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* strace.c: Define new detach_on_execve, skip_startup_execve bool variables.
(init): Set detach_on_execve on -b, set skip_startup_execve if
"strace PROG" form is used.
(trace): Detach from process if -b and we see PTRACE_EVENT_EXEC event.
Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
* defs.h: Include <signal.h> unconditionally.
Other files were doing it unconditionally, so no harm done.
* bjm.c: Remove system includes which are already included by defs.h.
* pathtrace.c: Likewise.
* process.c: Likewise.
* signal.c: Likewise.
* strace.c: Likewise.
* stream.c: Likewise.
* syscall.c: Likewise.
* system.c: Likewise.
* util.c: Likewise.
Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
Bool variables are more compact in data and (on x86) on code too:
text data bss dec hex filename
237950 676 19044 257670 3ee86 strace.before
237838 676 19012 257526 3edf6 strace
* defs.h: Group library includes at the top of the file.
Rename dtime to Tflag, debug to debug_flag.
Change debug_flag,Tflag,qflag,not_failing_only,show_fd_path,tracing_paths
variable declarations from int to bool.
* strace.c: Change corresponding definitions. Do the same for static
variables iflag,rflag,print_pid_pfx.
Rename dtime to Tflag, debug to debug_flag.
* syscall.c: Rename dtime to Tflag, debug to debug_flag.
Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
Our logic which was deciding whether to print "<unfinished ...>"
thingy wasn't working properly for -ff case.
* defs.h: Group log generation-related declarations together.
Add a large comment which explains how it works.
Add declaration of line_ended() function.
* strace.c (line_ended): New function which sets up internal data
to indicate that previous line was finished.
(printleader): Change logic to fix log generation in -ff mode.
(newoutf): Make check for -ff mode consistent with other places.
(droptcb): Print "<detached ...>" if last line for this tcp wasn't finished.
(cleanup): Remove code to print "<unfinished ...>", printleader()
or detach() will do it instead.
(trace): Remove code to print "<unfinished ...>".
Add code which finishes threaded execve's incomplete line
with " <pid changed to PID ...>" message. Replace printing_tcp = NULL
followed by fflush() by line_ended() call.
* process.c (sys_exit): Call line_ended() to indicate that we finished priting.
* syscall.c (trace_syscall_exiting): Set printing_tcp to current tcp.
Call line_ended() to indicate that we finished priting.
Remove call to fflush(), it is done by line_ended() now.
Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
main() uses ~0.5k of stack for local variables and such. When we enter
main tracing loop, most of these variables are no longer used.
But they still take up stack for the entire life of strace.
We can avoid this wastage if we move init code into a separate function.
(Need to be careful and not allow automatic inlining).
* strace.c (init): New function. Most of pre-existing code of
main is now living here.
(main): Call init() to do initialization.
Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
* strace.c (tprintf): Move function up in the source file. No code changes.
(tprints): Likewise.
(printleader): Likewise.
(tabto): Likewise.
Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
TCB_STRACE_CHILD is used for the case when "strace PROG" is ^C-ed
or something like that. strace should not just exit - it should
do something with its child (such as signal it too).
In -D case, PROG is not really a child of _strace_, it is a child
of strace's parent. It's ok to handle it exactly as an attached process.
While we are at it, remove nonsensical special-casing of TCB_STRACE_CHILD
in printing of "<unfinished ...>" message.
* strace.c (startup_attach): Don't set TCB_STRACE_CHILD if -D.
(trace): Print "<unfinished ...>" on error regardless of TCB_STRACE_CHILD.
Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
Before this change:
$ strace -D -p1
strace: -D and -p are mutually exclusive options
Process 1 detached <==== WRONG! (and we try to SIGSTOP it!!!)
* defs.h: Change the meaning of TCB_ATTACHED: now it means "this tracee
is attached to us". Add TCB_STRACE_CHILD: "this tracee is our child".
* strace.c (kill_save_errno): Move up. No code changes.
(process_opt_p_list): Don't set TCB_ATTACHED on new tcb.
(startup_attach): Change how we work with TCB_ATTACHED.
Set TCB_STRACE_CHILD on -D.
(startup_child): Use kill_save_errno instead of kill.
Set TCB_ATTACHED and TCB_STRACE_CHILD on attached strace child.
If we are in -D case, don't set TCB_ATTACHED (we aren't attached yet).
(detach): do not do PTRACE_DETACH if TCB_ATTACHED is not set.
