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* defs.h: Remove sigtrap80 field from struct tcb.

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* strace.c: Add ptrace_stop_sig static variable
and use it in place of tcp->sigtrap80.
Add ptrace_opts_set static flag variable.
(trace): Set ptrace options once, not per-process.
If unexpected SIGTRAP is later received,
revert back to using SIGTRAP
(assume old, broken kernel).
This commit is contained in:
Denys Vlasenko 2008-12-29 19:13:27 +00:00
parent b1efe53531
commit 96d5a76109
3 changed files with 31 additions and 26 deletions
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11
ChangeLog
View File

@ -1,3 +1,14 @@
2008-12-29 Denys Vlasenko <dvlasenk@redhat.com>
* defs.h: Remove sigtrap80 field from struct tcb.
* strace.c: Add ptrace_stop_sig static variable
and use it in place of tcp->sigtrap80.
Add ptrace_opts_set static flag variable.
(trace): Set ptrace options once, not per-process.
If unexpected SIGTRAP is later received,
revert back to using SIGTRAP
(assume old, broken kernel).
2008-12-22 Denys Vlasenko <dvlasenk@redhat.com>
Make strace correctly handle SIGTRAP produced by e.g.

2
defs.h
View File

@ -324,8 +324,6 @@ struct tcb {
int nclone_waiting; /* clone threads in wait4 (TCB_SUSPENDED) */
/* (1st arg of wait4()) */
#endif
int sigtrap80; /* What sig we consider to be ptrace stop */
/* (can be SIGTRAP or (SIGTRAP|0x80) only) */
long baddr; /* `Breakpoint' address */
long inst[2]; /* Instructions on above */
int pfd; /* proc file descriptor */

44
strace.c
View File

@ -77,6 +77,8 @@
#endif
#endif
#endif
extern char **environ;
int debug = 0, followfork = 0;
int dtime = 0, cflag = 0, xflag = 0, qflag = 0;
@ -87,6 +89,8 @@ int not_failing_only = 0;
static int exit_code = 0;
static int strace_child = 0;
static int ptrace_stop_sig = SIGTRAP;
static bool ptrace_opts_set;
static char *username = NULL;
uid_t run_uid;
@ -99,7 +103,6 @@ FILE *outf;
struct tcb **tcbtab;
unsigned int nprocs, tcbtabsize;
char *progname;
extern char **environ;
static int detach P((struct tcb *tcp, int sig));
static int trace P((void));
@ -943,7 +946,6 @@ alloc_tcb(int pid, int command_options_parsed)
tcp->nclone_waiting = 0;
#endif
tcp->flags = TCB_INUSE | TCB_STARTUP;
tcp->sigtrap80 = SIGTRAP;
tcp->outf = outf; /* Initialise to current out file */
tcp->stime.tv_sec = 0;
tcp->stime.tv_usec = 0;
@ -1550,7 +1552,7 @@ int sig;
break;
}
error = ptrace_restart(PTRACE_CONT, tcp,
WSTOPSIG(status) == tcp->sigtrap80 ? 0
WSTOPSIG(status) == ptrace_stop_sig ? 0
: WSTOPSIG(status));
if (error < 0)
break;
@ -2416,17 +2418,24 @@ Process %d attached (waiting for parent)\n",
* on ptrace-generated SIGTRAPs, and mark
* execve's SIGTRAP with PTRACE_EVENT_EXEC.
*/
if (tcp->sigtrap80 == SIGTRAP
&& ptrace(PTRACE_SETOPTIONS, pid, (char *) 0,
(void *) (PTRACE_O_TRACESYSGOOD | PTRACE_O_TRACEEXEC)) == 0) {
tcp->sigtrap80 = SIGTRAP | 0x80;
if (!ptrace_opts_set) {
ptrace_opts_set = 1;
/*
* NB: even if this "succeeds", we can
* revert back to SIGTRAP if we later see
* that it didnt really work.
* Old kernels are known to lie here.
*/
if (ptrace(PTRACE_SETOPTIONS, pid, (char *) 0,
(void *) (PTRACE_O_TRACESYSGOOD | PTRACE_O_TRACEEXEC)) == 0)
ptrace_stop_sig = SIGTRAP | 0x80;
}
#endif
goto tracing;
}
#if defined LINUX && defined PT_SETOPTIONS
if (tcp->sigtrap80 != SIGTRAP && WSTOPSIG(status) == SIGTRAP) {
if (ptrace_stop_sig != SIGTRAP && WSTOPSIG(status) == SIGTRAP) {
/*
* We told ptrace to report SIGTRAP | 0x80 on this process
* but got bare SIGTRAP. This can be a genuine SIGTRAP:
@ -2458,27 +2467,14 @@ Process %d attached (waiting for parent)\n",
if (si.si_signo != SIGTRAP
|| (si.si_code != SI_KERNEL && si.si_code != SI_USER)
) {
fprintf(stderr, "bogus SIGTRAP (si_code:%x), assuming it's ptrace stop\n", si.si_code);
/* Set WSTOPSIG(status) = (SIGTRAP | 0x80). */
status |= 0x8000;
fprintf(stderr, "bogus SIGTRAP (si_code:%x), assuming old kernel\n", si.si_code);
ptrace_stop_sig = SIGTRAP;
}
}
}
if (WSTOPSIG(status) == (SIGTRAP | 0x80)
/* && tcp->sigtrap80 == SIGTRAP - redundant */
) {
/*
* If tcp->sigtrap80 == SIGTRAP but we got it
* ORed with 0x80, it's a CLONE_PTRACEd child
* which inherited "SIGTRAP | 0x80" setting.
* Whee. Just record this remarkable fact.
*/
tcp->sigtrap80 = (SIGTRAP | 0x80);
}
#endif
if (WSTOPSIG(status) != tcp->sigtrap80) {
if (WSTOPSIG(status) != ptrace_stop_sig) {
/* This isn't a ptrace stop. */
if (WSTOPSIG(status) == SIGSTOP &&