用eclipse实现NDK调试常见问题总结

在用eclipse实现NDK调试时遇到了一些问题，现在做一些总结。

1. Method ‘NewStringUTF’ could not be resolved

• CDT的bug，可以通过设置去除检查机制：
  
• 不过这样会去除所有的方法检查，并不是一个好的解决办法。
• 参考http://blog.csdn.net/brokge/article/details/39929525

2. Avoid hardcoding the debug mode

• 也是通过去掉检查机制解决的，具体请参考如下文章http://jingyan.baidu.com/article/636f38bb217a83d6b84610cd.html
• 也可以直接通过在工程根目录下的lint.xml中写入：

<?xml version="1.0" encoding="UTF-8"?><lint>    <issue id="HardcodedDebugMode">        <ignore path="AndroidManifest.xml" />    </issue></lint>

3. ERROR: Could not extract package’s data directory. Are you sure that your installed application is debuggable?

3.1 ndk-gdb.sh脚本

读ndk-gdb.sh脚本，可知上述错误是由以下这段代码引起的：

adb_var_shell2 DATA_DIR run-as $PACKAGE_NAME /system/bin/sh -c pwdif [ $? != 0 -o -z "$DATA_DIR" ] ; then    echo "ERROR: Could not extract package's data directory. Are you sure that"    echo "       your installed application is debuggable?"    exit 1fi

其中$PACKAGE_NAME就是所要调试应用的app的包名。
而run-as $PACKAGE_NAME的原理大概就是获取该app的权限。
在adb shell中执行run-as $PACKAGE_NAME会得到如下信息：

Package $PACKAGE_NAME has corrupt installation

3.2 run-as.c源码

阅读run-as.c源码

    /* check that the data directory path is valid */    if (check_data_path(info.dataDir, info.uid) < 0) {        panic("Package '%s' has corrupt installation\n", pkgname);        return 1;    }

3.3 check_data_path()及check_directory_ownership()

check_data_path()方法定义如下：

/* This function is used to check the data directory path for safety. * We check that every sub-directory is owned by the 'system' user * and exists and is not a symlink. We also check that the full directory * path is properly owned by the user ID. * * Return 0 on success, -1 on error. */intcheck_data_path(const char* dataPath, uid_t  uid){    int  nn;    /* the path should be absolute */    if (dataPath[0] != '/') {        errno = EINVAL;        return -1;    }    /* look for all sub-paths, we do that by finding     * directory separators in the input path and     * checking each sub-path independently     */    for (nn = 1; dataPath[nn] != '\0'; nn++)    {        char subpath[PATH_MAX];        /* skip non-separator characters */        if (dataPath[nn] != '/')            continue;        /* handle trailing separator case */        if (dataPath[nn+1] == '\0') {            break;        }        /* found a separator, check that dataPath is not too long. */        if (nn >= (int)(sizeof subpath)) {            errno = EINVAL;            return -1;        }        /* reject any '..' subpath */        if (nn >= 3               &&            dataPath[nn-3] == '/' &&            dataPath[nn-2] == '.' &&            dataPath[nn-1] == '.') {            errno = EINVAL;            return -1;        }        /* copy to 'subpath', then check ownership */        memcpy(subpath, dataPath, nn);        subpath[nn] = '\0';        if (check_directory_ownership(subpath, AID_SYSTEM) < 0)            return -1;    }    /* All sub-paths were checked, now verify that the full data     * directory is owned by the application uid     */    if (check_directory_ownership(dataPath, uid) < 0)        return -1;    /* all clear */    return 0;}

大概意思就是对/data，/data/data/，及/data/data/$PACKAGE_NAME这几个路径调用 check_directory_ownership()方法。

/* Check that a given directory: * - exists * - is owned by a given uid/gid * - is a real directory, not a symlink * - isn't readable or writable by others * * Return 0 on success, or -1 on error. * errno is set to EINVAL in case of failed check. */static intcheck_directory_ownership(const char* path, uid_t uid){    int ret;    struct stat st;    do {        ret = lstat(path, &st);    } while (ret < 0 && errno == EINTR);    if (ret < 0)        return -1;    /* must be a real directory, not a symlink */    if (!S_ISDIR(st.st_mode))        goto BAD;    /* must be owned by specific uid/gid */    if (st.st_uid != uid || st.st_gid != uid)        goto BAD;    /* must not be readable or writable by others */    if ((st.st_mode & (S_IROTH|S_IWOTH)) != 0)        goto BAD;    /* everything ok */    return 0;BAD:    errno = EINVAL;    return -1;}

3.4 总结

结合check_data_path()方法，可知/data和/data/data两个路径，必须为system所有，根据if (check_directory_ownership(subpath, AID_SYSTEM) < 0)
return -1;这句，而/data，/data/data和/data/data/$PACKAGE_NAME
每个路径均不能对其他用户具有读写权限才可以。根据这些限制对相应路径做修改即可。
我的手机出现问题的原因是/data路径权限是

于是执行chmod 771 /data之后，再次执行ndk-gdb就成功了。

参考http://www.cnblogs.com/dyingbleed/archive/2012/10/07/2713991.html

4.执行ndk-gdb时，报jdb找不到

在执行ndk-gdb时加上-nowait参数
参考http://blog.csdn.net/atlanticevix/article/details/45028797