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>
36 #include <sys/resource.h>
42 #include <sys/utsname.h>
44 # include <sys/prctl.h>
48 #include "printsiginfo.h"
50 /* In some libc, these aren't declared. Do it ourself: */
51 extern char **environ;
56 /* if this is true do the stack trace for every system call */
57 bool stack_trace_enabled = false;
60 #if defined __NR_tkill
61 # define my_tkill(tid, sig) syscall(__NR_tkill, (tid), (sig))
63 /* kill() may choose arbitrarily the target task of the process group
64 while we later wait on a that specific TID. PID process waits become
65 TID task specific waits for a process under ptrace(2). */
66 # warning "tkill(2) not available, risk of strace hangs!"
67 # define my_tkill(tid, sig) kill((tid), (sig))
70 /* Glue for systems without a MMU that cannot provide fork() */
71 #if !defined(HAVE_FORK)
73 # define NOMMU_SYSTEM 1
76 # define fork() vfork()
79 const unsigned int syscall_trap_sig = SIGTRAP | 0x80;
81 cflag_t cflag = CFLAG_NONE;
82 unsigned int followfork = 0;
83 unsigned int ptrace_setoptions = PTRACE_O_TRACESYSGOOD | PTRACE_O_TRACEEXEC;
84 unsigned int xflag = 0;
88 bool count_wallclock = 0;
89 unsigned int qflag = 0;
90 static unsigned int tflag = 0;
91 static bool rflag = 0;
92 static bool print_pid_pfx = 0;
97 INTR_ANYWHERE = 1, /* don't block/ignore any signals */
98 INTR_WHILE_WAIT = 2, /* block fatal signals while decoding syscall. default */
99 INTR_NEVER = 3, /* block fatal signals. default if '-o FILE PROG' */
100 INTR_BLOCK_TSTP_TOO = 4, /* block fatal signals and SIGTSTP (^Z) */
104 /* We play with signal mask only if this mode is active: */
105 #define interactive (opt_intr == INTR_WHILE_WAIT)
108 * daemonized_tracer supports -D option.
109 * With this option, strace forks twice.
110 * Unlike normal case, with -D *grandparent* process exec's,
111 * becoming a traced process. Child exits (this prevents traced process
112 * from having children it doesn't expect to have), and grandchild
113 * attaches to grandparent similarly to strace -p PID.
114 * This allows for more transparent interaction in cases
115 * when process and its parent are communicating via signals,
116 * wait() etc. Without -D, strace process gets lodged in between,
117 * disrupting parent<->child link.
119 static bool daemonized_tracer = 0;
122 static int post_attach_sigstop = TCB_IGNORE_ONE_SIGSTOP;
123 # define use_seize (post_attach_sigstop == 0)
125 # define post_attach_sigstop TCB_IGNORE_ONE_SIGSTOP
129 /* Sometimes we want to print only succeeding syscalls. */
130 bool not_failing_only = 0;
132 /* Show path associated with fd arguments */
133 unsigned int show_fd_path = 0;
135 static bool detach_on_execve = 0;
136 /* Are we "strace PROG" and need to skip detach on first execve? */
137 static bool skip_one_b_execve = 0;
138 /* Are we "strace PROG" and need to hide everything until execve? */
139 bool hide_log_until_execve = 0;
141 static int exit_code = 0;
142 static int strace_child = 0;
143 static int strace_tracer_pid = 0;
145 static char *username = NULL;
146 static uid_t run_uid;
147 static gid_t run_gid;
149 unsigned int max_strlen = DEFAULT_STRLEN;
150 static int acolumn = DEFAULT_ACOLUMN;
151 static char *acolumn_spaces;
153 static char *outfname = NULL;
154 /* If -ff, points to stderr. Else, it's our common output log */
155 static FILE *shared_log;
157 struct tcb *printing_tcp = NULL;
158 static struct tcb *current_tcp;
160 static struct tcb **tcbtab;
161 static unsigned int nprocs, tcbtabsize;
162 static const char *progname;
164 unsigned os_release; /* generated from uname()'s u.release */
166 static void detach(struct tcb *tcp);
167 static void cleanup(void);
168 static void interrupt(int sig);
169 static sigset_t empty_set, blocked_set;
171 #ifdef HAVE_SIG_ATOMIC_T
172 static volatile sig_atomic_t interrupted;
174 static volatile int interrupted;
177 #ifndef HAVE_STRERROR
179 #if !HAVE_DECL_SYS_ERRLIST
181 extern char *sys_errlist[];
187 static char buf[sizeof("Unknown error %d") + sizeof(int)*3];
189 if (err_no < 1 || err_no >= sys_nerr) {
190 sprintf(buf, "Unknown error %d", err_no);
193 return sys_errlist[err_no];
196 #endif /* HAVE_STERRROR */
199 usage(FILE *ofp, int exitval)
202 usage: strace [-CdffhiqrtttTvVxxy] [-I n] [-e expr]...\n\
203 [-a column] [-o file] [-s strsize] [-P path]...\n\
204 -p pid... / [-D] [-E var=val]... [-u username] PROG [ARGS]\n\
205 or: strace -c[df] [-I n] [-e expr]... [-O overhead] [-S sortby]\n\
206 -p pid... / [-D] [-E var=val]... [-u username] PROG [ARGS]\n\
207 -c -- count time, calls, and errors for each syscall and report summary\n\
208 -C -- like -c but also print regular output\n\
209 -w -- summarise syscall latency (default is system time)\n\
210 -d -- enable debug output to stderr\n\
211 -D -- run tracer process as a detached grandchild, not as parent\n\
212 -f -- follow forks, -ff -- with output into separate files\n\
213 -i -- print instruction pointer at time of syscall\n\
214 -q -- suppress messages about attaching, detaching, etc.\n\
215 -r -- print relative timestamp, -t -- absolute timestamp, -tt -- with usecs\n\
216 -T -- print time spent in each syscall\n\
217 -v -- verbose mode: print unabbreviated argv, stat, termios, etc. args\n\
218 -x -- print non-ascii strings in hex, -xx -- print all strings in hex\n\
219 -y -- print paths associated with file descriptor arguments\n\
220 -yy -- print ip:port pairs associated with socket file descriptors\n\
221 -h -- print help message, -V -- print version\n\
222 -a column -- alignment COLUMN for printing syscall results (default %d)\n\
223 -b execve -- detach on this syscall\n\
224 -e expr -- a qualifying expression: option=[!]all or option=[!]val1[,val2]...\n\
225 options: trace, abbrev, verbose, raw, signal, read, write\n\
226 -I interruptible --\n\
227 1: no signals are blocked\n\
228 2: fatal signals are blocked while decoding syscall (default)\n\
229 3: fatal signals are always blocked (default if '-o FILE PROG')\n\
230 4: fatal signals and SIGTSTP (^Z) are always blocked\n\
231 (useful to make 'strace -o FILE PROG' not stop on ^Z)\n\
232 -o file -- send trace output to FILE instead of stderr\n\
233 -O overhead -- set overhead for tracing syscalls to OVERHEAD usecs\n\
234 -p pid -- trace process with process id PID, may be repeated\n\
235 -s strsize -- limit length of print strings to STRSIZE chars (default %d)\n\
236 -S sortby -- sort syscall counts by: time, calls, name, nothing (default %s)\n\
237 -u username -- run command as username handling setuid and/or setgid\n\
238 -E var=val -- put var=val in the environment for command\n\
239 -E var -- remove var from the environment for command\n\
240 -P path -- trace accesses to path\n\
243 "-k obtain stack trace between each syscall (experimental)\n\
246 /* ancient, no one should use it
247 -F -- attempt to follow vforks (deprecated, use -f)\n\
249 /* this is broken, so don't document it
250 -z -- print only succeeding syscalls\n\
252 , DEFAULT_ACOLUMN, DEFAULT_STRLEN, DEFAULT_SORTBY);
256 static void ATTRIBUTE_NORETURN
259 if (strace_tracer_pid == getpid()) {
266 static void verror_msg(int err_no, const char *fmt, va_list p)
272 /* We want to print entire message with single fprintf to ensure
273 * message integrity if stderr is shared with other programs.
