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fs_rom: realloc only when dataspace grew 

Fixes #1377
This commit is contained in:
Norman Feske 2014-11-23 01:12:54 +01:00 committed by Christian Helmuth
parent ff422ccc6e
commit 623bc82e07
1 changed files with 29 additions and 7 deletions
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36
repos/os/src/server/fs_rom/main.cc
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@ -147,6 +147,11 @@ class Rom_session_component : public Genode::Rpc_object<Genode::Rom_session>
*/
File_system::File_handle _file_handle;
/**
* Size of current version of the file
*/
File_system::file_size_t _file_size = 0;
/**
* Handle of currently watched compound directory
*
@ -285,11 +290,24 @@ class Rom_session_component : public Genode::Rpc_object<Genode::Rom_session>
/*
* On each repeated call of this function, the dataspace is
* replaced with a new one that contains the most current file
* content.
* content. The dataspace is re-allocated if the new version
* of the file has become bigger.
*/
if (_file_ds.valid()) {
env()->ram_session()->free(_file_ds);
_file_ds = Ram_dataspace_capability();
{
File_handle const file_handle = _open_file(_fs, _file_path);
if (file_handle.valid()) {
File_system::file_size_t const new_file_size =
_fs.status(file_handle).size;
if (_file_ds.valid() && (new_file_size > _file_size)) {
env()->ram_session()->free(_file_ds);
/* mark as invalid */
_file_ds = Ram_dataspace_capability();
_file_size = 0;
}
}
_fs.close(file_handle);
}
/* close and then re-open the file */
@ -315,8 +333,11 @@ class Rom_session_component : public Genode::Rpc_object<Genode::Rom_session>
/* allocate new RAM dataspace according to file size */
if (file_size > 0) {
try {
_file_ds = env()->ram_session()->alloc(file_size); }
catch (...) {
if (!_file_ds.valid()) {
_file_ds = env()->ram_session()->alloc(file_size);
_file_size = file_size;
}
} catch (...) {
PERR("couldn't allocate memory for file, empty result\n");
_file_ds = Ram_dataspace_capability();
return;
@ -413,7 +434,8 @@ class Rom_root : public Genode::Root_component<Rom_session_component>
PINF("connection for file '%s' requested\n", filename);
/* create new session for the requested file */
return new (md_alloc()) Rom_session_component(_fs, filename, _sig_rec);
return new (md_alloc())
Rom_session_component(_fs, filename, _sig_rec);
}
public: