Back out revision 1.19 and 1.20 until I find mental clarity to deal with

issues bde pointed out.

1 files changed, 7 insertions, 1 deletions

diff --git a/usr.bin/tail/tail.c b/usr.bin/tail/tail.c
index fa1e8f6..9162d17 100644
--- a/usr.bin/tail/tail.c
+++ b/usr.bin/tail/tail.c
@@ -219,7 +219,13 @@ main(int argc, char *argv[])
 			exit(1);
 		}
 
-		if ((sb.st_mode & S_IFMT) == S_IFSOCK || (sb.st_mode & S_IFMT) == S_IFIFO) {
+		/*
+		 * Determine if input is a pipe.  4.4BSD will set the SOCKET
+		 * bit in the st_mode field for pipes.  Fix this then.
+		 */
+		if (lseek(fileno(stdin), (off_t)0, SEEK_CUR) == -1 &&
+		    errno == ESPIPE) {
+			errno = 0;
 			fflag = 0;		/* POSIX.2 requires this. */
 		}