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;
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 */
202 usage: strace [-CdffhiqrtttTvVwxxy] [-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[dfw] [-I n] [-e expr]... [-O overhead] [-S sortby]\n\
206 -p pid... / [-D] [-E var=val]... [-u username] PROG [ARGS]\n\
209 -a column alignment COLUMN for printing syscall results (default %d)\n\
210 -i print instruction pointer at time of syscall\n\
211 -o file send trace output to FILE instead of stderr\n\
212 -q suppress messages about attaching, detaching, etc.\n\
213 -r print relative timestamp\n\
214 -s strsize limit length of print strings to STRSIZE chars (default %d)\n\
215 -t print absolute timestamp\n\
216 -tt print absolute timestamp with usecs\n\
217 -T print time spent in each syscall\n\
218 -x print non-ascii strings in hex\n\
219 -xx print all strings in hex\n\
220 -y print paths associated with file descriptor arguments\n\
221 -yy print protocol specific information associated with socket file descriptors\n\
224 -c count time, calls, and errors for each syscall and report summary\n\
225 -C like -c but also print regular output\n\
226 -O overhead set overhead for tracing syscalls to OVERHEAD usecs\n\
227 -S sortby sort syscall counts by: time, calls, name, nothing (default %s)\n\
228 -w summarise syscall latency (default is system time)\n\
231 -e expr a qualifying expression: option=[!]all or option=[!]val1[,val2]...\n\
232 options: trace, abbrev, verbose, raw, signal, read, write\n\
233 -P path trace accesses to path\n\
236 -b execve detach on execve syscall\n\
237 -D run tracer process as a detached grandchild, not as parent\n\
239 -ff follow forks with output into separate files\n\
241 1: no signals are blocked\n\
242 2: fatal signals are blocked while decoding syscall (default)\n\
243 3: fatal signals are always blocked (default if '-o FILE PROG')\n\
244 4: fatal signals and SIGTSTP (^Z) are always blocked\n\
245 (useful to make 'strace -o FILE PROG' not stop on ^Z)\n\
248 -E var remove var from the environment for command\n\
249 -E var=val put var=val in the environment for command\n\
250 -p pid trace process with process id PID, may be repeated\n\
251 -u username run command as username handling setuid and/or setgid\n\
254 -d enable debug output to stderr\n\
255 -v verbose mode: print unabbreviated argv, stat, termios, etc. args\n\
256 -h print help message\n\
260 " -k obtain stack trace between each syscall (experimental)\n\
263 /* ancient, no one should use it
264 -F -- attempt to follow vforks (deprecated, use -f)\n\
266 /* this is broken, so don't document it
267 -z -- print only succeeding syscalls\n\
269 , DEFAULT_ACOLUMN, DEFAULT_STRLEN, DEFAULT_SORTBY);
273 static void ATTRIBUTE_NORETURN
276 if (strace_tracer_pid == getpid()) {
283 static void verror_msg(int err_no, const char *fmt, va_list p)
289 /* We want to print entire message with single fprintf to ensure
290 * message integrity if stderr is shared with other programs.
291 * Thus we use vasprintf + single fprintf.
294 if (vasprintf(&msg, fmt, p) >= 0) {
296 fprintf(stderr, "%s: %s: %s\n", progname, msg, strerror(err_no));
298 fprintf(stderr, "%s: %s\n", progname, msg);
301 /* malloc in vasprintf failed, try it without malloc */
302 fprintf(stderr, "%s: ", progname);
303 vfprintf(stderr, fmt, p);
305 fprintf(stderr, ": %s\n", strerror(err_no));
309 /* We don't switch stderr to buffered, thus fprintf(stderr)
310 * always flushes its output and this is not necessary: */
311 /* fflush(stderr); */
314 void error_msg(const char *fmt, ...)
318 verror_msg(0, fmt, p);
322 void error_msg_and_die(const char *fmt, ...)
326 verror_msg(0, fmt, p);
330 void error_msg_and_help(const char *fmt, ...)
335 verror_msg(0, fmt, p);
337 fprintf(stderr, "Try '%s -h' for more information.\n", progname);
341 void perror_msg(const char *fmt, ...)
345 verror_msg(errno, fmt, p);
349 void perror_msg_and_die(const char *fmt, ...)
353 verror_msg(errno, fmt, p);
358 error_opt_arg(int opt, const char *arg)
360 error_msg_and_help("invalid -%c argument: '%s'", opt, arg);
363 static const char *ptrace_attach_cmd;
366 ptrace_attach_or_seize(int pid)
371 return ptrace_attach_cmd = "PTRACE_ATTACH",
372 ptrace(PTRACE_ATTACH, pid, 0L, 0L);
373 r = ptrace(PTRACE_SEIZE, pid, 0L, (unsigned long) ptrace_setoptions);
375 return ptrace_attach_cmd = "PTRACE_SEIZE", r;
376 r = ptrace(PTRACE_INTERRUPT, pid, 0L, 0L);
377 return ptrace_attach_cmd = "PTRACE_INTERRUPT", r;
379 return ptrace_attach_cmd = "PTRACE_ATTACH",
380 ptrace(PTRACE_ATTACH, pid, 0L, 0L);
385 * Used when we want to unblock stopped traced process.
386 * Should be only used with PTRACE_CONT, PTRACE_DETACH and PTRACE_SYSCALL.
387 * Returns 0 on success or if error was ESRCH
388 * (presumably process was killed while we talk to it).
389 * Otherwise prints error message and returns -1.
392 ptrace_restart(int op, struct tcb *tcp, int sig)
398 ptrace(op, tcp->pid, (void *) 0, (long) sig);
404 if (op == PTRACE_CONT)
406 if (op == PTRACE_DETACH)
409 if (op == PTRACE_LISTEN)
413 * Why curcol != 0? Otherwise sometimes we get this:
415 * 10252 kill(10253, SIGKILL) = 0
416 * <ptrace(SYSCALL,10252):No such process>10253 ...next decode...
418 * 10252 died after we retrieved syscall exit data,
419 * but before we tried to restart it. Log looks ugly.
421 if (current_tcp && current_tcp->curcol != 0) {
422 tprintf(" <ptrace(%s):%s>\n", msg, strerror(err));
428 perror_msg("ptrace(PTRACE_%s,pid:%d,sig:%d)", msg, tcp->pid, sig);
433 set_cloexec_flag(int fd)
437 flags = fcntl(fd, F_GETFD);
439 /* Can happen only if fd is bad.
440 * Should never happen: if it does, we have a bug
441 * in the caller. Therefore we just abort
442 * instead of propagating the error.
444 perror_msg_and_die("fcntl(%d, F_GETFD)", fd);
447 newflags = flags | FD_CLOEXEC;
448 if (flags == newflags)
451 fcntl(fd, F_SETFD, newflags); /* never fails */
455 kill_save_errno(pid_t pid, int sig)
457 int saved_errno = errno;
459 (void) kill(pid, sig);
464 * When strace is setuid executable, we have to swap uids
465 * before and after filesystem and process management operations.
