[PATCH] tail: fix tailing non seekable files on certain systems

[Pádraig Brady]

* src/tail.c (tail_bytes): On systems were blksize_t is unsigned
and the same size or wider than off_t (android for example),
our initialized (off_t) -1 would be promoted to unsigned before
comparison, and thus fail to follow the appropriate path.
* NEWS: Mention the fix.
This issue was introduced in commit v8.23-47-g2662702
Reported at https://github.com/termux/termux-app/issues/233
---
 NEWS       | 4 ++++
 src/tail.c | 2 +-
 2 files changed, 5 insertions(+), 1 deletion(-)

diff --git a/NEWS b/NEWS
index 2a2515b..3626c3d 100644
--- a/NEWS
+++ b/NEWS
@@ -25,6 +25,10 @@ GNU coreutils NEWS                                    -*- 
outline -*-
   stty no longer crashes when processing settings with -F also specified.
   [bug introduced in fileutils-4.0]
 
+  tail --bytes again supports non seekable inputs on all systems.
+  On systems like android it always tried to process as seekable inputs.
+  [bug introduced in coreutils-8.24]
+
   timeout will again notice its managed command exiting, even when
   invoked with blocked CHLD signal, or in a narrow window where
   this CHLD signal from the exiting child was missed.  In each case
diff --git a/src/tail.c b/src/tail.c
index 536d034..642c448 100644
--- a/src/tail.c
+++ b/src/tail.c
@@ -1855,7 +1855,7 @@ tail_bytes (const char *pretty_filename, int fd, 
uintmax_t n_bytes,
           else if ((current_pos = lseek (fd, -n_bytes, SEEK_END)) != -1)
             end_pos = current_pos + n_bytes;
         }
-      if (end_pos <= ST_BLKSIZE (stats))
+      if (end_pos <= (off_t) ST_BLKSIZE (stats))
         return pipe_bytes (pretty_filename, fd, n_bytes, read_pos);
       if (current_pos == -1)
         current_pos = xlseek (fd, 0, SEEK_CUR, pretty_filename);
-- 
2.9.3