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This patch reduces the number of exception types by facilitating globally defined exceptions for common usage patterns shared by most services. In particular, RPC functions that demand a session-resource upgrade not longer reflect this condition via a session-specific exception but via the 'Out_of_ram' or 'Out_of_caps' types. Furthermore, the 'Parent::Service_denied', 'Parent::Unavailable', 'Root::Invalid_args', 'Root::Unavailable', 'Service::Invalid_args', 'Service::Unavailable', and 'Local_service::Factory::Denied' types have been replaced by the single 'Service_denied' exception type defined in 'session/session.h'. This consolidation eases the error handling (there are fewer exceptions to handle), alleviates the need to convert exceptions along the session-creation call chain, and avoids possible aliasing problems (catching the wrong type with the same name but living in a different scope). |
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| .. | ||
| directory.h | ||
| file.h | ||
| lx_util.h | ||
| main.cc | ||
| node.h | ||
| README | ||
| symlink.h | ||
| target.mk | ||
This directory contains an Genode file-system service to Linux host fs wrapper. Configuration ~~~~~~~~~~~~~ Access to the file system can be tailored for each session depending on the session's label. By default, no permissions are granted to any session. To selectively permit access to (a part of) the file system, at least one policy must be defined. The following configuration illustates the way of how to express policy. ! <config> ! <!-- constrain sessions according to their labels --> ! <policy label="noux -> root" root="/" /> ! <policy label="noux -> home" root="/home/user" writeable="yes" /> ! <policy label="noux -> tmp" root="/tmp" writeable="yes" /> ! </config> Session-specific access-control policy is expressed via one or more '<policy>' nodes. At session-creation time, each policy node is matched against the label of the new session. If the label of a policy node matches, the defined policy is applied. If multiple policies match, the one with the longest 'label' attribute (the most specific one) is selected. A policy node may contain the following attributes. The mandatory 'root' attribute defines the viewport of the session onto the file system. The optional 'writeable' attribute grants the permission to modify the file system. Example ~~~~~~~ To illustrate the use of lx_fs, refer to the 'base-linux/run/lx_fs.run' script. Notes ~~~~~ If the Linux file system experiences changes from other processes 'inotify' may help to keep the servers cache up-to-date. This is not implemented yet.