From f76c8ad30bd9afb60ba9071817f56cb04309d5eb Mon Sep 17 00:00:00 2001
From: Dominique Martinet <asmadeus@codewreck.org>
Date: Mon, 17 Sep 2018 11:01:24 +0900
Subject: [PATCH] pager history buffer: alloc buffer progressively

Realloc buffer 1MB at a time until the configured size is reached
---
 kitty/data-types.h |  2 +-
 kitty/history.c    | 19 ++++++++++++++++---
 2 files changed, 17 insertions(+), 4 deletions(-)

diff --git a/kitty/data-types.h b/kitty/data-types.h
index c07122830..a7519a3ee 100644
--- a/kitty/data-types.h
+++ b/kitty/data-types.h
@@ -174,7 +174,7 @@ typedef struct {
 } HistoryBufSegment;
 
 typedef struct {
-    index_type bufsize;
+    index_type bufsize, maxsz;
     Py_UCS4 *buffer;
     index_type start, end;
     index_type bufend;
diff --git a/kitty/history.c b/kitty/history.c
index 1b84a83aa..740aefe33 100644
--- a/kitty/history.c
+++ b/kitty/history.c
@@ -60,12 +60,23 @@ alloc_pagerhist(unsigned int pagerhist_sz) {
     if (!pagerhist_sz) return NULL;
     pagerhist_sz *= 1024*1024;
     ph = PyMem_Calloc(1, sizeof(PagerHistoryBuf));
-    ph->bufsize = pagerhist_sz / sizeof(Py_UCS4);
-    ph->buffer = PyMem_RawMalloc(pagerhist_sz);
+    ph->maxsz = pagerhist_sz / sizeof(Py_UCS4);
+    ph->bufsize = 1024*1024 / sizeof(Py_UCS4);
+    ph->buffer = PyMem_RawMalloc(1024*1024);
     if (!ph->buffer) { PyMem_Free(ph); return NULL; }
     return ph;
 }
 
+static inline bool
+pagerhist_extend(PagerHistoryBuf *ph) {
+    if (ph->bufsize >= ph->maxsz) return false;
+    void *newbuf = PyMem_Realloc(ph->buffer, ph->bufsize * sizeof(Py_UCS4) + 1024*1024);
+    if (!newbuf) return false;
+    ph->buffer = newbuf;
+    ph->bufsize += 1024*1024 / sizeof(Py_UCS4);
+    return true;
+}
+
 static PyObject *
 new(PyTypeObject *type, PyObject *args, PyObject UNUSED *kwds) {
     HistoryBuf *self;
@@ -156,7 +167,9 @@ pagerhist_push(HistoryBuf *self) {
     if (ph->start != ph->end && !l.continued) {
         ph->buffer[ph->end++] = '\n';
     }
-    if (ph->bufsize - ph->end < 1024) { ph->bufend = ph->end; ph->end = 0; }
+    if (ph->bufsize - ph->end < 1024 && !pagerhist_extend(ph)) {
+        ph->bufend = ph->end; ph->end = 0;
+    }
     ph->end += line_as_ansi(&l, ph->buffer + ph->end, 1023);
     ph->buffer[ph->end++] = '\r';
     if (ph->bufend) {