SchOS/include/posix.h

// SPDX-License-Identifier: Apache-2.0
// SchOS — POSIX-compatibility types used by kernel syscall handlers.
#pragma once
#include "types.h"
#include "date.h"

// struct iovec is declared in two headers on purpose, and guarded so that
// including both is not an error.
//
// posix.h has it because readv/writev need it; this file has it because a
// userspace program including <socket.h> for sendmsg must get a complete
// struct msghdr without also having to know about a kernel header. Both
// definitions are identical and both are Linux's layout.
//
// The guard is not cosmetic. C23 permits redeclaring a struct with identical
// members and GCC 15 defaults to C23, so the duplicate was invisible on the
// gcc path -- while clang defaults to gnu17 and rejected it, which broke the
// one toolchain shell.nix exists to provide and which the UEFI loader needs.
#ifndef SCH_IOVEC_DEFINED
#define SCH_IOVEC_DEFINED
struct iovec {
    void   *iov_base;
    uint64  iov_len;
};
#endif

// Linux's IOV_MAX. readv/writev used to cap iovcnt at 16 -- which is legal,
// since POSIX only requires 16 -- and returned EINVAL above it. But programs
// are written against the platform they run on, and on Linux that limit is
// 1024: toybox's `yes` builds a 256-entry iovec and writev()s it in a loop,
// so `yes | head -2` failed with "Invalid argument" before producing a single
// byte. Nothing here costs per-entry memory; the count is just a loop bound.
#define UIO_MAXIOV 1024

// Simplified termios (matches Linux x86_64 layout enough for basic use).
struct termios {
    uint32 c_iflag;
    uint32 c_oflag;
    uint32 c_cflag;
    uint32 c_lflag;
    uint8  c_line;
    uint8  c_cc[19];
    uint32 c_ispeed;
    uint32 c_ospeed;
};

// Terminal flags, with Linux's values. The kernel honours the ones marked
// below; the rest are accepted and stored so a program that sets them and
// reads them back sees what it wrote, which is what cfmakeraw() and every
// line-editing library actually check.
//
// c_iflag
#define IGNBRK  0000001
#define BRKINT  0000002
#define IGNPAR  0000004
#define PARMRK  0000010
#define INPCK   0000020
#define ISTRIP  0000040   // honoured: strip the eighth bit
#define INLCR   0000100   // honoured: NL -> CR on input
#define IGNCR   0000200   // honoured: drop CR
#define ICRNL   0000400   // honoured: CR -> NL on input
#define IUCLC   0001000
#define IXON    0002000
#define IXANY   0004000
#define IXOFF   0010000
#define IMAXBEL 0020000
#define IUTF8   0040000

// c_oflag
#define OPOST   0000001   // honoured: enable output processing
#define OLCUC   0000002
#define ONLCR   0000004   // honoured: NL -> CR NL on output
#define OCRNL   0000010
#define ONOCR   0000020
#define ONLRET  0000040

// c_cflag
#define CS8     0000060
#define CREAD   0000200
#define HUPCL   0002000
#define CLOCAL  0004000

// c_lflag
#define ISIG    0000001   // honoured: INTR/QUIT/SUSP generate signals
#define ICANON  0000002   // honoured: line-at-a-time with editing
#define ECHO    0000010   // honoured
#define ECHOE   0000020   // honoured: ERASE rubs the character out
#define ECHOK   0000040
#define ECHONL  0000100   // honoured: echo NL even with ECHO off
#define NOFLSH  0000200
#define TOSTOP  0000400
#define IEXTEN  0100000

// c_cc indices (Linux order). VMIN/VTIME share slots with VEOF/VEOL, which is
// why they are only meaningful in the mode the other pair is not.
#define VINTR    0
#define VQUIT    1
#define VERASE   2
#define VKILL    3
#define VEOF     4
#define VTIME    5
#define VMIN     6
#define VSWTC    7
#define VSTART   8
#define VSTOP    9
#define VSUSP   10
#define VEOL    11
#define VREPRINT 12
#define VDISCARD 13
#define VWERASE 14
#define VLNEXT  15
#define VEOL2   16

struct winsize {
    uint16 ws_row;
    uint16 ws_col;
    uint16 ws_xpixel;
    uint16 ws_ypixel;
};

struct rlimit {
    uint64 rlim_cur;
    uint64 rlim_max;
};

// Linux ioctl codes we handle.
#define TCGETS      0x5401
#define TCSETS      0x5402
#define TCSETSW     0x5403
#define TCSETSF     0x5404
#define TCFLSH      0x540B
// TCFLSH queue selectors. Not a pointer -- these are the argument itself.
#define TCIFLUSH    0
#define TCOFLUSH    1
#define TCIOFLUSH   2
#define TIOCGPGRP   0x540F
#define TIOCSPGRP   0x5410
#define TIOCGWINSZ  0x5413
#define TIOCSWINSZ  0x5414
#define TIOCSCTTY   0x540E