274 * Thus we use vasprintf + single fprintf.
277 if (vasprintf(&msg, fmt, p) >= 0) {
279 fprintf(stderr, "%s: %s: %s\n", progname, msg, strerror(err_no));
281 fprintf(stderr, "%s: %s\n", progname, msg);
284 /* malloc in vasprintf failed, try it without malloc */
285 fprintf(stderr, "%s: ", progname);
286 vfprintf(stderr, fmt, p);
288 fprintf(stderr, ": %s\n", strerror(err_no));
292 /* We don't switch stderr to buffered, thus fprintf(stderr)
293 * always flushes its output and this is not necessary: */
294 /* fflush(stderr); */
297 void error_msg(const char *fmt, ...)
301 verror_msg(0, fmt, p);
305 void error_msg_and_die(const char *fmt, ...)
309 verror_msg(0, fmt, p);
313 void perror_msg(const char *fmt, ...)
317 verror_msg(errno, fmt, p);
321 void perror_msg_and_die(const char *fmt, ...)
325 verror_msg(errno, fmt, p);
330 error_opt_arg(int opt, const char *arg)
332 error_msg_and_die("Invalid -%c argument: '%s'", opt, arg);
337 ptrace_attach_or_seize(int pid)
341 return ptrace(PTRACE_ATTACH, pid, 0L, 0L);
342 r = ptrace(PTRACE_SEIZE, pid, 0L, (unsigned long) ptrace_setoptions);
345 r = ptrace(PTRACE_INTERRUPT, pid, 0L, 0L);
349 # define ptrace_attach_or_seize(pid) ptrace(PTRACE_ATTACH, (pid), 0, 0)
353 * Used when we want to unblock stopped traced process.
354 * Should be only used with PTRACE_CONT, PTRACE_DETACH and PTRACE_SYSCALL.
355 * Returns 0 on success or if error was ESRCH
356 * (presumably process was killed while we talk to it).
357 * Otherwise prints error message and returns -1.
360 ptrace_restart(int op, struct tcb *tcp, int sig)
366 ptrace(op, tcp->pid, (void *) 0, (long) sig);
372 if (op == PTRACE_CONT)
374 if (op == PTRACE_DETACH)
377 if (op == PTRACE_LISTEN)
381 * Why curcol != 0? Otherwise sometimes we get this:
383 * 10252 kill(10253, SIGKILL) = 0
384 * <ptrace(SYSCALL,10252):No such process>10253 ...next decode...
386 * 10252 died after we retrieved syscall exit data,
387 * but before we tried to restart it. Log looks ugly.
389 if (current_tcp && current_tcp->curcol != 0) {
390 tprintf(" <ptrace(%s):%s>\n", msg, strerror(err));
396 perror_msg("ptrace(PTRACE_%s,pid:%d,sig:%d)", msg, tcp->pid, sig);
401 set_cloexec_flag(int fd)
405 flags = fcntl(fd, F_GETFD);
407 /* Can happen only if fd is bad.
408 * Should never happen: if it does, we have a bug
409 * in the caller. Therefore we just abort
410 * instead of propagating the error.
412 perror_msg_and_die("fcntl(%d, F_GETFD)", fd);
415 newflags = flags | FD_CLOEXEC;
416 if (flags == newflags)
419 fcntl(fd, F_SETFD, newflags); /* never fails */
422 static void kill_save_errno(pid_t pid, int sig)
424 int saved_errno = errno;
426 (void) kill(pid, sig);
431 * When strace is setuid executable, we have to swap uids
432 * before and after filesystem and process management operations.
437 int euid = geteuid(), uid = getuid();
439 if (euid != uid && setreuid(euid, uid) < 0) {
440 perror_msg_and_die("setreuid");
444 #ifdef _LARGEFILE64_SOURCE
446 # define fopen_for_output fopen64
448 # define fopen_for_output fopen
450 # define struct_stat struct stat64
451 # define stat_file stat64
452 # define struct_dirent struct dirent64
453 # define read_dir readdir64
454 # define struct_rlimit struct rlimit64
455 # define set_rlimit setrlimit64
457 # define fopen_for_output fopen
458 # define struct_stat struct stat
459 # define stat_file stat
460 # define struct_dirent struct dirent
461 # define read_dir readdir
462 # define struct_rlimit struct rlimit
463 # define set_rlimit setrlimit
467 strace_fopen(const char *path)
472 fp = fopen_for_output(path, "w");
474 perror_msg_and_die("Can't fopen '%s'", path);
476 set_cloexec_flag(fileno(fp));
480 static int popen_pid = 0;
483 # define _PATH_BSHELL "/bin/sh"
487 * We cannot use standard popen(3) here because we have to distinguish
488 * popen child process from other processes we trace, and standard popen(3)
489 * does not export its child's pid.
492 strace_popen(const char *command)
500 perror_msg_and_die("pipe");
502 set_cloexec_flag(fds[1]); /* never fails */
506 perror_msg_and_die("vfork");
513 perror_msg_and_die("dup2");
516 execl(_PATH_BSHELL, "sh", "-c", command, NULL);
517 perror_msg_and_die("Can't execute '%s'", _PATH_BSHELL);
524 fp = fdopen(fds[1], "w");
531 tprintf(const char *fmt, ...)
537 int n = strace_vfprintf(current_tcp->outf, fmt, args);
539 if (current_tcp->outf != stderr)
540 perror_msg("%s", outfname);
542 current_tcp->curcol += n;
547 #ifndef HAVE_FPUTS_UNLOCKED
548 # define fputs_unlocked fputs
552 tprints(const char *str)
555 int n = fputs_unlocked(str, current_tcp->outf);
557 current_tcp->curcol += strlen(str);
560 if (current_tcp->outf != stderr)
561 perror_msg("%s", outfname);
569 current_tcp->curcol = 0;
570 fflush(current_tcp->outf);
573 printing_tcp->curcol = 0;
579 printleader(struct tcb *tcp)
581 /* If -ff, "previous tcb we printed" is always the same as current,
582 * because we have per-tcb output files.
