Cleanups on top of "handle SIGTRAP properly" change,
based on Dmitry's comments. * defs.h ([p]error_msg[_and_die]): Declare new functions. * strace.c (SYSCALLTRAP): Rename to syscall_trap_sig. ([p]error_msg[_and_die]): Define new functions. (strace_tracer_pid): New variable, it controls which pid will do cleanup on exit via [p]error_msg_and_die. (main): Set strace_tracer_pid to our initial pid. (startup_attach): Change strace_tracer_pid if we are in -D mode. (test_ptrace_setoptions_for_all): Minor changes to logic, such as better diagnostic messages.
This commit is contained in:
Denys Vlasenko
parent
35aba6a8dd
commit
75422766d5
15
defs.h
15
defs.h
@ -339,6 +339,10 @@ extern int mp_ioctl (int f, int c, void *a, int s);
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# endif
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#endif /* LINUX */
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#if !defined __GNUC__
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# define __attribute__(x) /*nothing*/
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#endif
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/* Trace Control Block */
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struct tcb {
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short flags; /* See below for TCB_ values */
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@ -515,6 +519,11 @@ extern struct tcb *tcp_last;
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enum bitness_t { BITNESS_CURRENT = 0, BITNESS_32 };
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void error_msg(const char *fmt, ...) __attribute__ ((format(printf, 1, 2)));
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void perror_msg(const char *fmt, ...) __attribute__ ((format(printf, 1, 2)));
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void error_msg_and_die(const char *fmt, ...) __attribute__ ((noreturn, format(printf, 1, 2)));
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void perror_msg_and_die(const char *fmt, ...) __attribute__ ((noreturn, format(printf, 1, 2)));
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extern int set_personality(int personality);
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extern const char *xlookup(const struct xlat *, int);
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extern struct tcb *alloc_tcb(int, int);
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@ -630,11 +639,7 @@ extern int proc_open(struct tcb *tcp, int attaching);
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#define printtv_special(tcp, addr) \
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printtv_bitness((tcp), (addr), BITNESS_CURRENT, 1)
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extern void tprintf(const char *fmt, ...)
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#ifdef __GNUC__
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__attribute__ ((format (printf, 1, 2)))
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#endif
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;
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extern void tprintf(const char *fmt, ...) __attribute__ ((format (printf, 1, 2)));
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#ifndef HAVE_STRERROR
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const char *strerror(int);
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116
strace.c
116
strace.c
@ -87,7 +87,7 @@ int debug = 0, followfork = 0;
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unsigned int ptrace_setoptions_followfork = 0;
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unsigned int ptrace_setoptions_for_all = 0;
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/* Which WSTOPSIG(status) value marks syscall traps? */
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static unsigned int SYSCALLTRAP = SIGTRAP;
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static unsigned int syscall_trap_sig = SIGTRAP;
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int dtime = 0, xflag = 0, qflag = 0;
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cflag_t cflag = CFLAG_NONE;
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static int iflag = 0, interactive = 0, pflag_seen = 0, rflag = 0, tflag = 0;
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@ -116,6 +116,7 @@ int tracing_paths = 0;
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static int exit_code = 0;
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static int strace_child = 0;
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static int strace_tracer_pid = 0;
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static char *username = NULL;
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uid_t run_uid;
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@ -215,29 +216,62 @@ usage: strace [-CdDffhiqrtttTvVxxy] [-a column] [-e expr] ... [-o file]\n\
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exit(exitval);
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}
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static void error_msg_and_die(const char *fmt, ...)
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#if defined __GNUC__
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__attribute__ ((noreturn, format(printf, 1, 2)))
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#endif
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;
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static void error_msg_and_die(const char *fmt, ...)
