Utility that waits for a (redirected) printer to become ready, sets it as default and launches a program.

WaitForPrinter.c

/* Copyright (C) 2017-2018 Manuel Meitinger
 * 
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 2 of the License, or
 * (at your option) any later version.
 * 
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 * 
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */

#define STRICT
#include <Windows.h>

#pragma comment(linker, "/ENTRY:Run")
#pragma comment(linker, "/SUBSYSTEM:WINDOWS")
#pragma comment(lib, "Kernel32.lib")
#pragma comment(lib, "User32.lib")
#pragma comment(lib, "Winspool.lib")

#define MessageTitle L"..."
#define DefaultPrinterPrefix L"..."
#define NumberOfRetries 100
#define ProgramToRun L"..."

#define DO(what, op)                                                                 \
    if (!(op))                                                                       \
    {                                                                                \
        exitCode = GetLastError();                                                   \
        MessageBoxW(NULL, L"Cannot " what L".", MessageTitle, MB_OK | MB_ICONERROR); \
        goto Cleanup;                                                                \
    }

void Run(void)
{
    UINT exitCode = ERROR_SUCCESS;
    DWORD size = 0x1000;
    LPPRINTER_INFO_4W printers = NULL;
    BOOL found;
    INT retry;
    DWORD count;
    BOOL success;
    LPPRINTER_INFO_4W newPrinters;
    LPWSTR printer;
    INT offset;
    LPWSTR cmdLine;
    BOOL escaped;
    LPWSTR newCmdLine = NULL;
    STARTUPINFOW startup;
    PROCESS_INFORMATION process = {NULL, NULL};

    DO(L"allocate buffer", printers = HeapAlloc(GetProcessHeap(), 0, size));
    found = FALSE;
    retry = 0;
    while (!found && retry < NumberOfRetries)
    {
        DO(L"query printers", (success = EnumPrintersW(PRINTER_ENUM_LOCAL | PRINTER_ENUM_CONNECTIONS, NULL, 4, (LPBYTE)printers, size, &size, &count)) || GetLastError() == ERROR_INSUFFICIENT_BUFFER);
        if (!success)
        {
            DO(L"reallocate buffer", newPrinters = HeapReAlloc(GetProcessHeap(), 0, printers, size));
            printers = newPrinters;
            continue;
        }
        while (count-- > 0)
        {
            printer = printers[count].pPrinterName;
            offset = 0;
            while (DefaultPrinterPrefix[offset] && printer[offset] == DefaultPrinterPrefix[offset])
            {
                offset++;
            }
            if (!DefaultPrinterPrefix[offset])
            {
                SetDefaultPrinterW(printer);
                found = TRUE;
                break;
            }
        }
        Sleep(1000);
        retry++;
    }
    if (!found)
    {
        MessageBoxW(NULL, L"Printer not found: " DefaultPrinterPrefix, MessageTitle, MB_OK | MB_ICONWARNING);
    }
    cmdLine = GetCommandLineW();
    escaped = FALSE;
    offset = 0;
    while (cmdLine[offset])
    {
        if (cmdLine[offset] == L'"')
        {
            escaped = !escaped;
        }
        else if (!escaped && cmdLine[offset] <= L' ')
        {
            break;
        }
        offset++;
    }
    DO(L"allocate cmd line", newCmdLine = HeapAlloc(GetProcessHeap(), 0, (lstrlenW(ProgramToRun) + lstrlenW(cmdLine + offset) + 1) * sizeof(WCHAR)));
    DO(L"set application", lstrcpyW(newCmdLine, ProgramToRun));
    DO(L"set arguments", lstrcatW(newCmdLine, cmdLine + offset));
    SecureZeroMemory(&startup, sizeof(startup));
    startup.cb = sizeof(startup);
    DO(L"launch program", CreateProcessW(NULL, newCmdLine, NULL, NULL, FALSE, 0, NULL, NULL, &startup, &process));
    DO(L"wait for program", WaitForSingleObject(process.hProcess, INFINITE) == WAIT_OBJECT_0);

Cleanup:
    if (process.hThread)
    {
        CloseHandle(process.hThread);
    }
    if (process.hProcess)
    {
        CloseHandle(process.hProcess);
    }
    if (newCmdLine)
    {
        HeapFree(GetProcessHeap(), 0, newCmdLine);
    }
    if (printers)
    {
        HeapFree(GetProcessHeap(), 0, printers);
    }
    ExitProcess(exitCode);
}