588 current_tcp = printing_tcp;
589 if (printing_tcp->curcol != 0 && (followfork < 2 || printing_tcp == tcp)) {
591 * case 1: we have a shared log (i.e. not -ff), and last line
592 * wasn't finished (same or different tcb, doesn't matter).
593 * case 2: split log, we are the same tcb, but our last line
594 * didn't finish ("SIGKILL nuked us after syscall entry" etc).
596 tprints(" <unfinished ...>\n");
597 printing_tcp->curcol = 0;
603 current_tcp->curcol = 0;
606 tprintf("%-5d ", tcp->pid);
607 else if (nprocs > 1 && !outfname)
608 tprintf("[pid %5u] ", tcp->pid);
611 char str[sizeof("HH:MM:SS")];
612 struct timeval tv, dtv;
613 static struct timeval otv;
615 gettimeofday(&tv, NULL);
619 tv_sub(&dtv, &tv, &otv);
620 tprintf("%6ld.%06ld ",
621 (long) dtv.tv_sec, (long) dtv.tv_usec);
624 else if (tflag > 2) {
625 tprintf("%ld.%06ld ",
626 (long) tv.tv_sec, (long) tv.tv_usec);
629 time_t local = tv.tv_sec;
630 strftime(str, sizeof(str), "%T", localtime(&local));
632 tprintf("%s.%06ld ", str, (long) tv.tv_usec);
644 if (current_tcp->curcol < acolumn)
645 tprints(acolumn_spaces + current_tcp->curcol);
648 /* Should be only called directly *after successful attach* to a tracee.
649 * Otherwise, "strace -oFILE -ff -p<nonexistant_pid>"
650 * may create bogus empty FILE.<nonexistant_pid>, and then die.
653 newoutf(struct tcb *tcp)
655 tcp->outf = shared_log; /* if not -ff mode, the same file is for all */
656 if (followfork >= 2) {
657 char name[520 + sizeof(int) * 3];
658 sprintf(name, "%.512s.%u", outfname, tcp->pid);
659 tcp->outf = strace_fopen(name);
666 /* Allocate some more TCBs and expand the table.
667 We don't want to relocate the TCBs because our
668 callers have pointers and it would be a pain.
669 So tcbtab is a table of pointers. Since we never
670 free the TCBs, we allocate a single chunk of many. */
671 unsigned int i = tcbtabsize;
672 struct tcb *newtcbs = xcalloc(tcbtabsize, sizeof(newtcbs[0]));
673 struct tcb **newtab = xreallocarray(tcbtab, tcbtabsize * 2,
677 while (i < tcbtabsize)
678 tcbtab[i++] = newtcbs++;
687 if (nprocs == tcbtabsize)
690 for (i = 0; i < tcbtabsize; i++) {
693 memset(tcp, 0, sizeof(*tcp));
695 #if SUPPORTED_PERSONALITIES > 1
696 tcp->currpers = current_personality;
700 if (stack_trace_enabled)
701 unwind_tcb_init(tcp);
706 error_msg("new tcb for pid %d, active tcbs:%d",
711 error_msg_and_die("bug in alloctcb");
715 droptcb(struct tcb *tcp)
721 if (stack_trace_enabled) {
728 error_msg("dropped tcb for pid %d, %d remain",
732 if (followfork >= 2) {
733 if (tcp->curcol != 0)
734 fprintf(tcp->outf, " <detached ...>\n");
737 if (printing_tcp == tcp && tcp->curcol != 0)
738 fprintf(tcp->outf, " <detached ...>\n");
743 if (current_tcp == tcp)
745 if (printing_tcp == tcp)
748 memset(tcp, 0, sizeof(*tcp));
751 /* Detach traced process.
752 * Never call DETACH twice on the same process as both unattached and
753 * attached-unstopped processes give the same ESRCH. For unattached process we
754 * would SIGSTOP it and wait for its SIGSTOP notification forever.
757 detach(struct tcb *tcp)
763 * Linux wrongly insists the child be stopped
764 * before detaching. Arghh. We go through hoops
765 * to make a clean break of things.
768 # undef PTRACE_DETACH
769 # define PTRACE_DETACH PTRACE_SUNDETACH
772 if (!(tcp->flags & TCB_ATTACHED))
775 /* We attached but possibly didn't see the expected SIGSTOP.
776 * We must catch exactly one as otherwise the detached process
777 * would be left stopped (process state T).
779 if (tcp->flags & TCB_IGNORE_ONE_SIGSTOP)
782 error = ptrace(PTRACE_DETACH, tcp->pid, 0, 0);
784 /* On a clear day, you can see forever. */
787 if (errno != ESRCH) {
788 /* Shouldn't happen. */
789 perror_msg("detach: ptrace(PTRACE_DETACH,%u)", tcp->pid);
792 /* ESRCH: process is either not stopped or doesn't exist. */
793 if (my_tkill(tcp->pid, 0) < 0) {
795 /* Shouldn't happen. */
796 perror_msg("detach: tkill(%u,0)", tcp->pid);
797 /* else: process doesn't exist. */
800 /* Process is not stopped, need to stop it. */
803 * With SEIZE, tracee can be in group-stop already.
804 * In this state sending it another SIGSTOP does nothing.
805 * Need to use INTERRUPT.
806 * Testcase: trying to ^C a "strace -p <stopped_process>".
808 error = ptrace(PTRACE_INTERRUPT, tcp->pid, 0, 0);
812 perror_msg("detach: ptrace(PTRACE_INTERRUPT,%u)", tcp->pid);
815 error = my_tkill(tcp->pid, SIGSTOP);
819 perror_msg("detach: tkill(%u,SIGSTOP)", tcp->pid);
821 /* Either process doesn't exist, or some weird error. */
825 /* We end up here in three cases:
826 * 1. We sent PTRACE_INTERRUPT (use_seize case)
827 * 2. We sent SIGSTOP (!use_seize)
828 * 3. Attach SIGSTOP was already pending (TCB_IGNORE_ONE_SIGSTOP set)
832 if (waitpid(tcp->pid, &status, __WALL) < 0) {
836 * if (errno == ECHILD) break;
837 * ^^^ WRONG! We expect this PID to exist,
838 * and want to emit a message otherwise:
840 perror_msg("detach: waitpid(%u)", tcp->pid);
843 if (!WIFSTOPPED(status)) {
845 * Tracee exited or was killed by signal.
846 * We shouldn't normally reach this place:
847 * we don't want to consume exit status.
848 * Consider "strace -p PID" being ^C-ed:
849 * we want merely to detach from PID.
