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"strace_child = pid" assignment was racing in NOMMU case
because of vfork (no way to know which process would win).
After this change, strace_child is set to nonzero only
in one process after [v]fork.
Signed-off-by: Denys Vlasenko <dvlasenk@redhat.com>
We can use tcb::pid == 0 as an indicator of free tcb,
and we already have strace_child variable which holds
pid of our child, if any.
Signed-off-by: Denys Vlasenko <dvlasenk@redhat.com>
I stumbeld over this case when I used "exec stace ...".
* strace.c (trace): Do not exit if we see an unknown pid in wait4.
Signed-off-by: Denys Vlasenko <dvlasenk@redhat.com>
* strace.c (detach): Use goto's instead of excessive nesting.
Drop sigstop_expected and interrupt_done variables.
Signed-off-by: Denys Vlasenko <dvlasenk@redhat.com>
* strace.c (detach): If TCB_IGNORE_ONE_SIGSTOP is set,
di not PTRACE_DETACH - wait for SIGSTOP first.
Signed-off-by: Denys Vlasenko <dvlasenk@redhat.com>
* strace.c (detach): Warn if we see ECHILD from waitpid.
Explain in comments that we don't normally expect !WIFSTOPPED
either, and also that PTRACE_CONT failure isn't expected
(the "break" there is a "I'm confused, bailing out" code style)..
Signed-off-by: Denys Vlasenko <dvlasenk@redhat.com>
* 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>
__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>
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>
Current implementation of -qq does not allow suppressing exit status
messages without suppressing signal delivery messages, which is not
good. There is a traditional "-e signal=none" syntax that can be used
to suppress all signal delivery messages.
This partially reverts commit v4.7-222-g01997cf.
* strace.c (trace): Do not suppress signal delivery messages with -qq.
* strace.1: Update documentation about -qq option.
On NOMMU systems in "strace PROG" case, we have no way to attach to
the tracee before it calls execve unless in -D mode. That is, the
first execve call is very likely to be missed, and setting
hide_log_until_execve just results to empty log.
* strace.c (init) [NOMMU_SYSTEM]: Do not set hide_log_until_execve
unless in -D mode.
* strace.c [HAVE_PRCTL]: Include sys/prctl.h.
(startup_child) [HAVE_PRCTL && PR_SET_PTRACER && PR_SET_PTRACER_ANY]:
In -D mode, allow tracing the process that is going to become the
tracee.
Tested with "./strace [-D] [-q] [-bexecve] env true",
all cases seem to work.
* defs.h: Declare new variable: bool hide_log_until_execve.
* strace.c: Define hide_log_until_execve.
Rename skip_startup_execve to skip_one_b_execve.
(startup_child): Do not set skip_one_b_execve = 1 here.
(init): If "strace PROG" case (as opposed to "strace -pPID"),
set skip_one_b_execve and hide_log_until_execve to 1.
(trace): Don't print signal messages if hide_log_until_execve == 1.
* syscall.c (trace_syscall_entering):
Skip syscall printing if hide_log_until_execve == 1.
Reset hide_log_until_execve if we enter execve syscall.
(trace_syscall_exiting): Skip syscall printing if hide_log_until_execve == 1.
Signed-off-by: Denys Vlasenko <dvlasenk@redhat.com>
Even with the -q flag specified, tracing output is still mixed
with messages about signals and process exit status, which is
often irrelevant. Allow the -q option to be repeated to force
the suppression of signals / exit status info too.
* defs.h: Change 'qflag' from 'bool' to 'unsigned int'.
* strace.1: Document ability to repeat '-q' option.
* strace.c: Allow '-q' to be repeated to quieten process
exit status and signal messages.
Signed-off-by: Daniel P. Berrange <berrange@redhat.com>
strace already has a mechanism to use fopen64 for output when the 64-bit
version of fopen is available on 32-bit architectures. Apply this
mechanism for other three functions to make strace fully adopted for
64-bit types.
