2 * Copyright (c) 1991, 1992 Paul Kranenburg <pk@cs.few.eur.nl>
3 * Copyright (c) 1993 Branko Lankester <branko@hacktic.nl>
4 * Copyright (c) 1993, 1994, 1995, 1996 Rick Sladkey <jrs@world.std.com>
5 * Copyright (c) 1996-1999 Wichert Akkerman <wichert@cistron.nl>
8 * Redistribution and use in source and binary forms, with or without
9 * modification, are permitted provided that the following conditions
11 * 1. Redistributions of source code must retain the above copyright
12 * notice, this list of conditions and the following disclaimer.
13 * 2. Redistributions in binary form must reproduce the above copyright
14 * notice, this list of conditions and the following disclaimer in the
15 * documentation and/or other materials provided with the distribution.
16 * 3. The name of the author may not be used to endorse or promote products
17 * derived from this software without specific prior written permission.
19 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
20 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
21 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
22 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
23 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
24 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
25 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
26 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
27 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
28 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
33 #include <sys/param.h>
35 #include <sys/resource.h>
41 #include <sys/utsname.h>
43 # include <sys/prctl.h>
48 /* In some libc, these aren't declared. Do it ourself: */
49 extern char **environ;
54 /* if this is true do the stack trace for every system call */
55 bool stack_trace_enabled = false;
58 #if defined __NR_tkill
59 # define my_tkill(tid, sig) syscall(__NR_tkill, (tid), (sig))
61 /* kill() may choose arbitrarily the target task of the process group
62 while we later wait on a that specific TID. PID process waits become
63 TID task specific waits for a process under ptrace(2). */
64 # warning "tkill(2) not available, risk of strace hangs!"
65 # define my_tkill(tid, sig) kill((tid), (sig))
68 /* Glue for systems without a MMU that cannot provide fork() */
69 #if !defined(HAVE_FORK)
71 # define NOMMU_SYSTEM 1
74 # define fork() vfork()
77 const unsigned int syscall_trap_sig = SIGTRAP | 0x80;
79 cflag_t cflag = CFLAG_NONE;
80 unsigned int followfork = 0;
81 unsigned int ptrace_setoptions = PTRACE_O_TRACESYSGOOD | PTRACE_O_TRACEEXEC;
82 unsigned int xflag = 0;
86 bool count_wallclock = 0;
87 unsigned int qflag = 0;
88 static unsigned int tflag = 0;
89 static bool rflag = 0;
90 static bool print_pid_pfx = 0;
95 INTR_ANYWHERE = 1, /* don't block/ignore any signals */
96 INTR_WHILE_WAIT = 2, /* block fatal signals while decoding syscall. default */
97 INTR_NEVER = 3, /* block fatal signals. default if '-o FILE PROG' */
98 INTR_BLOCK_TSTP_TOO = 4, /* block fatal signals and SIGTSTP (^Z) */
102 /* We play with signal mask only if this mode is active: */
103 #define interactive (opt_intr == INTR_WHILE_WAIT)
106 * daemonized_tracer supports -D option.
107 * With this option, strace forks twice.
108 * Unlike normal case, with -D *grandparent* process exec's,
109 * becoming a traced process. Child exits (this prevents traced process
110 * from having children it doesn't expect to have), and grandchild
111 * attaches to grandparent similarly to strace -p PID.
112 * This allows for more transparent interaction in cases
113 * when process and its parent are communicating via signals,
114 * wait() etc. Without -D, strace process gets lodged in between,
115 * disrupting parent<->child link.
117 static bool daemonized_tracer = 0;
120 static int post_attach_sigstop = TCB_IGNORE_ONE_SIGSTOP;
121 # define use_seize (post_attach_sigstop == 0)
123 # define post_attach_sigstop TCB_IGNORE_ONE_SIGSTOP
127 /* Sometimes we want to print only succeeding syscalls. */
128 bool not_failing_only = 0;
130 /* Show path associated with fd arguments */
131 unsigned int show_fd_path = 0;
133 static bool detach_on_execve = 0;
134 /* Are we "strace PROG" and need to skip detach on first execve? */
135 static bool skip_one_b_execve = 0;
136 /* Are we "strace PROG" and need to hide everything until execve? */
137 bool hide_log_until_execve = 0;
139 static int exit_code = 0;
140 static int strace_child = 0;
141 static int strace_tracer_pid = 0;
143 static char *username = NULL;
144 static uid_t run_uid;
145 static gid_t run_gid;
147 unsigned int max_strlen = DEFAULT_STRLEN;
148 static int acolumn = DEFAULT_ACOLUMN;
149 static char *acolumn_spaces;
151 static char *outfname = NULL;
152 /* If -ff, points to stderr. Else, it's our common output log */
153 static FILE *shared_log;
155 struct tcb *printing_tcp = NULL;
156 static struct tcb *current_tcp;
158 static struct tcb **tcbtab;
159 static unsigned int nprocs, tcbtabsize;
160 static const char *progname;
162 unsigned os_release; /* generated from uname()'s u.release */
164 static void detach(struct tcb *tcp);
165 static void cleanup(void);
166 static void interrupt(int sig);
167 static sigset_t empty_set, blocked_set;
169 #ifdef HAVE_SIG_ATOMIC_T
170 static volatile sig_atomic_t interrupted;
172 static volatile int interrupted;
175 #ifndef HAVE_STRERROR
177 #if !HAVE_DECL_SYS_ERRLIST
179 extern char *sys_errlist[];
185 static char buf[sizeof("Unknown error %d") + sizeof(int)*3];
187 if (err_no < 1 || err_no >= sys_nerr) {
188 sprintf(buf, "Unknown error %d", err_no);
191 return sys_errlist[err_no];
194 #endif /* HAVE_STERRROR */
197 usage(FILE *ofp, int exitval)
200 usage: strace [-CdffhiqrtttTvVxxy] [-I n] [-e expr]...\n\
201 [-a column] [-o file] [-s strsize] [-P path]...\n\
202 -p pid... / [-D] [-E var=val]... [-u username] PROG [ARGS]\n\
203 or: strace -c[df] [-I n] [-e expr]... [-O overhead] [-S sortby]\n\
204 -p pid... / [-D] [-E var=val]... [-u username] PROG [ARGS]\n\
205 -c -- count time, calls, and errors for each syscall and report summary\n\
206 -C -- like -c but also print regular output\n\
207 -w -- summarise syscall latency (default is system time)\n\
208 -d -- enable debug output to stderr\n\
209 -D -- run tracer process as a detached grandchild, not as parent\n\
210 -f -- follow forks, -ff -- with output into separate files\n\
211 -i -- print instruction pointer at time of syscall\n\
212 -q -- suppress messages about attaching, detaching, etc.\n\
213 -r -- print relative timestamp, -t -- absolute timestamp, -tt -- with usecs\n\
214 -T -- print time spent in each syscall\n\
215 -v -- verbose mode: print unabbreviated argv, stat, termios, etc. args\n\
216 -x -- print non-ascii strings in hex, -xx -- print all strings in hex\n\
217 -y -- print paths associated with file descriptor arguments\n\
218 -yy -- print ip:port pairs associated with socket file descriptors\n\
219 -h -- print help message, -V -- print version\n\
220 -a column -- alignment COLUMN for printing syscall results (default %d)\n\
221 -b execve -- detach on this syscall\n\
222 -e expr -- a qualifying expression: option=[!]all or option=[!]val1[,val2]...\n\
223 options: trace, abbrev, verbose, raw, signal, read, write\n\
224 -I interruptible --\n\
225 1: no signals are blocked\n\
226 2: fatal signals are blocked while decoding syscall (default)\n\
227 3: fatal signals are always blocked (default if '-o FILE PROG')\n\
228 4: fatal signals and SIGTSTP (^Z) are always blocked\n\
229 (useful to make 'strace -o FILE PROG' not stop on ^Z)\n\
230 -o file -- send trace output to FILE instead of stderr\n\
231 -O overhead -- set overhead for tracing syscalls to OVERHEAD usecs\n\
232 -p pid -- trace process with process id PID, may be repeated\n\
233 -s strsize -- limit length of print strings to STRSIZE chars (default %d)\n\
234 -S sortby -- sort syscall counts by: time, calls, name, nothing (default %s)\n\
235 -u username -- run command as username handling setuid and/or setgid\n\
236 -E var=val -- put var=val in the environment for command\n\
237 -E var -- remove var from the environment for command\n\
238 -P path -- trace accesses to path\n\
241 "-k obtain stack trace between each syscall (experimental)\n\
244 /* ancient, no one should use it
245 -F -- attempt to follow vforks (deprecated, use -f)\n\
247 /* this is broken, so don't document it
248 -z -- print only succeeding syscalls\n\
250 , DEFAULT_ACOLUMN, DEFAULT_STRLEN, DEFAULT_SORTBY);
254 static void die(void) __attribute__ ((noreturn));
255 static void die(void)
257 if (strace_tracer_pid == getpid()) {
264 static void verror_msg(int err_no, const char *fmt, va_list p)
270 /* We want to print entire message with single fprintf to ensure
271 * message integrity if stderr is shared with other programs.
