int my_entrance()
{
if (fork_syscall() == 0) {
// son
while(1) {
print_char('S');
}
} else {
// dad
while(1) {
print_char('D');
}
}
return 0;
}
void
stackdump(void)
{
int pid, core_pid;
/* get name now -- will be same for children */
char *exec_name = get_application_name();
char core_name[128];
char tmp_name[128];
snprintf(tmp_name, 128, "%s.%d", TEMPORARY_FILENAME, get_process_id());
#ifdef VMX86_SERVER
if (os_in_vmkernel_userworld()) {
return; /* no local gdb, no multithreaded fork */
}
#endif
#if VERBOSE
SYSLOG_INTERNAL_ERROR("about to fork parent %d to dump core", get_process_id());
#endif
/* Fork a child to dump core */
pid = fork_syscall();
if (pid == 0) { /* child */
#if VERBOSE
SYSLOG_INTERNAL_ERROR("about to dump core in process %d parent %d thread " TIDFMT
"",
get_process_id(), get_parent_id(), get_thread_id());
#endif
/* We used to use abort here, but that had lots of complications with
* pthreads and libc, so now we just dereference NULL.
*/
if (!set_default_signal_action(SIGSEGV)) {
SYSLOG_INTERNAL_ERROR("ERROR in setting handler");
exit_process_syscall(1);
}
*(volatile int *)NULL = 0;
#if VERBOSE
SYSLOG_INTERNAL_ERROR("about to exit process %d", get_process_id());
#endif
exit_process_syscall(0);
} else if (pid == -1) {
SYSLOG_INTERNAL_ERROR("ERROR: could not fork to dump core");
exit_process_syscall(1);
}
#if VERBOSE
SYSLOG_INTERNAL_ERROR("parent %d %d waiting for child %d", get_process_id(),
get_thread_id(), pid);
#endif
/* Parent continues */
core_pid = pid;
while (wait_syscall(NULL) != pid) {
/* wait for core to be dumped */
}
#if VERBOSE
SYSLOG_INTERNAL_ERROR("about to fork 2nd child to run gdb");
#endif
/* Fork a 2nd child to run gdb */
pid = fork_syscall();
if (pid == 0) { /* child */
file_t fp;
int fd;
const char *argv[16];
int i;
int execve_errno;
/* Open a temporary file for the input: the "where" command */
fp = os_open(tmp_name, OS_OPEN_REQUIRE_NEW | OS_OPEN_WRITE);
os_write(fp, DEBUGGER_COMMAND, strlen(DEBUGGER_COMMAND));
os_close(fp);
fd = open_syscall(tmp_name, O_RDONLY, 0);
if (fd < 0) {
SYSLOG_INTERNAL_ERROR("ERROR: open failed on temporary file");
exit_process_syscall(1);
}
#if !BATCH_MODE
/* Redirect stdin from the temporary file */
close_syscall(0); /* close stdin */
dup_syscall(fd); /* replace file descriptor 0 with reference to temp file */
#endif
close_syscall(fd); /* close the other reference to temporary file */
/* Find the core file */
strncpy(core_name, CORE_NAME, 127);
core_name[127] = '\0'; /* if max no null */
fd = open_syscall(core_name, O_RDONLY, 0);
if (fd < 0) {
snprintf(core_name, 128, "%s.%d", CORE_NAME, core_pid);
SYSLOG_INTERNAL_ERROR("core not found, trying %s", core_name);
fd = open_syscall(core_name, O_RDONLY, 0);
if (fd < 0) {
SYSLOG_INTERNAL_ERROR("ERROR: no core file found!");
exit_process_syscall(1);
}
}
close_syscall(fd);
/* avoid running the debugger under us!
* FIXME: just remove our libraries, instead of entire env var?
*/
unsetenv("LD_PRELOAD");
SYSLOG_INTERNAL_ERROR("-------------------------------------------");
SYSLOG_INTERNAL_ERROR("stackdump: --- now running the debugger ---");
SYSLOG_INTERNAL_ERROR("%s %s %s %s", DEBUGGER, QUIET_MODE, exec_name, core_name);
SYSLOG_INTERNAL_ERROR("-------------------------------------------");
i = 0;
/* We rely on /usr/bin/env to do the PATH search for gdb on our behalf.
*/
argv[i++] = "/usr/bin/env";
argv[i++] = DEBUGGER;
argv[i++] = QUIET_MODE;
#if BATCH_MODE
argv[i++] = "-x";
argv[i++] = tmp_name;
argv[i++] = "-batch";
#endif
argv[i++] = exec_name;
argv[i++] = core_name;
argv[i++] = NULL;
execve_errno = execve_syscall("/usr/bin/env", argv, our_environ);
SYSLOG_INTERNAL_ERROR("ERROR: execve failed for debugger: %d", -execve_errno);
exit_process_syscall(1);
} else if (pid == -1) {
SYSLOG_INTERNAL_ERROR("ERROR: could not fork to run debugger");
exit_process_syscall(1);
}
/* Parent continues */
/* while(wait(NULL)>0) waits for all children, and could hang, so: */
while (wait_syscall(NULL) != pid) {
/* empty loop */
}
/* Wait for these children to complete before returning */
while (wait_syscall(NULL) > 0) {
/* empty loop */
}
os_delete_file(tmp_name); /* clean up the temporary file */
SYSLOG_INTERNAL_ERROR("-------------------------------------------");
}
