From 72d3f8f8e248a08e71ec5184aaaacd04cb877159 Mon Sep 17 00:00:00 2001
From: Matthieu Gautier <mgautier@kymeria.fr>
Date: Wed, 26 Aug 2020 12:25:21 +0200
Subject: [PATCH] Fix segmentation fault with curl requests.

Use a heap allocated buffer (with lifetime of Aria2 class) instead of
a stack allocated one.

Original fix made by @ZaWertun. Kudos to him.

Fix #kiwix/kiwix-desktop#123, kiwix/kiwix-desktop#513
and kiwix/kiwix-desktop#423
---
 src/aria2.cpp | 10 +++++-----
 src/aria2.h   |  1 +
 2 files changed, 6 insertions(+), 5 deletions(-)

diff --git a/src/aria2.cpp b/src/aria2.cpp
index 5aea07f45..9e0f5eacc 100644
--- a/src/aria2.cpp
+++ b/src/aria2.cpp
@@ -26,6 +26,7 @@ Aria2::Aria2():
   mp_aria(nullptr),
   m_port(42042),
   m_secret("kiwixariarpc"),
+  m_curlErrorBuffer(new char[CURL_ERROR_SIZE]),
   mp_curl(nullptr)
 {
   m_downloadDir = getDataDirectory();
@@ -83,24 +84,23 @@ Aria2::Aria2():
   }
   mp_aria = Subprocess::run(callCmd);
   mp_curl = curl_easy_init();
-  char errbuf[CURL_ERROR_SIZE];
   curl_easy_setopt(mp_curl, CURLOPT_URL, "http://localhost/rpc");
   curl_easy_setopt(mp_curl, CURLOPT_PORT, m_port);
   curl_easy_setopt(mp_curl, CURLOPT_POST, 1L);
-  curl_easy_setopt(mp_curl, CURLOPT_ERRORBUFFER, errbuf);
+  curl_easy_setopt(mp_curl, CURLOPT_ERRORBUFFER, m_curlErrorBuffer.get());
 
   int watchdog = 50;
   while(--watchdog) {
     sleep(10);
-    errbuf[0] = 0;
+    m_curlErrorBuffer[0] = 0;
     auto res = curl_easy_perform(mp_curl);
     if (res == CURLE_OK) {
       break;
     } else if (watchdog == 1) {
       std::cerr <<" curl_easy_perform() failed." << std::endl;
       fprintf(stderr, "\nlibcurl: (%d) ", res);
-      if (errbuf[0] != 0) {
-        std::cerr << errbuf << std::endl;
+      if (m_curlErrorBuffer[0] != 0) {
+        std::cerr << m_curlErrorBuffer.get() << std::endl;
       } else {
         std::cerr << curl_easy_strerror(res) << std::endl;
       }
diff --git a/src/aria2.h b/src/aria2.h
index 3401310eb..b07018f00 100644
--- a/src/aria2.h
+++ b/src/aria2.h
@@ -24,6 +24,7 @@ class Aria2
     int m_port;
     std::string m_secret;
     std::string m_downloadDir;
+    std::unique_ptr<char[]> m_curlErrorBuffer;
     CURL* mp_curl;
     std::mutex m_lock;