(cleanup): Check TCB_STRACE_CHILD instead of TCB_ATTACHED.
(trace): Likewise.
Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
In this case we were printing PIDs to LOG.* files
even though it is not necessary.
The fix is in the addition of "&& followfork < 2" condition.
* strace.c: Remove pflag_seen variable, add print_pid_pfx one.
(process_opt_p_list): Do not pflag_seen++.
(main): Use "nprocs != 0" condition instead of "pflag_seen != 0".
Set print_pid_pfx before entering main tracing loop.
(printleader): Use print_pid_pfx to decide whether to print pid prefix.
Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
* defs.h: Clarify meaning of TCB_ATTACHED. No code changes.
* strace.c (process_opt_p_list): New function.
(main): Call process_opt_p_list to process -p PIDs argument.
Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
Conditions such as defined(LINUX) are always true now,
defined(FREEBSD) etc are always false.
When if directive has them as subexpressions, it can be simplified.
Another trivial changes here are fixes for directive indentation.
Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
This change is generated by running every source through the following command:
unifdef -DLINUX -Dlinux -USUNOS4 -USVR4 -UUNIXWARE -UFREEBSD
-USUNOS4_KERNEL_ARCH_KLUDGE -UHAVE_MP_PROCFS
-UHAVE_POLLABLE_PROCFS -UHAVE_PR_SYSCALL -UUSE_PROCFS file.c
Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
The native_scno field is not so much used in the code than before.
In many cases sys_func is checked instead, and for most of syscall
entries there is no need to initialize native_scno.
* linux/i386/syscallent.h: Remove native_scno initialization for
_exit, read, write, waitpid, execve, wait4, sysfs, readv, writev,
pread64, pwrite64, exit_group, waitid, send, recv, sendto and
recvfrom syscall entries.
* linux/syscall.h: Do not define no longer used SYS_waitid and
SYS_sub_* constants.
[IA64]: Do not define SYS_waitpid and SYS32_* constants.
* defs.h: Do not define no longer used __NR_exit_group constant.
* strace.c [USE_PROCFS] (proc_open): Use sys_func to check for execve.
* strace.c (usage): Tweak help text: remove unpaired closing brackets,
make -V and -h sit on separate lines (hard to see them otherwise).
Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
text data bss dec hex filename
239474 672 20484 260630 3fa16 strace.before
239234 668 19044 258946 3f382 strace
* file.c (sprint_open_modes): Reduce static buffer size.
Simplify separator printing.
* signal.c (sprintsigmask): Reduce static buffer size.
Simplify separator printing and printing of almost full masks.
Use stpcpy instead of sprintf and strcpy+strlen.
* strace.c (startup_child): Don't strchr() for ':' twice in a row.
* util.c (sprintflags): Exit loop early if possible.
Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
Defaults are often ok, but when they are not, people get confused.
"Why can't I kill strace?" and "Why strace dies on ^C when I want
to _tracee_ to die instead?" are typical complaints.
* strace.c: Replace 'interactive' variable with 'opt_intr' variable.
Define INTR_foo constants for its possible values.
Define 'interactive' as a macro.
(usage): Document -I n option.
(main): Parse -I n option, modify signal handling to accomidate new
-I 1 and -I 4 modes.
Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
* strace.c (interrupt): Remember signal number.
(cleanup): If we exiting due to signal, send that signal to child tracee.
Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
All new code is predicated on "ifdef USE_SEIZE". If it is not defined,
behavior is not changed.
If USE_SEIZE is enabled and run-time check shows that PTRACE_SEIZE works, then:
- All attaching is done with PTRACE_SEIZE + PTRACE_INTERRUPT.
This means that we no longer generate (and possibly race with) SIGSTOP.
- PTRACE_EVENT_STOP will be generated if tracee is group-stopped.
When we detect it, we issue PTRACE_LISTEN instead of PTRACE_SYSCALL.
This leaves tracee stopped. This fixes the inability to SIGSTOP or ^Z
a straced process.
* defs.h: Add commented-out "define USE_SEIZE 1" and define PTRACE_SEIZE
and related constants.
* strace.c: New variable post_attach_sigstop shows whether we age going
to expect SIGSTOP on attach (IOW: are we going to use PTRACE_SEIZE).
(ptrace_attach_or_seize): New function. Uses PTRACE_ATTACH or
PTRACE_SEIZE + PTRACE_INTERRUPT to attach to given pid.