272 * Thus we use vasprintf + single fprintf.
275 if (vasprintf(&msg, fmt, p) >= 0) {
277 fprintf(stderr, "%s: %s: %s\n", progname, msg, strerror(err_no));
279 fprintf(stderr, "%s: %s\n", progname, msg);
282 /* malloc in vasprintf failed, try it without malloc */
283 fprintf(stderr, "%s: ", progname);
284 vfprintf(stderr, fmt, p);
286 fprintf(stderr, ": %s\n", strerror(err_no));
290 /* We don't switch stderr to buffered, thus fprintf(stderr)
291 * always flushes its output and this is not necessary: */
292 /* fflush(stderr); */
295 void error_msg(const char *fmt, ...)
299 verror_msg(0, fmt, p);
303 void error_msg_and_die(const char *fmt, ...)
307 verror_msg(0, fmt, p);
311 void perror_msg(const char *fmt, ...)
315 verror_msg(errno, fmt, p);
319 void perror_msg_and_die(const char *fmt, ...)
323 verror_msg(errno, fmt, p);
327 void die_out_of_memory(void)
329 static bool recursed = 0;
333 error_msg_and_die("Out of memory");
337 error_opt_arg(int opt, const char *arg)
339 error_msg_and_die("Invalid -%c argument: '%s'", opt, arg);
344 ptrace_attach_or_seize(int pid)
348 return ptrace(PTRACE_ATTACH, pid, 0L, 0L);
349 r = ptrace(PTRACE_SEIZE, pid, 0L, (unsigned long) ptrace_setoptions);
352 r = ptrace(PTRACE_INTERRUPT, pid, 0L, 0L);
356 # define ptrace_attach_or_seize(pid) ptrace(PTRACE_ATTACH, (pid), 0, 0)
360 * Used when we want to unblock stopped traced process.
361 * Should be only used with PTRACE_CONT, PTRACE_DETACH and PTRACE_SYSCALL.
362 * Returns 0 on success or if error was ESRCH
363 * (presumably process was killed while we talk to it).
364 * Otherwise prints error message and returns -1.
367 ptrace_restart(int op, struct tcb *tcp, int sig)
373 ptrace(op, tcp->pid, (void *) 0, (long) sig);
379 if (op == PTRACE_CONT)
381 if (op == PTRACE_DETACH)
384 if (op == PTRACE_LISTEN)
388 * Why curcol != 0? Otherwise sometimes we get this:
390 * 10252 kill(10253, SIGKILL) = 0
391 * <ptrace(SYSCALL,10252):No such process>10253 ...next decode...
393 * 10252 died after we retrieved syscall exit data,
394 * but before we tried to restart it. Log looks ugly.
396 if (current_tcp && current_tcp->curcol != 0) {
397 tprintf(" <ptrace(%s):%s>\n", msg, strerror(err));
403 perror_msg("ptrace(PTRACE_%s,pid:%d,sig:%d)", msg, tcp->pid, sig);
408 set_cloexec_flag(int fd)
412 flags = fcntl(fd, F_GETFD);
414 /* Can happen only if fd is bad.
415 * Should never happen: if it does, we have a bug
416 * in the caller. Therefore we just abort
417 * instead of propagating the error.
419 perror_msg_and_die("fcntl(%d, F_GETFD)", fd);
422 newflags = flags | FD_CLOEXEC;
423 if (flags == newflags)
426 fcntl(fd, F_SETFD, newflags); /* never fails */
429 static void kill_save_errno(pid_t pid, int sig)
431 int saved_errno = errno;
433 (void) kill(pid, sig);
438 * When strace is setuid executable, we have to swap uids
439 * before and after filesystem and process management operations.
444 int euid = geteuid(), uid = getuid();
446 if (euid != uid && setreuid(euid, uid) < 0) {
447 perror_msg_and_die("setreuid");
451 #ifdef _LARGEFILE64_SOURCE
453 # define fopen_for_output fopen64
455 # define fopen_for_output fopen
457 # define struct_stat struct stat64
458 # define stat_file stat64
459 # define struct_dirent struct dirent64
460 # define read_dir readdir64
461 # define struct_rlimit struct rlimit64
462 # define set_rlimit setrlimit64
464 # define fopen_for_output fopen
465 # define struct_stat struct stat
466 # define stat_file stat
467 # define struct_dirent struct dirent
468 # define read_dir readdir
469 # define struct_rlimit struct rlimit
470 # define set_rlimit setrlimit
474 strace_fopen(const char *path)
479 fp = fopen_for_output(path, "w");
481 perror_msg_and_die("Can't fopen '%s'", path);
483 set_cloexec_flag(fileno(fp));
487 static int popen_pid = 0;
490 # define _PATH_BSHELL "/bin/sh"
494 * We cannot use standard popen(3) here because we have to distinguish
495 * popen child process from other processes we trace, and standard popen(3)
496 * does not export its child's pid.
499 strace_popen(const char *command)
507 perror_msg_and_die("pipe");
509 set_cloexec_flag(fds[1]); /* never fails */
513 perror_msg_and_die("vfork");
520 perror_msg_and_die("dup2");
523 execl(_PATH_BSHELL, "sh", "-c", command, NULL);
524 perror_msg_and_die("Can't execute '%s'", _PATH_BSHELL);
531 fp = fdopen(fds[1], "w");
538 tprintf(const char *fmt, ...)
544 int n = strace_vfprintf(current_tcp->outf, fmt, args);
546 if (current_tcp->outf != stderr)
547 perror_msg("%s", outfname);
549 current_tcp->curcol += n;
554 #ifndef HAVE_FPUTS_UNLOCKED
555 # define fputs_unlocked fputs
559 tprints(const char *str)
562 int n = fputs_unlocked(str, current_tcp->outf);
564 current_tcp->curcol += strlen(str);
567 if (current_tcp->outf != stderr)
568 perror_msg("%s", outfname);
576 current_tcp->curcol = 0;
577 fflush(current_tcp->outf);
580 printing_tcp->curcol = 0;
586 printleader(struct tcb *tcp)
588 /* If -ff, "previous tcb we printed" is always the same as current,
589 * because we have per-tcb output files.
