Windows: Work around an oddity when a pipe with no reader is written to.

On Windows, write() is implemented using WriteFile(). After the reader
closed its end of the pipe, the first WriteFile() returns
ERROR_BROKEN_PIPE (which translates to EPIPE), subsequent WriteFile()s
return ERROR_NO_DATA, which is translated to EINVAL.

Signed-off-by: Johannes Sixt <johannes.sixt@telecom.at>

write_or_die.c

@@ -34,7 +34,12 @@ void maybe_flush_or_die(FILE *f, const char *desc)
 			return;
 	}
 	if (fflush(f)) {
-		if (errno == EPIPE)
+		/*
+		 * On Windows, EPIPE is returned only by the first write()
+		 * after the reading end has closed its handle; subsequent
+		 * write()s return EINVAL.
+		 */
+		if (errno == EPIPE || errno == EINVAL)
 			exit(0);
 		die("write failure on %s: %s", desc, strerror(errno));
 	}