(startup_attach): Use ptrace_attach_or_seize() instead of ptrace(PTRACE_ATTACH).
(startup_child): Conditionally use alternative attach method using PTRACE_SEIZE.
(test_ptrace_setoptions_followfork): More robust parameters to PTRACE_TRACEME.
(test_ptrace_seize): New function to test whether PTRACE_SEIZE works.
(main): Call test_ptrace_seize() while initializing.
(trace): If PTRACE_EVENT_STOP is seen, restart using PTRACE_LISTEN in order
to not let tracee run.
* process.c: Decode PTRACE_SEIZE, PTRACE_INTERRUPT, PTRACE_LISTEN.
* util.c (ptrace_restart): Add "LISTEN" to a possible error message.
Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
* defs.h: Rename tcp_last to printing_tcp. Explain what it means.
Remove printtrailer() function.
* process.c (sys_exit): Convert printtrailer() call to "printing_tcp = NULL".
* strace.c: Add new variable printing_tcp.
(cleanup): Convert printtrailer() call to "printing_tcp = NULL".
(trace): Likewise.
(trace): Fix checks for incomplete line - it was working wrongly if last syscall was exit.
(printleader): Set printing_tcp.
(printtrailer): Remove this function.
* syscall.c: Remove tcp_last variable.
(trace_syscall_entering): Don't set printing_tcp, printleader call now does it.
(trace_syscall_exiting): Convert printtrailer() call to "printing_tcp = NULL".
Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
Since 3.0, Linux has a way to identify which thread execve'ed.
This patch makes use of it in order to properly dispose
of disappeared ("superseded") thread leader,
and replace it with execve'ed thread.
Before this patch, strace was "leaking" thread which exec'ed.
It was thinking that it still runs. It would look like this:
18460 pause( <unfinished ...> <=== thread leader
18466 execve("/proc/self/exe", ["exe", "exe"], [/* 47 vars */] <unfinished ...>
18465 +++ exited with 0 +++ <=== exits from other threads
18460 <... pause resumed> ) = 0
The last line is wrong: it's not pause resumed, it's execve resumed.
If thread leader would do exit instead of pause, it is much worse:
strace panics because it thinks it sees return from exit syscall!
And strace isn't aware 18466 (exec'ed thread) is gone.
It still thinks it's executes execve syscall.
* strace.c: New variable "static char *os_release".
(get_os_release): New static function.
(main): Call get_os_release to retrieve Linux version.
(trace): If we see PTRACE_EVENT_EXEC, retrieve old pid, and if it
differs from new one, free one of tcbs and print correct messages.
Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
text data bss dec hex filename
238258 668 28676 267602 41552 strace.before
238274 668 20484 259426 3f562 strace
* strace.c (main): Allocate -o OUTFILE buffer only if needed:
unused buffer in bss is not entirely free.
Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
This change partially reverts commit 44d0532.
In code before commit 44d0532, single fprintf was used on purpose:
we want to send entire message as one write() call. Since stderr
is unbuffered, separate fprintf's to it always result in separate
writes, they are not coalesced. If we aren't the only program
which writes to this particular stderr, this may result
in interleaved messages.
Since this function is not performance critical, I guess
it's ok to make it less efficient.
* strace.c (verror_msg): Attempt to print the message in single
write operation. Use separate fprintfs as a fallback if malloc fails.
Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
On attempts to block or set SIGTRAP handler,
for example, using sigaction syscall, we generate
an additional SIGSTOP.
This change gets rid of this SIGSTOP sending/ignoring.
It appears to work just fine.
It also works if I force strace to not use PTRACE_O_TRACESYSGOOD,
which means strace stops will be marked with SIGTRAP,
not (SIGTRAP | 0x80) - I wondered maybe that's when
this hack is needed.
So, why we even have TCB_SIGTRAPPED? No one knows. It predates
version control: this code was present in the initial commit,
in 1999. No adequate comments, either.
Moreover, TCB_SIGTRAPPED is not set in sys_rt_sigaction
and sys_sigprocmask syscalls - the ones which are most usually
used to implement signal blocking, it is only set in obsolete
sys_signal, sys_sigaction, sys_sigsetmask, and in some dead
non-Linux code.
I think whatever bug it was fixing is gone long ago -
at least as long as sys_rt_sigaction is used by glibc.