595 current_tcp = printing_tcp;
596 if (printing_tcp->curcol != 0 && (followfork < 2 || printing_tcp == tcp)) {
598 * case 1: we have a shared log (i.e. not -ff), and last line
599 * wasn't finished (same or different tcb, doesn't matter).
600 * case 2: split log, we are the same tcb, but our last line
601 * didn't finish ("SIGKILL nuked us after syscall entry" etc).
603 tprints(" <unfinished ...>\n");
604 printing_tcp->curcol = 0;
610 current_tcp->curcol = 0;
613 tprintf("%-5d ", tcp->pid);
614 else if (nprocs > 1 && !outfname)
615 tprintf("[pid %5u] ", tcp->pid);
618 char str[sizeof("HH:MM:SS")];
619 struct timeval tv, dtv;
620 static struct timeval otv;
622 gettimeofday(&tv, NULL);
626 tv_sub(&dtv, &tv, &otv);
627 tprintf("%6ld.%06ld ",
628 (long) dtv.tv_sec, (long) dtv.tv_usec);
631 else if (tflag > 2) {
632 tprintf("%ld.%06ld ",
633 (long) tv.tv_sec, (long) tv.tv_usec);
636 time_t local = tv.tv_sec;
637 strftime(str, sizeof(str), "%T", localtime(&local));
639 tprintf("%s.%06ld ", str, (long) tv.tv_usec);
651 if (current_tcp->curcol < acolumn)
652 tprints(acolumn_spaces + current_tcp->curcol);
655 /* Should be only called directly *after successful attach* to a tracee.
656 * Otherwise, "strace -oFILE -ff -p<nonexistant_pid>"
657 * may create bogus empty FILE.<nonexistant_pid>, and then die.
660 newoutf(struct tcb *tcp)
662 tcp->outf = shared_log; /* if not -ff mode, the same file is for all */
663 if (followfork >= 2) {
664 char name[520 + sizeof(int) * 3];
665 sprintf(name, "%.512s.%u", outfname, tcp->pid);
666 tcp->outf = strace_fopen(name);
673 /* Allocate some more TCBs and expand the table.
674 We don't want to relocate the TCBs because our
675 callers have pointers and it would be a pain.
676 So tcbtab is a table of pointers. Since we never
677 free the TCBs, we allocate a single chunk of many. */
678 unsigned int i = tcbtabsize;
679 struct tcb *newtcbs = calloc(tcbtabsize, sizeof(newtcbs[0]));
680 struct tcb **newtab = realloc(tcbtab, tcbtabsize * 2 * sizeof(tcbtab[0]));
681 if (!newtab || !newtcbs)
685 while (i < tcbtabsize)
686 tcbtab[i++] = newtcbs++;
695 if (nprocs == tcbtabsize)
698 for (i = 0; i < tcbtabsize; i++) {
701 memset(tcp, 0, sizeof(*tcp));
703 #if SUPPORTED_PERSONALITIES > 1
704 tcp->currpers = current_personality;
708 if (stack_trace_enabled)
709 unwind_tcb_init(tcp);
714 fprintf(stderr, "new tcb for pid %d, active tcbs:%d\n", tcp->pid, nprocs);
718 error_msg_and_die("bug in alloctcb");
722 droptcb(struct tcb *tcp)
728 if (stack_trace_enabled) {
735 fprintf(stderr, "dropped tcb for pid %d, %d remain\n", tcp->pid, nprocs);
738 if (followfork >= 2) {
739 if (tcp->curcol != 0)
740 fprintf(tcp->outf, " <detached ...>\n");
743 if (printing_tcp == tcp && tcp->curcol != 0)
744 fprintf(tcp->outf, " <detached ...>\n");
749 if (current_tcp == tcp)
751 if (printing_tcp == tcp)
754 memset(tcp, 0, sizeof(*tcp));
757 /* Detach traced process.
758 * Never call DETACH twice on the same process as both unattached and
759 * attached-unstopped processes give the same ESRCH. For unattached process we
760 * would SIGSTOP it and wait for its SIGSTOP notification forever.
763 detach(struct tcb *tcp)
769 * Linux wrongly insists the child be stopped
770 * before detaching. Arghh. We go through hoops
771 * to make a clean break of things.
774 # undef PTRACE_DETACH
775 # define PTRACE_DETACH PTRACE_SUNDETACH
778 if (!(tcp->flags & TCB_ATTACHED))
781 /* We attached but possibly didn't see the expected SIGSTOP.
782 * We must catch exactly one as otherwise the detached process
783 * would be left stopped (process state T).
785 if (tcp->flags & TCB_IGNORE_ONE_SIGSTOP)
788 error = ptrace(PTRACE_DETACH, tcp->pid, 0, 0);
790 /* On a clear day, you can see forever. */
793 if (errno != ESRCH) {
794 /* Shouldn't happen. */
795 perror_msg("detach: ptrace(PTRACE_DETACH,%u)", tcp->pid);
798 /* ESRCH: process is either not stopped or doesn't exist. */
799 if (my_tkill(tcp->pid, 0) < 0) {
801 /* Shouldn't happen. */
802 perror_msg("detach: tkill(%u,0)", tcp->pid);
803 /* else: process doesn't exist. */
806 /* Process is not stopped, need to stop it. */
809 * With SEIZE, tracee can be in group-stop already.
810 * In this state sending it another SIGSTOP does nothing.
811 * Need to use INTERRUPT.
812 * Testcase: trying to ^C a "strace -p <stopped_process>".
814 error = ptrace(PTRACE_INTERRUPT, tcp->pid, 0, 0);
818 perror_msg("detach: ptrace(PTRACE_INTERRUPT,%u)", tcp->pid);
821 error = my_tkill(tcp->pid, SIGSTOP);
825 perror_msg("detach: tkill(%u,SIGSTOP)", tcp->pid);
827 /* Either process doesn't exist, or some weird error. */
831 /* We end up here in three cases:
832 * 1. We sent PTRACE_INTERRUPT (use_seize case)
833 * 2. We sent SIGSTOP (!use_seize)
834 * 3. Attach SIGSTOP was already pending (TCB_IGNORE_ONE_SIGSTOP set)
838 if (waitpid(tcp->pid, &status, __WALL) < 0) {
842 * if (errno == ECHILD) break;
843 * ^^^ WRONG! We expect this PID to exist,
844 * and want to emit a message otherwise:
846 perror_msg("detach: waitpid(%u)", tcp->pid);
849 if (!WIFSTOPPED(status)) {
851 * Tracee exited or was killed by signal.
852 * We shouldn't normally reach this place:
853 * we don't want to consume exit status.
854 * Consider "strace -p PID" being ^C-ed:
855 * we want merely to detach from PID.
857 * However, we _can_ end up here if tracee
862 sig = WSTOPSIG(status);
864 fprintf(stderr, "detach wait: event:%d sig:%d\n",
865 (unsigned)status >> 16, sig);
867 unsigned event = (unsigned)status >> 16;
868 if (event == PTRACE_EVENT_STOP /*&& sig == SIGTRAP*/) {
870 * sig == SIGTRAP: PTRACE_INTERRUPT stop.