// Virtual terminal control, Linux's numbers. The argument to VT_ACTIVATE and
// VT_WAITACTIVE is a 1-based terminal number passed by value, not a pointer.
#define VT_OPENQRY   0x5600   // first free terminal, out through a pointer
#define VT_GETMODE   0x5601
#define VT_SETMODE   0x5602
#define VT_GETSTATE  0x5603   // struct vt_stat
#define VT_ACTIVATE  0x5606
#define VT_WAITACTIVE 0x5607

// VT_SETMODE modes. VT_AUTO is the kernel switching on its own; VT_PROCESS
// means a program has taken switching over and the kernel must keep its hands
// off the keyboard.
#define VT_AUTO      0x00
#define VT_PROCESS   0x01
#define VT_ACKACQ    0x02

// VT_SETCHORD / VT_GETCHORD -- which key combination the kernel switches on.
// SchOS's own, not Linux's: Linux hardcodes Ctrl+Alt+F<n> and nobody has ever
// needed to move it, because Linux is the host. A guest does need to move it,
// because the right answer depends entirely on what the host grabs first --
// and that is not something the guest can discover.
#define VT_GETCHORD  0x5620
#define VT_SETCHORD  0x5621

// KB_GETLAYOUT / KB_SETLAYOUT / KB_LISTLAYOUT -- which keyboard layout the
// console uses. SchOS's own, and deliberately not Linux's KDGKBENT: that
// interface hands over one key of one table at a time and expects userspace to
// own the whole map, which means a `loadkeys` that ships its own data files and
// a boot that is broken until one is loaded. The layouts live in the kernel
// here, and userspace names the one it wants.
#define KB_GETLAYOUT   0x5622      // fill in the active layout
#define KB_SETLAYOUT   0x5623      // switch to the layout named in `name`
#define KB_LISTLAYOUT  0x5624      // describe layout `index`; -EINVAL past end

struct kb_layout {
    uint16 index;                  // in for KB_LISTLAYOUT, out for KB_GETLAYOUT
    char   name[16];               // "us", "pl", "de"
    char   desc[96];               // human-readable, for `loadkeys -l`
};

// Modifier bits, matched exactly. These mirror kernel/dev/kbd.h's values so
// that userspace and the keyboard driver cannot drift apart.
#define VTC_SHIFT    0x01      // kbd.h SHIFT  (1<<0)
#define VTC_CTRL     0x02      // kbd.h CTL    (1<<1)
#define VTC_ALT      0x04      // kbd.h ALT    (1<<2)
#define VTC_RALT     0x80      // kbd.h RALT   (1<<7) -- NOT (1<<3); that is
                               // CAPSLOCK, and bits 3..6 are the other locks
                               // and the E0 prefix flag

// Well-known base scancodes for the `base` field below.
#define VTC_BASE_F1  0x3B      // F1..F6
#define VTC_BASE_1   0x02      // the number row, 1..6

struct vt_chord {
    uint16 mods;     // exactly these modifiers held, and no others
    uint16 base;     // scancode of the key meaning terminal 1
};

struct vt_mode {
    char  mode;               // VT_AUTO or VT_PROCESS
    char  waitv;              // unused here
    short relsig;             // signal on release -- not delivered yet
    short acqsig;             // signal on acquire -- not delivered yet
    short frsig;              // unused
};

struct vt_stat {
    uint16 v_active;          // active terminal, 1-based
    uint16 v_signal;          // unused; Linux keeps it for VT_SETMODE
    uint16 v_state;           // bitmask of terminals in use, bit 1 = tty1
};
#define TIOCGSERIAL 0x541E
#define FIONREAD    0x541B
// FICLONE: share another file's data blocks with this one. The argument is a
// file descriptor, not a pointer. Linux's value, so `cp --reflink` works.
#define FICLONE     0x40049409
#define TIOCEXCL    0x540C
#define TIOCNXCL    0x540D

// arch_prctl commands
#define ARCH_SET_GS 0x1001
#define ARCH_SET_FS 0x1002
#define ARCH_GET_FS 0x1003
#define ARCH_GET_GS 0x1004

// clone flags (subset)
#define CLONE_VM      0x00000100
#define CLONE_THREAD  0x00010000
#define CLONE_SIGHAND 0x00000800

// futex ops
#define FUTEX_WAIT         0
#define FUTEX_WAKE         1
#define FUTEX_WAIT_PRIVATE 128
#define FUTEX_WAKE_PRIVATE 129

// Resource limit codes (POSIX)
#define RLIMIT_AS     9
#define RLIMIT_STACK  3
#define RLIMIT_NOFILE 7

