/* Replacements for functions needed specifically by the 'imagex' program in
 * Windows native builds; also, Windows-specific code to acquire and release
 * privileges needed to backup and restore files */

#ifndef __WIN32__
#  error "This file contains Windows code"
#endif

#include "imagex-win32.h"
#include <windows.h>
#include <errno.h>
#include <string.h>
#include <assert.h>
#include <stdio.h>

/* Replacement for glob() in Windows native builds that operates on wide
 * characters. */
int
win32_wglob(const wchar_t *pattern, int flags,
	    int (*errfunc)(const wchar_t *epath, int eerrno),
	    glob_t *pglob)
{
	WIN32_FIND_DATAW dat;
	DWORD err;
	HANDLE hFind;
	int ret;
	size_t nspaces;

	const wchar_t *backslash, *end_slash;
	size_t prefix_len;

	backslash = wcsrchr(pattern, L'\\');
	end_slash = wcsrchr(pattern, L'/');

	if (backslash > end_slash)
		end_slash = backslash;

	if (end_slash)
		prefix_len = end_slash - pattern + 1;
	else
		prefix_len = 0;

	/* This function does not support all functionality of the POSIX glob(),
	 * so make sure the parameters are consistent with supported
	 * functionality. */
	assert(errfunc == NULL);
	assert((flags & GLOB_ERR) == GLOB_ERR);
	assert((flags & ~(GLOB_NOSORT | GLOB_ERR)) == 0);

	hFind = FindFirstFileW(pattern, &dat);
	if (hFind == INVALID_HANDLE_VALUE) {
		err = GetLastError();
		if (err == ERROR_FILE_NOT_FOUND) {
			errno = 0;
			return GLOB_NOMATCH;
		} else {
			/* The other possible error codes for FindFirstFile()
			 * are undocumented. */
			errno = EIO;
			return GLOB_ABORTED;
		}
	}
	pglob->gl_pathc = 0;
	pglob->gl_pathv = NULL;
	nspaces = 0;
	do {
		wchar_t *path;
		if (pglob->gl_pathc == nspaces) {
			size_t new_nspaces;
			wchar_t **pathv;

		 	new_nspaces = nspaces * 2 + 1;	
			pathv = realloc(pglob->gl_pathv,
					new_nspaces * sizeof(pglob->gl_pathv[0]));
			if (!pathv)
				goto oom;
			pglob->gl_pathv = pathv;
			nspaces = new_nspaces;
		}
		size_t filename_len = wcslen(dat.cFileName);
		size_t len_needed = prefix_len + filename_len;

		path = malloc((len_needed + 1) * sizeof(wchar_t));
		if (!path)
			goto oom;

		wmemcpy(path, pattern, prefix_len);
		wmemcpy(path + prefix_len, dat.cFileName, filename_len + 1);
		pglob->gl_pathv[pglob->gl_pathc++] = path;
	} while (FindNextFileW(hFind, &dat));
	err = GetLastError();
	CloseHandle(hFind);
	if (err == ERROR_NO_MORE_FILES) {
		errno = 0;
		return 0;
	} else {
		/* Other possible error codes for FindNextFile() are
		 * undocumented */
		errno = EIO;
		ret = GLOB_ABORTED;
		goto fail_globfree;
	}
oom:
	CloseHandle(hFind);
	errno = ENOMEM;
	ret = GLOB_NOSPACE;
fail_globfree:
	globfree(pglob);
	return ret;
}

void
globfree(glob_t *pglob)
{
	size_t i;
	for (i = 0; i < pglob->gl_pathc; i++)
		free(pglob->gl_pathv[i]);
	free(pglob->gl_pathv);
}

static bool
win32_modify_privilege(const wchar_t *privilege, bool enable)
{
	HANDLE hToken;
	LUID luid;
	TOKEN_PRIVILEGES newState;
	bool ret = false;

	if (!OpenProcessToken(GetCurrentProcess(),
			      TOKEN_ADJUST_PRIVILEGES | TOKEN_QUERY,
			      &hToken))
		goto out;

	if (!LookupPrivilegeValueW(NULL, privilege, &luid))
		goto out;

	newState.PrivilegeCount = 1;
	newState.Privileges[0].Luid = luid;
	newState.Privileges[0].Attributes = (enable ? SE_PRIVILEGE_ENABLED : 0);
	ret = AdjustTokenPrivileges(hToken, FALSE, &newState, 0, NULL, NULL);
	CloseHandle(hToken);
out:
	if (!ret) {
		fwprintf(stderr, L"WARNING: Failed to %ls privilege %s\n",
			enable ? L"enable" : L"disable", privilege);
		fwprintf(stderr,
			L"WARNING: The program will continue, "
			L"but if permission issues are\n"
			L"encountered, you may need to run "
			L"this program as the administrator\n");
	}
	return ret;
}

static void
win32_modify_capture_privileges(bool enable)
{
	win32_modify_privilege(SE_BACKUP_NAME, enable);
	win32_modify_privilege(SE_SECURITY_NAME, enable);
}

static void
win32_modify_restore_privileges(bool enable)
{
	win32_modify_privilege(SE_RESTORE_NAME, enable);
	win32_modify_privilege(SE_SECURITY_NAME, enable);
	win32_modify_privilege(SE_TAKE_OWNERSHIP_NAME, enable);
}

void
win32_acquire_capture_privileges()
{
	win32_modify_capture_privileges(true);
}

void
win32_release_capture_privileges()
{
	win32_modify_capture_privileges(false);
}

void
win32_acquire_restore_privileges()
{
	win32_modify_restore_privileges(true);
}

void
win32_release_restore_privileges()
{
	win32_modify_restore_privileges(false);
}

/* Convert a string from the "current Windows codepage" to UTF-16LE. */
wchar_t *
win32_mbs_to_wcs(const char *mbs, size_t mbs_nbytes, size_t *num_wchars_ret)
{
	if (mbs_nbytes > INT_MAX) {
		fwprintf(stderr, L"ERROR: too much data (%zu bytes)!\n",
			 mbs_nbytes);
		return NULL;
	}
	if (mbs_nbytes == 0) {
		*num_wchars_ret = 0;
		return (wchar_t*)mbs;
	}
	int len = MultiByteToWideChar(CP_ACP,
				      MB_ERR_INVALID_CHARS,
				      mbs,
				      mbs_nbytes,
				      NULL,
				      0);
	if (len <= 0)
		goto out_invalid;
	wchar_t *wcs = malloc(len * sizeof(wchar_t));
	if (!wcs) {
		fwprintf(stderr, L"ERROR: out of memory!\n");
		return NULL;
	}
	int len2 = MultiByteToWideChar(CP_ACP,
				       MB_ERR_INVALID_CHARS,
				       mbs,
				       mbs_nbytes,
				       wcs,
				       len);
	if (len2 != len) {
		free(wcs);
		goto out_invalid;
	}
	*num_wchars_ret = len;
	return wcs;
out_invalid:
	fwprintf(stderr,
L"ERROR: Invalid multi-byte string in the text file you provided as input!\n"
L"       Maybe try converting your text file to UTF-16LE?\n"
	);
	return NULL;
}

static inline bool
is_path_separator(wchar_t c)
{
	return c == L'/' || c == L'\\';
}

/* basename() (modifying, trailing-slash stripping version) for wide-character
 * strings. */
wchar_t *
win32_wbasename(wchar_t *path)
{
	wchar_t *p = wcschr(path, L'\0');

	p--;
	while (p >= path && is_path_separator(*p))
		*p-- = '\0';
	while (p >= path && !is_path_separator(*p))
		p--;
	p++;
	return p;
}