851 * However, we _can_ end up here if tracee
856 sig = WSTOPSIG(status);
858 error_msg("detach wait: event:%d sig:%d",
859 (unsigned)status >> 16, sig);
861 unsigned event = (unsigned)status >> 16;
862 if (event == PTRACE_EVENT_STOP /*&& sig == SIGTRAP*/) {
864 * sig == SIGTRAP: PTRACE_INTERRUPT stop.
865 * sig == other: process was already stopped
866 * with this stopping sig (see tests/detach-stopped).
867 * Looks like re-injecting this sig is not necessary
868 * in DETACH for the tracee to remain stopped.
873 * PTRACE_INTERRUPT is not guaranteed to produce
874 * the above event if other ptrace-stop is pending.
875 * See tests/detach-sleeping testcase:
876 * strace got SIGINT while tracee is sleeping.
877 * We sent PTRACE_INTERRUPT.
878 * We see syscall exit, not PTRACE_INTERRUPT stop.
879 * We won't get PTRACE_INTERRUPT stop
880 * if we would CONT now. Need to DETACH.
882 if (sig == syscall_trap_sig)
884 /* else: not sure in which case we can be here.
885 * Signal stop? Inject it while detaching.
887 ptrace_restart(PTRACE_DETACH, tcp, sig);
890 /* Note: this check has to be after use_seize check */
891 /* (else, in use_seize case SIGSTOP will be mistreated) */
892 if (sig == SIGSTOP) {
893 /* Detach, suppressing SIGSTOP */
894 ptrace_restart(PTRACE_DETACH, tcp, 0);
897 if (sig == syscall_trap_sig)
899 /* Can't detach just yet, may need to wait for SIGSTOP */
900 error = ptrace_restart(PTRACE_CONT, tcp, sig);
902 /* Should not happen.
903 * Note: ptrace_restart returns 0 on ESRCH, so it's not it.
904 * ptrace_restart already emitted error message.
911 if (!qflag && (tcp->flags & TCB_ATTACHED))
912 error_msg("Process %u detached", tcp->pid);
918 process_opt_p_list(char *opt)
922 * We accept -p PID,PID; -p "`pidof PROG`"; -p "`pgrep PROG`".
923 * pidof uses space as delim, pgrep uses newline. :(
926 char *delim = opt + strcspn(opt, ", \n\t");
930 pid = string_to_uint(opt);
932 error_msg_and_die("Invalid process id: '%s'", opt);
934 if (pid == strace_tracer_pid) {
935 error_msg_and_die("I'm sorry, I can't let you do that, Dave.");
952 * Block user interruptions as we would leave the traced
953 * process stopped (process state T) if we would terminate in
954 * between PTRACE_ATTACH and wait4() on SIGSTOP.
955 * We rely on cleanup() from this point on.
958 sigprocmask(SIG_BLOCK, &blocked_set, NULL);
960 if (daemonized_tracer) {
963 perror_msg_and_die("fork");
965 if (pid) { /* parent */
967 * Wait for grandchild to attach to straced process
968 * (grandparent). Grandchild SIGKILLs us after it attached.
969 * Grandparent's wait() is unblocked by our death,
970 * it proceeds to exec the straced program.
973 _exit(0); /* paranoia */
976 /* We will be the tracer process. Remember our new pid: */
977 strace_tracer_pid = getpid();
980 for (tcbi = 0; tcbi < tcbtabsize; tcbi++) {
986 /* Is this a process we should attach to, but not yet attached? */
987 if (tcp->flags & TCB_ATTACHED)
988 continue; /* no, we already attached it */
990 if (followfork && !daemonized_tracer) {
991 char procdir[sizeof("/proc/%d/task") + sizeof(int) * 3];
994 sprintf(procdir, "/proc/%d/task", tcp->pid);
995 dir = opendir(procdir);
997 unsigned int ntid = 0, nerr = 0;
1000 while ((de = read_dir(dir)) != NULL) {
1001 struct tcb *cur_tcp;
1004 if (de->d_fileno == 0)
1006 /* we trust /proc filesystem */
1007 tid = atoi(de->d_name);
1011 if (ptrace_attach_or_seize(tid) < 0) {
1014 error_msg("attach to pid %d failed", tid);
1018 error_msg("attach to pid %d succeeded", tid);
1020 if (tid != tcp->pid)
1021 cur_tcp = alloctcb(tid);
1022 cur_tcp->flags |= TCB_ATTACHED | TCB_STARTUP | post_attach_sigstop;
1027 sigprocmask(SIG_SETMASK, &empty_set, NULL);
1030 sigprocmask(SIG_BLOCK, &blocked_set, NULL);
1034 perror_msg("attach: ptrace(PTRACE_ATTACH, ...)");
1040 ? "Process %u attached with %u threads"
1041 : "Process %u attached",
1044 if (!(tcp->flags & TCB_ATTACHED)) {
1045 /* -p PID, we failed to attach to PID itself
1046 * but did attach to some of its sibling threads.
1052 } /* if (opendir worked) */
1054 if (ptrace_attach_or_seize(tcp->pid) < 0) {
1055 perror_msg("attach: ptrace(PTRACE_ATTACH, ...)");
1059 tcp->flags |= TCB_ATTACHED | TCB_STARTUP | post_attach_sigstop;
1062 error_msg("attach to pid %d (main) succeeded", tcp->pid);
1064 if (daemonized_tracer) {
1066 * Make parent go away.
1067 * Also makes grandparent's wait() unblock.
1069 kill(getppid(), SIGKILL);
1073 error_msg("Process %u attached", tcp->pid);
1074 } /* for each tcbtab[] */
1078 sigprocmask(SIG_SETMASK, &empty_set, NULL);
1081 /* Stack-o-phobic exec helper, in the hope to work around
1082 * NOMMU + "daemonized tracer" difficulty.
1084 struct exec_params {
1091 static struct exec_params params_for_tracee;
1093 static void ATTRIBUTE_NOINLINE ATTRIBUTE_NORETURN
1096 struct exec_params *params = ¶ms_for_tracee;
1098 if (params->fd_to_close >= 0)
1099 close(params->fd_to_close);
1100 if (!daemonized_tracer && !use_seize) {
1101 if (ptrace(PTRACE_TRACEME, 0L, 0L, 0L) < 0) {
1102 perror_msg_and_die("ptrace(PTRACE_TRACEME, ...)");
1106 if (username != NULL) {
1108 * It is important to set groups before we
1109 * lose privileges on setuid.
1111 if (initgroups(username, run_gid) < 0) {
1112 perror_msg_and_die("initgroups");
1114 if (setregid(run_gid, params->run_egid) < 0) {
1115 perror_msg_and_die("setregid");
1117 if (setreuid(run_uid, params->run_euid) < 0) {
1118 perror_msg_and_die("setreuid");
1121 else if (geteuid() != 0)
1122 if (setreuid(run_uid, run_uid) < 0) {
1123 perror_msg_and_die("setreuid");
1126 if (!daemonized_tracer) {
1128 * Induce a ptrace stop. Tracer (our parent)
1129 * will resume us with PTRACE_SYSCALL and display
1130 * the immediately following execve syscall.