470 int euid = geteuid(), uid = getuid();
472 if (euid != uid && setreuid(euid, uid) < 0) {
473 perror_msg_and_die("setreuid");
477 #ifdef _LARGEFILE64_SOURCE
479 # define fopen_for_output fopen64
481 # define fopen_for_output fopen
483 # define struct_stat struct stat64
484 # define stat_file stat64
485 # define struct_dirent struct dirent64
486 # define read_dir readdir64
487 # define struct_rlimit struct rlimit64
488 # define set_rlimit setrlimit64
490 # define fopen_for_output fopen
491 # define struct_stat struct stat
492 # define stat_file stat
493 # define struct_dirent struct dirent
494 # define read_dir readdir
495 # define struct_rlimit struct rlimit
496 # define set_rlimit setrlimit
500 strace_fopen(const char *path)
505 fp = fopen_for_output(path, "w");
507 perror_msg_and_die("Can't fopen '%s'", path);
509 set_cloexec_flag(fileno(fp));
513 static int popen_pid = 0;
516 # define _PATH_BSHELL "/bin/sh"
520 * We cannot use standard popen(3) here because we have to distinguish
521 * popen child process from other processes we trace, and standard popen(3)
522 * does not export its child's pid.
525 strace_popen(const char *command)
533 perror_msg_and_die("pipe");
535 set_cloexec_flag(fds[1]); /* never fails */
539 perror_msg_and_die("vfork");
546 perror_msg_and_die("dup2");
549 execl(_PATH_BSHELL, "sh", "-c", command, NULL);
550 perror_msg_and_die("Can't execute '%s'", _PATH_BSHELL);
557 fp = fdopen(fds[1], "w");
564 tprintf(const char *fmt, ...)
570 int n = strace_vfprintf(current_tcp->outf, fmt, args);
572 if (current_tcp->outf != stderr)
573 perror_msg("%s", outfname);
575 current_tcp->curcol += n;
580 #ifndef HAVE_FPUTS_UNLOCKED
581 # define fputs_unlocked fputs
585 tprints(const char *str)
588 int n = fputs_unlocked(str, current_tcp->outf);
590 current_tcp->curcol += strlen(str);
593 if (current_tcp->outf != stderr)
594 perror_msg("%s", outfname);
602 current_tcp->curcol = 0;
603 fflush(current_tcp->outf);
606 printing_tcp->curcol = 0;
612 printleader(struct tcb *tcp)
614 /* If -ff, "previous tcb we printed" is always the same as current,
615 * because we have per-tcb output files.
621 current_tcp = printing_tcp;
622 if (printing_tcp->curcol != 0 && (followfork < 2 || printing_tcp == tcp)) {
624 * case 1: we have a shared log (i.e. not -ff), and last line
625 * wasn't finished (same or different tcb, doesn't matter).
626 * case 2: split log, we are the same tcb, but our last line
627 * didn't finish ("SIGKILL nuked us after syscall entry" etc).
629 tprints(" <unfinished ...>\n");
630 printing_tcp->curcol = 0;
636 current_tcp->curcol = 0;
639 tprintf("%-5d ", tcp->pid);
640 else if (nprocs > 1 && !outfname)
641 tprintf("[pid %5u] ", tcp->pid);
644 char str[sizeof("HH:MM:SS")];
645 struct timeval tv, dtv;
646 static struct timeval otv;
648 gettimeofday(&tv, NULL);
652 tv_sub(&dtv, &tv, &otv);
653 tprintf("%6ld.%06ld ",
654 (long) dtv.tv_sec, (long) dtv.tv_usec);
657 else if (tflag > 2) {
658 tprintf("%ld.%06ld ",
659 (long) tv.tv_sec, (long) tv.tv_usec);
662 time_t local = tv.tv_sec;
663 strftime(str, sizeof(str), "%T", localtime(&local));
665 tprintf("%s.%06ld ", str, (long) tv.tv_usec);
677 if (current_tcp->curcol < acolumn)
678 tprints(acolumn_spaces + current_tcp->curcol);
681 /* Should be only called directly *after successful attach* to a tracee.
682 * Otherwise, "strace -oFILE -ff -p<nonexistant_pid>"
683 * may create bogus empty FILE.<nonexistant_pid>, and then die.
686 newoutf(struct tcb *tcp)
688 tcp->outf = shared_log; /* if not -ff mode, the same file is for all */
689 if (followfork >= 2) {
690 char name[520 + sizeof(int) * 3];
691 sprintf(name, "%.512s.%u", outfname, tcp->pid);
692 tcp->outf = strace_fopen(name);
699 /* Allocate some (more) TCBs (and expand the table).
700 We don't want to relocate the TCBs because our
701 callers have pointers and it would be a pain.
702 So tcbtab is a table of pointers. Since we never
703 free the TCBs, we allocate a single chunk of many. */
704 unsigned int new_tcbtabsize, alloc_tcbtabsize;
708 alloc_tcbtabsize = tcbtabsize;
709 new_tcbtabsize = tcbtabsize * 2;
711 new_tcbtabsize = alloc_tcbtabsize = 1;
714 newtcbs = xcalloc(alloc_tcbtabsize, sizeof(newtcbs[0]));
715 tcbtab = xreallocarray(tcbtab, new_tcbtabsize, sizeof(tcbtab[0]));
716 while (tcbtabsize < new_tcbtabsize)
717 tcbtab[tcbtabsize++] = newtcbs++;
726 if (nprocs == tcbtabsize)
729 for (i = 0; i < tcbtabsize; i++) {
732 memset(tcp, 0, sizeof(*tcp));
734 #if SUPPORTED_PERSONALITIES > 1
735 tcp->currpers = current_personality;
739 if (stack_trace_enabled)
740 unwind_tcb_init(tcp);
745 error_msg("new tcb for pid %d, active tcbs:%d",
750 error_msg_and_die("bug in alloctcb");
754 get_tcb_priv_data(const struct tcb *tcp)
756 return tcp->_priv_data;
760 set_tcb_priv_data(struct tcb *tcp, void *const priv_data,
761 void (*const free_priv_data)(void *))
766 tcp->_free_priv_data = free_priv_data;
767 tcp->_priv_data = priv_data;
773 free_tcb_priv_data(struct tcb *tcp)
775 if (tcp->_priv_data) {
776 if (tcp->_free_priv_data) {
777 tcp->_free_priv_data(tcp->_priv_data);
778 tcp->_free_priv_data = NULL;
780 tcp->_priv_data = NULL;
785 droptcb(struct tcb *tcp)
790 free_tcb_priv_data(tcp);
793 if (stack_trace_enabled) {
800 error_msg("dropped tcb for pid %d, %d remain",
804 if (followfork >= 2) {
805 if (tcp->curcol != 0)
806 fprintf(tcp->outf, " <detached ...>\n");
809 if (printing_tcp == tcp && tcp->curcol != 0)
810 fprintf(tcp->outf, " <detached ...>\n");
815 if (current_tcp == tcp)
817 if (printing_tcp == tcp)
820 memset(tcp, 0, sizeof(*tcp));
823 /* Detach traced process.
