github.com/afumu/libc@v0.0.6/musl/src/network/if_indextoname.c (about)

     1  #define _GNU_SOURCE
     2  #include <net/if.h>
     3  #include <sys/socket.h>
     4  #include <sys/ioctl.h>
     5  #include <string.h>
     6  #include <errno.h>
     7  #include "syscall.h"
     8  
     9  char *if_indextoname(unsigned index, char *name)
    10  {
    11  	struct ifreq ifr;
    12  	int fd, r;
    13  
    14  	if ((fd = socket(AF_UNIX, SOCK_DGRAM|SOCK_CLOEXEC, 0)) < 0) return 0;
    15  	ifr.ifr_ifindex = index;
    16  	r = ioctl(fd, SIOCGIFNAME, &ifr);
    17  	__syscall(SYS_close, fd);
    18  	if (r < 0) {
    19  		if (errno == ENODEV) errno = ENXIO;
    20  		return 0;
    21  	}
    22  	return strncpy(name, ifr.ifr_name, IF_NAMESIZE);
    23  }