1131 * Can't do this on NOMMU systems, we are after
1132 * vfork: parent is blocked, stopping would deadlock.
1135 kill(getpid(), SIGSTOP);
1138 /* we depend on SIGCHLD set to SIG_DFL by init code */
1139 /* if it happens to be SIG_IGN'ed, wait won't block */
1144 execv(params->pathname, params->argv);
1145 perror_msg_and_die("exec");
1149 startup_child(char **argv)
1151 struct_stat statbuf;
1152 const char *filename;
1153 size_t filename_len;
1154 char pathname[PATH_MAX];
1159 filename_len = strlen(filename);
1161 if (filename_len > sizeof(pathname) - 1) {
1162 errno = ENAMETOOLONG;
1163 perror_msg_and_die("exec");
1165 if (strchr(filename, '/')) {
1166 strcpy(pathname, filename);
1168 #ifdef USE_DEBUGGING_EXEC
1170 * Debuggers customarily check the current directory
1171 * first regardless of the path but doing that gives
1172 * security geeks a panic attack.
1174 else if (stat_file(filename, &statbuf) == 0)
1175 strcpy(pathname, filename);
1176 #endif /* USE_DEBUGGING_EXEC */
1181 for (path = getenv("PATH"); path && *path; path += m) {
1182 const char *colon = strchr(path, ':');
1188 m = n = strlen(path);
1190 if (!getcwd(pathname, PATH_MAX))
1192 len = strlen(pathname);
1194 else if (n > sizeof pathname - 1)
1197 strncpy(pathname, path, n);
1200 if (len && pathname[len - 1] != '/')
1201 pathname[len++] = '/';
1202 if (filename_len + len > sizeof(pathname) - 1)
1204 strcpy(pathname + len, filename);
1205 if (stat_file(pathname, &statbuf) == 0 &&
1206 /* Accept only regular files
1207 with some execute bits set.
1208 XXX not perfect, might still fail */
1209 S_ISREG(statbuf.st_mode) &&
1210 (statbuf.st_mode & 0111))
1213 if (!path || !*path)
1216 if (stat_file(pathname, &statbuf) < 0) {
1217 perror_msg_and_die("Can't stat '%s'", filename);
1220 params_for_tracee.fd_to_close = (shared_log != stderr) ? fileno(shared_log) : -1;
1221 params_for_tracee.run_euid = (statbuf.st_mode & S_ISUID) ? statbuf.st_uid : run_uid;
1222 params_for_tracee.run_egid = (statbuf.st_mode & S_ISGID) ? statbuf.st_gid : run_gid;
1223 params_for_tracee.argv = argv;
1225 * On NOMMU, can be safely freed only after execve in tracee.
1226 * It's hard to know when that happens, so we just leak it.
1228 params_for_tracee.pathname = NOMMU_SYSTEM ? xstrdup(pathname) : pathname;
1230 #if defined HAVE_PRCTL && defined PR_SET_PTRACER && defined PR_SET_PTRACER_ANY
1231 if (daemonized_tracer)
1232 prctl(PR_SET_PTRACER, PR_SET_PTRACER_ANY);
1237 perror_msg_and_die("fork");
1239 if ((pid != 0 && daemonized_tracer)
1240 || (pid == 0 && !daemonized_tracer)
1242 /* We are to become the tracee. Two cases:
1244 * not -D: we are child
1249 /* We are the tracer */
1251 if (!daemonized_tracer) {
1254 /* child did PTRACE_TRACEME, nothing to do in parent */
1256 if (!NOMMU_SYSTEM) {
1257 /* Wait until child stopped itself */
1259 while (waitpid(pid, &status, WSTOPPED) < 0) {
1262 perror_msg_and_die("waitpid");
1264 if (!WIFSTOPPED(status) || WSTOPSIG(status) != SIGSTOP) {
1265 kill_save_errno(pid, SIGKILL);
1266 perror_msg_and_die("Unexpected wait status %x", status);
1269 /* Else: NOMMU case, we have no way to sync.
1270 * Just attach to it as soon as possible.
1271 * This means that we may miss a few first syscalls...
1274 if (ptrace_attach_or_seize(pid)) {
1275 kill_save_errno(pid, SIGKILL);
1276 perror_msg_and_die("Can't attach to %d", pid);
1281 tcp = alloctcb(pid);
1283 tcp->flags |= TCB_ATTACHED | TCB_STARTUP | post_attach_sigstop;
1285 tcp->flags |= TCB_ATTACHED | TCB_STARTUP;
1289 /* With -D, we are *child* here, IOW: different pid. Fetch it: */
1290 strace_tracer_pid = getpid();
1291 /* The tracee is our parent: */
1294 /* attaching will be done later, by startup_attach */
1295 /* note: we don't do newoutf(tcp) here either! */
1297 /* NOMMU BUG! -D mode is active, we (child) return,
1298 * and we will scribble over parent's stack!
1299 * When parent later unpauses, it segfaults.
1302 * (1) by declaring exec_or_die() NORETURN,
1303 * hopefully compiler will just jump to it
1304 * instead of call (won't push anything to stack),
1305 * (2) by trying very hard in exec_or_die()
1306 * to not use any stack,
1307 * (3) having a really big (PATH_MAX) stack object
1308 * in this function, which creates a "buffer" between
1309 * child's and parent's stack pointers.
1310 * This may save us if (1) and (2) failed
1311 * and compiler decided to use stack in exec_or_die() anyway
1312 * (happens on i386 because of stack parameter passing).
1314 * A cleaner solution is to use makecontext + setcontext
1315 * to create a genuine separate stack and execute on it.
1322 test_ptrace_seize(void)
1326 /* Need fork for test. NOMMU has no forks */
1328 post_attach_sigstop = 0; /* this sets use_seize to 1 */
1334 perror_msg_and_die("fork");
1341 /* PTRACE_SEIZE, unlike ATTACH, doesn't force tracee to trap. After
1342 * attaching tracee continues to run unless a trap condition occurs.
1343 * PTRACE_SEIZE doesn't affect signal or group stop state.
1345 if (ptrace(PTRACE_SEIZE, pid, 0, 0) == 0) {
1346 post_attach_sigstop = 0; /* this sets use_seize to 1 */
1347 } else if (debug_flag) {
1348 error_msg("PTRACE_SEIZE doesn't work");
1354 int status, tracee_pid;
1357 tracee_pid = waitpid(pid, &status, 0);
1358 if (tracee_pid <= 0) {
1361 perror_msg_and_die("%s: unexpected wait result %d",
1362 __func__, tracee_pid);
1364 if (WIFSIGNALED(status)) {
1367 error_msg_and_die("%s: unexpected wait status %x",
1371 #else /* !USE_SEIZE */
1372 # define test_ptrace_seize() ((void)0)
1376 get_os_release(void)
1382 perror_msg_and_die("uname");
1383 /* u.release has this form: "3.2.9[-some-garbage]" */
1387 if (!(*p >= '0' && *p <= '9'))
1388 error_msg_and_die("Bad OS release string: '%s'", u.release);
1389 /* Note: this open-codes KERNEL_VERSION(): */
1390 rel = (rel << 8) | atoi(p);
1391 if (rel >= KERNEL_VERSION(1,0,0))
1393 while (*p >= '0' && *p <= '9')
1396 if (rel >= KERNEL_VERSION(0,1,0)) {
1397 /* "X.Y-something" means "X.Y.0" */
1401 error_msg_and_die("Bad OS release string: '%s'", u.release);
1409 * Initialization part of main() was eating much stack (~0.5k),
1410 * which was unused after init.
