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https://github.com/tinygo-org/tinygo.git
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Ayke van Laethem
6bcb40fe01
This allows applications to mount filesystems in the os package. This is useful for mounting external flash filesystems, for example.
86 lines
3.0 KiB
Go
86 lines
3.0 KiB
Go
package os
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import (
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"strings"
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)
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// mounts lists the mount points currently mounted in the filesystem provided by
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// the os package. To resolve a path to a mount point, it is scanned from top to
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// bottom looking for the first prefix match.
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var mounts []mountPoint
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type mountPoint struct {
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// prefix is a filesystem prefix, that always starts and ends with a forward
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// slash. To denote the root filesystem, use a single slash: "/".
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// This allows fast checking whether a path lies within a mount point.
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prefix string
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// filesystem is the Filesystem implementation that is mounted at this mount
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// point.
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filesystem Filesystem
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}
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// Filesystem provides an interface for generic filesystem drivers mounted in
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// the os package. The errors returned must be one of the os.Err* errors, or a
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// custom error if one doesn't exist. It should not be a *PathError because
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// errors will be wrapped with a *PathError by the filesystem abstraction.
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//
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// WARNING: this interface is not finalized and may change in a future version.
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type Filesystem interface {
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// OpenFile opens the named file.
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OpenFile(name string, flag int, perm FileMode) (FileHandle, error)
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// Mkdir creates a new directoy with the specified permission (before
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// umask). Some filesystems may not support directories or permissions.
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Mkdir(name string, perm FileMode) error
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// Remove removes the named file or (empty) directory.
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Remove(name string) error
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}
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// FileHandle is an interface that should be implemented by filesystems
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// implementing the Filesystem interface.
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//
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// WARNING: this interface is not finalized and may change in a future version.
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type FileHandle interface {
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// Read reads up to len(b) bytes from the file.
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Read(b []byte) (n int, err error)
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// Write writes up to len(b) bytes to the file.
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Write(b []byte) (n int, err error)
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// Close closes the file, making it unusable for further writes.
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Close() (err error)
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}
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// findMount returns the appropriate (mounted) filesystem to use for a given
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// filename plus the path relative to that filesystem.
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func findMount(path string) (Filesystem, string) {
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for i := len(mounts) - 1; i >= 0; i-- {
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mount := mounts[i]
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if strings.HasPrefix(path, mount.prefix) {
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return mount.filesystem, path[len(mount.prefix)-1:]
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}
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}
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if isOS {
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// Assume that the first entry in the mounts slice is the OS filesystem
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// at the root of the directory tree. Use it as-is, to support relative
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// paths.
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return mounts[0].filesystem, path
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}
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return nil, path
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}
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// Mount mounts the given filesystem in the filesystem abstraction layer of the
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// os package. It is not possible to unmount filesystems. Filesystems added
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// later will override earlier filesystems.
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//
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// The provided prefix must start and end with a forward slash. This is true for
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// the root directory ("/") for example.
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func Mount(prefix string, filesystem Filesystem) {
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if prefix[0] != '/' || prefix[len(prefix)-1] != '/' {
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panic("os.Mount: invalid prefix")
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}
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mounts = append(mounts, mountPoint{prefix, filesystem})
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}
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