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[Bug threads/10227] New: GDB resumes inferior unexpectedly when receiving ignored signal; step/next behave as continue
- From: "ppluzhnikov at google dot com" <sourceware-bugzilla at sourceware dot org>
- To: gdb-prs at sourceware dot org
- Date: 2 Jun 2009 06:15:32 -0000
- Subject: [Bug threads/10227] New: GDB resumes inferior unexpectedly when receiving ignored signal; step/next behave as continue
- Reply-to: sourceware-bugzilla at sourceware dot org
Reproduces in 32 and 64-bit mode using CVS Head.
The test case below generates endless stream of SIGPIPEs, which are
SIG_IGNored.
When "handle SIGPIPE nostop noprint pass" is in effect, everything works
as expected.
But when "handle SIGPIPE nostop print pass", then executing "next" turns
into "continue" instead, as can be seen in this log:
$ gdb64-cvs ./a.out
GNU gdb (GDB) 6.8.50.20090601-cvs
...
This GDB was configured as "x86_64-unknown-linux-gnu".
For bug reporting instructions, please see:
<http://www.gnu.org/software/gdb/bugs/>...
(gdb) b foo
Breakpoint 1 at 0x40070d: file sigpipe.c, line 22.
(gdb) handle SIGPIPE nostop print pass
(gdb) run
[Thread debugging using libthread_db enabled]
[New Thread 0x40800950 (LWP 29291)]
Breakpoint 1, foo () at sigpipe.c:22
22 return 42;
(gdb) finish
0x00000000004007a7 in main () at sigpipe.c:53
53 int x = foo();
Value returned is $1 = 42
(gdb) next
54 bar(x);
(gdb) next
Program received signal SIGPIPE, Broken pipe.
Breakpoint 1, foo () at sigpipe.c:22 <<< How did we end up inside foo() ???
22 return 42; <<< We should have stopped on line 53.
--- cut ---
/* compile with "gcc -pthread -g t.c"
* Test program generates an endless stream of SIGPIPE in second thread. */
#include <stdlib.h>
#include <unistd.h>
#include <signal.h>
#include <pthread.h>
void *fn(void *p)
{
int fd = *(int*)p;
while (1) {
int x = 1;
x++;
x++;
write(fd, &x, sizeof(x));
}
}
int foo()
{
return 42;
}
int bar(int x)
{
return x - 1;
}
int main()
{
int fd[2];
pthread_t tid;
signal(SIGPIPE, SIG_IGN);
if (pipe(fd) == -1)
return 1;
switch (fork()) {
case 0:
/* child */
exit(0);
case -1:
return 1;
default:
/* parent */
close(fd[0]);
pthread_create(&tid, 0, fn, &fd[1]);
}
while (1) {
int x = foo();
bar(x);
}
return 0;
}
--- cut ---
--
Summary: GDB resumes inferior unexpectedly when receiving ignored
signal; step/next behave as continue
Product: gdb
Version: 6.8
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: threads
AssignedTo: unassigned at sourceware dot org
ReportedBy: ppluzhnikov at google dot com
CC: gdb-prs at sourceware dot org
GCC build triplet: x86_64-unknown-linux-gnu
GCC host triplet: x86_64-unknown-linux-gnu
GCC target triplet: x86_64-unknown-linux-gnu
http://sourceware.org/bugzilla/show_bug.cgi?id=10227
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