[PATCH] history: reverse the order in the file-positions list --> latest first

Putting the record for the last-edited file at the top of the list
ensures that the newest entry will be encountered first and thus
reused.  It also makes searching the list faster, because the files
that the user is likely to edit soon again will be near the top of
the list instead of near the end.

This fixes https://savannah.gnu.org/bugs/?67120.

Problem existed since version 2.3.0,
since position logging was introduced.
---
 src/history.c | 41 ++++++++++++-----------------------------
 1 file changed, 12 insertions(+), 29 deletions(-)

diff --git a/src/history.c b/src/history.c
index b72431cf..7d75e88a 100644
--- a/src/history.c
+++ b/src/history.c
@@ -410,11 +410,11 @@ void load_poshistory(void)
 	char *phrase = NULL;
 	struct stat fileinfo;
 	size_t dummy = 0;
-	ssize_t count = 0;
+	int count = 0;
 	ssize_t length;
 
 	/* Read and parse each line, and store the extracted data. */
-	while ((length = getline(&phrase, &dummy, histfile)) > 1) {
+	while (count++ < 200 && (length = getline(&phrase, &dummy, histfile)) > 1) {
 		stanza = strchr(phrase, '/');
 		length -= (stanza - phrase);
 
@@ -448,17 +448,6 @@ void load_poshistory(void)
 			lastitem->next = newitem;
 
 		lastitem = newitem;
-
-		/* Impose a limit, so the file will not grow indefinitely. */
-		if (++count > 200) {
-			poshiststruct *drop_record = position_history;
-
-			position_history = position_history->next;
-
-			free(drop_record->filename);
-			free(drop_record->anchors);
-			free(drop_record);
-		}
 	}
 
 	if (fclose(histfile) == EOF)
@@ -476,6 +465,7 @@ void save_poshistory(void)
 	FILE *histfile = fopen(poshistname, "wb");
 	struct stat fileinfo;
 	poshiststruct *item;
+	int count = 0;
 
 	if (histfile == NULL) {
 		jot_error(N_("Error writing %s: %s"), poshistname, strerror(errno));
@@ -486,7 +476,7 @@ void save_poshistory(void)
 	if (chmod(poshistname, S_IRUSR | S_IWUSR) < 0)
 		jot_error(N_("Cannot limit permissions on %s: %s"), poshistname, strerror(errno));
 
-	for (item = position_history; item != NULL; item = item->next) {
+	for (item = position_history; item != NULL && count++ < 200; item = item->next) {
 		char *path_and_place;
 		size_t length = (item->anchors == NULL) ? 0 : strlen(item->anchors);
 
@@ -580,31 +570,24 @@ void update_poshistory(void)
 
 	theone = item;
 
-	/* If we didn't find it, make a new node; otherwise, if we're
-	 * not at the end, move the matching one to the end. */
+	/* If no match was found, make a new node; otherwise, unlink the match. */
 	if (theone == NULL) {
 		theone = nmalloc(sizeof(poshiststruct));
 		theone->filename = copy_of(fullpath);
 		theone->anchors = NULL;
-		if (position_history == NULL)
-			position_history = theone;
-		else
-			previous->next = theone;
-	} else if (item->next != NULL) {
-		if (previous == NULL)
-			position_history = item->next;
-		else
-			previous->next = item->next;
-		while (item->next != NULL)
-			item = item->next;
-		item->next = theone;
+	} else if (previous)
+		previous->next = theone->next;
+
+	/* Place the found or new node at the beginning, if not already there. */
+	if (theone != position_history) {
+		theone->next = position_history;
+		position_history = theone;
 	}
 
 	/* Store the last cursor position. */
 	theone->linenumber = openfile->current->lineno;
 	theone->columnnumber = xplustabs() + 1;
 	theone->anchors = free_and_assign(theone->anchors, stringify_anchors());
-	theone->next = NULL;
 
 	free(fullpath);
 
-- 
2.48.1