Do not assert on SIGTERM and backup modified buffers on signal induced termination

src/buffer_manager.cc

@@ -105,6 +105,15 @@ void BufferManager::set_last_used_buffer(Buffer& buffer)
     m_buffers.emplace(m_buffers.begin(), &buffer);
 }
 
+void BufferManager::backup_modified_buffers()
+{
+    for (auto& buf : m_buffers)
+    {
+        if ((buf->flags() & Buffer::Flags::File) and buf->is_modified())
+            write_buffer_to_backup_file(*buf);
+    }
+}
+
 CandidateList BufferManager::complete_buffer_name(StringView prefix,
                                                   ByteCount cursor_pos)
 {

src/buffer_manager.hh

@@ -34,6 +34,8 @@ public:
     Buffer& get_buffer(StringView name);
     void    set_last_used_buffer(Buffer& buffer);
 
+    void backup_modified_buffers();
+
     CandidateList complete_buffer_name(StringView prefix,
                                        ByteCount cursor_pos = -1);
 

src/file.cc

@@ -209,6 +209,19 @@ void write_buffer_to_file(Buffer& buffer, StringView filename)
     buffer.run_hook_in_own_context("BufWritePost", buffer.name());
 }
 
+void write_buffer_to_backup_file(Buffer& buffer)
+{
+    char pattern[PATH_MAX+1];
+    snprintf(pattern, PATH_MAX+1, ".%s.kak.XXXXXX",
+             real_path(buffer.name()).c_str());
+    int fd = mkstemp(pattern);
+    if (fd >= 0)
+    {
+        write_buffer_to_fd(buffer, fd);
+        close(fd);
+    }
+}
+
 String find_file(StringView filename, memoryview<String> paths)
 {
     struct stat buf;

src/file.hh

@@ -36,6 +36,7 @@ Buffer* create_buffer_from_file(String filename);
 
 void write_buffer_to_file(Buffer& buffer, StringView filename);
 void write_buffer_to_fd(Buffer& buffer, int fd);
+void write_buffer_to_backup_file(Buffer& buffer);
 
 String find_file(StringView filename, memoryview<String> paths);
 

src/main.cc

@@ -252,10 +252,18 @@ void signal_handler(int signal)
         case SIGQUIT: text = "SIGQUIT"; break;
         case SIGTERM: text = "SIGTERM"; break;
     }
-    on_assert_failed(text);
+    if (signal != SIGTERM)
+        on_assert_failed(text);
+
     if (Server::has_instance())
         Server::instance().close_session();
-    abort();
+    if (BufferManager::has_instance())
+        BufferManager::instance().backup_modified_buffers();
+
+    if (signal == SIGTERM)
+        exit(-1);
+    else
+        abort();
 }
 
 int run_client(StringView session, StringView init_command)