871 * sig == other: process was already stopped
872 * with this stopping sig (see tests/detach-stopped).
873 * Looks like re-injecting this sig is not necessary
874 * in DETACH for the tracee to remain stopped.
879 * PTRACE_INTERRUPT is not guaranteed to produce
880 * the above event if other ptrace-stop is pending.
881 * See tests/detach-sleeping testcase:
882 * strace got SIGINT while tracee is sleeping.
883 * We sent PTRACE_INTERRUPT.
884 * We see syscall exit, not PTRACE_INTERRUPT stop.
885 * We won't get PTRACE_INTERRUPT stop
886 * if we would CONT now. Need to DETACH.
888 if (sig == syscall_trap_sig)
890 /* else: not sure in which case we can be here.
891 * Signal stop? Inject it while detaching.
893 ptrace_restart(PTRACE_DETACH, tcp, sig);
896 /* Note: this check has to be after use_seize check */
897 /* (else, in use_seize case SIGSTOP will be mistreated) */
898 if (sig == SIGSTOP) {
899 /* Detach, suppressing SIGSTOP */
900 ptrace_restart(PTRACE_DETACH, tcp, 0);
903 if (sig == syscall_trap_sig)
905 /* Can't detach just yet, may need to wait for SIGSTOP */
906 error = ptrace_restart(PTRACE_CONT, tcp, sig);
908 /* Should not happen.
909 * Note: ptrace_restart returns 0 on ESRCH, so it's not it.
910 * ptrace_restart already emitted error message.
917 if (!qflag && (tcp->flags & TCB_ATTACHED))
918 fprintf(stderr, "Process %u detached\n", tcp->pid);
924 process_opt_p_list(char *opt)
928 * We accept -p PID,PID; -p "`pidof PROG`"; -p "`pgrep PROG`".
929 * pidof uses space as delim, pgrep uses newline. :(
932 char *delim = opt + strcspn(opt, ", \n\t");
936 pid = string_to_uint(opt);
938 error_msg_and_die("Invalid process id: '%s'", opt);
940 if (pid == strace_tracer_pid) {
941 error_msg_and_die("I'm sorry, I can't let you do that, Dave.");
958 * Block user interruptions as we would leave the traced
959 * process stopped (process state T) if we would terminate in
960 * between PTRACE_ATTACH and wait4() on SIGSTOP.
961 * We rely on cleanup() from this point on.
964 sigprocmask(SIG_BLOCK, &blocked_set, NULL);
966 if (daemonized_tracer) {
969 perror_msg_and_die("fork");
971 if (pid) { /* parent */
973 * Wait for grandchild to attach to straced process
974 * (grandparent). Grandchild SIGKILLs us after it attached.
975 * Grandparent's wait() is unblocked by our death,
976 * it proceeds to exec the straced program.
979 _exit(0); /* paranoia */
982 /* We will be the tracer process. Remember our new pid: */
983 strace_tracer_pid = getpid();
986 for (tcbi = 0; tcbi < tcbtabsize; tcbi++) {
992 /* Is this a process we should attach to, but not yet attached? */
993 if (tcp->flags & TCB_ATTACHED)
994 continue; /* no, we already attached it */
996 if (followfork && !daemonized_tracer) {
997 char procdir[sizeof("/proc/%d/task") + sizeof(int) * 3];
1000 sprintf(procdir, "/proc/%d/task", tcp->pid);
1001 dir = opendir(procdir);
1003 unsigned int ntid = 0, nerr = 0;
1006 while ((de = read_dir(dir)) != NULL) {
1007 struct tcb *cur_tcp;
1010 if (de->d_fileno == 0)
1012 /* we trust /proc filesystem */
1013 tid = atoi(de->d_name);
1017 if (ptrace_attach_or_seize(tid) < 0) {
1020 fprintf(stderr, "attach to pid %d failed\n", tid);
1024 fprintf(stderr, "attach to pid %d succeeded\n", tid);
1026 if (tid != tcp->pid)
1027 cur_tcp = alloctcb(tid);
1028 cur_tcp->flags |= TCB_ATTACHED | TCB_STARTUP | post_attach_sigstop;
1033 sigprocmask(SIG_SETMASK, &empty_set, NULL);
1036 sigprocmask(SIG_BLOCK, &blocked_set, NULL);
1040 perror_msg("attach: ptrace(PTRACE_ATTACH, ...)");
1045 fprintf(stderr, ntid > 1
1046 ? "Process %u attached with %u threads\n"
1047 : "Process %u attached\n",
1050 if (!(tcp->flags & TCB_ATTACHED)) {
1051 /* -p PID, we failed to attach to PID itself
1052 * but did attach to some of its sibling threads.
1058 } /* if (opendir worked) */
1060 if (ptrace_attach_or_seize(tcp->pid) < 0) {
1061 perror_msg("attach: ptrace(PTRACE_ATTACH, ...)");
1065 tcp->flags |= TCB_ATTACHED | TCB_STARTUP | post_attach_sigstop;
1068 fprintf(stderr, "attach to pid %d (main) succeeded\n", tcp->pid);
1070 if (daemonized_tracer) {
1072 * Make parent go away.
1073 * Also makes grandparent's wait() unblock.
1075 kill(getppid(), SIGKILL);
1080 "Process %u attached\n",
1082 } /* for each tcbtab[] */
1086 sigprocmask(SIG_SETMASK, &empty_set, NULL);
1089 /* Stack-o-phobic exec helper, in the hope to work around
1090 * NOMMU + "daemonized tracer" difficulty.
1092 struct exec_params {
1099 static struct exec_params params_for_tracee;
1100 static void __attribute__ ((noinline, noreturn))
1103 struct exec_params *params = ¶ms_for_tracee;
1105 if (params->fd_to_close >= 0)
1106 close(params->fd_to_close);
1107 if (!daemonized_tracer && !use_seize) {
1108 if (ptrace(PTRACE_TRACEME, 0L, 0L, 0L) < 0) {
1109 perror_msg_and_die("ptrace(PTRACE_TRACEME, ...)");
1113 if (username != NULL) {
1115 * It is important to set groups before we
1116 * lose privileges on setuid.
1118 if (initgroups(username, run_gid) < 0) {
1119 perror_msg_and_die("initgroups");
1121 if (setregid(run_gid, params->run_egid) < 0) {
1122 perror_msg_and_die("setregid");
1124 if (setreuid(run_uid, params->run_euid) < 0) {
1125 perror_msg_and_die("setreuid");
1128 else if (geteuid() != 0)
1129 if (setreuid(run_uid, run_uid) < 0) {
1130 perror_msg_and_die("setreuid");
1133 if (!daemonized_tracer) {
1135 * Induce a ptrace stop. Tracer (our parent)
1136 * will resume us with PTRACE_SYSCALL and display
1137 * the immediately following execve syscall.
1138 * Can't do this on NOMMU systems, we are after
1139 * vfork: parent is blocked, stopping would deadlock.
1142 kill(getpid(), SIGSTOP);
1145 /* we depend on SIGCHLD set to SIG_DFL by init code */
1146 /* if it happens to be SIG_IGN'ed, wait won't block */
1151 execv(params->pathname, params->argv);
1152 perror_msg_and_die("exec");
1156 startup_child(char **argv)
1158 struct_stat statbuf;
1159 const char *filename;
1160 size_t filename_len;
1161 char pathname[PATH_MAX];
1166 filename_len = strlen(filename);
1168 if (filename_len > sizeof(pathname) - 1) {
1169 errno = ENAMETOOLONG;
1170 perror_msg_and_die("exec");
1172 if (strchr(filename, '/')) {
1173 strcpy(pathname, filename);
1175 #ifdef USE_DEBUGGING_EXEC
1177 * Debuggers customarily check the current directory
1178 * first regardless of the path but doing that gives
1179 * security geeks a panic attack.