824 * Never call DETACH twice on the same process as both unattached and
825 * attached-unstopped processes give the same ESRCH. For unattached process we
826 * would SIGSTOP it and wait for its SIGSTOP notification forever.
829 detach(struct tcb *tcp)
835 * Linux wrongly insists the child be stopped
836 * before detaching. Arghh. We go through hoops
837 * to make a clean break of things.
840 if (!(tcp->flags & TCB_ATTACHED))
843 /* We attached but possibly didn't see the expected SIGSTOP.
844 * We must catch exactly one as otherwise the detached process
845 * would be left stopped (process state T).
847 if (tcp->flags & TCB_IGNORE_ONE_SIGSTOP)
850 error = ptrace(PTRACE_DETACH, tcp->pid, 0, 0);
852 /* On a clear day, you can see forever. */
855 if (errno != ESRCH) {
856 /* Shouldn't happen. */
857 perror_msg("detach: ptrace(PTRACE_DETACH,%u)", tcp->pid);
860 /* ESRCH: process is either not stopped or doesn't exist. */
861 if (my_tkill(tcp->pid, 0) < 0) {
863 /* Shouldn't happen. */
864 perror_msg("detach: tkill(%u,0)", tcp->pid);
865 /* else: process doesn't exist. */
868 /* Process is not stopped, need to stop it. */
871 * With SEIZE, tracee can be in group-stop already.
872 * In this state sending it another SIGSTOP does nothing.
873 * Need to use INTERRUPT.
874 * Testcase: trying to ^C a "strace -p <stopped_process>".
876 error = ptrace(PTRACE_INTERRUPT, tcp->pid, 0, 0);
880 perror_msg("detach: ptrace(PTRACE_INTERRUPT,%u)", tcp->pid);
883 error = my_tkill(tcp->pid, SIGSTOP);
887 perror_msg("detach: tkill(%u,SIGSTOP)", tcp->pid);
889 /* Either process doesn't exist, or some weird error. */
893 /* We end up here in three cases:
894 * 1. We sent PTRACE_INTERRUPT (use_seize case)
895 * 2. We sent SIGSTOP (!use_seize)
896 * 3. Attach SIGSTOP was already pending (TCB_IGNORE_ONE_SIGSTOP set)
900 if (waitpid(tcp->pid, &status, __WALL) < 0) {
904 * if (errno == ECHILD) break;
905 * ^^^ WRONG! We expect this PID to exist,
906 * and want to emit a message otherwise:
908 perror_msg("detach: waitpid(%u)", tcp->pid);
911 if (!WIFSTOPPED(status)) {
913 * Tracee exited or was killed by signal.
914 * We shouldn't normally reach this place:
915 * we don't want to consume exit status.
916 * Consider "strace -p PID" being ^C-ed:
917 * we want merely to detach from PID.
919 * However, we _can_ end up here if tracee
924 sig = WSTOPSIG(status);
926 error_msg("detach wait: event:%d sig:%d",
927 (unsigned)status >> 16, sig);
929 unsigned event = (unsigned)status >> 16;
930 if (event == PTRACE_EVENT_STOP /*&& sig == SIGTRAP*/) {
932 * sig == SIGTRAP: PTRACE_INTERRUPT stop.
933 * sig == other: process was already stopped
934 * with this stopping sig (see tests/detach-stopped).
935 * Looks like re-injecting this sig is not necessary
936 * in DETACH for the tracee to remain stopped.
941 * PTRACE_INTERRUPT is not guaranteed to produce
942 * the above event if other ptrace-stop is pending.
943 * See tests/detach-sleeping testcase:
944 * strace got SIGINT while tracee is sleeping.
945 * We sent PTRACE_INTERRUPT.
946 * We see syscall exit, not PTRACE_INTERRUPT stop.
947 * We won't get PTRACE_INTERRUPT stop
948 * if we would CONT now. Need to DETACH.
950 if (sig == syscall_trap_sig)
952 /* else: not sure in which case we can be here.
953 * Signal stop? Inject it while detaching.
955 ptrace_restart(PTRACE_DETACH, tcp, sig);
958 /* Note: this check has to be after use_seize check */
959 /* (else, in use_seize case SIGSTOP will be mistreated) */
960 if (sig == SIGSTOP) {
961 /* Detach, suppressing SIGSTOP */
962 ptrace_restart(PTRACE_DETACH, tcp, 0);
965 if (sig == syscall_trap_sig)
967 /* Can't detach just yet, may need to wait for SIGSTOP */
968 error = ptrace_restart(PTRACE_CONT, tcp, sig);
970 /* Should not happen.
971 * Note: ptrace_restart returns 0 on ESRCH, so it's not it.
972 * ptrace_restart already emitted error message.
979 if (!qflag && (tcp->flags & TCB_ATTACHED))
980 error_msg("Process %u detached", tcp->pid);
986 process_opt_p_list(char *opt)
990 * We accept -p PID,PID; -p "`pidof PROG`"; -p "`pgrep PROG`".
991 * pidof uses space as delim, pgrep uses newline. :(
994 char *delim = opt + strcspn(opt, ", \n\t");
998 pid = string_to_uint(opt);
1000 error_msg_and_die("Invalid process id: '%s'", opt);
1002 if (pid == strace_tracer_pid) {
1003 error_msg_and_die("I'm sorry, I can't let you do that, Dave.");
1014 attach_tcb(struct tcb *const tcp)
1016 if (ptrace_attach_or_seize(tcp->pid) < 0) {
1017 perror_msg("attach: ptrace(%s, %d)",
1018 ptrace_attach_cmd, tcp->pid);
1023 tcp->flags |= TCB_ATTACHED | TCB_STARTUP | post_attach_sigstop;
1026 error_msg("attach to pid %d (main) succeeded", tcp->pid);
1028 char procdir[sizeof("/proc/%d/task") + sizeof(int) * 3];
1030 unsigned int ntid = 0, nerr = 0;
1032 if (followfork && tcp->pid != strace_child &&
1033 sprintf(procdir, "/proc/%d/task", tcp->pid) > 0 &&
1034 (dir = opendir(procdir)) != NULL) {
1037 while ((de = read_dir(dir)) != NULL) {
1038 if (de->d_fileno == 0)
1041 int tid = string_to_uint(de->d_name);
1042 if (tid <= 0 || tid == tcp->pid)
1046 if (ptrace_attach_or_seize(tid) < 0) {
1049 perror_msg("attach: ptrace(%s, %d)",
1050 ptrace_attach_cmd, tid);
1054 error_msg("attach to pid %d succeeded", tid);
1056 struct tcb *tid_tcp = alloctcb(tid);
1057 tid_tcp->flags |= TCB_ATTACHED | TCB_STARTUP |
1058 post_attach_sigstop;
1067 error_msg("Process %u attached"
1069 tcp->pid, ntid - nerr + 1);
1071 error_msg("Process %u attached",
1077 startup_attach(void)
1079 pid_t parent_pid = strace_tracer_pid;
1084 * Block user interruptions as we would leave the traced
1085 * process stopped (process state T) if we would terminate in
1086 * between PTRACE_ATTACH and wait4() on SIGSTOP.
1087 * We rely on cleanup() from this point on.
