X-Git-Url: https://git.subgeniuskitty.com/unix-history/.git/blobdiff_plain/1c15e88899094343f75aeba04122cd96a96b428e..af359dea2e5ab3e937b62107ecd6a51d78189ed7:/usr/src/lib/libc/stdio/ftell.c

diff --git a/usr/src/lib/libc/stdio/ftell.c b/usr/src/lib/libc/stdio/ftell.c
index 04c15a8c95..168a4ea119 100644
--- a/usr/src/lib/libc/stdio/ftell.c
+++ b/usr/src/lib/libc/stdio/ftell.c
@@ -1,35 +1,88 @@
-#if defined(LIBC_SCCS) && !defined(lint)
-static char sccsid[] = "@(#)ftell.c	5.2 (Berkeley) 3/9/86";
-#endif LIBC_SCCS and not lint
-
-/*
- * Return file offset.
- * Coordinates with buffering.
+/*-
+ * Copyright (c) 1990 The Regents of the University of California.
+ * All rights reserved.
+ *
+ * This code is derived from software contributed to Berkeley by
+ * Chris Torek.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ * 3. All advertising materials mentioning features or use of this software
+ *    must display the following acknowledgement:
+ *	This product includes software developed by the University of
+ *	California, Berkeley and its contributors.
+ * 4. Neither the name of the University nor the names of its contributors
+ *    may be used to endorse or promote products derived from this software
+ *    without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
+ * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
+ * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
+ * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+ * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
+ * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+ * SUCH DAMAGE.
  */
 
-#include	<stdio.h>
-long	lseek();
+#if defined(LIBC_SCCS) && !defined(lint)
+static char sccsid[] = "@(#)ftell.c	5.4 (Berkeley) 2/5/91";
+#endif /* LIBC_SCCS and not lint */
 
+#include <stdio.h>
+#include <errno.h>
+#include "local.h"
 
-long ftell(iop)
-register FILE *iop;
+/*
+ * ftell: return current offset.
+ */
+long
+ftell(fp)
+	register const FILE *fp;
 {
-	register long tres;
-	register adjust;
+	register fpos_t pos;
+
+	if (fp->_seek == NULL) {
+		errno = ESPIPE;			/* historic practice */
+		return (-1L);
+	}
 
-	if (iop->_cnt < 0)
-		iop->_cnt = 0;
-	if (iop->_flag&_IOREAD)
-		adjust = - iop->_cnt;
-	else if (iop->_flag&(_IOWRT|_IORW)) {
-		adjust = 0;
-		if (iop->_flag&_IOWRT && iop->_base && (iop->_flag&_IONBF)==0)
-			adjust = iop->_ptr - iop->_base;
-	} else
-		return(-1);
-	tres = lseek(fileno(iop), 0L, 1);
-	if (tres<0)
-		return(tres);
-	tres += adjust;
-	return(tres);
+	/*
+	 * Find offset of underlying I/O object, then
+	 * adjust for buffered bytes.
+	 */
+	if (fp->_flags & __SOFF)
+		pos = fp->_offset;
+	else {
+		pos = (*fp->_seek)(fp->_cookie, (fpos_t)0, SEEK_CUR);
+		if (pos == -1L)
+			return (pos);
+	}
+	if (fp->_flags & __SRD) {
+		/*
+		 * Reading.  Any unread characters (including
+		 * those from ungetc) cause the position to be
+		 * smaller than that in the underlying object.
+		 */
+		pos -= fp->_r;
+		if (HASUB(fp))
+			pos -= fp->_ur;
+	} else if (fp->_flags & __SWR && fp->_p != NULL) {
+		/*
+		 * Writing.  Any buffered characters cause the
+		 * position to be greater than that in the
+		 * underlying object.
+		 */
+		pos += fp->_p - fp->_bf._base;
+	}
+	return (pos);
 }