未定义的引用property_get [英] undefined reference to property_get

问题描述

我的目标做微调，以找到合适的线程优先级。

My aims to do fine tuning to find proper thread priority.

线程我关注的是位于下/硬件/ my_company / codeC / openmax_il /

The thread I concern is located in under /hardware/my_company/codec/openmax_il/

我修改两个文件

1. Android.mk

1. Android.mk

在LOCAL_C_INCLUDES列表中添加$（TOP）/系统/核心/包括，如下图

Add "$(TOP)/system/core/include" in the list of LOCAL_C_INCLUDES as below

LOCAL_C_INCLUDES:= \

    blur blur blur
    $(TOP)/hardware/my_company/camera/v4l2_camerahal \
    $(TOP)/system/core/include

在我的源文件。

In my source file.

#include <cutils/properties.h>

int componentInit(blur blur blur)
{
   int ret = 0;

   blur blur blur

   // To find proper thread priority
   char value[92];
   property_get("omx.video_enc.priority", value, "0");
   setVideoEncoderPriority(atoi(value));

   return ret;
}

不过，我遇到的链接错误

But, I encountered the linking error of

 error: undefined reference to 'property_get'
 collect2: ld returned 1 exit status

如果有人可以帮助这一点，那将是对我好。 ：）

If anyone helps this, it would be good to me. :)

感谢

推荐答案

这听起来像你想使用 __ system_property_get（），这是定义在＆LT; SYS / system_properties.h＆GT; 。从标题：

It sounds like you want to use __system_property_get(), which is defined in <sys/system_properties.h>. From that header:

/* Look up a system property by name, copying its value and a
** \0 terminator to the provided pointer.  The total bytes
** copied will be no greater than PROP_VALUE_MAX.  Returns
** the string length of the value.  A property that is not
** defined is identical to a property with a length 0 value.
*/
int __system_property_get(const char *name, char *value);

这签名是不是正是你要寻找的使用，因为你有没有定义属性时的默认值是什么。由于 __ system_property_get（）中的财产没有被定义的事件返回0，你可以很容易地补充自己动手。

This signature is not exactly what you're looking to use, since you have a default value in the event the property isn't defined. Since __system_property_get() returns 0 in the event of the property not being defined, you can easily supplement this yourself.

下面是如何我已经解决了这个问题在我自己的本土code，它很适合我（虽然缺少缓冲区溢出检查，这将是一个更好的解决方案的话）：

Here is how I've solved the issue in my own native code, and it works well for me (though it is lacking buffer overflow checking, which would be a better solution):

#include <sys/system_properties.h>
int android_property_get(const char *key, char *value, const char *default_value)
{
    int iReturn = __system_property_get(key, value);
    if (!iReturn) strcpy(value, default_value);
    return iReturn;
}

这篇关于未定义的引用property_get的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！