1181 else if (stat_file(filename, &statbuf) == 0)
1182 strcpy(pathname, filename);
1183 #endif /* USE_DEBUGGING_EXEC */
1188 for (path = getenv("PATH"); path && *path; path += m) {
1189 const char *colon = strchr(path, ':');
1195 m = n = strlen(path);
1197 if (!getcwd(pathname, PATH_MAX))
1199 len = strlen(pathname);
1201 else if (n > sizeof pathname - 1)
1204 strncpy(pathname, path, n);
1207 if (len && pathname[len - 1] != '/')
1208 pathname[len++] = '/';
1209 if (filename_len + len > sizeof(pathname) - 1)
1211 strcpy(pathname + len, filename);
1212 if (stat_file(pathname, &statbuf) == 0 &&
1213 /* Accept only regular files
1214 with some execute bits set.
1215 XXX not perfect, might still fail */
1216 S_ISREG(statbuf.st_mode) &&
1217 (statbuf.st_mode & 0111))
1220 if (!path || !*path)
1223 if (stat_file(pathname, &statbuf) < 0) {
1224 perror_msg_and_die("Can't stat '%s'", filename);
1227 params_for_tracee.fd_to_close = (shared_log != stderr) ? fileno(shared_log) : -1;
1228 params_for_tracee.run_euid = (statbuf.st_mode & S_ISUID) ? statbuf.st_uid : run_uid;
1229 params_for_tracee.run_egid = (statbuf.st_mode & S_ISGID) ? statbuf.st_gid : run_gid;
1230 params_for_tracee.argv = argv;
1232 * On NOMMU, can be safely freed only after execve in tracee.
1233 * It's hard to know when that happens, so we just leak it.
1235 params_for_tracee.pathname = NOMMU_SYSTEM ? strdup(pathname) : pathname;
1237 #if defined HAVE_PRCTL && defined PR_SET_PTRACER && defined PR_SET_PTRACER_ANY
1238 if (daemonized_tracer)
1239 prctl(PR_SET_PTRACER, PR_SET_PTRACER_ANY);
1244 perror_msg_and_die("fork");
1246 if ((pid != 0 && daemonized_tracer)
1247 || (pid == 0 && !daemonized_tracer)
1249 /* We are to become the tracee. Two cases:
1251 * not -D: we are child
1256 /* We are the tracer */
1258 if (!daemonized_tracer) {
1261 /* child did PTRACE_TRACEME, nothing to do in parent */
1263 if (!NOMMU_SYSTEM) {
1264 /* Wait until child stopped itself */
1266 while (waitpid(pid, &status, WSTOPPED) < 0) {
1269 perror_msg_and_die("waitpid");
1271 if (!WIFSTOPPED(status) || WSTOPSIG(status) != SIGSTOP) {
1272 kill_save_errno(pid, SIGKILL);
1273 perror_msg_and_die("Unexpected wait status %x", status);
1276 /* Else: NOMMU case, we have no way to sync.
1277 * Just attach to it as soon as possible.
1278 * This means that we may miss a few first syscalls...
1281 if (ptrace_attach_or_seize(pid)) {
1282 kill_save_errno(pid, SIGKILL);
1283 perror_msg_and_die("Can't attach to %d", pid);
1288 tcp = alloctcb(pid);
1290 tcp->flags |= TCB_ATTACHED | TCB_STARTUP | post_attach_sigstop;
1292 tcp->flags |= TCB_ATTACHED | TCB_STARTUP;
1296 /* With -D, we are *child* here, IOW: different pid. Fetch it: */
1297 strace_tracer_pid = getpid();
1298 /* The tracee is our parent: */
1301 /* attaching will be done later, by startup_attach */
1302 /* note: we don't do newoutf(tcp) here either! */
1304 /* NOMMU BUG! -D mode is active, we (child) return,
1305 * and we will scribble over parent's stack!
1306 * When parent later unpauses, it segfaults.
1309 * (1) by declaring exec_or_die() NORETURN,
1310 * hopefully compiler will just jump to it
1311 * instead of call (won't push anything to stack),
1312 * (2) by trying very hard in exec_or_die()
1313 * to not use any stack,
1314 * (3) having a really big (PATH_MAX) stack object
1315 * in this function, which creates a "buffer" between
1316 * child's and parent's stack pointers.
1317 * This may save us if (1) and (2) failed
1318 * and compiler decided to use stack in exec_or_die() anyway
1319 * (happens on i386 because of stack parameter passing).
1321 * A cleaner solution is to use makecontext + setcontext
1322 * to create a genuine separate stack and execute on it.
1329 test_ptrace_seize(void)
1333 /* Need fork for test. NOMMU has no forks */
1335 post_attach_sigstop = 0; /* this sets use_seize to 1 */
1341 perror_msg_and_die("fork");
1348 /* PTRACE_SEIZE, unlike ATTACH, doesn't force tracee to trap. After
1349 * attaching tracee continues to run unless a trap condition occurs.
1350 * PTRACE_SEIZE doesn't affect signal or group stop state.
1352 if (ptrace(PTRACE_SEIZE, pid, 0, 0) == 0) {
1353 post_attach_sigstop = 0; /* this sets use_seize to 1 */
1354 } else if (debug_flag) {
1355 fprintf(stderr, "PTRACE_SEIZE doesn't work\n");
1361 int status, tracee_pid;
1364 tracee_pid = waitpid(pid, &status, 0);
1365 if (tracee_pid <= 0) {
1368 perror_msg_and_die("%s: unexpected wait result %d",
1369 __func__, tracee_pid);
1371 if (WIFSIGNALED(status)) {
1374 error_msg_and_die("%s: unexpected wait status %x",
1378 #else /* !USE_SEIZE */
1379 # define test_ptrace_seize() ((void)0)
1383 get_os_release(void)
1389 perror_msg_and_die("uname");
1390 /* u.release has this form: "3.2.9[-some-garbage]" */
1394 if (!(*p >= '0' && *p <= '9'))
1395 error_msg_and_die("Bad OS release string: '%s'", u.release);
1396 /* Note: this open-codes KERNEL_VERSION(): */
1397 rel = (rel << 8) | atoi(p);
1398 if (rel >= KERNEL_VERSION(1,0,0))
1400 while (*p >= '0' && *p <= '9')
1403 if (rel >= KERNEL_VERSION(0,1,0)) {
1404 /* "X.Y-something" means "X.Y.0" */
1408 error_msg_and_die("Bad OS release string: '%s'", u.release);
1416 * Initialization part of main() was eating much stack (~0.5k),
1417 * which was unused after init.
1418 * We can reuse it if we move init code into a separate function.
1420 * Don't want main() to inline us and defeat the reason
1421 * we have a separate function.