1090 sigprocmask(SIG_BLOCK, &blocked_set, NULL);
1092 if (daemonized_tracer) {
1095 perror_msg_and_die("fork");
1097 if (pid) { /* parent */
1099 * Wait for grandchild to attach to straced process
1100 * (grandparent). Grandchild SIGKILLs us after it attached.
1101 * Grandparent's wait() is unblocked by our death,
1102 * it proceeds to exec the straced program.
1105 _exit(0); /* paranoia */
1108 /* We will be the tracer process. Remember our new pid: */
1109 strace_tracer_pid = getpid();
1112 for (tcbi = 0; tcbi < tcbtabsize; tcbi++) {
1118 /* Is this a process we should attach to, but not yet attached? */
1119 if (tcp->flags & TCB_ATTACHED)
1120 continue; /* no, we already attached it */
1122 if (tcp->pid == parent_pid || tcp->pid == strace_tracer_pid) {
1124 perror_msg("attach: pid %d", tcp->pid);
1132 sigprocmask(SIG_SETMASK, &empty_set, NULL);
1135 sigprocmask(SIG_BLOCK, &blocked_set, NULL);
1137 } /* for each tcbtab[] */
1139 if (daemonized_tracer) {
1141 * Make parent go away.
1142 * Also makes grandparent's wait() unblock.
1144 kill(parent_pid, SIGKILL);
1150 sigprocmask(SIG_SETMASK, &empty_set, NULL);
1153 /* Stack-o-phobic exec helper, in the hope to work around
1154 * NOMMU + "daemonized tracer" difficulty.
1156 struct exec_params {
1163 static struct exec_params params_for_tracee;
1165 static void ATTRIBUTE_NOINLINE ATTRIBUTE_NORETURN
1168 struct exec_params *params = ¶ms_for_tracee;
1170 if (params->fd_to_close >= 0)
1171 close(params->fd_to_close);
1172 if (!daemonized_tracer && !use_seize) {
1173 if (ptrace(PTRACE_TRACEME, 0L, 0L, 0L) < 0) {
1174 perror_msg_and_die("ptrace(PTRACE_TRACEME, ...)");
1178 if (username != NULL) {
1180 * It is important to set groups before we
1181 * lose privileges on setuid.
1183 if (initgroups(username, run_gid) < 0) {
1184 perror_msg_and_die("initgroups");
1186 if (setregid(run_gid, params->run_egid) < 0) {
1187 perror_msg_and_die("setregid");
1189 if (setreuid(run_uid, params->run_euid) < 0) {
1190 perror_msg_and_die("setreuid");
1193 else if (geteuid() != 0)
1194 if (setreuid(run_uid, run_uid) < 0) {
1195 perror_msg_and_die("setreuid");
1198 if (!daemonized_tracer) {
1200 * Induce a ptrace stop. Tracer (our parent)
1201 * will resume us with PTRACE_SYSCALL and display
1202 * the immediately following execve syscall.
1203 * Can't do this on NOMMU systems, we are after
1204 * vfork: parent is blocked, stopping would deadlock.
1207 kill(getpid(), SIGSTOP);
1210 /* we depend on SIGCHLD set to SIG_DFL by init code */
1211 /* if it happens to be SIG_IGN'ed, wait won't block */
1216 execv(params->pathname, params->argv);
1217 perror_msg_and_die("exec");
1221 * Open a dummy descriptor for use as a placeholder.
1222 * The descriptor is O_RDONLY with FD_CLOEXEC flag set.
1223 * A read attempt from such descriptor ends with EOF,
1224 * a write attempt is rejected with EBADF.
1227 open_dummy_desc(void)
1232 perror_msg_and_die("pipe");
1234 set_cloexec_flag(fds[0]);
1238 /* placeholder fds status for stdin and stdout */
1239 static bool fd_is_placeholder[2];
1242 * Ensure that all standard file descriptors are open by opening placeholder
1243 * file descriptors for those standard file descriptors that are not open.
1245 * The information which descriptors have been made open is saved
1246 * in fd_is_placeholder for later use.
1249 ensure_standard_fds_opened(void)
1253 while ((fd = open_dummy_desc()) <= 2) {
1256 fd_is_placeholder[fd] = true;
1264 * Redirect stdin and stdout unless they have been opened earlier
1265 * by ensure_standard_fds_opened as placeholders.
1268 redirect_standard_fds(void)
1273 * It might be a good idea to redirect stderr as well,
1274 * but we sometimes need to print error messages.
1276 for (i = 0; i <= 1; ++i) {
1277 if (!fd_is_placeholder[i]) {
1285 startup_child(char **argv)
1287 struct_stat statbuf;
1288 const char *filename;
1289 size_t filename_len;
1290 char pathname[PATH_MAX];
1295 filename_len = strlen(filename);
1297 if (filename_len > sizeof(pathname) - 1) {
1298 errno = ENAMETOOLONG;
1299 perror_msg_and_die("exec");
1301 if (strchr(filename, '/')) {
1302 strcpy(pathname, filename);
1304 #ifdef USE_DEBUGGING_EXEC
1306 * Debuggers customarily check the current directory
1307 * first regardless of the path but doing that gives
1308 * security geeks a panic attack.
1310 else if (stat_file(filename, &statbuf) == 0)
1311 strcpy(pathname, filename);
1312 #endif /* USE_DEBUGGING_EXEC */
1317 for (path = getenv("PATH"); path && *path; path += m) {
1318 const char *colon = strchr(path, ':');
1324 m = n = strlen(path);
1326 if (!getcwd(pathname, PATH_MAX))
1328 len = strlen(pathname);
1330 else if (n > sizeof pathname - 1)
1333 strncpy(pathname, path, n);
1336 if (len && pathname[len - 1] != '/')
1337 pathname[len++] = '/';
1338 if (filename_len + len > sizeof(pathname) - 1)
1340 strcpy(pathname + len, filename);
1341 if (stat_file(pathname, &statbuf) == 0 &&
1342 /* Accept only regular files
1343 with some execute bits set.
1344 XXX not perfect, might still fail */
1345 S_ISREG(statbuf.st_mode) &&
1346 (statbuf.st_mode & 0111))
1349 if (!path || !*path)
1352 if (stat_file(pathname, &statbuf) < 0) {
1353 perror_msg_and_die("Can't stat '%s'", filename);
1356 params_for_tracee.fd_to_close = (shared_log != stderr) ? fileno(shared_log) : -1;
1357 params_for_tracee.run_euid = (statbuf.st_mode & S_ISUID) ? statbuf.st_uid : run_uid;
1358 params_for_tracee.run_egid = (statbuf.st_mode & S_ISGID) ? statbuf.st_gid : run_gid;
1359 params_for_tracee.argv = argv;
1361 * On NOMMU, can be safely freed only after execve in tracee.
1362 * It's hard to know when that happens, so we just leak it.
