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Message-ID: <afd776760511271057l5e3c4e3fq14b0b9ba4cdc7c9a@mail.gmail.com>
Date: Sun, 27 Nov 2005 12:57:47 -0600
From: Mohamed El Dawy <msdawy@gmail.com>
To: linux-kernel@vger.kernel.org
Subject: What's wrong with this really simple function?
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Hi,
 I have created this 5-liner system call, which basically opens a
file, write "Hello World" to it, and then returns. That's all.

Now, when I actually call it, it creates the file successfully but
writes nothing to it. The file is created and is only zero bytes. So,
either write didn't write, or close didn't close. Any help would be
greatly appreciated.

#define SUCCESS 0
#define CANT_OPEN_FILE 1
#define YOU_ARE_NOT_ROOT 3
#define OTHER_STUPID_ERROR 4

asmlinkage long sys_dump(char * filename)
{
    int fd;
    if(!capable(CAP_SYS_ADMIN))
        return YOU_ARE_NOT_ROOT;

    fd=sys_open(filename,O_CREAT|O_WRONLY|O_TRUNC,S_IRWXU);
    if(fd==-1)
        return CANT_OPEN_FILE;

    if(sys_write(fd,"Hello World From inside the kernel!",35)==0)
    {
        sys_close(fd);
        return OTHER_STUPID_ERROR;
    }

    sys_close(fd);
    return SUCCESS;
}
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