fixed memory corruptions due to undoing the teco_machine_stringbuilding_t::codepage

* It's contained in teco_machine_main_t which is created per macro call frame.
  So after macro calls, the machine no longer exists.
  It is therefore unsafe to undo its members indiscriminately.
* On the other hand, we must undo the codepage setting when run interactively,
  so it is now only undone when belonging to the commandline macro frame.
* This was actually causing memory corruptions on every fnkeys cursor movement, but never
  caused crashes - probably because the invalid pointers are always pointing to unused
  parts of the C call stack.
* Initially broken in b31b8871.

5 files changed, 42 insertions, 8 deletions

diff --git a/src/core-commands.c b/src/core-commands.c
index a390fa4..befb6e8 100644
--- a/src/core-commands.c
+++ b/src/core-commands.c
@@ -2759,8 +2759,12 @@ teco_state_insert_initial(teco_machine_main_t *ctx, GError **error)
 	/*
 	 * Current document's encoding determines the behaviour of
 	 * string building constructs.
+	 *
+	 * NOTE: This is not safe to undo in macro calls.
 	 */
-	teco_undo_guint(ctx->expectstring.machine.codepage) = teco_interface_get_codepage();
+	if (ctx == &teco_cmdline.machine)
+		teco_undo_guint(ctx->expectstring.machine.codepage);
+	ctx->expectstring.machine.codepage = teco_interface_get_codepage();
 
 	if (!teco_expressions_eval(FALSE, error))
 		return FALSE;
diff --git a/src/parser.c b/src/parser.c
index 8cb26e7..4e42833 100644
--- a/src/parser.c
+++ b/src/parser.c
@@ -35,6 +35,7 @@
 #include "ring.h"
 #include "glob.h"
 #include "error.h"
+#include "cmdline.h"
 #include "core-commands.h"
 #include "goto-commands.h"
 #include "parser.h"
@@ -906,8 +907,15 @@ teco_machine_stringbuilding_clear(teco_machine_stringbuilding_t *ctx)
 gboolean
 teco_state_expectstring_initial(teco_machine_main_t *ctx, GError **error)
 {
-	if (ctx->mode == TECO_MODE_NORMAL)
-		teco_undo_guint(ctx->expectstring.machine.codepage) = teco_default_codepage();
+	if (ctx->mode > TECO_MODE_NORMAL)
+		return TRUE;
+
+	/*
+	 * NOTE: This is not safe to undo in macro calls.
+	 */
+	if (ctx == &teco_cmdline.machine)
+		teco_undo_guint(ctx->expectstring.machine.codepage);
+	ctx->expectstring.machine.codepage = teco_default_codepage();
 	return TRUE;
 }
 
diff --git a/src/qreg-commands.c b/src/qreg-commands.c
index 41e4465..f8bb4cb 100644
--- a/src/qreg-commands.c
+++ b/src/qreg-commands.c
@@ -29,6 +29,7 @@
 #include "interface.h"
 #include "ring.h"
 #include "parser.h"
+#include "cmdline.h"
 #include "core-commands.h"
 #include "qreg.h"
 #include "qreg-commands.h"
@@ -492,8 +493,11 @@ teco_state_setqregstring_building_initial(teco_machine_main_t *ctx, GError **err
 	/*
 	 * The expected codepage of string building constructs is determined
 	 * by the Q-Register.
+	 *
+	 * NOTE: This is not safe to undo in macro calls.
 	 */
-	teco_undo_guint(ctx->expectstring.machine.codepage);
+	if (ctx == &teco_cmdline.machine)
+		teco_undo_guint(ctx->expectstring.machine.codepage);
 	return qreg->vtable->get_string(qreg, NULL, NULL, &ctx->expectstring.machine.codepage, error);
 }
 
diff --git a/src/search.c b/src/search.c
index db85283..22dc726 100644
--- a/src/search.c
+++ b/src/search.c
@@ -35,6 +35,7 @@
 #include "parser.h"
 #include "core-commands.h"
 #include "error.h"
+#include "cmdline.h"
 #include "search.h"
 
 typedef struct {
@@ -60,7 +61,12 @@ teco_state_search_initial(teco_machine_main_t *ctx, GError **error)
 	if (ctx->mode > TECO_MODE_NORMAL)
 		return TRUE;
 
-	teco_undo_guint(ctx->expectstring.machine.codepage) = teco_interface_get_codepage();
+	/*
+	 * NOTE: This is not safe to undo in macro calls.
+	 */
+	if (ctx == &teco_cmdline.machine)
+		teco_undo_guint(ctx->expectstring.machine.codepage);
+	ctx->expectstring.machine.codepage = teco_interface_get_codepage();
 
 	if (G_UNLIKELY(!teco_search_qreg_machine))
 		teco_search_qreg_machine = teco_machine_qregspec_new(TECO_QREG_REQUIRED, ctx->qreg_table_locals,
@@ -1046,8 +1052,15 @@ TECO_DEFINE_STATE_SEARCH(teco_state_search_delete);
 static gboolean
 teco_state_replace_insert_initial(teco_machine_main_t *ctx, GError **error)
 {
-	if (ctx->mode == TECO_MODE_NORMAL)
-		teco_undo_guint(ctx->expectstring.machine.codepage) = teco_interface_get_codepage();
+	if (ctx->mode > TECO_MODE_NORMAL)
+		return TRUE;
+
+	/*
+	 * NOTE: This is not safe to undo in macro calls.
+	 */
+	if (ctx == &teco_cmdline.machine)
+		teco_undo_guint(ctx->expectstring.machine.codepage);
+	ctx->expectstring.machine.codepage = teco_interface_get_codepage();
 	return TRUE;
 }
 
diff --git a/src/spawn.c b/src/spawn.c
index 445acc5..cb1ef75 100644
--- a/src/spawn.c
+++ b/src/spawn.c
@@ -43,6 +43,7 @@
 #include "core-commands.h"
 #include "qreg-commands.h"
 #include "error.h"
+#include "cmdline.h"
 #include "spawn.h"
 
 /*
@@ -167,8 +168,12 @@ teco_state_execute_initial(teco_machine_main_t *ctx, GError **error)
 	/*
 	 * Command-lines and file names are always assumed to be UTF-8,
 	 * unless we set TECO_ED_DEFAULT_ANSI.
+	 *
+	 * NOTE: This is not safe to undo in macro calls.
 	 */
-	teco_undo_guint(ctx->expectstring.machine.codepage) = teco_default_codepage();
+	if (ctx == &teco_cmdline.machine)
+		teco_undo_guint(ctx->expectstring.machine.codepage);
+	ctx->expectstring.machine.codepage = teco_default_codepage();
 
 	if (!teco_expressions_eval(FALSE, error))
 		return FALSE;