1411 * We can reuse it if we move init code into a separate function.
1413 * Don't want main() to inline us and defeat the reason
1414 * we have a separate function.
1416 static void ATTRIBUTE_NOINLINE
1417 init(int argc, char *argv[])
1423 struct sigaction sa;
1425 progname = argv[0] ? argv[0] : "strace";
1427 /* Make sure SIGCHLD has the default action so that waitpid
1428 definitely works without losing track of children. The user
1429 should not have given us a bogus state to inherit, but he might
1430 have. Arguably we should detect SIG_IGN here and pass it on
1431 to children, but probably noone really needs that. */
1432 signal(SIGCHLD, SIG_DFL);
1434 strace_tracer_pid = getpid();
1436 os_release = get_os_release();
1438 /* Allocate the initial tcbtab. */
1439 tcbtabsize = argc; /* Surely enough for all -p args. */
1440 tcbtab = xcalloc(tcbtabsize, sizeof(tcbtab[0]));
1441 tcp = xcalloc(tcbtabsize, sizeof(*tcp));
1442 for (tcbi = 0; tcbi < tcbtabsize; tcbi++)
1443 tcbtab[tcbi] = tcp++;
1445 shared_log = stderr;
1446 set_sortby(DEFAULT_SORTBY);
1447 set_personality(DEFAULT_PERSONALITY);
1448 qualify("trace=all");
1449 qualify("abbrev=all");
1450 qualify("verbose=all");
1451 #if DEFAULT_QUAL_FLAGS != (QUAL_TRACE | QUAL_ABBREV | QUAL_VERBOSE)
1452 # error Bug in DEFAULT_QUAL_FLAGS
1454 qualify("signal=all");
1455 while ((c = getopt(argc, argv,
1456 "+b:cCdfFhiqrtTvVwxyz"
1457 #ifdef USE_LIBUNWIND
1461 "a:e:o:O:p:s:S:u:E:P:I:")) != EOF) {
1464 if (strcmp(optarg, "execve") != 0)
1465 error_msg_and_die("Syscall '%s' for -b isn't supported",
1467 detach_on_execve = 1;
1470 if (cflag == CFLAG_BOTH) {
1471 error_msg_and_die("-c and -C are mutually exclusive");
1473 cflag = CFLAG_ONLY_STATS;
1476 if (cflag == CFLAG_ONLY_STATS) {
1477 error_msg_and_die("-c and -C are mutually exclusive");
1485 daemonized_tracer = 1;
1504 /* fall through to tflag++ */
1512 count_wallclock = 1;
1521 qualify("abbrev=none");
1524 printf("%s -- version %s\n", PACKAGE_NAME, VERSION);
1528 not_failing_only = 1;
1531 acolumn = string_to_uint(optarg);
1533 error_opt_arg(c, optarg);
1539 outfname = xstrdup(optarg);
1542 i = string_to_uint(optarg);
1544 error_opt_arg(c, optarg);
1548 process_opt_p_list(optarg);
1551 pathtrace_select(optarg);
1554 i = string_to_uint(optarg);
1556 error_opt_arg(c, optarg);
1563 username = xstrdup(optarg);
1565 #ifdef USE_LIBUNWIND
1567 stack_trace_enabled = true;
1571 if (putenv(optarg) < 0)
1572 die_out_of_memory();
1575 opt_intr = string_to_uint(optarg);
1576 if (opt_intr <= 0 || opt_intr >= NUM_INTR_OPTS)
1577 error_opt_arg(c, optarg);
1585 /* argc -= optind; - no need, argc is not used below */
1587 acolumn_spaces = xmalloc(acolumn + 1);
1588 memset(acolumn_spaces, ' ', acolumn);
1589 acolumn_spaces[acolumn] = '\0';
1591 /* Must have PROG [ARGS], or -p PID. Not both. */
1592 if (!argv[0] == !nprocs)
1595 if (nprocs != 0 && daemonized_tracer) {
1596 error_msg_and_die("-D and -p are mutually exclusive");
1602 if (followfork >= 2 && cflag) {
1603 error_msg_and_die("(-c or -C) and -ff are mutually exclusive");
1606 if (count_wallclock && !cflag) {
1607 error_msg_and_die("-w must be given with (-c or -C)");
1610 if (cflag == CFLAG_ONLY_STATS) {
1612 error_msg("-%c has no effect with -c", 'i');
1613 #ifdef USE_LIBUNWIND
1614 if (stack_trace_enabled)
1615 error_msg("-%c has no effect with -c", 'k');
1618 error_msg("-%c has no effect with -c", 'r');
1620 error_msg("-%c has no effect with -c", 't');
1622 error_msg("-%c has no effect with -c", 'T');
1624 error_msg("-%c has no effect with -c", 'y');
1627 #ifdef USE_LIBUNWIND
1628 if (stack_trace_enabled)
1632 /* See if they want to run as another user. */
1633 if (username != NULL) {
1634 struct passwd *pent;
1636 if (getuid() != 0 || geteuid() != 0) {
1637 error_msg_and_die("You must be root to use the -u option");
1639 pent = getpwnam(username);
1641 error_msg_and_die("Cannot find user '%s'", username);
1643 run_uid = pent->pw_uid;
1644 run_gid = pent->pw_gid;
1652 ptrace_setoptions |= PTRACE_O_TRACECLONE |
1653 PTRACE_O_TRACEFORK |
1654 PTRACE_O_TRACEVFORK;
1656 error_msg("ptrace_setoptions = %#x", ptrace_setoptions);
1657 test_ptrace_seize();
1659 /* Check if they want to redirect the output. */
1661 /* See if they want to pipe the output. */
1662 if (outfname[0] == '|' || outfname[0] == '!') {
1664 * We can't do the <outfname>.PID funny business
1665 * when using popen, so prohibit it.
1667 if (followfork >= 2)
1668 error_msg_and_die("Piping the output and -ff are mutually exclusive");
1669 shared_log = strace_popen(outfname + 1);
1671 else if (followfork < 2)
1672 shared_log = strace_fopen(outfname);
1674 /* -ff without -o FILE is the same as single -f */
1675 if (followfork >= 2)
1679 if (!outfname || outfname[0] == '|' || outfname[0] == '!') {
1680 char *buf = xmalloc(BUFSIZ);
1681 setvbuf(shared_log, buf, _IOLBF, BUFSIZ);
1683 if (outfname && argv[0]) {
1685 opt_intr = INTR_NEVER;
1690 opt_intr = INTR_WHILE_WAIT;
1692 /* argv[0] -pPID -oFILE Default interactive setting
1693 * yes 0 0 INTR_WHILE_WAIT
1694 * no 1 0 INTR_WHILE_WAIT
1695 * yes 0 1 INTR_NEVER
1696 * no 1 1 INTR_WHILE_WAIT
1699 sigemptyset(&empty_set);
1700 sigemptyset(&blocked_set);
1702 /* startup_child() must be called before the signal handlers get
1703 * installed below as they are inherited into the spawned process.