Again, since glibc (and uclibc) uses sys_rt_sigaction
and sys_sigprocmask, modified code paths are not used
by most programs anyway.
* defs.h: Remove definition of TCB_SIGTRAPPED.
* signal.c (sys_sigvec): Don't set TCB_SIGTRAPPED and don't send SIGSTOP.
(sys_sigsetmask): Likewise.
(sys_sigaction): Likewise.
(sys_signal): Likewise.
* strace.c (trace): Remove code which executes if TCB_SIGTRAPPED is set.
Signed-off-by: Denys Vlasenko <dvlasenk@redhat.com>
I observed a case when signal delivery message was buffered
by stdio until it was flushed along with the next syscall
entry message.
* strace.c (trace): Flush output buffers in a few more cases.
Signed-off-by: Denys Vlasenko <dvlasenk@redhat.com>
Before this patch, if a thread got nuked by exit in another thread
and we happened to poke it at the same time, we print "????(" thingy
and detach the thread. Since we removed "detach before death" logic,
this no longer matches the behavior of other threads.
Before patch:
[pid 1780] exit_group(1) = ?
[pid 1778] ????( <unfinished ...>
Process 1778 detached
[pid 5860] +++ exited with 1 +++
After:
[pid 17765] exit_group(1) = ?
[pid 21680] ????( <unfinished ...>
[pid 17791] +++ exited with 1 +++
[pid 21680] +++ exited with 1 +++
* strace (trace): Do not detach from tracee which experienced ptrace error.
Signed-off-by: Denys Vlasenko <dvlasenk@redhat.com>
* strace.c (detach): Drop sig parameter - it is zero in all calls.
(cleanup): Don't pass sig = 0 to detach() call.
(detach): Ditto.
Signed-off-by: Denys Vlasenko <dvlasenk@redhat.com>
On syscall entry, save current personality in the tcb structure
along with scno.
On syscall exit, restore current personality from the tcb structure.
* defs.h (struct tcb) [SUPPORTED_PERSONALITIES > 1]: Add currpers
field.
* strace.c (alloc_tcb) [SUPPORTED_PERSONALITIES > 1]: Initialize
tcp->currpers.
* syscall.c (update_personality) [SUPPORTED_PERSONALITIES > 1]: New
function.
(get_scno, trace_syscall_exiting): Use it.
Reported-by: Michael A Fetterman <mafetter@nvidia.com>
We set ptrace options when we see post-attach SIGSTOP.
This is wrong: it's better to set them right away on the very first
stop (whichever it will be). It also will make adding SEIZE support easier,
since SEIZE has no post-attach SIGSTOP.
We do it by adding a new bit, TCB_IGNORE_ONE_SIGSTOP, and treating
TCB_STARTUP and TCB_IGNORE_ONE_SIGSTOP as two slightly different things.
* defs.h: Add a new flag bit, TCB_IGNORE_ONE_SIGSTOP.
* process.c (internal_fork): Set TCB_IGNORE_ONE_SIGSTOP on a newly added child.
* strace.c (startup_attach): Set TCB_IGNORE_ONE_SIGSTOP after attach.
Fix a case when "strace -p PID" found PID dead but sone other of its threads
still alive.
(startup_child): Set TCB_IGNORE_ONE_SIGSTOP after attach, _if needed_.
This fixes a bogus case where we can ignore a _real_ SIGSTOP on NOMMU.
(detach): Perform anti-SIGSTOP dance only if TCB_IGNORE_ONE_SIGSTOP is set,
not if TCB_STARTUP is set.
(trace): Set TCB_IGNORE_ONE_SIGSTOP after attach.
Clear TCB_STARTUP and initialize tracee on the very first tracee stop.
Clear TCB_IGNORE_ONE_SIGSTOP when SIGSTOP is seen.
Signed-off-by: Denys Vlasenko <dvlasenk@redhat.com>
This fixes logic in detach() which thinks that TCB_STARTUP
means that we are already attached, but did not see SIGSTOP yet.
This also allows to get rid of TCB_ATTACH_DONE flag.
* process.c (internal_fork): Set TCB_STARTUP after attach.
* strace.c (startup_attach): Likewise.
(startup_child): Likewise.
(alloc_tcb): Do not set TCB_STARTUP on tcb allocation - we are
not attached yet.
(trace): Set TCB_STARTUP when we detech an auto-attached child.
Signed-off-by: Denys Vlasenko <dvlasenk@redhat.com>
