fix so if falls off the beginning of the file doesn't discard first byte

SCCS-vsn: usr.bin/tail/forward.c 5.4

diff --git a/usr/src/usr.bin/tail/forward.c b/usr/src/usr.bin/tail/forward.c
index 599c6c0..c6e4510 100644 (file)
--- a/usr/src/usr.bin/tail/forward.c
+++ b/usr/src/usr.bin/tail/forward.c
@@ -9,7 +9,7 @@
  */
 
 #ifndef lint
  */
 
 #ifndef lint

-static char sccsid[] = "@(#)forward.c  5.3 (Berkeley) %G%";
+static char sccsid[] = "@(#)forward.c  5.4 (Berkeley) %G%";

 #endif /* not lint */
 
 #include <sys/types.h>
 #endif /* not lint */
 
 #include <sys/types.h>


@@ -160,16 +160,17 @@ rlines(fp, off, sbp)
        if ((p = mmap(NULL,
            size, PROT_READ, MAP_FILE, fileno(fp), (off_t)0)) == (caddr_t)-1)
                err("%s", strerror(errno));
        if ((p = mmap(NULL,
            size, PROT_READ, MAP_FILE, fileno(fp), (off_t)0)) == (caddr_t)-1)
                err("%s", strerror(errno));

-       p += size - 1;

 
        /* Last char is special, ignore whether newline or not. */
 
        /* Last char is special, ignore whether newline or not. */

-       while (--size)
-               if (*--p == '\n' && !--off)
+       for (p += size - 1; --size;)
+               if (*--p == '\n' && !--off) {
+                       ++p;

                        break;
                        break;

+               }

 
        /* Set the file pointer to reflect the length displayed. */
        size = sbp->st_size - size;
 
        /* Set the file pointer to reflect the length displayed. */
        size = sbp->st_size - size;

-       WR(p + 1, size);
+       WR(p, size);

        if (fseek(fp, sbp->st_size, SEEK_SET) == -1)
                ierr();
 }
        if (fseek(fp, sbp->st_size, SEEK_SET) == -1)
                ierr();
 }