From 76f8c51055cb1b69d087b113453764227160bc05 Mon Sep 17 00:00:00 2001
From: midipix <writeonce@midipix.org>
Date: May 23 2020 05:59:02 +0000
Subject: driver: write & copy modes: pre-allocate a robust-file-copy memory region.


---

diff --git a/src/driver/tpax_driver_ctx.c b/src/driver/tpax_driver_ctx.c
index c27ce90..926eb07 100644
--- a/src/driver/tpax_driver_ctx.c
+++ b/src/driver/tpax_driver_ctx.c
@@ -4,12 +4,15 @@
 /*  Released under GPLv2 and GPLv3; see COPYING.TPAX. */
 /******************************************************/
 
+#define _DEFAULT_SOURCE 1
+
 #include <stdint.h>
 #include <stdlib.h>
 #include <string.h>
 #include <unistd.h>
 #include <fcntl.h>
 #include <errno.h>
+#include <sys/mman.h>
 
 #define ARGV_DRIVER
 
@@ -279,6 +282,16 @@ static struct tpax_driver_ctx_impl * tpax_driver_ctx_alloc(
 		if (!entry->fopt)
 			*units++ = entry->arg;
 
+	if (cctx->drvflags & TPAX_DRIVER_EXEC_MODE_WRITE_COPY) {
+		ictx->ctx.bufsize = 64 * 1024;
+		ictx->ctx.bufaddr = mmap(0,ictx->ctx.bufsize,PROT_READ|PROT_WRITE,MAP_ANONYMOUS,-1,0);
+	}
+
+	if (ictx->ctx.bufaddr == MAP_FAILED) {
+		ictx->ctx.bufaddr = 0;
+		ictx->ctx.bufsize = 0;
+	}
+
 	ictx->ctx.ctx.units = ictx->units;
 	ictx->ctx.ctx.errv  = ictx->ctx.errinfp;
 	return &ictx->ctx;
@@ -539,6 +552,9 @@ int tpax_get_driver_ctx(
 
 static void tpax_free_driver_ctx_impl(struct tpax_driver_ctx_alloc * ictx)
 {
+	if (ictx->ctx.bufaddr)
+		munmap(ictx->ctx.bufaddr,ictx->ctx.bufsize);
+
 	argv_free(ictx->meta);
 	free(ictx);
 }
diff --git a/src/internal/tpax_driver_impl.h b/src/internal/tpax_driver_impl.h
index c99553a..56c40b2 100644
--- a/src/internal/tpax_driver_impl.h
+++ b/src/internal/tpax_driver_impl.h
@@ -50,6 +50,8 @@ struct tpax_driver_ctx_impl {
 	struct tpax_error_info **     erricap;
 	struct tpax_error_info *      erriptr[64];
 	struct tpax_error_info        erribuf[64];
+	void *                        bufaddr;
+	size_t                        bufsize;
 };
 
 struct tpax_unit_ctx_impl {