Change BufWritePre/BufWritePost logic

Run them in client context if possible, and give them the target
filename instead of the buffer name.

Fixes #823

src/commands.cc

@@ -313,7 +313,10 @@ void write_buffer(const ParametersParser& parser, Context& context, const ShellC
 
     auto filename = parser.positional_count() == 0 ?
                         buffer.name() : parse_filename(parser[0]);
+
+    context.hooks().run_hook("BufWritePre", filename, context);
     write_buffer_to_file(buffer, filename);
+    context.hooks().run_hook("BufWritePost", filename, context);
 }
 
 const CommandDesc write_cmd = {
@@ -334,7 +337,11 @@ void write_all_buffers()
     {
         if ((buffer->flags() & Buffer::Flags::File) and buffer->is_modified()
             and !(buffer->flags() & Buffer::Flags::ReadOnly))
+        {
+            buffer->run_hook_in_own_context("BufWritePre", buffer->name());
             write_buffer_to_file(*buffer, buffer->name());
+            buffer->run_hook_in_own_context("BufWritePost", buffer->name());
+        }
     }
 }
 

src/file.cc

@@ -256,23 +256,17 @@ void write_buffer_to_fd(Buffer& buffer, int fd)
 
 void write_buffer_to_file(Buffer& buffer, StringView filename)
 {
-    buffer.run_hook_in_own_context("BufWritePre", buffer.name());
+    int fd = open(parse_filename(filename).c_str(),
+                  O_CREAT | O_WRONLY | O_TRUNC, 0644);
+    if (fd == -1)
+        throw file_access_error(filename, strerror(errno));
+    auto close_fd = on_scope_end([fd]{ close(fd); });
 
-    {
+    write_buffer_to_fd(buffer, fd);
-        int fd = open(parse_filename(filename).c_str(),
-                      O_CREAT | O_WRONLY | O_TRUNC, 0644);
-        if (fd == -1)
-            throw file_access_error(filename, strerror(errno));
-        auto close_fd = on_scope_end([fd]{ close(fd); });
-
-        write_buffer_to_fd(buffer, fd);
-    }
 
     if ((buffer.flags() & Buffer::Flags::File) and
         real_path(filename) == real_path(buffer.name()))
         buffer.notify_saved();
-
-    buffer.run_hook_in_own_context("BufWritePost", buffer.name());
 }
 
 void write_buffer_to_backup_file(Buffer& buffer)