Added a basic errno.h

libc/errno/errno.c

@@ -0,0 +1,4 @@
+#include <errno.h>
+
+_errno_t errno = 0;
+

libc/include/errno.h

@@ -0,0 +1,39 @@
+#ifndef _ERRNO_H
+#define _ERRNO_H
+
+// Basic POSIX defined error idk
+enum {
+    EPERM = 1,  // Operation not permitted
+    ENOENT,     // No such file or directory
+    ESRCH,      // No such process
+    EINTR,      // Interrupted system call
+    EIO,        // I/O error
+    ENXIO,      // No such device or address
+    E2BIG,      // Argument list too long
+    ENOEXEC,    // Exec format error
+    EBADF,      // Bad file descriptor
+    ECHILD,     // No child processes
+    EAGAIN,     // Resource temporarily unavailable
+    ENOMEM,     // Out of memory
+    EACCES,     // Permission denied
+    EFAULT,     // Bad address
+    EBUSY,      // Device or resource busy
+    EEXIST,     // File exists
+    ENOTDIR,    // Not a directory
+    EISDIR,     // Is a directory
+    EINVAL,     // Invalid argument
+    ENFILE,     // File table overflow
+    EMFILE,     // Too many open files
+    ENOTTY,     // Not a typewriter
+    EFBIG,      // File too large
+    ENOSPC,     // No space left on device
+    ESPIPE,     // Illegal seek
+    EROFS,      // Read-only file system
+    EMLINK,     // Too many links
+    EPIPE,      // Broken pipe
+    EDQUOT,     // Disk quota exceeded
+};
+
+extern int errno;
+
+#endif