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static void die(void) __attribute__ ((noreturn));
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static void die(void)
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{
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if (strace_tracer_pid == getpid()) {
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cflag = 0;
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cleanup();
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}
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exit(1);
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}
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static void verror_msg(int err_no, const char *fmt, va_list p)
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{
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char *msg;
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va_list p;
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va_start(p, fmt);
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msg = NULL;
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vasprintf(&msg, fmt, p);
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if (msg) {
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fprintf(stderr, "%s: %s\n", progname, msg);
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fflush(NULL);
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if (err_no)
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fprintf(stderr, "%s: %s: %s\n", progname, msg, strerror(err_no));
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else
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fprintf(stderr, "%s: %s\n", progname, msg);
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free(msg);
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}
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va_end(p);
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}
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/* TODO? cflag = 0; -- or else cleanup() may print summary */
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cleanup();
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fflush(NULL);
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_exit(1);
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void error_msg(const char *fmt, ...)
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{
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va_list p;
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va_start(p, fmt);
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verror_msg(0, fmt, p);
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va_end(p);
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}
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void error_msg_and_die(const char *fmt, ...)
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{
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va_list p;
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va_start(p, fmt);
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verror_msg(0, fmt, p);
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die();
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}
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void perror_msg(const char *fmt, ...)
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{
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va_list p;
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va_start(p, fmt);
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verror_msg(errno, fmt, p);
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va_end(p);
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}
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void perror_msg_and_die(const char *fmt, ...)
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{
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va_list p;
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va_start(p, fmt);
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verror_msg(errno, fmt, p);
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die();
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}
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#ifdef SVR4
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@ -429,14 +463,17 @@ startup_attach(void)
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}
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if (pid) { /* parent */
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/*
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* Wait for child to attach to straced process
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* (our parent). Child SIGKILLs us after it attached.
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* Parent's wait() is unblocked by our death,
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* Wait for grandchild to attach to straced process
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* (grandparent). Grandchild SIGKILLs us after it attached.
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* Grandparent's wait() is unblocked by our death,
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* it proceeds to exec the straced program.
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*/
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pause();
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_exit(0); /* paranoia */
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}
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/* grandchild */
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/* We will be the tracer process. Remember our new pid: */
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strace_tracer_pid = getpid();
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}
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for (tcbi = 0; tcbi < tcbtabsize; tcbi++) {
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@ -613,8 +650,8 @@ startup_child (char **argv)
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cleanup();
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exit(1);
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}
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if ((pid != 0 && daemonized_tracer) /* parent: to become a traced process */
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|| (pid == 0 && !daemonized_tracer) /* child: to become a traced process */
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if ((pid != 0 && daemonized_tracer) /* -D: parent to become a traced process */
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|| (pid == 0 && !daemonized_tracer) /* not -D: child to become a traced process */
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) {
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pid = getpid();
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#ifdef USE_PROCFS
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@ -710,6 +747,9 @@ startup_child (char **argv)
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}
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/* We are the tracer. */
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/* With -D, we are *child* here, IOW: different pid. Fetch it. */
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strace_tracer_pid = getpid();
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tcp = alloctcb(daemonized_tracer ? getppid() : pid);
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if (daemonized_tracer) {
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/* We want subsequent startup_attach() to attach to it. */
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@ -817,13 +857,13 @@ test_ptrace_setoptions_for_all(void)
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pid = fork();
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if (pid < 0)
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error_msg_and_die("fork failed");
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perror_msg_and_die("fork");
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if (pid == 0) {
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pid = getpid();
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if (ptrace(PTRACE_TRACEME, 0L, 0L, 0L) < 0)
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/* "parent, something is deeply wrong!" */
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kill(pid, SIGKILL);
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/* Note: exits with exitcode 1 */
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perror_msg_and_die("%s: PTRACE_TRACEME doesn't work", __func__);
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kill(pid, SIGSTOP);
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_exit(0); /* parent should see entry into this syscall */
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}
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@ -837,10 +877,14 @@ test_ptrace_setoptions_for_all(void)
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if (errno == EINTR)
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continue;
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kill(pid, SIGKILL);
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error_msg_and_die("%s: unexpected wait result %d", __func__, tracee_pid);
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perror_msg_and_die("%s: unexpected wait result %d", __func__, tracee_pid);
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}
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if (WIFEXITED(status)) {
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if (WEXITSTATUS(status) == 0)
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break;
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/* PTRACE_TRACEME failed in child. This is fatal. */
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exit(1);
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}
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if (WIFEXITED(status))
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break;
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if (!WIFSTOPPED(status)) {
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kill(pid, SIGKILL);
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error_msg_and_die("%s: unexpected wait status %x", __func__, status);
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@ -852,19 +896,21 @@ test_ptrace_setoptions_for_all(void)
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* and thus will decide to not use the option.
