RE: mmap(): enodev

May 25, 2014

      Hello,

thanks a lot, Sunday is never a good day for working, what a mistake :-) !
___________
From: Pawan Prakash Sharma [pawanprakash101@gmail.com]
Sent: 25 May 2014 15:19
To: Pietro Paolini
Cc: kernelnewbies@kernelnewbies.org
Subject: Re: mmap(): enodev

Hi Pietro,

Following line is buggy one

if ((fd = open(FILENAME, O_RDWR) == -1)) <--- here fd will have
Boolean value only

it should be

if ((fd = open(FILENAME, O_RDWR)) == -1)

Check the operator precedence for more clarification. Also I hope the
file you are opening already exists.

Regards,
-Pawan

On Sun, May 25, 2014 at 6:16 PM, Pietro Paolini <P.Paolini@genexis.eu> wrote:
...
Hello everyone,
in order to try to use mmap() to perform IPC I am writing a test program like this :
int main(char **argv, int argn)
{
        char *addr;
        int fd;
if ((fd = open(FILENAME, O_RDWR) == -1)) {
                perror("open:");
                exit(1);
        }
        addr = mmap(NULL, SIZE, PROT_READ | PROT_WRITE, MAP_SHARED, fd, 0);
        if (addr == MAP_FAILED) {
                printf("mmap() : %p %s", addr, strerror(errno));
                exit(1);
        }
        close(fd);
....
I am running under
Linux crunchbang 3.2.0-4-amd64 #1 SMP Debian 3.2.54-2 x86_64 GNU/Linux
My problem is that everytime I have got an "No such device" error which I don't fully get, could a problem of my platoform
or am I simply doing something wrong ?
Thanks all,
Pietro
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