1364 params_for_tracee.pathname = NOMMU_SYSTEM ? xstrdup(pathname) : pathname;
1366 #if defined HAVE_PRCTL && defined PR_SET_PTRACER && defined PR_SET_PTRACER_ANY
1367 if (daemonized_tracer)
1368 prctl(PR_SET_PTRACER, PR_SET_PTRACER_ANY);
1373 perror_msg_and_die("fork");
1375 if ((pid != 0 && daemonized_tracer)
1376 || (pid == 0 && !daemonized_tracer)
1378 /* We are to become the tracee. Two cases:
1380 * not -D: we are child
1385 /* We are the tracer */
1387 if (!daemonized_tracer) {
1390 /* child did PTRACE_TRACEME, nothing to do in parent */
1392 if (!NOMMU_SYSTEM) {
1393 /* Wait until child stopped itself */
1395 while (waitpid(pid, &status, WSTOPPED) < 0) {
1398 perror_msg_and_die("waitpid");
1400 if (!WIFSTOPPED(status) || WSTOPSIG(status) != SIGSTOP) {
1401 kill_save_errno(pid, SIGKILL);
1402 perror_msg_and_die("Unexpected wait status %x", status);
1405 /* Else: NOMMU case, we have no way to sync.
1406 * Just attach to it as soon as possible.
1407 * This means that we may miss a few first syscalls...
1410 if (ptrace_attach_or_seize(pid)) {
1411 kill_save_errno(pid, SIGKILL);
1412 perror_msg_and_die("attach: ptrace(%s, %d)",
1413 ptrace_attach_cmd, pid);
1418 tcp = alloctcb(pid);
1420 tcp->flags |= TCB_ATTACHED | TCB_STARTUP | post_attach_sigstop;
1422 tcp->flags |= TCB_ATTACHED | TCB_STARTUP;
1426 /* With -D, we are *child* here, the tracee is our parent. */
1427 strace_child = strace_tracer_pid;
1428 strace_tracer_pid = getpid();
1429 alloctcb(strace_child);
1430 /* attaching will be done later, by startup_attach */
1431 /* note: we don't do newoutf(tcp) here either! */
1433 /* NOMMU BUG! -D mode is active, we (child) return,
1434 * and we will scribble over parent's stack!
1435 * When parent later unpauses, it segfaults.
1438 * (1) by declaring exec_or_die() NORETURN,
1439 * hopefully compiler will just jump to it
1440 * instead of call (won't push anything to stack),
1441 * (2) by trying very hard in exec_or_die()
1442 * to not use any stack,
1443 * (3) having a really big (PATH_MAX) stack object
1444 * in this function, which creates a "buffer" between
1445 * child's and parent's stack pointers.
1446 * This may save us if (1) and (2) failed
1447 * and compiler decided to use stack in exec_or_die() anyway
1448 * (happens on i386 because of stack parameter passing).
1450 * A cleaner solution is to use makecontext + setcontext
1451 * to create a genuine separate stack and execute on it.
1455 * A case where straced process is part of a pipe:
1456 * { sleep 1; yes | head -n99999; } | strace -o/dev/null sh -c 'exec <&-; sleep 9'
1457 * If strace won't close its fd#0, closing it in tracee is not enough:
1458 * the pipe is still open, it has a reader. Thus, "head" will not get its
1459 * SIGPIPE at once, on the first write.
1461 * Preventing it by redirecting strace's stdin/out.
1462 * (Don't leave fds 0 and 1 closed, this is bad practice: future opens
1463 * will reuse them, unexpectedly making a newly opened object "stdin").
1465 redirect_standard_fds();
1470 test_ptrace_seize(void)
1474 /* Need fork for test. NOMMU has no forks */
1476 post_attach_sigstop = 0; /* this sets use_seize to 1 */
1482 perror_msg_and_die("fork");
1489 /* PTRACE_SEIZE, unlike ATTACH, doesn't force tracee to trap. After
1490 * attaching tracee continues to run unless a trap condition occurs.
1491 * PTRACE_SEIZE doesn't affect signal or group stop state.
1493 if (ptrace(PTRACE_SEIZE, pid, 0, 0) == 0) {
1494 post_attach_sigstop = 0; /* this sets use_seize to 1 */
1495 } else if (debug_flag) {
1496 error_msg("PTRACE_SEIZE doesn't work");
1502 int status, tracee_pid;
1505 tracee_pid = waitpid(pid, &status, 0);
1506 if (tracee_pid <= 0) {
1509 perror_msg_and_die("%s: unexpected wait result %d",
1510 __func__, tracee_pid);
1512 if (WIFSIGNALED(status)) {
1515 error_msg_and_die("%s: unexpected wait status %x",
1519 #else /* !USE_SEIZE */
1520 # define test_ptrace_seize() ((void)0)
1524 get_os_release(void)
1530 perror_msg_and_die("uname");
1531 /* u.release has this form: "3.2.9[-some-garbage]" */
1535 if (!(*p >= '0' && *p <= '9'))
1536 error_msg_and_die("Bad OS release string: '%s'", u.release);
1537 /* Note: this open-codes KERNEL_VERSION(): */
1538 rel = (rel << 8) | atoi(p);
1539 if (rel >= KERNEL_VERSION(1,0,0))
1541 while (*p >= '0' && *p <= '9')
1544 if (rel >= KERNEL_VERSION(0,1,0)) {
1545 /* "X.Y-something" means "X.Y.0" */
1549 error_msg_and_die("Bad OS release string: '%s'", u.release);
1557 * Initialization part of main() was eating much stack (~0.5k),
1558 * which was unused after init.
1559 * We can reuse it if we move init code into a separate function.
1561 * Don't want main() to inline us and defeat the reason
1562 * we have a separate function.
