From 6fde7d8a51a18eb127a375e78b88df6c5e7a7f91 Mon Sep 17 00:00:00 2001
From: Benno Schulenberg <bensberg@telfort.nl>
Date: Sun, 25 Sep 2022 15:51:02 +0200
Subject: [PATCH] input: allocate two small character buffers too, and never
 free them

Analogous to commit 3922b531: instead of allocating and later freeing
a tiny fragment of memory for every character that the user enters (in
the edit window or at a prompt), reserve a small piece in the beginning
and retain it, and increase (but never decrease) its size as needed.

This addresses the second part of https://savannah.gnu.org/bugs/?63086.
---
 src/nano.c   | 18 +++++++++++-------
 src/prompt.c | 17 +++++++++++------
 2 files changed, 22 insertions(+), 13 deletions(-)

diff --git a/src/nano.c b/src/nano.c
index 0302e971..206f54ed 100644
--- a/src/nano.c
+++ b/src/nano.c
@@ -1547,6 +1547,8 @@ void process_a_keystroke(void)
 		/* The keystroke we read in: a character or a shortcut. */
 	static char *puddle = NULL;
 		/* The input buffer for actual characters. */
+	static size_t capacity = 12;
+		/* The size of the input buffer; gets doubled whenever needed. */
 	static size_t depth = 0;
 		/* The length of the input buffer. */
 #ifndef NANO_TINY
@@ -1593,21 +1595,23 @@ void process_a_keystroke(void)
 				refresh_needed = TRUE;
 			}
 #endif
-			/* Store the byte, and leave room for a terminating zero. */
-			puddle = nrealloc(puddle, depth + 2);
+			/* When the input buffer (plus room for terminating NUL) is full,
+			 * extend it; otherwise, if it does not exist yet, create it. */
+			if (depth + 1 == capacity) {
+				capacity = 2 * capacity;
+				puddle = nrealloc(puddle, capacity);
+			} else if (!puddle)
+				puddle = nmalloc(capacity);
+
 			puddle[depth++] = (char)input;
 		}
 	}
 
 	/* If we have a command, or if there aren't any other key codes waiting,
 	 * it's time to insert the gathered bytes into the edit buffer. */
-	if ((function || waiting_keycodes() == 0) && puddle != NULL) {
+	if (depth > 0 && (function || waiting_keycodes() == 0)) {
 		puddle[depth] = '\0';
-
 		inject(puddle, depth);
-
-		free(puddle);
-		puddle = NULL;
 		depth = 0;
 	}
 
diff --git a/src/prompt.c b/src/prompt.c
index f99bec25..df697f2b 100644
--- a/src/prompt.c
+++ b/src/prompt.c
@@ -256,6 +256,8 @@ void absorb_character(int input, functionptrtype function)
 {
 	static char *puddle = NULL;
 		/* The input buffer. */
+	static size_t capacity = 8;
+		/* The size of the input buffer; gets doubled whenever needed. */
 	static size_t depth = 0;
 		/* The length of the input buffer. */
 
@@ -267,7 +269,14 @@ void absorb_character(int input, functionptrtype function)
 			beep();
 		else if (!ISSET(RESTRICTED) || currmenu != MWRITEFILE ||
 						openfile->filename[0] == '\0') {
-			puddle = nrealloc(puddle, depth + 2);
+			/* When the input buffer (plus room for terminating NUL) is full,
+			 * extend it; otherwise, if it does not exist yet, create it. */
+			if (depth + 1 == capacity) {
+				capacity = 2 * capacity;
+				puddle = nrealloc(puddle, capacity);
+			} else if (!puddle)
+				puddle = nmalloc(capacity);
+
 			puddle[depth++] = (char)input;
 		}
 	}
@@ -275,13 +284,9 @@ void absorb_character(int input, functionptrtype function)
 	/* If we got a shortcut, or if there aren't any other keystrokes waiting,
 	 * it's time to insert all characters in the input buffer (if not empty)
 	 * into the answer, and then clear the input buffer. */
-	if ((function || waiting_keycodes() == 0) && puddle != NULL) {
+	if (depth > 0 && (function || waiting_keycodes() == 0)) {
 		puddle[depth] = '\0';
-
 		inject_into_answer(puddle, depth);
-
-		free(puddle);
-		puddle = NULL;
 		depth = 0;
 	}
 }