1704 * Also we do not need to be protected by them as during interruption
1705 * in the startup_child() mode we kill the spawned process anyway.
1708 if (!NOMMU_SYSTEM || daemonized_tracer)
1709 hide_log_until_execve = 1;
1710 skip_one_b_execve = 1;
1711 startup_child(argv);
1714 sa.sa_handler = SIG_IGN;
1715 sigemptyset(&sa.sa_mask);
1717 sigaction(SIGTTOU, &sa, NULL); /* SIG_IGN */
1718 sigaction(SIGTTIN, &sa, NULL); /* SIG_IGN */
1719 if (opt_intr != INTR_ANYWHERE) {
1720 if (opt_intr == INTR_BLOCK_TSTP_TOO)
1721 sigaction(SIGTSTP, &sa, NULL); /* SIG_IGN */
1723 * In interactive mode (if no -o OUTFILE, or -p PID is used),
1724 * fatal signals are blocked while syscall stop is processed,
1725 * and acted on in between, when waiting for new syscall stops.
1726 * In non-interactive mode, signals are ignored.
1728 if (opt_intr == INTR_WHILE_WAIT) {
1729 sigaddset(&blocked_set, SIGHUP);
1730 sigaddset(&blocked_set, SIGINT);
1731 sigaddset(&blocked_set, SIGQUIT);
1732 sigaddset(&blocked_set, SIGPIPE);
1733 sigaddset(&blocked_set, SIGTERM);
1734 sa.sa_handler = interrupt;
1736 /* SIG_IGN, or set handler for these */
1737 sigaction(SIGHUP, &sa, NULL);
1738 sigaction(SIGINT, &sa, NULL);
1739 sigaction(SIGQUIT, &sa, NULL);
1740 sigaction(SIGPIPE, &sa, NULL);
1741 sigaction(SIGTERM, &sa, NULL);
1743 if (nprocs != 0 || daemonized_tracer)
1746 /* Do we want pids printed in our -o OUTFILE?
1747 * -ff: no (every pid has its own file); or
1748 * -f: yes (there can be more pids in the future); or
1749 * -p PID1,PID2: yes (there are already more than one pid)
1751 print_pid_pfx = (outfname && followfork < 2 && (followfork == 1 || nprocs > 1));
1762 for (i = 0; i < tcbtabsize; i++) {
1763 struct tcb *tcp = tcbtab[i];
1764 if (tcp->pid == pid)
1778 /* 'interrupted' is a volatile object, fetch it only once */
1779 fatal_sig = interrupted;
1781 fatal_sig = SIGTERM;
1783 for (i = 0; i < tcbtabsize; i++) {
1788 error_msg("cleanup: looking at pid %u", tcp->pid);
1789 if (tcp->pid == strace_child) {
1790 kill(tcp->pid, SIGCONT);
1791 kill(tcp->pid, fatal_sig);
1796 call_summary(shared_log);
1806 print_debug_info(const int pid, int status)
1808 const unsigned int event = (unsigned int) status >> 16;
1809 char buf[sizeof("WIFEXITED,exitcode=%u") + sizeof(int)*3 /*paranoia:*/ + 16];
1810 char evbuf[sizeof(",EVENT_VFORK_DONE (%u)") + sizeof(int)*3 /*paranoia:*/ + 16];
1813 if (WIFSIGNALED(status))
1815 sprintf(buf, "WIFSIGNALED,%ssig=%s",
1816 WCOREDUMP(status) ? "core," : "",
1817 signame(WTERMSIG(status)));
1819 sprintf(buf, "WIFSIGNALED,sig=%s",
1820 signame(WTERMSIG(status)));
1822 if (WIFEXITED(status))
1823 sprintf(buf, "WIFEXITED,exitcode=%u", WEXITSTATUS(status));
1824 if (WIFSTOPPED(status))
1825 sprintf(buf, "WIFSTOPPED,sig=%s", signame(WSTOPSIG(status)));
1827 /* Should never be seen */
1828 if (WIFCONTINUED(status))
1829 strcpy(buf, "WIFCONTINUED");
1833 static const char *const event_names[] = {
1834 [PTRACE_EVENT_CLONE] = "CLONE",
1835 [PTRACE_EVENT_FORK] = "FORK",
1836 [PTRACE_EVENT_VFORK] = "VFORK",
1837 [PTRACE_EVENT_VFORK_DONE] = "VFORK_DONE",
1838 [PTRACE_EVENT_EXEC] = "EXEC",
1839 [PTRACE_EVENT_EXIT] = "EXIT",
1840 /* [PTRACE_EVENT_STOP (=128)] would make biggish array */
1842 const char *e = "??";
1843 if (event < ARRAY_SIZE(event_names))
1844 e = event_names[event];
1845 else if (event == PTRACE_EVENT_STOP)
1847 sprintf(evbuf, ",EVENT_%s (%u)", e, event);
1849 error_msg("[wait(0x%06x) = %u] %s%s", status, pid, buf, evbuf);
1853 maybe_allocate_tcb(const int pid, int status)
1855 if (!WIFSTOPPED(status)) {
1856 if (detach_on_execve && pid == strace_child) {
1857 /* example: strace -bexecve sh -c 'exec true' */
1862 * This can happen if we inherited an unknown child.
1863 * Example: (sleep 1 & exec strace true)
1865 error_msg("Exit of unknown pid %u ignored", pid);
1869 /* We assume it's a fork/vfork/clone child */
1870 struct tcb *tcp = alloctcb(pid);
1871 tcp->flags |= TCB_ATTACHED | TCB_STARTUP | post_attach_sigstop;
1874 error_msg("Process %d attached", pid);
1877 /* This can happen if a clone call used
1878 * CLONE_PTRACE itself.