1564 static void ATTRIBUTE_NOINLINE
1565 init(int argc, char *argv[])
1569 struct sigaction sa;
1571 progname = argv[0] ? argv[0] : "strace";
1573 /* Make sure SIGCHLD has the default action so that waitpid
1574 definitely works without losing track of children. The user
1575 should not have given us a bogus state to inherit, but he might
1576 have. Arguably we should detect SIG_IGN here and pass it on
1577 to children, but probably noone really needs that. */
1578 signal(SIGCHLD, SIG_DFL);
1580 strace_tracer_pid = getpid();
1582 os_release = get_os_release();
1584 shared_log = stderr;
1585 set_sortby(DEFAULT_SORTBY);
1586 set_personality(DEFAULT_PERSONALITY);
1587 qualify("trace=all");
1588 qualify("abbrev=all");
1589 qualify("verbose=all");
1590 #if DEFAULT_QUAL_FLAGS != (QUAL_TRACE | QUAL_ABBREV | QUAL_VERBOSE)
1591 # error Bug in DEFAULT_QUAL_FLAGS
1593 qualify("signal=all");
1594 while ((c = getopt(argc, argv,
1595 "+b:cCdfFhiqrtTvVwxyz"
1596 #ifdef USE_LIBUNWIND
1600 "a:e:o:O:p:s:S:u:E:P:I:")) != EOF) {
1603 if (strcmp(optarg, "execve") != 0)
1604 error_msg_and_die("Syscall '%s' for -b isn't supported",
1606 detach_on_execve = 1;
1609 if (cflag == CFLAG_BOTH) {
1610 error_msg_and_help("-c and -C are mutually exclusive");
1612 cflag = CFLAG_ONLY_STATS;
1615 if (cflag == CFLAG_ONLY_STATS) {
1616 error_msg_and_help("-c and -C are mutually exclusive");
1624 daemonized_tracer = 1;
1643 /* fall through to tflag++ */
1651 count_wallclock = 1;
1660 qualify("abbrev=none");
1663 printf("%s -- version %s\n", PACKAGE_NAME, VERSION);
1667 not_failing_only = 1;
1670 acolumn = string_to_uint(optarg);
1672 error_opt_arg(c, optarg);
1678 outfname = xstrdup(optarg);
1681 i = string_to_uint(optarg);
1683 error_opt_arg(c, optarg);
1687 process_opt_p_list(optarg);
1690 pathtrace_select(optarg);
1693 i = string_to_uint(optarg);
1695 error_opt_arg(c, optarg);
1702 username = xstrdup(optarg);
1704 #ifdef USE_LIBUNWIND
1706 stack_trace_enabled = true;
1710 if (putenv(optarg) < 0)
1711 die_out_of_memory();
1714 opt_intr = string_to_uint(optarg);
1715 if (opt_intr <= 0 || opt_intr >= NUM_INTR_OPTS)
1716 error_opt_arg(c, optarg);
1719 error_msg_and_help(NULL);
1724 /* argc -= optind; - no need, argc is not used below */
1726 acolumn_spaces = xmalloc(acolumn + 1);
1727 memset(acolumn_spaces, ' ', acolumn);
1728 acolumn_spaces[acolumn] = '\0';
1730 if (!argv[0] && !nprocs) {
1731 error_msg_and_help("must have PROG [ARGS] or -p PID");
1734 if (!argv[0] && daemonized_tracer) {
1735 error_msg_and_help("PROG [ARGS] must be specified with -D");
1741 if (followfork >= 2 && cflag) {
1742 error_msg_and_help("(-c or -C) and -ff are mutually exclusive");
1745 if (count_wallclock && !cflag) {
1746 error_msg_and_help("-w must be given with (-c or -C)");
1749 if (cflag == CFLAG_ONLY_STATS) {
1751 error_msg("-%c has no effect with -c", 'i');
1752 #ifdef USE_LIBUNWIND
1753 if (stack_trace_enabled)
1754 error_msg("-%c has no effect with -c", 'k');
1757 error_msg("-%c has no effect with -c", 'r');
1759 error_msg("-%c has no effect with -c", 't');
1761 error_msg("-%c has no effect with -c", 'T');
1763 error_msg("-%c has no effect with -c", 'y');
1766 #ifdef USE_LIBUNWIND
1767 if (stack_trace_enabled)
1771 /* See if they want to run as another user. */
1772 if (username != NULL) {
1773 struct passwd *pent;
1775 if (getuid() != 0 || geteuid() != 0) {
1776 error_msg_and_die("You must be root to use the -u option");
1778 pent = getpwnam(username);
1780 error_msg_and_die("Cannot find user '%s'", username);
1782 run_uid = pent->pw_uid;
1783 run_gid = pent->pw_gid;
1791 ptrace_setoptions |= PTRACE_O_TRACECLONE |
1792 PTRACE_O_TRACEFORK |
1793 PTRACE_O_TRACEVFORK;
1795 error_msg("ptrace_setoptions = %#x", ptrace_setoptions);
1796 test_ptrace_seize();
1799 * Is something weird with our stdin and/or stdout -
1800 * for example, may they be not open? In this case,
1801 * ensure that none of the future opens uses them.
1803 * This was seen in the wild when /proc/sys/kernel/core_pattern
1804 * was set to "|/bin/strace -o/tmp/LOG PROG":
1805 * kernel runs coredump helper with fd#0 open but fd#1 closed (!),
1806 * therefore LOG gets opened to fd#1, and fd#1 is closed by
1807 * "don't hold up stdin/out open" code soon after.
1809 ensure_standard_fds_opened();
1811 /* Check if they want to redirect the output. */
1813 /* See if they want to pipe the output. */
1814 if (outfname[0] == '|' || outfname[0] == '!') {
1816 * We can't do the <outfname>.PID funny business
1817 * when using popen, so prohibit it.
1819 if (followfork >= 2)
1820 error_msg_and_help("piping the output and -ff are mutually exclusive");
1821 shared_log = strace_popen(outfname + 1);
1823 else if (followfork < 2)
1824 shared_log = strace_fopen(outfname);
1826 /* -ff without -o FILE is the same as single -f */
1827 if (followfork >= 2)
1831 if (!outfname || outfname[0] == '|' || outfname[0] == '!') {
1832 char *buf = xmalloc(BUFSIZ);
1833 setvbuf(shared_log, buf, _IOLBF, BUFSIZ);
1835 if (outfname && argv[0]) {
1837 opt_intr = INTR_NEVER;
1842 opt_intr = INTR_WHILE_WAIT;
1844 /* argv[0] -pPID -oFILE Default interactive setting
1845 * yes * 0 INTR_WHILE_WAIT
1846 * no 1 0 INTR_WHILE_WAIT
1847 * yes * 1 INTR_NEVER
1848 * no 1 1 INTR_WHILE_WAIT
1851 sigemptyset(&empty_set);
1852 sigemptyset(&blocked_set);
1854 /* startup_child() must be called before the signal handlers get
1855 * installed below as they are inherited into the spawned process.
1856 * Also we do not need to be protected by them as during interruption
1857 * in the startup_child() mode we kill the spawned process anyway.
1860 if (!NOMMU_SYSTEM || daemonized_tracer)
1861 hide_log_until_execve = 1;
1862 skip_one_b_execve = 1;
1863 startup_child(argv);
1866 sa.sa_handler = SIG_IGN;
1867 sigemptyset(&sa.sa_mask);
1869 sigaction(SIGTTOU, &sa, NULL); /* SIG_IGN */
1870 sigaction(SIGTTIN, &sa, NULL); /* SIG_IGN */
1871 if (opt_intr != INTR_ANYWHERE) {
1872 if (opt_intr == INTR_BLOCK_TSTP_TOO)
1873 sigaction(SIGTSTP, &sa, NULL); /* SIG_IGN */
1875 * In interactive mode (if no -o OUTFILE, or -p PID is used),
1876 * fatal signals are blocked while syscall stop is processed,
1877 * and acted on in between, when waiting for new syscall stops.
1878 * In non-interactive mode, signals are ignored.
1880 if (opt_intr == INTR_WHILE_WAIT) {
1881 sigaddset(&blocked_set, SIGHUP);
1882 sigaddset(&blocked_set, SIGINT);
1883 sigaddset(&blocked_set, SIGQUIT);
1884 sigaddset(&blocked_set, SIGPIPE);
1885 sigaddset(&blocked_set, SIGTERM);
1886 sa.sa_handler = interrupt;
1888 /* SIG_IGN, or set handler for these */
1889 sigaction(SIGHUP, &sa, NULL);
1890 sigaction(SIGINT, &sa, NULL);
1891 sigaction(SIGQUIT, &sa, NULL);
1892 sigaction(SIGPIPE, &sa, NULL);
1893 sigaction(SIGTERM, &sa, NULL);
1895 if (nprocs != 0 || daemonized_tracer)
1898 /* Do we want pids printed in our -o OUTFILE?
