/*
 * iscygpty.c -- part of ptycheck
 * https://github.com/k-takata/ptycheck
 *
 * Copyright (c) 2015-2017 K.Takata
 *
 * You can redistribute it and/or modify it under the terms of either
 * the MIT license (as described below) or the Vim license.
 *
 * Permission is hereby granted, free of charge, to any person obtaining
 * a copy of this software and associated documentation files (the
 * "Software"), to deal in the Software without restriction, including
 * without limitation the rights to use, copy, modify, merge, publish,
 * distribute, sublicense, and/or sell copies of the Software, and to
 * permit persons to whom the Software is furnished to do so, subject to
 * the following conditions:
 *
 * The above copyright notice and this permission notice shall be
 * included in all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
 * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
 * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
 * IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY
 * CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,
 * TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
 * SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
 */

#ifdef _WIN32

#include <ctype.h>
#include <io.h>
#include <wchar.h>
#include <windows.h>

#ifdef USE_FILEEXTD
/* VC 7.1 or earlier doesn't support SAL. */
#if !defined(_MSC_VER) || (_MSC_VER < 1400)
#define __out
#define __in
#define __in_opt
#endif
/* Win32 FileID API Library:
 * http://www.microsoft.com/en-us/download/details.aspx?id=22599
 * Needed for WinXP. */
#include <fileextd.h>
#else /* USE_FILEEXTD */
/* VC 8 or earlier. */
#if defined(_MSC_VER) && (_MSC_VER < 1500)
#ifdef ENABLE_STUB_IMPL
#define STUB_IMPL
#else
#error "Win32 FileID API Library is required for VC2005 or earlier."
#endif
#endif
#endif /* USE_FILEEXTD */

#if _WIN32_WINNT >= 0x0600
#define USE_DYNFILEID // we need to enable it for supporting xp
#endif
#ifdef USE_DYNFILEID
typedef BOOL(WINAPI *pfnGetFileInformationByHandleEx)(HANDLE hFile,
                                                      FILE_INFO_BY_HANDLE_CLASS FileInformationClass,
                                                      LPVOID lpFileInformation,
                                                      DWORD dwBufferSize);
static pfnGetFileInformationByHandleEx pGetFileInformationByHandleEx = NULL;

#ifndef USE_FILEEXTD
static BOOL WINAPI stub_GetFileInformationByHandleEx(HANDLE hFile,
                                                     FILE_INFO_BY_HANDLE_CLASS FileInformationClass,
                                                     LPVOID lpFileInformation,
                                                     DWORD dwBufferSize) {
    return FALSE;
}
#endif

static void setup_fileid_api(void) {
    if (pGetFileInformationByHandleEx != NULL) {
        return;
    }
    pGetFileInformationByHandleEx = (pfnGetFileInformationByHandleEx)
        GetProcAddress(GetModuleHandle(TEXT("kernel32.dll")), "GetFileInformationByHandleEx");
    if (pGetFileInformationByHandleEx == NULL) {
#ifdef USE_FILEEXTD
        pGetFileInformationByHandleEx = GetFileInformationByHandleEx;
#else
        pGetFileInformationByHandleEx = stub_GetFileInformationByHandleEx;
#endif
    }
}
#else
#define pGetFileInformationByHandleEx GetFileInformationByHandleEx
#define setup_fileid_api()
#endif

#define is_wprefix(s, prefix) (wcsncmp((s), (prefix), sizeof(prefix) / sizeof(WCHAR) - 1) == 0)

/* Check if the fd handle is a cygwin/msys's pty. */
int is_cygpty(HANDLE h) {
#if defined(STUB_IMPL)
    return 0;
#elif _WIN32_WINNT >= 0x0600
    int size = sizeof(FILE_NAME_INFO) + sizeof(WCHAR) * (MAX_PATH - 1);
    FILE_NAME_INFO *nameinfo;
    WCHAR *p = NULL;

    setup_fileid_api();

    if (h == INVALID_HANDLE_VALUE) {
        return 0;
    }
    /* Cygwin/msys's pty is a pipe. */
    if (GetFileType(h) != FILE_TYPE_PIPE) {
        return 0;
    }
    nameinfo = (FILE_NAME_INFO *)malloc(size + sizeof(WCHAR));
    if (nameinfo == NULL) {
        return 0;
    }
    /* Check the name of the pipe:
     * '\{cygwin,msys}-XXXXXXXXXXXXXXXX-ptyN-{from,to}-master' */
    if (pGetFileInformationByHandleEx(h, FileNameInfo, nameinfo, size)) {
        nameinfo->FileName[nameinfo->FileNameLength / sizeof(WCHAR)] = L'\0';
        p = nameinfo->FileName;
        if (is_wprefix(p, L"\\cygwin-")) { /* Cygwin */
            p += 8;
        } else if (is_wprefix(p, L"\\msys-")) { /* MSYS and MSYS2 */
            p += 6;
        } else {
            p = NULL;
        }
        if (p != NULL) {
            while (*p && isxdigit(*p)) { /* Skip 16-digit hexadecimal. */
                ++p;
            }
            if (is_wprefix(p, L"-pty")) {
                p += 4;
            } else {
                p = NULL;
            }
        }
        if (p != NULL) {
            while (*p && isdigit(*p)) { /* Skip pty number. */
                ++p;
            }
            if (is_wprefix(p, L"-from-master")) {
                //p += 12;
            } else if (is_wprefix(p, L"-to-master")) {
                //p += 10;
            } else {
                p = NULL;
            }
        }
    }
    free(nameinfo);
    return (p != NULL);
#else
    return 0;
#endif
}

#endif /* _WIN32 */