Copy stable/10@r272459 to releng/10.1 as part of
the 10.1-RELEASE process.

Approved by: re (implicit)
Sponsored by: The FreeBSD Foundation

Copy head (r256279) to stable/10 as part of the 10.0-RELEASE cycle.

Approved by: re (implicit)
Sponsored by: The FreeBSD Foundation

Print file names without stdio buffering to avoid mixing buffered and
unbuffered ouput.

PR: bin/176886
Reviewed by: mjg

Add missing static keywords to tail(1)

tail: Fix crash if -F'ed file's filesystem disappears.

If tail notices that a file it is following no longer exists (because stat()
fails), it will output any final lines and then close the file. If the read
operation also causes an error, such as when the filesystem is forcefully
unmounted, it closes the file as well, leading to fclose(NULL) and a
segmentation fault.

PR: bin/159750
Submitted by: swills
Approved by: re (kib)
MFC after: 1 week

Remove the advertising clause from UCB copyrighted files in usr.bin. This
is in accordance with the information provided at
ftp://ftp.cs.berkeley.edu/pub/4bsd/README.Impt.License.Change

Also add $FreeBSD$ to a few files to keep svn happy.

Discussed with: imp, rwatson

Change the behaviour of -F slightly; it now persists (forever) in
trying to open files rather than giving up when it encounters an
error. ENOENT errors are not reported.

As a result, files that are moved away then recreated are not at
risk of being 'lost' to tail. Files that are recreated and
temporarily have unreadable permissions will be shown when they
are fixed.

This behaviour is consistent with the GNU version of tail but
without the verbiage that goes with the GNU version.

This change also fixes error messages accompanying -f and -F.
They no longer report problems with (null)!

MFC after: 3 weeks

Better handle the -F case:
o When stat(2) fails (i.e. the file has been moved) there's no new
file with the same name yet, so keep showing the file that's open.
This yields the same behaviour as -f, for which we don't stat(2).
o When a new file with the same name has been created (i.e stat(2)
succeeds but the inode or device numbers differ from the opened
file), show any new lines in the opened file (i.e. the old or
rotated file) before reopening the new file.

These changes fix the observed behaviour that tail(1) doesn't show
the very last lines of the rotated (log) files.

PR: bin/101979
Tested by: Jos Backus <jos@catnook.com>
MFC after: 2 months

Add a -q option to suppress header lines when multiple files are specified.

Approved by: cperciva (mentor)
MFC after: 1 week

Unbreak tail -f on non-local filesystems.

Save last displayed file by having the "last" pointer global and save it
during we show the first file's tail. Instead of:

tarsier% tail -f 1 2
==> 1 <==
foo
bar

==> 2 <==
bar
foo

==> 2 <==
bar2
foo2

Now with this change, we have:

tarsier% tail -f 1 2
==> 1 <==
foo
bar

==> 2 <==
bar
foo
bar2
foo2

While I'm there, move a comment to where it should belong to. Also,
const'ify the "last" static because we will never need to change the
contents it points to.

MFC After: 1 week

Don't reprint file names unnecessarily.

PR: 75028
Submitted by: mteterin at 250-217 dot customer dot cloud9 dot net
MFC after: 7 days

Some variables became unused or global in the last change to this
file. Remove the now redundant declarations.

Add declarations for the new show and set_events functions and make
them static.

Add support for following more than one file i.e.
tail -f file1 file2

Convert to ANSI style function definitions.

Removed check of st_rdev changing in the -F support. st_rdev for regular
files is usually the first direct block pointer. Since FreeBSD does
automatic block reallocation to reduce filesystem fragmentation, the
file being tailed can be relocated to different blocks 'on-the-fly',
making the check for st_rdev unreliable. The result of this bug is
tail -F pseudo-randomnly thinking the file was rotated when it wasn't,
and as a result, spews out the entire file trying to catch up.

MFC after: 3 days

When doing tail -F, return if the freopen() of the file fails instead of
trying to use a null file pointer.

GCC 3.1 cleanup - add a break after default: at the end of a switch
statement.

remove __P

WARNS=2 fixes, use __FBSDID().

Since kqueue support was added to tail, the "-F" option (check for
renames/rotations) only detected cases where the file itself was
moved or deleted. If part of the path to the file (or a symlink
in the path) was changed instead, tail would not notice.

