How to create Unix Domain Socket with a specific permissions in C?

c, sockets, umask, unix, unix-socket

Solution

Another solution is to create a directory with the desired permissions, and then create the socket inside it (example code without any regard for error checking and buffer overflows):

// Create a directory with the proper permissions
mkdir(path, 0700);
// Append the name of the socket
strcat(path, "/socket_name");

// Create the socket normally
sockaddr_un address;
address.sun_family = AF_UNIX;
strcpy(address.sun_path, path);
int fd = socket(AF_UNIX, SOCK_STREAM, 0);
bind(fd, (sockaddr*)(&address), sizeof(address));
listen(fd, 100);

Problem

I have a simple code, like: ``` sockaddr_un address; address.sun_family = AF_UNIX; strcpy(address.sun_path, path); unlink(path); int fd = socket(AF_UNIX, SOCK_STREAM, 0); bind(fd, (sockaddr*)(&address), sizeof(address)); listen(fd, 100); ``` I want to atomically create the Unix Domain Socket file with a specific permissions, say: `0777`. The manual doesn't say anything about socket file permissions with regard to `umask` or whatever. Even, if the `umask` does affect the socket file, then it's not an atomic way - in multi-threaded program. I hope, there is a way to achieve my goal without using synchronization of `umask()` calls.

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