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Diffstat (limited to 'src/rust/tor_util/strings.rs')
| -rw-r--r-- | src/rust/tor_util/strings.rs | 136 |
1 files changed, 0 insertions, 136 deletions
diff --git a/src/rust/tor_util/strings.rs b/src/rust/tor_util/strings.rs deleted file mode 100644 index ede42c6ea8..0000000000 --- a/src/rust/tor_util/strings.rs +++ /dev/null @@ -1,136 +0,0 @@ -// Copyright (c) 2016-2019, The Tor Project, Inc. */ -// See LICENSE for licensing information */ - -//! Utilities for working with static strings. - -/// Create a `CStr` from a literal byte slice, appending a NUL byte to it first. -/// -/// # Warning -/// -/// The literal byte slice which is taken as an argument *MUST NOT* have any NUL -/// bytes (`b"\0"`) in it, anywhere, or else an empty string will be returned -/// (`CStr::from_bytes_with_nul_unchecked(b"\0")`) so as to avoid `panic!()`ing. -/// -/// # Examples -/// -/// ``` -/// #[macro_use] -/// extern crate tor_util; -/// -/// use std::ffi::CStr; -/// -/// # fn do_test() -> Result<&'static CStr, &'static str> { -/// let message: &'static str = "This is a test of the tsunami warning system."; -/// let tuesday: &'static CStr; -/// let original: &str; -/// -/// tuesday = cstr!("This is a test of the tsunami warning system."); -/// original = tuesday.to_str().or(Err("Couldn't unwrap CStr!"))?; -/// -/// assert!(original == message); -/// # -/// # Ok(tuesday) -/// # } -/// # fn main() { -/// # do_test(); // so that we can use the ? operator in the test -/// # } -/// ``` -/// It is also possible to pass several string literals to this macro. They -/// will be concatenated together in the order of the arguments, unmodified, -/// before finally being suffixed with a NUL byte: -/// -/// ``` -/// #[macro_use] -/// extern crate tor_util; -/// # -/// # use std::ffi::CStr; -/// # -/// # fn do_test() -> Result<&'static CStr, &'static str> { -/// -/// let quux: &'static CStr = cstr!("foo", "bar", "baz"); -/// let orig: &'static str = quux.to_str().or(Err("Couldn't unwrap CStr!"))?; -/// -/// assert!(orig == "foobarbaz"); -/// # Ok(quux) -/// # } -/// # fn main() { -/// # do_test(); // so that we can use the ? operator in the test -/// # } -/// ``` -/// This is useful for passing static strings to C from Rust FFI code. To do so -/// so, use the `.as_ptr()` method on the resulting `&'static CStr` to convert -/// it to the Rust equivalent of a C `const char*`: -/// -/// ``` -/// #[macro_use] -/// extern crate tor_util; -/// -/// use std::ffi::CStr; -/// use std::os::raw::c_char; -/// -/// pub extern "C" fn give_static_borrowed_string_to_c() -> *const c_char { -/// let hello: &'static CStr = cstr!("Hello, language my parents wrote."); -/// -/// hello.as_ptr() -/// } -/// # fn main() { -/// # let greetings = give_static_borrowed_string_to_c(); -/// # } -/// ``` -/// Note that the C code this static borrowed string is passed to *MUST NOT* -/// attempt to free the memory for the string. -/// -/// # Note -/// -/// An unfortunate limitation of the rustc compiler (as of 1.25.0-nightly), is -/// that the first example above compiles, but if we were to change the -/// assignment of `tuesday` as follows, it will fail to compile, because Rust -/// macros are expanded at parse time, and at parse time there is no symbol -/// table available. -/// -/// ```ignore -/// tuesday = cstr!(message); -/// ``` -/// with the error message `error: expected a literal`. -/// -/// # Returns -/// -/// If the string literals passed as arguments contain no NUL bytes anywhere, -/// then an `&'static CStr` containing the (concatenated) bytes of the string -/// literal(s) passed as arguments, with a NUL byte appended, is returned. -/// Otherwise, an `&'static CStr` containing a single NUL byte is returned (an -/// "empty" string in C). -#[macro_export] -macro_rules! cstr { - ($($bytes:expr),*) => ( - ::std::ffi::CStr::from_bytes_with_nul( - concat!($($bytes),*, "\0").as_bytes() - ).unwrap_or_default() - ) -} - -#[cfg(test)] -mod test { - use std::ffi::CStr; - - #[test] - fn cstr_macro() { - let _: &'static CStr = cstr!("boo"); - } - - #[test] - fn cstr_macro_multi_input() { - let quux: &'static CStr = cstr!("foo", "bar", "baz"); - - assert!(quux.to_str().unwrap() == "foobarbaz"); - } - - #[test] - fn cstr_macro_bad_input() { - let waving: &'static CStr = cstr!("waving not drowning o/"); - let drowning: &'static CStr = cstr!("\0 drowning not waving"); - - assert!(waving.to_str().unwrap() == "waving not drowning o/"); - assert!(drowning.to_str().unwrap() == "") - } -} |