* strace.c (struct_stat, stat_file, struct_dirent, read_dir,
struct_rlimit, set_rlimit): New macros.
(startup_attach): Use read_dir.
(startup_child): Use struct_stat and stat_file.
(main): Use struct_rlimit and set_rlimit.
While at it, added a small optimization of not remembering
the path twice if it happens to be the same.
text data bss dec hex filename
245111 680 10860 256651 3ea8b strace_old
245075 680 9804 255559 3e647 strace
Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
To not waste an option letter for just one trick,
extend -b to take a parameter:
"on which syscalls do you want to detach?".
Currently supports only execve.
While at it, fixed (by removing non-Linux and stale info)
and extended manpage text about -f.
Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
There is no need to print literal strings through "%s".
Only untrusted strings such as filenames need that.
Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
With -D, strdup'ing of pathname is necessary only on NOMMU.
Don't set skip_startup_execve to 1 if NOMMU and not in daemonized mode
(try "strace [-D] -b env echo HI" to see whether we detach on correct execve).
Fix test_ptrace_FOO shortcuts on NOMMU to always assume success
and _properly_ set all variables.
Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
This is a preparatory mass replace patch with no code changes.
The future change will need to typedef sysent to sysent0,
which results in compile failures when "struct sysent" string
gets mangled into "struct sysent0".
Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
By adding tcp->s_ent pointer tot syscall table entry,
we can replace sysent[tcp->scno] references by tcp->s_ent.
More importantly, we may ensure that tcp->s_ent is always valid,
regardless of tcp->scno value. This allows us to drop
SCNO_IS_VALID(tcp->scno) checks before we access syscall
table entry.
We can optimize (qual_flags[tcp->scno] & QUAL_foo) checks
with a similar technique.
Resulting code shrink:
text data bss dec hex filename
245975 700 19072 265747 40e13 strace.t3/strace
245703 700 19072 265475 40d03 strace.t4/strace
* count.c (count_syscall): Use cheaper SCNO_IN_RANGE() check.
* defs.h: Add "int qual_flg" and "const struct sysent *s_ent"
to struct tcb. Remove "int u_nargs" from it.
Add UNDEFINED_SCNO constant which will mark undefined scnos
in tcp->qual_flg.
* pathtrace.c (pathtrace_match): Drop SCNO_IS_VALID check.
Use tcp->s_ent instead of sysent[tcp->scno].
* process.c (sys_prctl): Use tcp->s_ent->nargs instead of tcp->u_nargs.
(sys_waitid): Likewise.
* strace.c (init): Add compile-time check that DEFAULT_QUAL_FLAGS
constant is consistent with init code.
* syscall.c (decode_socket_subcall): Use tcp->s_ent->nargs
instead of tcp->u_nargs. Set tcp->qual_flg and tcp->s_ent.
(decode_ipc_subcall): Likewise.
(printargs): Use tcp->s_ent->nargs instead of tcp->u_nargs.
(printargs_lu): Likewise.
(printargs_ld): Likewise.
(get_scno): [MIPS,ALPHA] Use cheaper SCNO_IN_RANGE() check.
If !SCNO_IS_VALID, set tcp->s_ent and tcp->qual_flg to default values.
(internal_fork): Use tcp->s_ent instead of sysent[tcp->scno].
(syscall_fixup_for_fork_exec): Remove SCNO_IS_VALID check.
Use tcp->s_ent instead of sysent[tcp->scno].
(get_syscall_args): Likewise.
(get_error): Drop SCNO_IS_VALID check where it is redundant.
(dumpio): Drop SCNO_IS_VALID check where it is redundant.
Use tcp->s_ent instead of sysent[tcp->scno].
(trace_syscall_entering): Use (tcp->qual_flg & UNDEFINED_SCNO) instead
of SCNO_IS_VALID check. Use tcp->s_ent instead of sysent[tcp->scno].
Drop SCNO_IS_VALID check where it is redundant.
Print undefined syscall name with undefined_scno_name(tcp).