1423 static void __attribute__ ((noinline))
1424 init(int argc, char *argv[])
1430 struct sigaction sa;
1432 progname = argv[0] ? argv[0] : "strace";
1434 /* Make sure SIGCHLD has the default action so that waitpid
1435 definitely works without losing track of children. The user
1436 should not have given us a bogus state to inherit, but he might
1437 have. Arguably we should detect SIG_IGN here and pass it on
1438 to children, but probably noone really needs that. */
1439 signal(SIGCHLD, SIG_DFL);
1441 strace_tracer_pid = getpid();
1443 os_release = get_os_release();
1445 /* Allocate the initial tcbtab. */
1446 tcbtabsize = argc; /* Surely enough for all -p args. */
1447 tcbtab = calloc(tcbtabsize, sizeof(tcbtab[0]));
1449 die_out_of_memory();
1450 tcp = calloc(tcbtabsize, sizeof(*tcp));
1452 die_out_of_memory();
1453 for (tcbi = 0; tcbi < tcbtabsize; tcbi++)
1454 tcbtab[tcbi] = tcp++;
1456 shared_log = stderr;
1457 set_sortby(DEFAULT_SORTBY);
1458 set_personality(DEFAULT_PERSONALITY);
1459 qualify("trace=all");
1460 qualify("abbrev=all");
1461 qualify("verbose=all");
1462 #if DEFAULT_QUAL_FLAGS != (QUAL_TRACE | QUAL_ABBREV | QUAL_VERBOSE)
1463 # error Bug in DEFAULT_QUAL_FLAGS
1465 qualify("signal=all");
1466 while ((c = getopt(argc, argv,
1467 "+b:cCdfFhiqrtTvVwxyz"
1468 #ifdef USE_LIBUNWIND
1472 "a:e:o:O:p:s:S:u:E:P:I:")) != EOF) {
1475 if (strcmp(optarg, "execve") != 0)
1476 error_msg_and_die("Syscall '%s' for -b isn't supported",
1478 detach_on_execve = 1;
1481 if (cflag == CFLAG_BOTH) {
1482 error_msg_and_die("-c and -C are mutually exclusive");
1484 cflag = CFLAG_ONLY_STATS;
1487 if (cflag == CFLAG_ONLY_STATS) {
1488 error_msg_and_die("-c and -C are mutually exclusive");
1496 daemonized_tracer = 1;
1515 /* fall through to tflag++ */
1523 count_wallclock = 1;
1532 qualify("abbrev=none");
1535 printf("%s -- version %s\n", PACKAGE_NAME, VERSION);
1539 not_failing_only = 1;
1542 acolumn = string_to_uint(optarg);
1544 error_opt_arg(c, optarg);
1550 outfname = strdup(optarg);
1553 i = string_to_uint(optarg);
1555 error_opt_arg(c, optarg);
1559 process_opt_p_list(optarg);
1562 pathtrace_select(optarg);
1565 i = string_to_uint(optarg);
1567 error_opt_arg(c, optarg);
1574 username = strdup(optarg);
1576 #ifdef USE_LIBUNWIND
1578 stack_trace_enabled = true;
1582 if (putenv(optarg) < 0)
1583 die_out_of_memory();
1586 opt_intr = string_to_uint(optarg);
1587 if (opt_intr <= 0 || opt_intr >= NUM_INTR_OPTS)
1588 error_opt_arg(c, optarg);
1596 /* argc -= optind; - no need, argc is not used below */
1598 acolumn_spaces = malloc(acolumn + 1);
1599 if (!acolumn_spaces)
1600 die_out_of_memory();
1601 memset(acolumn_spaces, ' ', acolumn);
1602 acolumn_spaces[acolumn] = '\0';
1604 /* Must have PROG [ARGS], or -p PID. Not both. */
1605 if (!argv[0] == !nprocs)
1608 if (nprocs != 0 && daemonized_tracer) {
1609 error_msg_and_die("-D and -p are mutually exclusive");
1615 if (followfork >= 2 && cflag) {
1616 error_msg_and_die("(-c or -C) and -ff are mutually exclusive");
1619 if (count_wallclock && !cflag) {
1620 error_msg_and_die("-w must be given with (-c or -C)");
1623 if (cflag == CFLAG_ONLY_STATS) {
1625 error_msg("-%c has no effect with -c", 'i');
1626 #ifdef USE_LIBUNWIND
1627 if (stack_trace_enabled)
1628 error_msg("-%c has no effect with -c", 'k');
1631 error_msg("-%c has no effect with -c", 'r');
1633 error_msg("-%c has no effect with -c", 't');
1635 error_msg("-%c has no effect with -c", 'T');
1637 error_msg("-%c has no effect with -c", 'y');
1640 #ifdef USE_LIBUNWIND
1641 if (stack_trace_enabled)
1645 /* See if they want to run as another user. */
1646 if (username != NULL) {
1647 struct passwd *pent;
1649 if (getuid() != 0 || geteuid() != 0) {
1650 error_msg_and_die("You must be root to use the -u option");
1652 pent = getpwnam(username);
1654 error_msg_and_die("Cannot find user '%s'", username);
1656 run_uid = pent->pw_uid;
1657 run_gid = pent->pw_gid;
1665 ptrace_setoptions |= PTRACE_O_TRACECLONE |
1666 PTRACE_O_TRACEFORK |
1667 PTRACE_O_TRACEVFORK;
1669 fprintf(stderr, "ptrace_setoptions = %#x\n", ptrace_setoptions);
1670 test_ptrace_seize();
1672 /* Check if they want to redirect the output. */
1674 /* See if they want to pipe the output. */
1675 if (outfname[0] == '|' || outfname[0] == '!') {
1677 * We can't do the <outfname>.PID funny business
1678 * when using popen, so prohibit it.
1680 if (followfork >= 2)
1681 error_msg_and_die("Piping the output and -ff are mutually exclusive");
1682 shared_log = strace_popen(outfname + 1);
1684 else if (followfork < 2)
1685 shared_log = strace_fopen(outfname);
1687 /* -ff without -o FILE is the same as single -f */
1688 if (followfork >= 2)
1692 if (!outfname || outfname[0] == '|' || outfname[0] == '!') {
1693 char *buf = malloc(BUFSIZ);
1695 die_out_of_memory();
1696 setvbuf(shared_log, buf, _IOLBF, BUFSIZ);
1698 if (outfname && argv[0]) {
1700 opt_intr = INTR_NEVER;
1704 opt_intr = INTR_WHILE_WAIT;
1706 /* argv[0] -pPID -oFILE Default interactive setting
1707 * yes 0 0 INTR_WHILE_WAIT
1708 * no 1 0 INTR_WHILE_WAIT
1709 * yes 0 1 INTR_NEVER
1710 * no 1 1 INTR_WHILE_WAIT
1713 sigemptyset(&empty_set);
1714 sigemptyset(&blocked_set);
1716 /* startup_child() must be called before the signal handlers get
1717 * installed below as they are inherited into the spawned process.
1718 * Also we do not need to be protected by them as during interruption
1719 * in the startup_child() mode we kill the spawned process anyway.
1722 if (!NOMMU_SYSTEM || daemonized_tracer)
1723 hide_log_until_execve = 1;
1724 skip_one_b_execve = 1;
1725 startup_child(argv);
1728 sa.sa_handler = SIG_IGN;
1729 sigemptyset(&sa.sa_mask);
1731 sigaction(SIGTTOU, &sa, NULL); /* SIG_IGN */
1732 sigaction(SIGTTIN, &sa, NULL); /* SIG_IGN */
1733 if (opt_intr != INTR_ANYWHERE) {
1734 if (opt_intr == INTR_BLOCK_TSTP_TOO)
1735 sigaction(SIGTSTP, &sa, NULL); /* SIG_IGN */
1737 * In interactive mode (if no -o OUTFILE, or -p PID is used),
1738 * fatal signals are blocked while syscall stop is processed,
1739 * and acted on in between, when waiting for new syscall stops.
