Cleanups. No logic changes.

* defs.h: Define new ptrace constants unconditionally.
* strace.c (detach): Fix comment.
(trace): Remove now unnecessary "if USE_SEIZE".

Signed-off-by: Denys Vlasenko <dvlasenk@redhat.com>
tests: prepare for parallel-tests support

* tests/Makefile.am (CLEANFILES): Calculate dynamically from TESTS.
* tests/init.sh (LOG): New variable.
* tests/detach-stopped: Use it.
* tests/net: Likewise.
* tests/qual_syscall: Likewise.
* tests/stat: Likewise.
* tests/strace-f: Likewise.
tests: enable parallel-tests support

* configure.ac (AM_INIT_AUTOMAKE): Add parallel-tests.
tests: enhance timeout checks

Run each test using a wrapper that does all necessary timeout checks.

* tests/run.sh: New file.
* tests/Makefile.am (EXTRA_DIST, LOG_COMPILER): Add it.
* tests/init.sh (check_strace, check_timeout): Remove.
* tests/detach-stopped: Update callers.
* tests/net: Likewise.
* tests/ptrace_setoptions: Likewise.
* tests/qual_syscall: Likewise.
* tests/stat: Likewise.
* tests/strace-f: Likewise.
tests: ensure that strace can detach from sleeping and stopped processes

* tests/set_ptracer_any.c: New file.
* tests/detach-sleeping: New test.
* tests/detach-stopped: Likewise.
* tests/Makefile.am (check_PROGRAMS): Add set_ptracer_any.
(TESTS): Add detach-sleeping and detach-stopped.
* tests/.gitignore: Add set_ptracer_any.
tests: parametrize "sleep 1"

* tests/init.sh (SLEEP_A_BIT): New variable.
* tests/detach-sleeping: Use it.
* tests/detach-stopped: Likewise.
tests: fix parallel-tests support in detach-* tests

* tests/detach-sleeping: Use $LOG file for set_ptracer_any output.
* tests/detach-stopped: Likewise.
tests: ensure that strace does not leave sleeping processes stopped

* tests/detach-sleeping: Do not send SIGCONT to the sleeping process.
tests: ensure that strace can detach from running processes

* tests/detach-running: New test.
* tests/Makefile.am (TESTS): Add it.
tests/detach-{running,sleeping,stopped}: check post-detach state

Check that traced process still exists and is in a right state
after strace detached from it.

Signed-off-by: Denys Vlasenko <dvlasenk@redhat.com>
tests: disable /proc based checks when /proc is not mounted

* tests/detach-running: Disable /proc based checks when
/proc/self/status is not available.
* tests/detach-sleeping: Likewise.
* tests/detach-stopped: Likewise.
USE_SEIZE: fix detaching from stopped processes

V3: split SEIZE/!SEIZE code paths to reduce confusion.
Extensively comment every possible case.
Verified that all tests/detach* tests work in both SEIZE and !SEIZE
cases.

* strace.c (detach): If PTRACE_SEIZE API is in use, stop the tracee
using PTRACE_INTERRUPT instead of sending it a SIGSTOP.
In a subsequent waitpid loop, correctly wait and suppress SIGSTOP
on detach if PTRACE_INTERRUPT wasn't used, or wait for any ptrace
stop and detach without suppressing signals.

Signed-off-by: Denys Vlasenko <dvlasenk@redhat.com>
Remove workarounds for ancient kernels lacking __WALL

__WALL is available and working at least since 2.4 kernels: 10 years ago.

* strace (detach): Remove workarounds for ancient kernels lacking __WALL.
Add missing EINTR check.
(trace): Remove workarounds for ancient kernels lacking __WALL.
Remove redundant double error printout.

Signed-off-by: Denys Vlasenko <dvlasenk@redhat.com>
Improve error messages in detach()

* strace.c (detach): Change return type from int to void.
Improve error meesages: show PID, tell exactly which operation fails.

Signed-off-by: Denys Vlasenko <dvlasenk@redhat.com>