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Refactor uses of objc_msgSend to no longer have clashing definitions

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This is very similar to what Apple's own headers encourage you to do (cast the function pointer before use instead of making new declarations).

Additionally, I'm documenting a few of the memory management rules we're following, ensuring that the `args` function doesn't leak memory (if you wrap it in an autorelease pool).
This commit is contained in:
Mads Marquart 2023-11-14 14:52:41 +01:00
parent c6c4abf584
commit 3b325bc25f
1 changed files with 44 additions and 37 deletions
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81
library/std/src/sys/pal/unix/args.rs
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@ -201,9 +201,9 @@ pub fn args() -> Args {
// As _NSGetArgc and _NSGetArgv aren't mentioned in iOS docs
// and use underscores in their names - they're most probably
// are considered private and therefore should be avoided
// Here is another way to get arguments using Objective C
// runtime
// are considered private and therefore should be avoided.
// Here is another way to get arguments using the Objective-C
// runtime.
//
// In general it looks like:
// res = Vec::new()
@ -213,53 +213,60 @@ pub fn args() -> Args {
// res
#[cfg(any(target_os = "ios", target_os = "tvos", target_os = "watchos"))]
pub fn args() -> Args {
use crate::ffi::OsString;
use crate::ffi::{c_char, c_void, OsString};
use crate::mem;
use crate::str;
type Sel = *const c_void;
type NsId = *const c_void;
type NSUInteger = usize;
extern "C" {
fn sel_registerName(name: *const libc::c_uchar) -> Sel;
fn objc_getClass(class_name: *const libc::c_uchar) -> NsId;
fn sel_registerName(name: *const c_char) -> Sel;
fn objc_getClass(class_name: *const c_char) -> NsId;
// This must be transmuted to an appropriate function pointer type before being called.
fn objc_msgSend();
}
#[cfg(target_arch = "aarch64")]
extern "C" {
fn objc_msgSend(obj: NsId, sel: Sel) -> NsId;
#[allow(clashing_extern_declarations)]
#[link_name = "objc_msgSend"]
fn objc_msgSend_ul(obj: NsId, sel: Sel, i: libc::c_ulong) -> NsId;
}
#[cfg(not(target_arch = "aarch64"))]
extern "C" {
fn objc_msgSend(obj: NsId, sel: Sel, ...) -> NsId;
#[allow(clashing_extern_declarations)]
#[link_name = "objc_msgSend"]
fn objc_msgSend_ul(obj: NsId, sel: Sel, ...) -> NsId;
}
type Sel = *const libc::c_void;
type NsId = *const libc::c_void;
const MSG_SEND_PTR: unsafe extern "C" fn() = objc_msgSend;
const MSG_SEND_NO_ARGUMENTS_RETURN_PTR: unsafe extern "C" fn(NsId, Sel) -> *const c_void =
unsafe { mem::transmute(MSG_SEND_PTR) };
const MSG_SEND_NO_ARGUMENTS_RETURN_NSUINTEGER: unsafe extern "C" fn(
NsId,
Sel,
) -> NSUInteger = unsafe { mem::transmute(MSG_SEND_PTR) };
const MSG_SEND_NSINTEGER_ARGUMENT_RETURN_PTR: unsafe extern "C" fn(
NsId,
Sel,
NSUInteger,
)
-> *const c_void = unsafe { mem::transmute(MSG_SEND_PTR) };
let mut res = Vec::new();
unsafe {
let process_info_sel =
sel_registerName(c"processInfo".as_ptr() as *const libc::c_uchar);
let arguments_sel = sel_registerName(c"arguments".as_ptr() as *const libc::c_uchar);
let utf8_sel = sel_registerName(c"UTF8String".as_ptr() as *const libc::c_uchar);
let count_sel = sel_registerName(c"count".as_ptr() as *const libc::c_uchar);
let object_at_sel =
sel_registerName(c"objectAtIndex:".as_ptr() as *const libc::c_uchar);
let process_info_sel = sel_registerName(c"processInfo".as_ptr());
let arguments_sel = sel_registerName(c"arguments".as_ptr());
let count_sel = sel_registerName(c"count".as_ptr());
let object_at_index_sel = sel_registerName(c"objectAtIndex:".as_ptr());
let utf8string_sel = sel_registerName(c"UTF8String".as_ptr());
let klass = objc_getClass(c"NSProcessInfo".as_ptr() as *const libc::c_uchar);
let info = objc_msgSend(klass, process_info_sel);
let args = objc_msgSend(info, arguments_sel);
let klass = objc_getClass(c"NSProcessInfo".as_ptr());
// `+[NSProcessInfo processInfo]` returns an object with +0 retain count, so no need to manually `retain/release`.
let info = MSG_SEND_NO_ARGUMENTS_RETURN_PTR(klass, process_info_sel);
let cnt: usize = mem::transmute(objc_msgSend(args, count_sel));
// `-[NSProcessInfo arguments]` returns an object with +0 retain count, so no need to manually `retain/release`.
let args = MSG_SEND_NO_ARGUMENTS_RETURN_PTR(info, arguments_sel);
let cnt = MSG_SEND_NO_ARGUMENTS_RETURN_NSUINTEGER(args, count_sel);
for i in 0..cnt {
let tmp = objc_msgSend_ul(args, object_at_sel, i as libc::c_ulong);
let utf_c_str: *const libc::c_char = mem::transmute(objc_msgSend(tmp, utf8_sel));
// `-[NSArray objectAtIndex:]` returns an object whose lifetime is tied to the array, so no need to manually `retain/release`.
let ns_string =
MSG_SEND_NSINTEGER_ARGUMENT_RETURN_PTR(args, object_at_index_sel, i);
// The lifetime of this pointer is tied to the NSString, as well as the current autorelease pool, which is why we heap-allocate the string below.
let utf_c_str: *const c_char =
MSG_SEND_NO_ARGUMENTS_RETURN_PTR(ns_string, utf8string_sel).cast();
let bytes = CStr::from_ptr(utf_c_str).to_bytes();
res.push(OsString::from(str::from_utf8(bytes).unwrap()))
}