(trace_syscall_exiting): Likewise.
* util.c (setbpt): Use tcp->s_ent instead of sysent[tcp->scno].
Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
pathname[] was getting destroyed, execve of garbage pathname
failing, and to top it off, the tracer's stack was also
smashed and trecer segfaulted.
* strace.c (exec_or_die): New function.
(startup_child): Don't use pathname[] contents after vfork,
make a malloced copy instead. Explain "NOMMU + -D bug"
and how we work around it.
Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
And while using it, I discovered that -D doesn't work too well
on NOMMU. Added a comment about it.
Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
Unlike PTRACE_GETREGS, this new method detects 32-bit processes
reliably, without checking segment register values which
are undocumented and aren't part of any sort of API.
While at it, also fixed x32 detection to use __X32_SYSCALL_BIT,
as it should have been from the beginning.
* defs.h: Declare os_release and KERNEL_VERSION.
* strace.c: Make os_release non-static, remove KERNEL_VERSION define.
* syscall.c: New struct i386_user_regs_struct,
static union x86_regs_union and struct iovec x86_io.
(printcall): Use i386_regs or x86_64_regs depending on x86_io.iov_len.
(get_regs): On x86 and kernels 2.6.30+, use PTRACE_GETREGSET,
on earlier kernels fall back to old method.
(get_scno): [X86] Determine personality based on regset size
on scno & __X32_SYSCALL_BIT.
(syscall_fixup_on_sysenter): Use i386_regs or x86_64_regs depending
on x86_io.iov_len.
(get_syscall_args): Likewise.
(get_error): Likewise.
Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
This change should speed up strace by a tiny bit.
More importantly, it makes it much more clear that
fork and exec fixups are not necessary for any reasonably
recent kernels. IOW: syscall_fixup_for_fork_exec() and its callees
are all dead code.
* defs.h: Declare new need_fork_exec_workarounds flag variable.
* strace.c: Define need_fork_exec_workarounds flag variable.
(test_ptrace_setoptions_followfork): Return 0/1 as success/fail indicator.
(test_ptrace_setoptions_for_all): Likewise.
(init): Set need_fork_exec_workarounds to TRUE if needed.
* syscall.c: Rename internal_syscall() to syscall_fixup_for_fork_exec().
(trace_syscall_entering): Call syscall_fixup_for_fork_exec() only if
need_fork_exec_workarounds == TRUE.
(trace_syscall_exiting): Likewise.
Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
strace -i was fetching PC with a separate PEEKUSER
despite having GETREGS data:
ptrace(PTRACE_GETREGS, 22331, 0, 0x8087f00) = 0
ptrace(PTRACE_PEEKUSER, 22331, 4*EIP, [0x80dd7b7]) = 0
write(3, "[080dd7b7] ioctl(0, SNDCTL_TMR_T"..., 82) = 82
ptrace(PTRACE_SYSCALL, 22331, 0, SIG_0) = 0
Now it does this:
ptrace(PTRACE_GETREGS, 22549, 0, 0x8087ea0) = 0
write(3, "[080dd7b7] ioctl(0, SNDCTL_TMR_T"..., 82) = 82
ptrace(PTRACE_SYSCALL, 22549, 0, SIG_0) = 0
Analogous improvement in sys_sigreturn() is also implemented.
* defs.h: Declare extern struct pt_regs regs for SPARC[64] and ARM.
Declare clear_regs(), get_regs() and get_regs_error flag variable.
* strace.c (trace): Call get_regs(pid) as soon as we know the tcb
and that it is stopped.
* syscall.c (get_regs): New function. Used to fetch registers early,
just after tracee has stopped.
(printcall): Move it here from util.c. Use global regs.REG data,
if available on the arch, instead of re-fetching it.
(get_scno): Use global regs.REG data.
(get_syscall_result): Likewise.
* signal.c (sys_sigreturn): Likewise.
* util.c (printcall): Moved to syscall.c.
Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
In case of normal strace termination, when the trace output is
redirected to a file or a pipe, close it and wait for the pipe
process termination.
* strace.c (main): Before normal exit, close shared_log when it
differs from stderr, and wait for popen_pid termination.
* defs.h: Define USE_SEIZE to 1. Remove PTRACE_SEIZE_DEVEL
and PTRACE_EVENT_STOP1.
* strace.c (ptrace_attach_or_seize): Replace PTRACE_SEIZE_DEVEL
with 0.
(trace): Do not check for PTRACE_EVENT_STOP1.
Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
We no longer track parent/child relationship between tracees.
Therefore, we no longer suspend new tracee until parent is seen
exiting form [v]fork/clone. The comment is obsolete.
* strace.c (trace): Remove outdated comment.
Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
* defs.h: Declare strace_vfprintf either as a alias to vfprintf
or as a bona fide function. USE_CUSTOM_PRINTF define controls whether
we use strace_vfprintf. By default, we don't.
* strace.c (tprintf): Call strace_vfprintf instead of vfprintf.
* vsprintf.c: New file, implements strace_vfprintf.
Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
The ptrace setoptions code will fork a child which goes to sleep and
expects the parent to continue on to do tests. Unfortunately, this
does not work on no-mmu systems as fork() is actually vfork() and any
vforked children will hang the parent until it exits or execs.
We might be able to make this test work on no-mmu systems with a bit
of work, but easier to just disable this for the release so it works
now.
* strace.c (test_ptrace_setoptions_for_all): Return if strace_vforked.
Signed-off-by: Mike Frysinger <vapier@gentoo.org>
* defs.h (string_to_uint): New prototype.
* util.c (string_to_uint): New function.
* strace.c (error_opt_arg): New function.
(process_opt_p_list): Use string_to_uint instead of atoi.
Terminate in case of invalid process id.
(init): Use string_to_uint instead of atoi.
Use error_opt_arg in case of invalid option argument.
* syscall.c (qual_syscall, qual_signal, qual_desc): Use string_to_uint
instead of atoi.
Instead of using "static FILE *outf and static unsigned int curcol"
to cache current outfile and its position, we can simply
remember current tcb and use its ->outf and ->curcol.
This allows to drop numerous "tcp->curcol = curcol" ops in trace().
Turns out we can't drop "static FILE *outf", but now its role is
a bit clearer: it newer changes after init, stays == stderr or
opened to shared log (which may be the same thing if neither -o
nor -ff was specified). Let's rename it then.
text data bss dec hex filename
236953 704 18944 256601 3ea59 strace.before.prev.commit
236905 704 18944 256553 3ea29 strace.before
236869 704 18944 256517 3ea05 strace
* strace.c: Replace curcol static variable by struct tcb *current_tcp.
Rename static FILE *outf to shared_log (since it no longer caches tcp->outf).
(ptrace_restart): Use current_tcp->curcol instead of curcol.
(tprintf): Check current_tcp != NULL instead of outf != NULL.
Use current_tcp->outf instead of outf, current_tcp->curcol instead of curcol.
(tprints): Likewise.
(line_ended): Likewise.
(printleader): Switch current tcb by "current_tcp = tcp" istead of
assignments to outf and curcol.
(droptcb): Set current_tcp to NULL if we dropped it.
(startup_child): Rename outf to shared_log.
(init): Likewise.
(cleanup): Likewise.
(trace): Simplify current tcp switching and current column handling.
Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
* strace.c (droptcb): Remove outfname check in "outfname && followfork >= 2" -
with recent changes, followfork >= 2 check guarantees that outfile
was specified, and _is already opened_.
(trace): Move tcb existence check before threaded execve handling.
This allows to remove tcp != NULL checks in threaded execve handling.
Rewrite threaded execve handling code to be less indented,
keeping the same logic.
Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
* strace.c (trace): Show "+++ exited..." with -C too.
Save tcp->curcol after PTRACE_LISTEN failure too, just in case.
Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