1740 * In non-interactive mode, signals are ignored.
1742 if (opt_intr == INTR_WHILE_WAIT) {
1743 sigaddset(&blocked_set, SIGHUP);
1744 sigaddset(&blocked_set, SIGINT);
1745 sigaddset(&blocked_set, SIGQUIT);
1746 sigaddset(&blocked_set, SIGPIPE);
1747 sigaddset(&blocked_set, SIGTERM);
1748 sa.sa_handler = interrupt;
1750 /* SIG_IGN, or set handler for these */
1751 sigaction(SIGHUP, &sa, NULL);
1752 sigaction(SIGINT, &sa, NULL);
1753 sigaction(SIGQUIT, &sa, NULL);
1754 sigaction(SIGPIPE, &sa, NULL);
1755 sigaction(SIGTERM, &sa, NULL);
1757 if (nprocs != 0 || daemonized_tracer)
1760 /* Do we want pids printed in our -o OUTFILE?
1761 * -ff: no (every pid has its own file); or
1762 * -f: yes (there can be more pids in the future); or
1763 * -p PID1,PID2: yes (there are already more than one pid)
1765 print_pid_pfx = (outfname && followfork < 2 && (followfork == 1 || nprocs > 1));
1776 for (i = 0; i < tcbtabsize; i++) {
1777 struct tcb *tcp = tcbtab[i];
1778 if (tcp->pid == pid)
1792 /* 'interrupted' is a volatile object, fetch it only once */
1793 fatal_sig = interrupted;
1795 fatal_sig = SIGTERM;
1797 for (i = 0; i < tcbtabsize; i++) {
1803 "cleanup: looking at pid %u\n", tcp->pid);
1804 if (tcp->pid == strace_child) {
1805 kill(tcp->pid, SIGCONT);
1806 kill(tcp->pid, fatal_sig);
1811 call_summary(shared_log);
1821 print_debug_info(const int pid, int status)
1823 const unsigned int event = (unsigned int) status >> 16;
1824 char buf[sizeof("WIFEXITED,exitcode=%u") + sizeof(int)*3 /*paranoia:*/ + 16];
1825 char evbuf[sizeof(",EVENT_VFORK_DONE (%u)") + sizeof(int)*3 /*paranoia:*/ + 16];
1828 if (WIFSIGNALED(status))
1830 sprintf(buf, "WIFSIGNALED,%ssig=%s",
1831 WCOREDUMP(status) ? "core," : "",
1832 signame(WTERMSIG(status)));
1834 sprintf(buf, "WIFSIGNALED,sig=%s",
1835 signame(WTERMSIG(status)));
1837 if (WIFEXITED(status))
1838 sprintf(buf, "WIFEXITED,exitcode=%u", WEXITSTATUS(status));
1839 if (WIFSTOPPED(status))
1840 sprintf(buf, "WIFSTOPPED,sig=%s", signame(WSTOPSIG(status)));
1842 /* Should never be seen */
1843 if (WIFCONTINUED(status))
1844 strcpy(buf, "WIFCONTINUED");
1848 static const char *const event_names[] = {
1849 [PTRACE_EVENT_CLONE] = "CLONE",
1850 [PTRACE_EVENT_FORK] = "FORK",
1851 [PTRACE_EVENT_VFORK] = "VFORK",
1852 [PTRACE_EVENT_VFORK_DONE] = "VFORK_DONE",
1853 [PTRACE_EVENT_EXEC] = "EXEC",
1854 [PTRACE_EVENT_EXIT] = "EXIT",
1855 /* [PTRACE_EVENT_STOP (=128)] would make biggish array */
1857 const char *e = "??";
1858 if (event < ARRAY_SIZE(event_names))
1859 e = event_names[event];
1860 else if (event == PTRACE_EVENT_STOP)
1862 sprintf(evbuf, ",EVENT_%s (%u)", e, event);
1864 fprintf(stderr, " [wait(0x%06x) = %u] %s%s\n", status, pid, buf, evbuf);
1868 maybe_allocate_tcb(const int pid, int status)
1870 if (!WIFSTOPPED(status)) {
1871 if (detach_on_execve && pid == strace_child) {
1872 /* example: strace -bexecve sh -c 'exec true' */
1877 * This can happen if we inherited an unknown child.
1878 * Example: (sleep 1 & exec strace true)
1880 error_msg("Exit of unknown pid %u ignored", pid);
1884 /* We assume it's a fork/vfork/clone child */
1885 struct tcb *tcp = alloctcb(pid);
1886 tcp->flags |= TCB_ATTACHED | TCB_STARTUP | post_attach_sigstop;
1889 fprintf(stderr, "Process %d attached\n", pid);
1892 /* This can happen if a clone call used
1893 * CLONE_PTRACE itself.
1895 ptrace(PTRACE_CONT, pid, (char *) 0, 0);
1896 error_msg("Stop of unknown pid %u seen, PTRACE_CONTed it", pid);
1902 maybe_switch_tcbs(struct tcb *tcp, const int pid)
1905 struct tcb *execve_thread;
1908 if (ptrace(PTRACE_GETEVENTMSG, pid, NULL, (long) &old_pid) < 0)
1910 /* Avoid truncation in pid2tcb() param passing */
1911 if (old_pid <= 0 || old_pid == pid)
1913 if ((unsigned long) old_pid > UINT_MAX)
1915 execve_thread = pid2tcb(old_pid);
1916 /* It should be !NULL, but I feel paranoid */
1920 if (execve_thread->curcol != 0) {
1922 * One case we are here is -ff:
1923 * try "strace -oLOG -ff test/threaded_execve"
1925 fprintf(execve_thread->outf, " <pid changed to %d ...>\n", pid);
1926 /*execve_thread->curcol = 0; - no need, see code below */
1928 /* Swap output FILEs (needed for -ff) */
1929 fp = execve_thread->outf;
1930 execve_thread->outf = tcp->outf;
1932 /* And their column positions */
1933 execve_thread->curcol = tcp->curcol;
1935 /* Drop leader, but close execve'd thread outfile (if -ff) */
1937 /* Switch to the thread, reusing leader's outfile and pid */
1938 tcp = execve_thread;
1940 if (cflag != CFLAG_ONLY_STATS) {
1942 tprintf("+++ superseded by execve in pid %lu +++\n", old_pid);
1944 tcp->flags |= TCB_REPRINT;
1951 print_signalled(struct tcb *tcp, const int pid, int status)
1953 if (pid == strace_child) {
1954 exit_code = 0x100 | WTERMSIG(status);
1958 if (cflag != CFLAG_ONLY_STATS
1959 && (qual_flags[WTERMSIG(status)] & QUAL_SIGNAL)
1963 tprintf("+++ killed by %s %s+++\n",
1964 signame(WTERMSIG(status)),
1965 WCOREDUMP(status) ? "(core dumped) " : "");
1967 tprintf("+++ killed by %s +++\n",
1968 signame(WTERMSIG(status)));
1975 print_exited(struct tcb *tcp, const int pid, int status)
1977 if (pid == strace_child) {
1978 exit_code = WEXITSTATUS(status);
1982 if (cflag != CFLAG_ONLY_STATS &&
1985 tprintf("+++ exited with %d +++\n", WEXITSTATUS(status));
1991 print_stopped(struct tcb *tcp, const siginfo_t *si, const unsigned int sig)
1993 if (cflag != CFLAG_ONLY_STATS
1994 && !hide_log_until_execve
1995 && (qual_flags[sig] & QUAL_SIGNAL)
1999 tprintf("--- %s ", signame(sig));
2000 printsiginfo(si, verbose(tcp));
2003 tprintf("--- stopped by %s ---\n", signame(sig));
2009 startup_tcb(struct tcb *tcp)
2012 fprintf(stderr, "pid %d has TCB_STARTUP, initializing it\n",
2015 tcp->flags &= ~TCB_STARTUP;
2019 fprintf(stderr, "setting opts 0x%x on pid %d\n",
2020 ptrace_setoptions, tcp->pid);
2021 if (ptrace(PTRACE_SETOPTIONS, tcp->pid, NULL, ptrace_setoptions) < 0) {
2022 if (errno != ESRCH) {
2023 /* Should never happen, really */
2024 perror_msg_and_die("PTRACE_SETOPTIONS");
2032 /* Returns true iff the main trace loop has to continue. */
2048 if (popen_pid != 0 && nprocs == 0)
2052 sigprocmask(SIG_SETMASK, &empty_set, NULL);
2053 pid = wait4(-1, &status, __WALL, (cflag ? &ru : NULL));
2056 sigprocmask(SIG_BLOCK, &blocked_set, NULL);
2059 if (wait_errno == EINTR)
2061 if (nprocs == 0 && wait_errno == ECHILD)
2064 * If nprocs > 0, ECHILD is not expected,
2065 * treat it as any other error here:
2068 perror_msg_and_die("wait4(__WALL)");
2071 if (pid == popen_pid) {
2072 if (!WIFSTOPPED(status))
2078 print_debug_info(pid, status);
2080 /* Look up 'pid' in our table. */
2084 tcp = maybe_allocate_tcb(pid, status);
2089 if (WIFSTOPPED(status))
2094 event = (unsigned int) status >> 16;
2096 if (event == PTRACE_EVENT_EXEC) {
2098 * Under Linux, execve changes pid to thread leader's pid,
2099 * and we see this changed pid on EVENT_EXEC and later,
2100 * execve sysexit. Leader "disappears" without exit
2101 * notification. Let user know that, drop leader's tcb,
2102 * and fix up pid in execve thread's tcb.
