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This patch changes the top-level directory layout as a preparatory step for improving the tools for managing 3rd-party source codes. The rationale is described in the issue referenced below. Issue #1082
58 lines
2.2 KiB
Plaintext
58 lines
2.2 KiB
Plaintext
This directory contains an in-memory file-system implementation.
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Configuration
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~~~~~~~~~~~~~
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Access to the file system can be tailored for each session depending on the
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session's label. By default, no permissions are granted to any session.
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To selectively permit access to (a part of) the file system, at least one
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ram_fs policy must be defined.
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The following configuration illustates the way of how to express policy.
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! <config>
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! <!-- preload RAM file system with some ROM images -->
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! <content>
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! <dir name="tmp">
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! <rom name="init" as="blubb" />
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! </dir>
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! <dir name="home">
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! <dir name="user">
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! <inline name=".vimrc">
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! set hidden
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! </inline>
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! </dir>
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! </dir>
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! </content>
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! <!-- constrain sessions according to their labels -->
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! <policy label="noux -> root" root="/" />
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! <policy label="noux -> home" root="/home/user" writeable="yes" />
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! <policy label="noux -> tmp" root="/tmp" writeable="yes" />
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! </config>
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The '<content>' sub node of the '<config>' node provides a way to pre-populate
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the file system with directories and files. Note that '<dir>' nodes can be
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arbitrarily nested. Files can be loaded from the ROM service. By adding the
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optional 'at' attribute to a rom node, the file name can be defined
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independently from the ROM module name. In addition to creating files from
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ROM modules, files can be created from data specified directly as part of the
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configuration using '<inline>' nodes. The content of such nodes is used as
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file content as is.
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Session-specific access-control policy is expressed via one or more '<policy>'
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nodes. At session-creation time, each policy node is matched against the label
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of the new session. If the label of a policy node matches, the defined policy
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is applied. If multiple policies match, the one with the longest 'label'
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attribute (the most specific one) is selected.
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A policy node may contain the following attributes. The mandatory 'root'
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attribute defines the viewport of the session onto the file system. The
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optional 'writeable' attribute grants the permission to modify the file system.
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Example
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~~~~~~~
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To illustrate the use of ram_fs, refer to the 'libports/run/libc_fs.run'
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script.
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