Fix this by ensuring that we stat the path at least once every
second in the -F case to check for changes. We still use kqueue
when possible to inform us quickly when the file has changed.

PR: bin/24955
Submitted by: Maxim Konovalov <maxim@macomnet.ru>
MFC after: 1 week

File positions are off_t nowdays, not long, so:
long -> off_t
strtol -> strtoll
fseek -> fseeko

NOTE: that fseek not works for >long offsets files per POSIX:

[EOVERFLOW] For fseek( ), the resulting file offset would be a value which
cannot be represented correctly in an object of type long.

o If the file being tailed is moved back to the original location,
resume using kqueue to monitor it, if possible.
o auto-clear the read filter on EOF; this is needed when tailing a FIFO.

Back out my fseeko -> fseek(END) change - we need to position on what we
displayed last, not to the end of file

Restore part of my fix spammed in v1.23:
fseeko(file_size, SEEK_SET) -> fseek(0L, SEEK_END)
1) File may grows between operations, so fseeko to file_size may miss
2) 0L, SEEK_END is the same code using in tail in all other places

Fix tail to work on files bigger than 2GB.

PR: 14786
Reviewed by: iedowse

Add comment explaining why size not passed directly to mmap, i.e. not relay
on its check.
KNF multi-line comments
(inspired by bde)

Use SSIZE_MAX instead of INT_MAX, as kernel does ssize_t check
Better explanation comment of FIXME section

Treat mmap() error as fatal too, i.e. do exit(1) instead of return

rlines() checks:
1) really check for size overflow by checking negative value.
2) since mmap() not support files over INT_MAX size, add check for it
until either mmap() will be fixed or tail will be rewritted to handle
large files alternatively.
3) replace fseek(... file_size, SEEK_SET) with fseek(... 0L, SEEK_END)
to avoid off_t -> long cast
4) Use exit() if file is too big instead of warning and wrong logic
afterwards.

Use EV_SET() macro to initialize kevent structure.

Remove register keyword usage with prejudice.
Modern compilers are smarter when it comes to allocating register
usage.

Properly constify some static arrays.

Also #if out some sccsid's and add rcsid's.

Convert calls to match new kqueue API.

If the kevent() registration fails (probably due to the underlying
filesystem not being kq-aware), then fall back to using sleep. This
allows tail to work with NFS filesystems again without chewing up CPU time.

When given the -F flag, resort to sleep/stat after the file was moved
or deleted. This allows a window where the file being tailed does not
exist at all, which is typically the case during log rotation. Switch
back to using kq (if possible) after the file is reopened.

Change <event.h> --> <sys/event.h>

Change tail to use kqueue/kevent to obtain a notification when
the file changes (when doing tail -{f|F}).

Add a new -F flag which is a superset of -f. It will cause tail to
stat() the file being followed and do a close/reopen if the file has been
renamed and/or rotated. This is damn useful for leaving running on files
in /var/log when newsyslog(8) rotates them.

Change select(0, NULL, ...) to usleep()

Fix a misleading comment. Rename a variable to make more sense.
Pointed out by by: bde

Fix a comment.

Submitted by: Mikael Karpberg <karpen@ocean.campus.luth.se>

In these days, waiting one full second for more to appear is far too long.
Let's try 250ms.

Sweep through the tree fixing mmap() usage:

- Use MAP_FAILED instead of the constant -1 to indicate
failure (required by POSIX).
- Removed flag arguments of '0' (required by POSIX).
- Fixed code which expected an error return of 0.
- Fixed code which thought any address with the high bit set
was an error.
- Check for failure where no checks were present.

Discussed with: bde

complete err() changes, actually use warn() in most instances

Dont forget to #include <err.h>

Fix some bogons:
- timeval in select loop was depending on not having the remaining time
returned from select(), causing a busy spin on an implementation that
does implement it.
- the err() usage was pretty bogus, some of the error messages had
strerror attached manually and then reattached by err().

one file somehow slipped by me in the previous commit
tidy up

This commit was generated by cvs2svn to compensate for changes in r1590,
which included commits to RCS files with non-trunk default branches.

BSD 4.4 Lite Usr.bin Sources