Question

android is a kind of linux,and it must support the posix.But,when it seems not support the syscall,open().
Here is the code for testing,and i compile it via NDK:

#include <unistd.h>
#include <stdio.h>
#include<sys/types.h>
#include<sys/stat.h>
#include<fcntl.h>

void main(){
    int fd;
    char pathname[128] = "/data/pwrite.txt";
    fd = open(pathname, O_WRONLY);
    if(fd==-1){
        printf("open fail.\n");

    }
    perror("/data/pwrite.txt");
}

and the following is the prompt that comes from android:

kaiwii@ubuntu:~$ adb shell /data/pwrite/test1
open fail.
/data/pwrite.txt: No such file or directory

Answer 1

I think that the problem is in the flags – you only use O_WRONLY. But if a file does not exist you should also create it using O_CREAT flag. So if a file does not exist you should call:

fd = open(pathname, O_WRONLY | O_CREAT);