How to make your Epson XP-342 print documents with varying page size

Because apparently, the official Linux driver just segfaults when the page size changes midway through a PDF. Patch for 1.7.26 (the current version in Portage) can be downloaded here. It's written for 1.7.22, but there have been no relevant upstream changes since then. The original code is a horror show. Building it produces more compiler warnings than my terminal's scrollback can handle and the original main loop is this busted thing:

while (1) {
      readPageHeaderAndIgnoreTheDimensionInfo();

      if (bEnd) {
	    if (!bCacheEmpty)
		  sendCachedData();
	    sendCurrentPage(); // wrong when the child isn't spawned yet
	    break;
      } else if (bCacheFull) {
	    sendCachedData();
	    cacheCurrentPage();
      }

      if (bFirstIteration)
	    initializeChildProcess();
      actuallyReadThePage();
}

Note that the function calls in this sketch don't correspond to function calls but code sections, which means the sendCachedData() section is copypasted; I basically had to rewrite this entire function for what should have been a two line fix. Somebody got paid for this! The driver also ignores other parts of the CUPS header; adding support for them is left to the masochistic reader.

Edit 2023-05-22: Updated from 1.7.22 to 1.7.26.

Edit 2023-01-31: Updated from 1.7.8 to 1.7.22. The only differences are the addition of a completely pointless safe_free function (free is already a nop on NULL…) and a fix for the child issue mentioned above, which my patch already fixes anyway.