2103 * Effectively, execve thread's tcb replaces leader's tcb.
2105 * BTW, leader is 'stuck undead' (doesn't report WIFEXITED
2106 * on exit syscall) in multithreaded programs exactly
2107 * in order to handle this case.
2109 * PTRACE_GETEVENTMSG returns old pid starting from Linux 3.0.
2110 * On 2.6 and earlier, it can return garbage.
2112 if (os_release >= KERNEL_VERSION(3,0,0))
2113 tcp = maybe_switch_tcbs(tcp, pid);
2115 if (detach_on_execve && !skip_one_b_execve) {
2116 detach(tcp); /* do "-b execve" thingy */
2119 skip_one_b_execve = 0;
2122 /* Set current output file */
2126 tv_sub(&tcp->dtime, &ru.ru_stime, &tcp->stime);
2127 tcp->stime = ru.ru_stime;
2130 if (WIFSIGNALED(status)) {
2131 print_signalled(tcp, pid, status);
2136 if (WIFEXITED(status)) {
2137 print_exited(tcp, pid, status);
2142 if (!WIFSTOPPED(status)) {
2144 * Neither signalled, exited or stopped.
2145 * How could that be?
2147 error_msg("pid %u not stopped!", pid);
2152 /* Is this the very first time we see this tracee stopped? */
2153 if (tcp->flags & TCB_STARTUP) {
2154 if (!startup_tcb(tcp))
2158 sig = WSTOPSIG(status);
2163 if (event == PTRACE_EVENT_STOP) {
2165 * PTRACE_INTERRUPT-stop or group-stop.
2166 * PTRACE_INTERRUPT-stop has sig == SIGTRAP here.
2178 goto restart_tracee_with_sig_0;
2182 * Is this post-attach SIGSTOP?
2183 * Interestingly, the process may stop
2184 * with STOPSIG equal to some other signal
2185 * than SIGSTOP if we happend to attach
2186 * just before the process takes a signal.
2188 if (sig == SIGSTOP && (tcp->flags & TCB_IGNORE_ONE_SIGSTOP)) {
2190 fprintf(stderr, "ignored SIGSTOP on pid %d\n", tcp->pid);
2191 tcp->flags &= ~TCB_IGNORE_ONE_SIGSTOP;
2192 goto restart_tracee_with_sig_0;
2195 if (sig != syscall_trap_sig) {
2199 * True if tracee is stopped by signal
2200 * (as opposed to "tracee received signal").
2201 * TODO: shouldn't we check for errno == EINVAL too?
2202 * We can get ESRCH instead, you know...
2204 stopped = ptrace(PTRACE_GETSIGINFO, pid, 0, (long) &si) < 0;
2208 print_stopped(tcp, stopped ? NULL : &si, sig);
2211 /* It's signal-delivery-stop. Inject the signal */
2212 goto restart_tracee;
2214 /* It's group-stop */
2217 * This ends ptrace-stop, but does *not* end group-stop.
2218 * This makes stopping signals work properly on straced process
2219 * (that is, process really stops. It used to continue to run).
2221 if (ptrace_restart(PTRACE_LISTEN, tcp, 0) < 0) {
2222 /* Note: ptrace_restart emitted error message */
2228 /* We don't have PTRACE_LISTEN support... */
2229 goto restart_tracee;
2232 /* We handled quick cases, we are permitted to interrupt now. */
2237 * This should be syscall entry or exit.
2240 if (trace_syscall(tcp) < 0) {
2242 * ptrace() failed in trace_syscall().
2243 * Likely a result of process disappearing mid-flight.
2244 * Observed case: exit_group() or SIGKILL terminating
2245 * all processes in thread group.
2246 * We assume that ptrace error was caused by process death.
2247 * We used to detach(tcp) here, but since we no longer
2248 * implement "detach before death" policy/hack,
2249 * we can let this process to report its death to us
2250 * normally, via WIFEXITED or WIFSIGNALED wait status.
2255 restart_tracee_with_sig_0:
2259 if (ptrace_restart(PTRACE_SYSCALL, tcp, sig) < 0) {
2260 /* Note: ptrace_restart emitted error message */
2269 main(int argc, char *argv[])
2274 * Run main tracing loop.
2276 * Used to be "while (nprocs != 0)", but in this testcase:
2277 * int main() { _exit(!!fork()); }
2278 * under strace -f, parent sometimes (rarely) manages
2279 * to exit before we see the first stop of the child,
2280 * and we are losing track of it:
2281 * 19923 clone(...) = 19924
2282 * 19923 exit_group(1) = ?
2283 * 19923 +++ exited with 1 +++
2284 * Waiting for ECHILD works better.
2285 * (However, if -o|logger is in use, we can't do that.
2286 * Can work around that by double-forking the logger,
2287 * but that loses the ability to wait for its completion on exit.
2295 if (shared_log != stderr)
2298 while (waitpid(popen_pid, NULL, 0) < 0 && errno == EINTR)
2301 if (exit_code > 0xff) {
2302 /* Avoid potential core file clobbering. */
2303 struct_rlimit rlim = {0, 0};
2304 set_rlimit(RLIMIT_CORE, &rlim);
2306 /* Child was killed by a signal, mimic that. */
2308 signal(exit_code, SIG_DFL);
2310 /* Paranoia - what if this signal is not fatal?
2311 Exit with 128 + signo then. */