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Pass addr=0 instead of 1 into restarting ptrace calls

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While we are at it, fold do_ptrace into its lone caller.
We no longer set tcp->ptrace_errno = ESRCH on ESRC error in upeek.
Other code paths where ptrace fails wern't doing it, and the code which
checks tcp->ptrace_errno even assumes it is never set to ESRCH.
(It was me who added this code sometime ago, so it was my fault
that it was a bit messy)

I ran sigkill_rain test and verified that unfinished syscalls are
still handled correctly.

* util.c (ptrace_restart): Do not pass addr=1 to ptrace(), pass 0 instead.
I have no idea why we were passing 1. Ptrace documentation says
that addr parameter is ignored.
(do_ptrace): Remove this function.
(upeek): Use ptrace() instead of do_ptrace().
* defs.h: Remove do_ptrace() declaration.

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
This commit is contained in:
Denys Vlasenko 2012-03-08 12:13:44 +01:00
parent 4c65c44478
commit 114aefd618
2 changed files with 3 additions and 29 deletions
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1
defs.h
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@ -466,7 +466,6 @@ extern void droptcb(struct tcb *);
extern void set_sortby(const char *);
extern void set_overhead(int);
extern void qualify(const char *);
extern long do_ptrace(int request, struct tcb *tcp, void *addr, void *data);
extern int ptrace_restart(int request, struct tcb *tcp, int sig);
extern int trace_syscall(struct tcb *);
extern void count_syscall(struct tcb *, struct timeval *);

31
util.c
View File

@ -165,31 +165,6 @@ stpcpy(char *dst, const char *src)
}
#endif
/*
* Generic ptrace wrapper which tracks ESRCH errors
* by setting tcp->ptrace_errno to ESRCH.
*
* We assume that ESRCH indicates likely process death (SIGKILL?),
* modulo bugs where process somehow ended up not stopped.
* Unfortunately kernel uses ESRCH for that case too. Oh well.
*
* Currently used by upeek() only.
* TODO: use this in all other ptrace() calls while decoding.
*/
long
do_ptrace(int request, struct tcb *tcp, void *addr, void *data)
{
long l;
errno = 0;
l = ptrace(request, tcp->pid, addr, (long) data);
/* Non-ESRCH errors might be our invalid reg/mem accesses,
* we do not record them. */
if (errno == ESRCH)
tcp->ptrace_errno = ESRCH;
return l;
}
/*
* Used when we want to unblock stopped traced process.
* Should be only used with PTRACE_CONT, PTRACE_DETACH and PTRACE_SYSCALL.
@ -204,7 +179,7 @@ ptrace_restart(int op, struct tcb *tcp, int sig)
const char *msg;
errno = 0;
ptrace(op, tcp->pid, (void *) 1, (long) sig);
ptrace(op, tcp->pid, (void *) 0, (long) sig);
err = errno;
if (!err || err == ESRCH)
return 0;
@ -219,7 +194,7 @@ ptrace_restart(int op, struct tcb *tcp, int sig)
if (op == PTRACE_LISTEN)
msg = "LISTEN";
#endif
perror_msg("ptrace(PTRACE_%s,pid:%d,1,sig:%d)", msg, tcp->pid, sig);
perror_msg("ptrace(PTRACE_%s,pid:%d,sig:%d)", msg, tcp->pid, sig);
return -1;
}
@ -1011,7 +986,7 @@ upeek(struct tcb *tcp, long off, long *res)
long val;
errno = 0;
val = do_ptrace(PTRACE_PEEKUSER, tcp, (char *) off, 0);
val = ptrace(PTRACE_PEEKUSER, tcp->pid, (char *) off, 0);
if (val == -1 && errno) {
if (errno != ESRCH) {
perror_msg("upeek: PTRACE_PEEKUSER pid:%d @0x%lx)", tcp->pid, off);