line to be read or written.  Seek offsets cannot be
+**	  manufactured, e.g., as physical char offsets in the file, as is
+**	  the case for binary files.  These restrictions apply because text
+**	  files are record structured on many systems, rather than simple
+**	  byte stream files as in UNIX.
+**
+**	- It is permissible to randomly seek about on a binary file, but
+**	  seeks must be aligned on XCHAR word boundaries in the file.  This
+**	  can be guaranteed by structuring the application so that it always
+**	  reads and writes binary data records that are an integral number
+**	  of integers in size.  If this is done the program is portable to
+**	  any IRAF machine as well as to UNIX.  Seek offsets are specified
+**	  in units of bytes and are zero-indexed, as in C.
+*/
+int
+fseek (
+  FILE	*fp,			/* operand file				*/
+  long	offset,			/* offset in file			*/
+  int	mode			/* 0=absolute, 1=relative, 2=from EOF	*/
+)
+{
+	register XINT	fd = fileno(fp);
+	int	text_file, stat;
+	long	c_note();
+
+
+	text_file = (c_fstati (fd, F_TYPE) == TEXT_FILE);
+	fp->_fflags &= ~_FEOF;
+
+	if (text_file) {
+	    switch (mode) {
+	    case 0:
+		if (offset == 0L)
+		    stat = c_seek (fd, BOFL);
+		else
+		    stat = c_seek (fd, offset);
+		break;
+	    case 2:
+		if (offset == 0L) {
+		    stat = c_seek (fd, EOFL);
+		    fp->_fflags |= _FEOF;
+		} else
+		    stat = ERR;
+		break;
+	    default:
+		stat = ERR;
+		break;
+	    }
+
+	} else {
+	    /* Random seeks on (non-streaming) binary files are permitted,
+	     * but the seek must be to an XCHAR offset.  This is checked
+	     * by c_seek, which takes a zero-indexed byte offset as argument.
+	     */
+	    switch (mode) {
+	    case 0:
+		stat = c_seek (fd, offset);
+		break;
+	    case 1:
+		stat = c_seek (fd, c_note(fd) + offset);
+		break;
+	    case 2:
+		if ((stat = c_seek (fd, EOFL)) != ERR) {
+		    if (offset == 0L)
+			fp->_fflags |= _FEOF;
+		    else
+			stat = c_seek (fd, c_note(fd) - offset);
+		}
+		break;
+	    default:
+		stat = ERR;
+	    }
+	}
+
+	return (stat);
+}
-- 
cgit