1 files changed, 22 insertions, 19 deletions

diff --git a/lib/libc/stdio/ftell.c b/lib/libc/stdio/ftell.c
index 745d500..152617f 100644
--- a/lib/libc/stdio/ftell.c
+++ b/lib/libc/stdio/ftell.c
@@ -88,7 +88,6 @@ _ftello(FILE *fp, fpos_t *offset)
 {
 	fpos_t pos;
 	size_t n;
-	int dflags;
 
 	if (fp->_seek == NULL) {
 		errno = ESPIPE;			/* historic practice */
@@ -119,29 +118,33 @@ _ftello(FILE *fp, fpos_t *offset)
 		}
 		if (HASUB(fp))
 			pos -= fp->_r;  /* Can be negative at this point. */
-	} else if ((fp->_flags & __SWR) && fp->_p != NULL) {
-		dflags = 0;
-		if (fp->_flags & __SAPP)
-			dflags = O_APPEND;
-		else if (fp->_file != -1 &&
-			 (dflags = _fcntl(fp->_file, F_GETFL)) < 0)
-			return (1);
-		if ((dflags & O_APPEND) &&
-		    (pos = _sseek(fp, (fpos_t)0, SEEK_END)) == -1) {
-			if ((fp->_flags & __SOPT) || __sflush(fp) ||
-			    (pos = _sseek(fp, (fpos_t)0, SEEK_CUR)) == -1)
-				return (1);
-			else {
-				*offset = pos;
-				return (0);
-			}
-		}
+	} else if ((fp->_flags & __SWR) && fp->_p != NULL &&
+	    (n = fp->_p - fp->_bf._base) > 0) {
 		/*
 		 * Writing.  Any buffered characters cause the
 		 * position to be greater than that in the
 		 * underlying object.
 		 */
-		n = fp->_p - fp->_bf._base;
+		if ((fp->_flags & __SAPP) || (fp->_flags2 & __S2OAP)) {
+			int serrno = errno;
+
+			errno = 0;
+			if ((pos = _sseek(fp, (fpos_t)0, SEEK_END)) == -1) {
+				if (errno == ESPIPE ||
+				    (fp->_flags & __SOPT) || __sflush(fp) ||
+				    (pos =
+				    _sseek(fp, (fpos_t)0, SEEK_CUR)) == -1)
+					return (1);
+				else {
+					errno = serrno;
+					*offset = pos;
+					return (0);
+				}
+			}
+			errno = serrno;
+			/* fp->_p can be changed in _sseek(), recalculate. */
+			n = fp->_p - fp->_bf._base;
+		}
 		if (pos > OFF_MAX - n) {
 			errno = EOVERFLOW;
 			return (1);