// clock IDs
#define CLOCK_REALTIME  0
#define CLOCK_MONOTONIC 1

struct timespec {
    long tv_sec;
    long tv_nsec;
};

struct itimerval {
    struct timeval it_interval;
    struct timeval it_value;
};

struct rusage {
    struct timeval ru_utime;
    struct timeval ru_stime;
    long ru_maxrss;
    long ru_ixrss;
    long ru_idrss;
    long ru_isrss;
    long ru_minflt;
    long ru_majflt;
    long ru_nswap;
    long ru_inblock;
    long ru_oublock;
    long ru_msgsnd;
    long ru_msgrcv;
    long ru_nsignals;
    long ru_nvcsw;
    long ru_nivcsw;
};

struct tms {
    long tms_utime;
    long tms_stime;
    long tms_cutime;
    long tms_cstime;
};

struct sysinfo {
    long   uptime;
    uint64 loads[3];
    uint64 totalram;
    uint64 freeram;
    uint64 sharedram;
    uint64 bufferram;
    uint64 totalswap;
    uint64 freeswap;
    uint16 procs;
    uint16 pad;
    uint32 pad2;
    uint64 totalhigh;
    uint64 freehigh;
    uint32 mem_unit;
    char   _f[8];
};

// Must match Linux's x86-64 struct statfs field for field, because the programs
// reading it were compiled against Linux's.
//
// f_fsid is the trap. Linux's fsid_t is `struct { int val[2]; }` -- eight bytes
// in total, not two eight-byte words -- and declaring it as int64[2] made this
// struct one slot too long from f_fsid onwards. Everything after it landed in
// the wrong place: userland read f_frsize out of f_namelen and got 255, so df
// computed its block counts in units of 255 bytes and reported a 32 MB root
// filesystem as 1992 KB. It went unnoticed for as long as it did because every
// field here used to be an invented constant, so the numbers were meaningless
// whichever slot they came from.
struct statfs {
    int64  f_type;
    int64  f_bsize;
    int64  f_blocks;
    int64  f_bfree;
    int64  f_bavail;
    int64  f_files;
    int64  f_ffree;
    int32  f_fsid[2];
    int64  f_namelen;
    int64  f_frsize;
    int64  f_flags;
    int64  f_spare[4];
};

// at-syscall dirfd sentinel
#define AT_FDCWD            (-100)
#define AT_REMOVEDIR        0x200
#define AT_SYMLINK_NOFOLLOW 0x100
#define AT_EMPTY_PATH       0x1000
#define AT_NO_AUTOMOUNT     0x800

// prctl options
#define PR_SET_NAME     15
#define PR_GET_NAME     16
#define PR_SET_DUMPABLE  4
#define PR_GET_DUMPABLE  3

// signal numbers (Linux x86_64 values), used by kill dispatch and
// default-action classification in sigsend()
#define SIGHUP    1
#define SIGINT    2
#define SIGQUIT   3
#define SIGILL    4
#define SIGABRT   6
#define SIGBUS    7
#define SIGFPE    8
#define SIGKILL   9
#define SIGUSR1  10
#define SIGSEGV  11
#define SIGUSR2  12
#define SIGPIPE  13
#define SIGALRM  14
#define SIGTERM  15
#define SIGCHLD  17
#define SIGCONT  18
#define SIGSTOP  19
// Job-control and the remaining standard signals. A shell needs the TSTP/
// TTIN/TTOU trio to implement ^Z and background-job terminal access at all;
// they were simply absent, so any reference to them failed to compile.
#define SIGTRAP   5
#define SIGTSTP  20
#define SIGTTIN  21
#define SIGTTOU  22
#define SIGURG   23
#define SIGXCPU  24
#define SIGXFSZ  25
#define SIGVTALRM 26
#define SIGPROF  27
#define SIGWINCH 28
#define SIGIO    29
#define SIGPWR   30
#define SIGSYS   31

// getrusage who
#define RUSAGE_SELF     0
#define RUSAGE_CHILDREN (-1)

// fallocate mode
#define FALLOC_FL_KEEP_SIZE 1

// poll(2) event bits (Linux values)
// mmap(2) protection and flags.
//
// These lived only in kernel/sys/sys_mem.c, so every userspace caller wrote
// its own copy -- cmd/fbinfo had one and cmd/pcitest wanted a third. Two
// private copies of a number the kernel compares against is a mismatch
// waiting to happen, and the symptom would be a mapping with the wrong
// permissions rather than an error.
#define PROT_NONE     0x0
#define PROT_READ     0x1
#define PROT_WRITE    0x2
#define PROT_EXEC     0x4

#define MAP_SHARED    0x01
#define MAP_PRIVATE   0x02
#define MAP_FIXED     0x10
#define MAP_ANONYMOUS 0x20

// waitpid() options. The kernel tests `options & 1`; this is that bit, named.
#define WNOHANG   0x001

#define POLLIN    0x001
#define POLLPRI   0x002
#define POLLOUT   0x004
#define POLLERR   0x008
#define POLLHUP   0x010
#define POLLNVAL  0x020

struct pollfd {
    int   fd;
    short events;
    short revents;
};