What is the header for the struct linux_dirent64? - c

Question

I'm exploring the getdents64 syscall. The resulting struct linux_dirent64 is not defined by the relevant headers. Both the related question and the example in man 2 getdirents64 are declaring their own structs. Although I'm aware of Linux syscall backwards compatibility, defining the struct locally like that looks like a hack. Is there another header I need to include that has this struct linux_dirent64 defined inside?
#define _GNU_SOURCE
#include <dirent.h>
#include <fcntl.h>
#include <stdio.h>
#include <unistd.h>
struct linux_dirent64 {
ino64_t d_ino;
off64_t d_off;
unsigned short d_reclen;
unsigned char d_type;
char d_name[];
};
void test() {
char buf[1024];
const int procfs = open("/proc", O_RDONLY | O_DIRECTORY | O_CLOEXEC);
getdents64(procfs, buf, 1024);
printf("%lu\n", ((struct linux_dirent64 *) buf)->d_ino);
close(procfs);
}

Answer 1

Change struct linux_dirent64 to just struct dirent64. This works with glibc 2.36. It is not necessary to include another header as #include <dirent.h> provides it with #define _GNU_SOURCE. The original code would look like the following:
#define _GNU_SOURCE
#include <dirent.h>
#include <fcntl.h>
#include <stdio.h>
#include <unistd.h>
void test() {
char buf[1024];
const int procfs = open("/proc", O_RDONLY | O_DIRECTORY | O_CLOEXEC);
getdents64(procfs, buf, 1024);
printf("%lu\n", ((struct dirent64 *) buf)->d_ino);
close(procfs);
}