when file can be opened for read but cannot be read from:

fail once (was twice) in forward case
fail once (was no times) in reverse case

this can happen when file is a directory on an NFS or procfs mount.

3 files changed, 11 insertions, 6 deletions

diff --git a/usr.bin/tail/extern.h b/usr.bin/tail/extern.h
index 65efc14..f1daa9b 100644
--- a/usr.bin/tail/extern.h
+++ b/usr.bin/tail/extern.h
@@ -42,8 +42,8 @@ enum STYLE { NOTSET = 0, FBYTES, FLINES, RBYTES, RLINES, REVERSE };
 void forward __P((FILE *, enum STYLE, long, struct stat *));
 void reverse __P((FILE *, enum STYLE, long, struct stat *));
 
-void bytes __P((FILE *, off_t));
-void lines __P((FILE *, off_t));
+int bytes __P((FILE *, off_t));
+int lines __P((FILE *, off_t));
 
 void err __P((int fatal, const char *fmt, ...));
 void ierr __P((void));
diff --git a/usr.bin/tail/read.c b/usr.bin/tail/read.c
index ad29dbd..94f3f0b 100644
--- a/usr.bin/tail/read.c
+++ b/usr.bin/tail/read.c
@@ -58,7 +58,7 @@ static char sccsid[] = "@(#)read.c	8.1 (Berkeley) 6/6/93";
  * it is displayed from the character closest to the beginning of the input to
  * the end.
  */
-void
+int
 bytes(fp, off)
 	register FILE *fp;
 	off_t off;
@@ -80,7 +80,7 @@ bytes(fp, off)
 	}
 	if (ferror(fp)) {
 		ierr();
-		return;
+		return 1;
 	}
 
 	if (rflag) {
@@ -125,7 +125,7 @@ bytes(fp, off)
  * it is displayed from the line closest to the beginning of the input to
  * the end.
  */
-void
+int
 lines(fp, off)
 	register FILE *fp;
 	off_t off;
@@ -171,7 +171,7 @@ lines(fp, off)
 	}
 	if (ferror(fp)) {
 		ierr();
-		return;
+		return 1;
 	}
 	if (cnt) {
 		lines[recno].l = sp;
diff --git a/usr.bin/tail/reverse.c b/usr.bin/tail/reverse.c
index 34cd980..4557064 100644
--- a/usr.bin/tail/reverse.c
+++ b/usr.bin/tail/reverse.c
@@ -200,6 +200,11 @@ r_buf(fp)
 		    len < BSZ && (ch = getc(fp)) != EOF; ++len)
 			*p++ = ch;
 
+		if (ferror(fp)) {
+			ierr();
+			return;
+		}
+
 		/*
 		 * If no input data for this block and we tossed some data,
 		 * recover it.