Fix bug with tail -f and pipes, plus a few other problems with tail.

diff --git a/ChangeLog b/ChangeLog
index ee8c833..26eeea6 100644 (file)
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,46 @@
+2004-07-23  Paul Eggert  <eggert@cs.ucla.edu>
+
+       Fix bug with "tail -f" reported by Rob Holland in
+       <http://lists.gnu.org/archive/html/bug-coreutils/2004-07/msg00054.html>.
+       Also, remove the undocumented and unsupported-since-2000
+       --max-consecutive-size-changes options.  Fix another related bug:
+       "tail" got confused if stdin, stdout, or stderr were closed.
+       Also, use output buffering even with "tail -f".
+       
+       * NEWS: Document this, plus yesterday's patch.
+       * doc/coreutils.texi (tail invocation): "size has remained the same"
+       -> "file has not changed", which is more accurate for fifos.
+       * lib/Makefile.am (libfetish_a_SOURCES): Add fcntl-safer.h,
+       open-safer.c.
+       * src/tail.c: Include fcntl-safer.h.
+       (COPY_TO_EOF): Set to UINTMAX_MAX, not OFF_T_MAX (which was wrong).
+       (COPY_A_BUFFER): New macro.
+       (struct File_spec): New members mtime, mode, blocking.
+       Remove member n_consecutive_size_changes.
+       (DEFAULT_MAX_N_CONSECUTIVE_SIZE_CHANGES,
+       max_n_consecutive_size_changes_between_opens,
+       MAX_CONSECUTIVE_SIZE_CHANGES_OPTION): Remove.
+       (long_options, tail_forever, parse_options):
+       Remove (non-)support for --max-consecutive-size-changes.
+       (record_open_fd): New function.
+       (recheck, tail_file): Use it.  Don't assume that stdin is open.
+       (dump_remainder): Add support for new COPY_A_BUFFER special value.
+       Treat errno==EAGAIN like EOF, since it might be a nonblocking read.
+       (recheck): New arg BLOCKING, specifying whether to use blocking reads.
+       All uses changed.
+       (n_live_files): Remove, replacing with...
+       (any_live_files): New function.  All uses changed.
+       (tail_forever): Use nonblocking I/O unless we know that blocking I/O
+       is safe; this avoids some hangs when reading from a fifo.
+       Avoid invoking fstat or sleep when using blocking I/O.
+       Do not check for changes to size if the file is not a regular file,
+       as the size is undefined in that case.
+       Check for changes to mtime or mode, too; this works for non-regular
+       files.
+       (tail_forever, main): Redo fflush strategy to work even when input
+       is nonblocking.  Don't use unbuffered output; just flush when needed.
+       * lib/fcntl-safer.h, open-safer.c: New files.
+       
 2004-07-22  Paul Eggert  <eggert@cs.ucla.edu>
 
        * src/tail.c (main): Ignore -f if no file operand is specified