// POSIX compatibility support for posix fd.

#include <ntlite/syscall.h>
#include "posix.h"
#include "posix_fd.h"

int errno = 0;

// Implements the status To Errno operation.
int PosixStatusToErrno(uint32_t s) {
    switch (s) {
        case 0x0000: return 0;       // STATUS_SUCCESS
        case 0x0002: return ENOSYS;  // STATUS_NOT_SUPPORTED
        case 0x0003: return EAGAIN;  // STATUS_TIMEOUT / would block
        case 0x0010: return EINVAL;  // STATUS_INVALID_PARAMETER
        case 0x0011: return EBADF;   // STATUS_INVALID_HANDLE
        case 0x0012: return ERANGE;  // STATUS_BUFFER_TOO_SMALL
        case 0x0020: return ENOMEM;  // STATUS_NO_MEMORY
        case 0x0021: return EACCES;  // STATUS_ACCESS_DENIED
        case 0x0022: return ENOENT;  // STATUS_NOT_FOUND
        case 0x0023: return EEXIST;  // STATUS_ALREADY_EXISTS
        case 0x0030: return ECONNRESET; // STATUS_OBJECT_DEAD
        case 0x0031: return EAGAIN;  // STATUS_QUEUE_FULL
        case 0x0032: return EAGAIN;  // STATUS_QUEUE_EMPTY
        default:     return EIO;
    }
}

static FD_ENTRY gFdTable[FD_TABLE_PIDS][FD_MAX];

// Implements the fd Init operation.
__declspec(dllexport) void PosixFdInit(void) {
    uint32_t pid = SysGetCurrentPid();
    uint32_t slot = pid % FD_TABLE_PIDS;

    // Clear this process's slice (handles inherited state from a previous
    // process that happened to land on the same slot - unlikely but safe).
    for (int i = 0; i < FD_MAX; i++)
        gFdTable[slot][i] = (FD_ENTRY){ FD_FREE, 0, false };

    gFdTable[slot][0] = (FD_ENTRY){ FD_CONSOLE_R, 0, true };
    gFdTable[slot][1] = (FD_ENTRY){ FD_CONSOLE_W, 0, true };
    gFdTable[slot][2] = (FD_ENTRY){ FD_CONSOLE_W, 0, true };
}

// Implements the fd Alloc operation.
__declspec(dllexport) int FdAlloc(uint32_t pid, FD_TYPE type, uint32_t khandle) {
    uint32_t slot = pid % FD_TABLE_PIDS;
    for (int fd = 3; fd < FD_MAX; fd++) {
        if (!gFdTable[slot][fd].Used) {
            gFdTable[slot][fd] = (FD_ENTRY){ type, khandle, true };
            return fd;
        }
    }
    errno = EMFILE;
    return -1;
}

// Implements the fd Get operation.
__declspec(dllexport) FD_ENTRY* FdGet(uint32_t pid, int fd) {
    if (fd < 0 || fd >= FD_MAX) { errno = EBADF; return (FD_ENTRY*)0; }
    uint32_t slot = pid % FD_TABLE_PIDS;
    FD_ENTRY* e = &gFdTable[slot][fd];
    if (!e->Used) { errno = EBADF; return (FD_ENTRY*)0; }
    return e;
}

// Implements the fd Free operation.
__declspec(dllexport) void FdFree(uint32_t pid, int fd) {
    if (fd < 0 || fd >= FD_MAX) return;
    uint32_t slot = pid % FD_TABLE_PIDS;
    gFdTable[slot][fd] = (FD_ENTRY){ FD_FREE, 0, false };
}