platform_system_core/debuggerd/utility.c

/* system/debuggerd/utility.c
**
** Copyright 2008, The Android Open Source Project
**
** Licensed under the Apache License, Version 2.0 (the "License"); 
** you may not use this file except in compliance with the License. 
** You may obtain a copy of the License at 
**
**     http://www.apache.org/licenses/LICENSE-2.0 
**
** Unless required by applicable law or agreed to in writing, software 
** distributed under the License is distributed on an "AS IS" BASIS, 
** WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 
** See the License for the specific language governing permissions and 
** limitations under the License.
*/

#include <stddef.h>
#include <stdbool.h>
#include <stdio.h>
#include <string.h>
#include <errno.h>
#include <unistd.h>
#include <signal.h>
#include <cutils/logd.h>
#include <sys/ptrace.h>
#include <sys/wait.h>

#include "utility.h"

const int sleep_time_usec = 50000;         /* 0.05 seconds */
const int max_total_sleep_usec = 10000000; /* 10 seconds */

void _LOG(log_t* log, bool in_tombstone_only, const char *fmt, ...) {
    char buf[512];

    va_list ap;
    va_start(ap, fmt);

    if (log && log->tfd >= 0) {
        int len;
        vsnprintf(buf, sizeof(buf), fmt, ap);
        len = strlen(buf);
        write(log->tfd, buf, len);
    }

    if (!in_tombstone_only && (!log || !log->quiet)) {
        __android_log_vprint(ANDROID_LOG_INFO, "DEBUG", fmt, ap);
    }
    va_end(ap);
}

int wait_for_signal(pid_t tid, int* total_sleep_time_usec) {
    for (;;) {
        int status;
        pid_t n = waitpid(tid, &status, __WALL | WNOHANG);
        if (n < 0) {
            if(errno == EAGAIN) continue;
            LOG("waitpid failed: %s\n", strerror(errno));
            return -1;
        } else if (n > 0) {
            XLOG("waitpid: n=%d status=%08x\n", n, status);
            if (WIFSTOPPED(status)) {
                return WSTOPSIG(status);
            } else {
                LOG("unexpected waitpid response: n=%d, status=%08x\n", n, status);
                return -1;
            }
        }

        if (*total_sleep_time_usec > max_total_sleep_usec) {
            LOG("timed out waiting for tid=%d to die\n", tid);
            return -1;
        }

        /* not ready yet */
        XLOG("not ready yet\n");
        usleep(sleep_time_usec);
        *total_sleep_time_usec += sleep_time_usec;
    }
}

void wait_for_stop(pid_t tid, int* total_sleep_time_usec) {
    siginfo_t si;
    while (TEMP_FAILURE_RETRY(ptrace(PTRACE_GETSIGINFO, tid, 0, &si)) < 0 && errno == ESRCH) {
        if (*total_sleep_time_usec > max_total_sleep_usec) {
            LOG("timed out waiting for tid=%d to stop\n", tid);
            break;
        }

        usleep(sleep_time_usec);
        *total_sleep_time_usec += sleep_time_usec;
    }
}