#include <unistd.h>
int main()
{
    const char msg[] = "Hello, glibc!\n";
    write(1, msg, sizeof(msg) - 1); // glibc's write() wrapper
    return 0;
}

#include <errno.h>
#include <syscall.h>
#include <unistd.h>

ssize_t write_no_glibc(int fd, const void *buf, size_t count)
{
    long ret;
    asm volatile(
        "syscall"
        : "=a"(ret)                                      // Output: result in rax
        : "a"(__NR_write), "D"(fd), "S"(buf), "d"(count) // Inputs
        : "rcx", "r11", "memory"                         // Clobbered registers
    );

    if (ret < 0)
    {
        errno = -ret; // Set errno on error
        return -1;
    }
    return ret; // Return bytes written
}

int main()
{
    const char msg[] = "Hello, glibc!\n";
    write_no_glibc(1, msg, sizeof(msg) - 1);
    return 0;
}