Move mbs out of struct Edit, use a global buffer

This saves 4K in the edit buffers, not to mention all the heap
allocations for the separate mbs buffers!

There might be a way to be more clever about capacities, but I don't
think it's worth it.

edit.c

@@ -41,32 +41,33 @@ static bool isword(wchar_t ch) {
 void editFree(struct Edit *e) {
 	free(e->buf);
 	free(e->cut.buf);
-	free(e->mbs.buf);
 	e->pos = e->len = e->cap = 0;
 	e->cut.len = 0;
-	e->mbs.pos = 0;
 }
 
-char *editString(struct Edit *e) {
+char *editString(const struct Edit *e, char **buf, size_t *cap, size_t *pos) {
-	size_t cap = e->len * MB_CUR_MAX + 1;
+	size_t req = e->len * MB_CUR_MAX + 1;
-	char *buf = realloc(e->mbs.buf, cap);
+	if (req > *cap) {
-	if (!buf) return NULL;
+		char *new = realloc(*buf, req);
-	e->mbs.buf = buf;
+		if (!new) return NULL;
+		*buf = new;
+		*cap = req;
+	}
 
 	const wchar_t *ptr = e->buf;
-	size_t len = wcsnrtombs(e->mbs.buf, &ptr, e->pos, cap-1, NULL);
+	size_t len = wcsnrtombs(*buf, &ptr, e->pos, *cap-1, NULL);
 	if (len == (size_t)-1) return NULL;
-	e->mbs.pos = len;
+	if (pos) *pos = len;
 
 	ptr = &e->buf[e->pos];
 	size_t n = wcsnrtombs(
-		&e->mbs.buf[len], &ptr, e->len - e->pos, cap-1 - len, NULL
+		*buf + len, &ptr, e->len - e->pos, *cap-1 - len, NULL
 	);
 	if (n == (size_t)-1) return NULL;
 	len += n;
 
-	e->mbs.buf[len] = '\0';
+	(*buf)[len] = '\0';
-	return e->mbs.buf;
+	return *buf;
 }
 
 int editReserve(struct Edit *e, size_t index, size_t count) {
@@ -212,11 +213,14 @@ static void fix(struct Edit *e, const char *str) {
 }
 
 static bool eq(struct Edit *e, const char *str1) {
+	size_t pos;
+	static size_t cap;
+	static char *buf;
+	editString(e, &buf, &cap, &pos);
 	const char *str2 = &str1[strlen(str1) + 1];
-	const char *buf = editString(e);
+	return pos == strlen(str1)
-	return e->mbs.pos == strlen(str1)
+		&& !strncmp(buf, str1, pos)
-		&& !strncmp(buf, str1, e->mbs.pos)
+		&& !strcmp(&buf[pos], str2);
-		&& !strcmp(&buf[e->mbs.pos], str2);
 }
 
 int main(void) {

edit.h

@@ -42,10 +42,6 @@ struct Edit {
 		wchar_t *buf;
 		size_t len;
 	} cut;
-	struct {
-		char *buf;
-		size_t pos;
-	} mbs;
 };
 
 enum EditFn {
@@ -76,8 +72,8 @@ int editVi(struct Edit *e, wchar_t ch);
 // Insert a character at the cursor.
 int editInsert(struct Edit *e, wchar_t ch);
 
-// Convert the buffer to a multi-byte string stored in e->mbs.
+// Convert the buffer to a multi-byte string.
-char *editString(struct Edit *e);
+char *editString(const struct Edit *e, char **buf, size_t *cap, size_t *pos);
 
 // Free all buffers.
 void editFree(struct Edit *e);

input.c

@@ -158,10 +158,15 @@ static char *inputStop(
 	return stop;
 }
 
+static size_t cap;
+static char *buf;
+
 void inputUpdate(void) {
 	uint id = windowID();
-	char *buf = editString(&edits[id]);
+
-	if (!buf) err(EX_OSERR, "editString");
+	size_t pos = 0;
+	const char *ptr = editString(&edits[id], &buf, &cap, &pos);
+	if (!ptr) err(EX_OSERR, "editString");
 
 	const char *prefix = "";
 	const char *prompt = self.nick;
@@ -192,7 +197,7 @@ void inputUpdate(void) {
 	} else {
 		prompt = "";
 	}
-	if (skip > &buf[edits[id].mbs.pos]) {
+	if (skip > &buf[pos]) {
 		prefix = prompt = suffix = "";
 		skip = buf;
 	}
@@ -209,14 +214,14 @@ void inputUpdate(void) {
 	waddstr(uiInput, suffix);
 	getyx(uiInput, y, x);
 
-	int pos;
+	int posx;
 	struct Style style = styleInput;
-	inputStop(styleInput, &style, skip, &buf[edits[id].mbs.pos]);
+	inputStop(styleInput, &style, skip, &buf[pos]);
-	getyx(uiInput, y, pos);
+	getyx(uiInput, y, posx);
 	wmove(uiInput, y, x);
 
+	ptr = skip;
 	style = styleInput;
-	const char *ptr = skip;
 	if (split) {
 		ptr = inputStop(styleInput, &style, ptr, &buf[split]);
 		style = styleInput;
@@ -224,7 +229,7 @@ void inputUpdate(void) {
 	}
 	inputAdd(styleInput, &style, ptr);
 	wclrtoeol(uiInput);
-	wmove(uiInput, y, pos);
+	wmove(uiInput, y, posx);
 }
 
 bool inputPending(uint id) {
@@ -381,7 +386,7 @@ fail:
 
 static void inputEnter(void) {
 	uint id = windowID();
-	char *cmd = editString(&edits[id]);
+	char *cmd = editString(&edits[id], &buf, &cap, NULL);
 	if (!cmd) err(EX_OSERR, "editString");
 
 	tabAccept();
@@ -459,8 +464,8 @@ static void keyCtrl(wchar_t ch) {
 		break; case L'L': clearok(curscr, true);
 		break; case L'N': windowShow(windowNum() + 1);
 		break; case L'P': windowShow(windowNum() - 1);
-		break; case L'R': windowSearch(editString(edit), -1);
+		break; case L'R': windowSearch(editString(edit, &buf, &cap, NULL), -1);
-		break; case L'S': windowSearch(editString(edit), +1);
+		break; case L'S': windowSearch(editString(edit, &buf, &cap, NULL), +1);
 		break; case L'T': error = editFn(edit, EditTranspose);
 		break; case L'U': error = editFn(edit, EditDeleteHead);
 		break; case L'V': windowScroll(ScrollPage, -1);