Struct Room 

pub struct Room {
    pub after: u32,
    pub before: u32,
}

How much room every function opens with for something to be written over it later.

What -fpatchable-function-entry= asks for, as the two halves a prologue deals in rather than as the total and the part the flag is written in. The room can be on either side of the function’s own label and the two sides are not the same thing: what is after the label is inside the function, which is what a patcher redirecting a call into it wants, and what is in front of it is outside, which is where a patcher that needs a whole instruction it can reach from the first one puts it.

Fields

after: u32

How many bytes go after the function’s own label.

before: u32

How many go in front of it.

Implementations

impl Room

pub const fn any(self) -> bool

Whether any room at all was asked for, which is what decides whether a function gets one.

=0 is a command line that asked for none, and gcc takes it and writes nothing, so the question is about the numbers rather than about whether the flag was written.

Trait Implementations

impl Clone for Room

fn clone(&self) -> Room

Returns a duplicate of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Copy for Room

impl Debug for Room

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl Default for Room

fn default() -> Room

Returns the “default value” for a type.

impl Eq for Room

impl PartialEq for Room

fn eq(&self, other: &Room) -> bool

Equality operator ==.

fn ne(&self, other: &Rhs) -> bool

Inequality operator !=.

impl StructuralPartialEq for Room