Copy stable/9 to releng/9.3 as part of the 9.3-RELEASE cycle.

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

MFC r239501:
- Use pid_t type instead of just int.

MFC r239611:
- Put arguments for print_syscall_ret() function in proper order.
Bug was introduced in r192025.

MFC r239898:
- Remove unused variables.
- Fix warnings about comparing signed and unsigned ints.

MFC r240005:
- Style(9) cleanup.

MFC r240364:
- Remove unused variables.
- Remove redundant return after err(3) call.

MFC r240393:
- Fix detaching under some circumstances.

When truss is detaching from very active process it is possible to
hang on waitpid(2) in restore_proc() forever, because
ptrace(PT_SYSCALL) must be called before detaching, to allow the
debugging process to continue execution. Also when truss called with
'-c' argument, it does not print anything after detach, because it
immediately exits from restore_proc().

To fix these two problems make detaching deferred, but then it is
impossible to detach from a process which does not do any system call.
To fix this issue use sigaction(2) instead of signal(3) to disable
SA_RESTART flag for waitpid(2) that makes it non-restartable. Remove
global variable child_pid, because now detaching is handled in context
where child's pid is known.

MFC r240562:
- Make truss thread-aware.

Approved by: kib (mentor)

Copy head to stable/9 as part of 9.0-RELEASE release cycle.

Approved by: re (implicit)

Fix typos in comments, no functional changes.

Found by: codespell
Reviewed by: alfred
MFC after: 1 week

s/sytem/system in comments, no functional changes.

Reviewed by: alfred@

Fix breakage introduced in r211725 and improve functionality of truss on
64-bit powerpc by adding 32-bit compatibility features.

Fix copyright spelling.

PR: 139825
Submitted by: Ruslan Mahmatkhanov

Correct off-by-one issue in truss(1) which happens when system call number
is nsyscalls.

PR: bin/134916
Submitted by: Steven Hartland <steven hartland multiplay co uk>
MFC after: 2 weeks

Reduce diff against my local version: replace malloc+memset() cases to calloc().

Add -c option to summarize number of calls, errors, and system time.

Reviewed by: alfred

Fix handling of Quad-type arguments. Previously, syscalls
containing 64-bit arguments would have explicit padding.
On 64-bit platforms there was no padding, so the dummy
argument was not covering anything. On 32-bit platforms
with weak alignment (i.e. i386) the 64-bit argument did
not need to be aligned, so there too an aditional argument
was introduced. On 32-bit platforms with strong alignment
(i.e. PowerPC) the dummy argument in fact cover the padding.
By elimininating the dummy argument, 64-bit platforms now
have 1 argument less. This also applies to 32-bit platforms
with weak alignment. On PowerPC this doesn't matter, because
the padding is still there. We just don't "name" it.
Deal with those 3 cases.

Approved by: re (kensmith)

MFp4: Bugfixes for truss(1):

- Fix logic handling execve(). We will not be able to
obtain information otherwise.
- truss coredump [1].
- truss does not work against itself [2].

PR: bin/58970 [1], bin/45193 [2]
Submitted by: Howard Su
Approved by: re (kensmith)

Make use of ptrace(2) instead of procfs in truss(1), eliminating
yet another need of an available /proc/ mount.

Tested with: make universe
Submitted by: howardsu
Reviewed by: alfred

Add powerpc support for truss.

Initial work by: Orlando Bassotto < orlando at break net >
Modified by: grehan