From be7e000389a2f65ef7918b1e94c9831eaf1f444c Mon Sep 17 00:00:00 2001
From: Benno Schulenberg <bensberg@telfort.nl>
Date: Thu, 20 Feb 2020 16:52:48 +0100
Subject: [PATCH] tweaks: pull the NUL-terminating of a string into a function

Also, avoid copying one byte too many that afterward gets
overwritten with '\0'.
---
 src/files.c |  3 +--
 src/help.c  |  3 +--
 src/nano.c  |  3 +--
 src/text.c  | 16 +++++-----------
 src/utils.c |  8 +++++---
 5 files changed, 13 insertions(+), 20 deletions(-)

diff --git a/src/files.c b/src/files.c
index 62ab9609..8e442d20 100644
--- a/src/files.c
+++ b/src/files.c
@@ -2228,8 +2228,7 @@ char *real_dir_from_tilde(const char *path)
 #ifdef HAVE_PWD_H
 		const struct passwd *userdata;
 
-		tilded = measured_copy(path, i + 1);
-		tilded[i] = '\0';
+		tilded = measured_copy(path, i);
 
 		do {
 			userdata = getpwent();
diff --git a/src/help.c b/src/help.c
index e5ff505e..9413dd9b 100644
--- a/src/help.c
+++ b/src/help.c
@@ -166,8 +166,7 @@ void show_help(void)
 
 	/* Extract the title from the head of the help text. */
 	length = break_line(help_text, MAX_BUF_SIZE, TRUE);
-	title = measured_copy(help_text, length + 1);
-	title[length] = '\0';
+	title = measured_copy(help_text, length);
 
 	titlebar(title);
 
diff --git a/src/nano.c b/src/nano.c
index 3b7941de..5683c913 100644
--- a/src/nano.c
+++ b/src/nano.c
@@ -223,8 +223,7 @@ void partition_buffer(linestruct *top, size_t top_x,
 	 * top of the partition from it, and save the text before top_x. */
 	foreline = top->prev;
 	top->prev = NULL;
-	antedata = measured_copy(top->data, top_x + 1);
-	antedata[top_x] = '\0';
+	antedata = measured_copy(top->data, top_x);
 
 	/* Remember which line is below the bottom of the partition, detach the
 	 * bottom of the partition from it, and save the text after bot_x. */
diff --git a/src/text.c b/src/text.c
index 7236ea42..0ed95d2f 100644
--- a/src/text.c
+++ b/src/text.c
@@ -261,9 +261,7 @@ void do_unindent(void)
 	 * possible, and saving the removed whitespace in the undo item. */
 	for (line = top; line != bot->next; line = line->next) {
 		size_t indent_len = length_of_white(line->data);
-		char *indentation = measured_copy(line->data, indent_len + 1);
-
-		indentation[indent_len] = '\0';
+		char *indentation = measured_copy(line->data, indent_len);
 
 		unindent_a_line(line, indent_len);
 		update_multiline_undo(line->lineno, indentation);
@@ -579,8 +577,7 @@ void do_undo(void)
 		}
 		t = make_new_node(f);
 		t->data = copy_of(u->strdata);
-		data = measured_copy(f->data, u->mark_begin_x + 1);
-		data[u->mark_begin_x] = '\0';
+		data = measured_copy(f->data, u->mark_begin_x);
 		free(f->data);
 		f->data = data;
 		splice_node(f, t);
@@ -725,8 +722,7 @@ void do_redo(void)
 		redidmsg = _("line break");
 		shoveline = make_new_node(f);
 		shoveline->data = copy_of(u->strdata);
-		data = measured_copy(f->data, u->begin + 1);
-		data[u->begin] = '\0';
+		data = measured_copy(f->data, u->begin);
 		free(f->data);
 		f->data = data;
 		splice_node(f, shoveline);
@@ -1906,8 +1902,7 @@ void justify_paragraph(linestruct **line, size_t par_len)
 	/* Copy the leading part (quoting + indentation) of the sample line. */
 	quote_len = quote_length(sampleline->data);
 	lead_len = quote_len + indent_length(sampleline->data + quote_len);
-	lead_string = measured_copy(sampleline->data, lead_len + 1);
-	lead_string[lead_len] = '\0';
+	lead_string = measured_copy(sampleline->data, lead_len);
 
 	/* Concatenate all lines of the paragraph into a single line. */
 	concat_paragraph(line, par_len);
@@ -1988,8 +1983,7 @@ void do_justify(bool full_justify)
 		/* Copy the leading part that is to be used for the new paragraph. */
 		quote_len = quote_length(first_par_line->data);
 		lead_len = quote_len + indent_length(first_par_line->data + quote_len);
-		the_lead = measured_copy(first_par_line->data, lead_len + 1);
-		the_lead[lead_len] = '\0';
+		the_lead = measured_copy(first_par_line->data, lead_len);
 
 		/* Copy the leading part that is to be used for the new paragraph after
 		 * its first line (if any): the quoting of the first line, plus the
diff --git a/src/utils.c b/src/utils.c
index 69557d21..ce5a7518 100644
--- a/src/utils.c
+++ b/src/utils.c
@@ -324,12 +324,14 @@ char *mallocstrcpy(char *dest, const char *src)
 	return dest;
 }
 
-/* Return an allocated copy of the first count characters of the given string. */
+/* Return an allocated copy of the first count characters
+ * of the given string, and NUL-terminate the copy. */
 char *measured_copy(const char *string, size_t count)
 {
-	char *thecopy = charalloc(count);
+	char *thecopy = charalloc(count + 1);
 
 	strncpy(thecopy, string, count);
+	thecopy[count] = '\0';
 
 	return thecopy;
 }
@@ -337,7 +339,7 @@ char *measured_copy(const char *string, size_t count)
 /* Return an allocated copy of the given string. */
 char *copy_of(const char *string)
 {
-	return measured_copy(string, strlen(string) + 1);
+	return measured_copy(string, strlen(string));
 }
 
 /* Free the string at dest and return the string at src. */