1899 * -ff: no (every pid has its own file); or
1900 * -f: yes (there can be more pids in the future); or
1901 * -p PID1,PID2: yes (there are already more than one pid)
1903 print_pid_pfx = (outfname && followfork < 2 && (followfork == 1 || nprocs > 1));
1914 for (i = 0; i < tcbtabsize; i++) {
1915 struct tcb *tcp = tcbtab[i];
1916 if (tcp->pid == pid)
1930 /* 'interrupted' is a volatile object, fetch it only once */
1931 fatal_sig = interrupted;
1933 fatal_sig = SIGTERM;
1935 for (i = 0; i < tcbtabsize; i++) {
1940 error_msg("cleanup: looking at pid %u", tcp->pid);
1941 if (tcp->pid == strace_child) {
1942 kill(tcp->pid, SIGCONT);
1943 kill(tcp->pid, fatal_sig);
1948 call_summary(shared_log);
1958 print_debug_info(const int pid, int status)
1960 const unsigned int event = (unsigned int) status >> 16;
1961 char buf[sizeof("WIFEXITED,exitcode=%u") + sizeof(int)*3 /*paranoia:*/ + 16];
1962 char evbuf[sizeof(",EVENT_VFORK_DONE (%u)") + sizeof(int)*3 /*paranoia:*/ + 16];
1965 if (WIFSIGNALED(status))
1967 sprintf(buf, "WIFSIGNALED,%ssig=%s",
1968 WCOREDUMP(status) ? "core," : "",
1969 signame(WTERMSIG(status)));
1971 sprintf(buf, "WIFSIGNALED,sig=%s",
1972 signame(WTERMSIG(status)));
1974 if (WIFEXITED(status))
1975 sprintf(buf, "WIFEXITED,exitcode=%u", WEXITSTATUS(status));
1976 if (WIFSTOPPED(status))
1977 sprintf(buf, "WIFSTOPPED,sig=%s", signame(WSTOPSIG(status)));
1979 /* Should never be seen */
1980 if (WIFCONTINUED(status))
1981 strcpy(buf, "WIFCONTINUED");
1985 static const char *const event_names[] = {
1986 [PTRACE_EVENT_CLONE] = "CLONE",
1987 [PTRACE_EVENT_FORK] = "FORK",
1988 [PTRACE_EVENT_VFORK] = "VFORK",
1989 [PTRACE_EVENT_VFORK_DONE] = "VFORK_DONE",
1990 [PTRACE_EVENT_EXEC] = "EXEC",
1991 [PTRACE_EVENT_EXIT] = "EXIT",
1992 /* [PTRACE_EVENT_STOP (=128)] would make biggish array */
1994 const char *e = "??";
1995 if (event < ARRAY_SIZE(event_names))
1996 e = event_names[event];
1997 else if (event == PTRACE_EVENT_STOP)
1999 sprintf(evbuf, ",EVENT_%s (%u)", e, event);
2001 error_msg("[wait(0x%06x) = %u] %s%s", status, pid, buf, evbuf);
2005 maybe_allocate_tcb(const int pid, int status)
2007 if (!WIFSTOPPED(status)) {
2008 if (detach_on_execve && pid == strace_child) {
2009 /* example: strace -bexecve sh -c 'exec true' */
2014 * This can happen if we inherited an unknown child.
2015 * Example: (sleep 1 & exec strace true)
2017 error_msg("Exit of unknown pid %u ignored", pid);
2021 /* We assume it's a fork/vfork/clone child */
2022 struct tcb *tcp = alloctcb(pid);
2023 tcp->flags |= TCB_ATTACHED | TCB_STARTUP | post_attach_sigstop;
2026 error_msg("Process %d attached", pid);
2029 /* This can happen if a clone call used
2030 * CLONE_PTRACE itself.
2032 ptrace(PTRACE_CONT, pid, NULL, 0);
2033 error_msg("Stop of unknown pid %u seen, PTRACE_CONTed it", pid);
2039 maybe_switch_tcbs(struct tcb *tcp, const int pid)
2042 struct tcb *execve_thread;
2045 if (ptrace(PTRACE_GETEVENTMSG, pid, NULL, (long) &old_pid) < 0)
2047 /* Avoid truncation in pid2tcb() param passing */
2048 if (old_pid <= 0 || old_pid == pid)
2050 if ((unsigned long) old_pid > UINT_MAX)
2052 execve_thread = pid2tcb(old_pid);
2053 /* It should be !NULL, but I feel paranoid */
2057 if (execve_thread->curcol != 0) {
2059 * One case we are here is -ff:
2060 * try "strace -oLOG -ff test/threaded_execve"
2062 fprintf(execve_thread->outf, " <pid changed to %d ...>\n", pid);
2063 /*execve_thread->curcol = 0; - no need, see code below */
2065 /* Swap output FILEs (needed for -ff) */
2066 fp = execve_thread->outf;
2067 execve_thread->outf = tcp->outf;
2069 /* And their column positions */
2070 execve_thread->curcol = tcp->curcol;
2072 /* Drop leader, but close execve'd thread outfile (if -ff) */
2074 /* Switch to the thread, reusing leader's outfile and pid */
2075 tcp = execve_thread;
2077 if (cflag != CFLAG_ONLY_STATS) {
2079 tprintf("+++ superseded by execve in pid %lu +++\n", old_pid);
2081 tcp->flags |= TCB_REPRINT;
2088 print_signalled(struct tcb *tcp, const int pid, int status)
2090 if (pid == strace_child) {
2091 exit_code = 0x100 | WTERMSIG(status);
2095 if (cflag != CFLAG_ONLY_STATS
2096 && (qual_flags[WTERMSIG(status)] & QUAL_SIGNAL)
2100 tprintf("+++ killed by %s %s+++\n",
2101 signame(WTERMSIG(status)),
2102 WCOREDUMP(status) ? "(core dumped) " : "");
2104 tprintf("+++ killed by %s +++\n",
2105 signame(WTERMSIG(status)));
2112 print_exited(struct tcb *tcp, const int pid, int status)
2114 if (pid == strace_child) {
2115 exit_code = WEXITSTATUS(status);
2119 if (cflag != CFLAG_ONLY_STATS &&
2122 tprintf("+++ exited with %d +++\n", WEXITSTATUS(status));
2128 print_stopped(struct tcb *tcp, const siginfo_t *si, const unsigned int sig)
2130 if (cflag != CFLAG_ONLY_STATS
2131 && !hide_log_until_execve
2132 && (qual_flags[sig] & QUAL_SIGNAL)
2136 tprintf("--- %s ", signame(sig));
2140 tprintf("--- stopped by %s ---\n", signame(sig));
2146 startup_tcb(struct tcb *tcp)
2149 error_msg("pid %d has TCB_STARTUP, initializing it", tcp->pid);
2151 tcp->flags &= ~TCB_STARTUP;
2155 error_msg("setting opts 0x%x on pid %d",
2156 ptrace_setoptions, tcp->pid);
2157 if (ptrace(PTRACE_SETOPTIONS, tcp->pid, NULL, ptrace_setoptions) < 0) {
2158 if (errno != ESRCH) {
2159 /* Should never happen, really */
2160 perror_msg_and_die("PTRACE_SETOPTIONS");
2166 /* Returns true iff the main trace loop has to continue. */
2183 * Used to exit simply when nprocs hits zero, but in this testcase:
2184 * int main() { _exit(!!fork()); }
2185 * under strace -f, parent sometimes (rarely) manages
2186 * to exit before we see the first stop of the child,
2187 * and we are losing track of it:
2188 * 19923 clone(...) = 19924
2189 * 19923 exit_group(1) = ?