1880 ptrace(PTRACE_CONT, pid, (char *) 0, 0);
1881 error_msg("Stop of unknown pid %u seen, PTRACE_CONTed it", pid);
1887 maybe_switch_tcbs(struct tcb *tcp, const int pid)
1890 struct tcb *execve_thread;
1893 if (ptrace(PTRACE_GETEVENTMSG, pid, NULL, (long) &old_pid) < 0)
1895 /* Avoid truncation in pid2tcb() param passing */
1896 if (old_pid <= 0 || old_pid == pid)
1898 if ((unsigned long) old_pid > UINT_MAX)
1900 execve_thread = pid2tcb(old_pid);
1901 /* It should be !NULL, but I feel paranoid */
1905 if (execve_thread->curcol != 0) {
1907 * One case we are here is -ff:
1908 * try "strace -oLOG -ff test/threaded_execve"
1910 fprintf(execve_thread->outf, " <pid changed to %d ...>\n", pid);
1911 /*execve_thread->curcol = 0; - no need, see code below */
1913 /* Swap output FILEs (needed for -ff) */
1914 fp = execve_thread->outf;
1915 execve_thread->outf = tcp->outf;
1917 /* And their column positions */
1918 execve_thread->curcol = tcp->curcol;
1920 /* Drop leader, but close execve'd thread outfile (if -ff) */
1922 /* Switch to the thread, reusing leader's outfile and pid */
1923 tcp = execve_thread;
1925 if (cflag != CFLAG_ONLY_STATS) {
1927 tprintf("+++ superseded by execve in pid %lu +++\n", old_pid);
1929 tcp->flags |= TCB_REPRINT;
1936 print_signalled(struct tcb *tcp, const int pid, int status)
1938 if (pid == strace_child) {
1939 exit_code = 0x100 | WTERMSIG(status);
1943 if (cflag != CFLAG_ONLY_STATS
1944 && (qual_flags[WTERMSIG(status)] & QUAL_SIGNAL)
1948 tprintf("+++ killed by %s %s+++\n",
1949 signame(WTERMSIG(status)),
1950 WCOREDUMP(status) ? "(core dumped) " : "");
1952 tprintf("+++ killed by %s +++\n",
1953 signame(WTERMSIG(status)));
1960 print_exited(struct tcb *tcp, const int pid, int status)
1962 if (pid == strace_child) {
1963 exit_code = WEXITSTATUS(status);
1967 if (cflag != CFLAG_ONLY_STATS &&
1970 tprintf("+++ exited with %d +++\n", WEXITSTATUS(status));
1976 print_stopped(struct tcb *tcp, const siginfo_t *si, const unsigned int sig)
1978 if (cflag != CFLAG_ONLY_STATS
1979 && !hide_log_until_execve
1980 && (qual_flags[sig] & QUAL_SIGNAL)
1984 tprintf("--- %s ", signame(sig));
1985 printsiginfo(si, verbose(tcp));
1988 tprintf("--- stopped by %s ---\n", signame(sig));
1994 startup_tcb(struct tcb *tcp)
1997 error_msg("pid %d has TCB_STARTUP, initializing it", tcp->pid);
1999 tcp->flags &= ~TCB_STARTUP;
2003 error_msg("setting opts 0x%x on pid %d",
2004 ptrace_setoptions, tcp->pid);
2005 if (ptrace(PTRACE_SETOPTIONS, tcp->pid, NULL, ptrace_setoptions) < 0) {
2006 if (errno != ESRCH) {
2007 /* Should never happen, really */
2008 perror_msg_and_die("PTRACE_SETOPTIONS");
2014 /* Returns true iff the main trace loop has to continue. */
2031 * Used to exit simply when nprocs hits zero, but in this testcase:
2032 * int main() { _exit(!!fork()); }
2033 * under strace -f, parent sometimes (rarely) manages
2034 * to exit before we see the first stop of the child,
2035 * and we are losing track of it:
2036 * 19923 clone(...) = 19924
2037 * 19923 exit_group(1) = ?
2038 * 19923 +++ exited with 1 +++
2039 * Exiting only when wait() returns ECHILD works better.
2041 if (popen_pid != 0) {
2042 /* However, if -o|logger is in use, we can't do that.
2043 * Can work around that by double-forking the logger,
2044 * but that loses the ability to wait for its completion
2045 * on exit. Oh well...
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) {
2155 if (get_scno(tcp) == 1)
2156 tcp->s_prev_ent = tcp->s_ent;
2159 sig = WSTOPSIG(status);
2164 if (event == PTRACE_EVENT_STOP) {
2166 * PTRACE_INTERRUPT-stop or group-stop.
2167 * PTRACE_INTERRUPT-stop has sig == SIGTRAP here.
2179 goto restart_tracee_with_sig_0;
2183 * Is this post-attach SIGSTOP?
2184 * Interestingly, the process may stop
2185 * with STOPSIG equal to some other signal
2186 * than SIGSTOP if we happend to attach
2187 * just before the process takes a signal.
2189 if (sig == SIGSTOP && (tcp->flags & TCB_IGNORE_ONE_SIGSTOP)) {
2191 error_msg("ignored SIGSTOP on pid %d", tcp->pid);
2192 tcp->flags &= ~TCB_IGNORE_ONE_SIGSTOP;
2193 goto restart_tracee_with_sig_0;
2196 if (sig != syscall_trap_sig) {
2200 * True if tracee is stopped by signal
2201 * (as opposed to "tracee received signal").
2202 * TODO: shouldn't we check for errno == EINVAL too?
2203 * We can get ESRCH instead, you know...
2205 stopped = ptrace(PTRACE_GETSIGINFO, pid, 0, (long) &si) < 0;
2209 print_stopped(tcp, stopped ? NULL : &si, sig);
2212 /* It's signal-delivery-stop. Inject the signal */
2213 goto restart_tracee;
2215 /* It's group-stop */
2218 * This ends ptrace-stop, but does *not* end group-stop.
2219 * This makes stopping signals work properly on straced process
2220 * (that is, process really stops. It used to continue to run).
2222 if (ptrace_restart(PTRACE_LISTEN, tcp, 0) < 0) {
2223 /* Note: ptrace_restart emitted error message */
2229 /* We don't have PTRACE_LISTEN support... */
2230 goto restart_tracee;
2233 /* We handled quick cases, we are permitted to interrupt now. */
2238 * This should be syscall entry or exit.
2241 if (trace_syscall(tcp) < 0) {
2243 * ptrace() failed in trace_syscall().
2244 * Likely a result of process disappearing mid-flight.
2245 * Observed case: exit_group() or SIGKILL terminating
2246 * all processes in thread group.
2247 * We assume that ptrace error was caused by process death.
2248 * We used to detach(tcp) here, but since we no longer
2249 * implement "detach before death" policy/hack,
2250 * we can let this process to report its death to us
2251 * normally, via WIFEXITED or WIFSIGNALED wait status.
2256 restart_tracee_with_sig_0:
2260 if (ptrace_restart(PTRACE_SYSCALL, tcp, sig) < 0) {
2261 /* Note: ptrace_restart emitted error message */
2270 main(int argc, char *argv[])
2279 if (shared_log != stderr)
2282 while (waitpid(popen_pid, NULL, 0) < 0 && errno == EINTR)
2285 if (exit_code > 0xff) {
2286 /* Avoid potential core file clobbering. */
2287 struct_rlimit rlim = {0, 0};
2288 set_rlimit(RLIMIT_CORE, &rlim);
2290 /* Child was killed by a signal, mimic that. */
2292 signal(exit_code, SIG_DFL);
2294 /* Paranoia - what if this signal is not fatal?
2295 Exit with 128 + signo then. */