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* IOW: the outcome of the test will be correct.
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*/
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ptrace(PTRACE_SETOPTIONS, pid, 0L, test_options);
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if (ptrace(PTRACE_SETOPTIONS, pid, 0L, test_options) < 0)
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if (errno != EINVAL)
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perror_msg("PTRACE_SETOPTIONS");
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}
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if (WSTOPSIG(status) == (SIGTRAP | 0x80)) {
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it_worked = 1;
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}
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if (ptrace(PTRACE_SYSCALL, pid, 0L, 0L) < 0) {
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kill(pid, SIGKILL);
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error_msg_and_die("PTRACE_SYSCALL doesn't work");
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perror_msg_and_die("PTRACE_SYSCALL doesn't work");
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}
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}
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if (it_worked) {
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SYSCALLTRAP = (SIGTRAP | 0x80);
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syscall_trap_sig = (SIGTRAP | 0x80);
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ptrace_setoptions_for_all = test_options;
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if (debug)
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fprintf(stderr, "ptrace_setoptions_for_all = %#x\n",
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@ -889,6 +935,8 @@ main(int argc, char *argv[])
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progname = argv[0] ? argv[0] : "strace";
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strace_tracer_pid = getpid();
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/* Allocate the initial tcbtab. */
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tcbtabsize = argc; /* Surely enough for all -p args. */
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if ((tcbtab = calloc(tcbtabsize, sizeof tcbtab[0])) == NULL) {
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@ -1000,7 +1048,7 @@ main(int argc, char *argv[])
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progname, optarg);
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break;
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}
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if (pid == getpid()) {
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if (pid == strace_tracer_pid) {
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fprintf(stderr, "%s: I'm sorry, I can't let you do that, Dave.\n", progname);
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break;
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}
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@ -1863,7 +1911,7 @@ int sig;
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break;
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}
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error = ptrace_restart(PTRACE_CONT, tcp,
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WSTOPSIG(status) == SYSCALLTRAP ? 0
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WSTOPSIG(status) == syscall_trap_sig ? 0
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: WSTOPSIG(status));
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if (error < 0)
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break;
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@ -2525,6 +2573,8 @@ handle_ptrace_event(int status, struct tcb *tcp)
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fprintf(stderr, "PTRACE_EVENT_EXEC on pid %d (ignored)\n", tcp->pid);
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return 0;
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}
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/* Some PTRACE_EVENT_foo we didn't ask for?! */
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error_msg("Unexpected status %x on pid %d", status, tcp->pid);
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return 1;
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}
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#endif
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@ -2756,7 +2806,7 @@ Process %d attached (waiting for parent)\n",
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if (ptrace(PTRACE_SETOPTIONS, tcp->pid, NULL, options) < 0) {
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if (errno != ESRCH) {
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/* Should never happen, really */
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error_msg_and_die("PTRACE_SETOPTIONS");
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perror_msg_and_die("PTRACE_SETOPTIONS");
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}
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}
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}
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@ -2764,7 +2814,7 @@ Process %d attached (waiting for parent)\n",
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goto tracing;
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}
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if (WSTOPSIG(status) != SYSCALLTRAP) {
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if (WSTOPSIG(status) != syscall_trap_sig) {
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if (WSTOPSIG(status) == SIGSTOP &&
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(tcp->flags & TCB_SIGTRAPPED)) {
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/*
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