Struct Options

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pub struct Options { /* private fields */ }

Expand description

Ordered collection of mount options — fstab(5) field 4.

Options are stored in order and parsed from a comma-separated string with support for quoted values containing commas.

§Examples

let opts = Options::parse("rw,noatime,size=10G").unwrap();
assert!(opts.has("rw"));
assert_eq!(opts.get("size"), Some("10G"));
assert_eq!(opts.len(), 3);

Implementations§

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impl Options

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pub fn new() -> Self

Create an empty options collection.

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pub fn defaults() -> Self

Create options with a single defaults flag.

This matches the convention that “defaults” is the standard placeholder for default mount options in /etc/fstab.

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pub fn parse(raw: &str) -> Result<Self, OptionsError>

Parse a comma-separated options string.

Supports quoted values (both single and double quotes) to preserve commas within values (e.g., context="unconfined_u:object_r:user_tmp_t:s0").

§Errors

Returns OptionsError::EmptyOptionName if an option has an empty name.

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pub fn is_empty(&self) -> bool

Returns true if the options collection is empty.

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pub fn len(&self) -> usize

Number of options in this collection.

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pub fn get(&self, name: &str) -> Option<&str>

Get the value of the last occurrence of an option by name.

Returns None if the option is not found or is a flag (no value). Returns Some("") if the option was specified with an empty value (e.g., key=).

§Last-option-wins semantics

Per mount(8), if an option appears multiple times, the last occurrence wins. This method scans from the end of the list.

§Examples

let opts = Options::parse("size=10G,ro").unwrap();
assert_eq!(opts.get("size"), Some("10G"));
assert_eq!(opts.get("ro"), None); // flag option has no value
assert_eq!(opts.get("nonexistent"), None);

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pub fn has(&self, name: &str) -> bool

Check whether an option by name is present (as a flag or key=value).

§Examples

let opts = Options::parse("rw,noatime,size=10G").unwrap();
assert!(opts.has("rw"));
assert!(opts.has("noatime"));
assert!(opts.has("size"));
assert!(!opts.has("ro"));

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pub fn contains(&self, name: &str) -> bool

Alias for has, for consistency with std::collections::HashSet.

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pub fn iter(&self) -> impl Iterator<Item = &OptItem>

Iterate over all option items in order.

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pub fn is_readonly(&self) -> bool

Whether the options imply a read-only mount.

Uses last-option-wins semantics: ro returns true, rw or defaults returns false.

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pub fn is_noauto(&self) -> bool

Whether the options imply noauto (do not mount automatically at boot).

Uses last-option-wins semantics.

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pub fn has_nofail(&self) -> bool

Whether the nofail option is present (do not halt boot on mount failure).

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pub fn is_netdev(&self) -> bool

Whether the _netdev option is present (network-backed device).

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pub fn mount_permission(&self) -> MountPermission

Determine the mount permission model based on options.

Uses last-option-wins semantics.

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pub fn set(&mut self, name: &str, value: Option<&str>) -> &mut Self

Set a mount option, replacing any existing occurrence with the same name.

The option is appended to the end (last-option-wins position).

§Examples

let mut opts = Options::parse("rw,noatime").unwrap();
opts.set("ro", None).set("size", Some("10G"));
assert!(opts.has("ro"));
assert_eq!(opts.get("size"), Some("10G"));
// Original "rw" replaced by "ro" (last-option-wins)
assert!(opts.is_readonly());