2190 * 19923 +++ exited with 1 +++
2191 * Exiting only when wait() returns ECHILD works better.
2193 if (popen_pid != 0) {
2194 /* However, if -o|logger is in use, we can't do that.
2195 * Can work around that by double-forking the logger,
2196 * but that loses the ability to wait for its completion
2197 * on exit. Oh well...
2204 sigprocmask(SIG_SETMASK, &empty_set, NULL);
2205 pid = wait4(-1, &status, __WALL, (cflag ? &ru : NULL));
2208 sigprocmask(SIG_BLOCK, &blocked_set, NULL);
2211 if (wait_errno == EINTR)
2213 if (nprocs == 0 && wait_errno == ECHILD)
2216 * If nprocs > 0, ECHILD is not expected,
2217 * treat it as any other error here:
2220 perror_msg_and_die("wait4(__WALL)");
2223 if (pid == popen_pid) {
2224 if (!WIFSTOPPED(status))
2230 print_debug_info(pid, status);
2232 /* Look up 'pid' in our table. */
2236 tcp = maybe_allocate_tcb(pid, status);
2241 if (WIFSTOPPED(status))
2246 event = (unsigned int) status >> 16;
2248 if (event == PTRACE_EVENT_EXEC) {
2250 * Under Linux, execve changes pid to thread leader's pid,
2251 * and we see this changed pid on EVENT_EXEC and later,
2252 * execve sysexit. Leader "disappears" without exit
2253 * notification. Let user know that, drop leader's tcb,
2254 * and fix up pid in execve thread's tcb.
2255 * Effectively, execve thread's tcb replaces leader's tcb.
2257 * BTW, leader is 'stuck undead' (doesn't report WIFEXITED
2258 * on exit syscall) in multithreaded programs exactly
2259 * in order to handle this case.
2261 * PTRACE_GETEVENTMSG returns old pid starting from Linux 3.0.
2262 * On 2.6 and earlier, it can return garbage.
2264 if (os_release >= KERNEL_VERSION(3,0,0))
2265 tcp = maybe_switch_tcbs(tcp, pid);
2267 if (detach_on_execve && !skip_one_b_execve) {
2268 detach(tcp); /* do "-b execve" thingy */
2271 skip_one_b_execve = 0;
2274 /* Set current output file */
2278 tv_sub(&tcp->dtime, &ru.ru_stime, &tcp->stime);
2279 tcp->stime = ru.ru_stime;
2282 if (WIFSIGNALED(status)) {
2283 print_signalled(tcp, pid, status);
2288 if (WIFEXITED(status)) {
2289 print_exited(tcp, pid, status);
2294 if (!WIFSTOPPED(status)) {
2296 * Neither signalled, exited or stopped.
2297 * How could that be?
2299 error_msg("pid %u not stopped!", pid);
2304 /* Is this the very first time we see this tracee stopped? */
2305 if (tcp->flags & TCB_STARTUP) {
2307 if (get_scno(tcp) == 1)
2308 tcp->s_prev_ent = tcp->s_ent;
2311 sig = WSTOPSIG(status);
2316 if (event == PTRACE_EVENT_STOP) {
2318 * PTRACE_INTERRUPT-stop or group-stop.
2319 * PTRACE_INTERRUPT-stop has sig == SIGTRAP here.
2331 goto restart_tracee_with_sig_0;
2335 * Is this post-attach SIGSTOP?
2336 * Interestingly, the process may stop
2337 * with STOPSIG equal to some other signal
2338 * than SIGSTOP if we happend to attach
2339 * just before the process takes a signal.
2341 if (sig == SIGSTOP && (tcp->flags & TCB_IGNORE_ONE_SIGSTOP)) {
2343 error_msg("ignored SIGSTOP on pid %d", tcp->pid);
2344 tcp->flags &= ~TCB_IGNORE_ONE_SIGSTOP;
2345 goto restart_tracee_with_sig_0;
2348 if (sig != syscall_trap_sig) {
2352 * True if tracee is stopped by signal
2353 * (as opposed to "tracee received signal").
2354 * TODO: shouldn't we check for errno == EINVAL too?
2355 * We can get ESRCH instead, you know...
2357 stopped = ptrace(PTRACE_GETSIGINFO, pid, 0, (long) &si) < 0;
2361 print_stopped(tcp, stopped ? NULL : &si, sig);
2364 /* It's signal-delivery-stop. Inject the signal */
2365 goto restart_tracee;
2367 /* It's group-stop */
2370 * This ends ptrace-stop, but does *not* end group-stop.
2371 * This makes stopping signals work properly on straced process
2372 * (that is, process really stops. It used to continue to run).
2374 if (ptrace_restart(PTRACE_LISTEN, tcp, 0) < 0) {
2375 /* Note: ptrace_restart emitted error message */
2381 /* We don't have PTRACE_LISTEN support... */
2382 goto restart_tracee;
2385 /* We handled quick cases, we are permitted to interrupt now. */
2390 * This should be syscall entry or exit.
2393 if (trace_syscall(tcp) < 0) {
2395 * ptrace() failed in trace_syscall().
2396 * Likely a result of process disappearing mid-flight.
2397 * Observed case: exit_group() or SIGKILL terminating
2398 * all processes in thread group.
2399 * We assume that ptrace error was caused by process death.
2400 * We used to detach(tcp) here, but since we no longer
2401 * implement "detach before death" policy/hack,
2402 * we can let this process to report its death to us
2403 * normally, via WIFEXITED or WIFSIGNALED wait status.
2408 restart_tracee_with_sig_0:
2412 if (ptrace_restart(PTRACE_SYSCALL, tcp, sig) < 0) {
2413 /* Note: ptrace_restart emitted error message */
2422 main(int argc, char *argv[])
2426 exit_code = !nprocs;
2433 if (shared_log != stderr)
2436 while (waitpid(popen_pid, NULL, 0) < 0 && errno == EINTR)
2439 if (exit_code > 0xff) {
2440 /* Avoid potential core file clobbering. */
2441 struct_rlimit rlim = {0, 0};
2442 set_rlimit(RLIMIT_CORE, &rlim);
2444 /* Child was killed by a signal, mimic that. */
2446 signal(exit_code, SIG_DFL);
2448 /* Paranoia - what if this signal is not fatal?
2449 Exit with 128 + signo then. */