+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