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Re-implement SDK discovery instead of using xcrun
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Original file line number | Diff line number | Diff line change |
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use std::fs; | ||
use std::io::ErrorKind; | ||
use std::path::{Path, PathBuf}; | ||
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use crate::errors::AppleSdkError; | ||
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#[cfg(test)] | ||
mod tests; | ||
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// TOCTOU is not _really_ an issue with our use of `try_exists` in here, we mostly use it for | ||
// diagnostics, and these directories are global state that the user may change anytime anyhow. | ||
fn try_exists(path: &Path) -> Result<bool, AppleSdkError> { | ||
path.try_exists().map_err(|error| AppleSdkError::FailedReading { path: path.to_owned(), error }) | ||
} | ||
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/// Get the SDK path for an SDK under `/Library/Developer/CommandLineTools`. | ||
fn sdk_root_in_sdks_dir(sdks_dir: impl Into<PathBuf>, sdk_name: &str) -> PathBuf { | ||
let mut path = sdks_dir.into(); | ||
path.push("SDKs"); | ||
path.push(sdk_name); | ||
path.set_extension("sdk"); | ||
path | ||
} | ||
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/// Get the SDK path for an SDK under `/Applications/Xcode.app/Contents/Developer`. | ||
fn sdk_root_in_developer_dir(developer_dir: impl Into<PathBuf>, sdk_name: &str) -> PathBuf { | ||
let mut path = developer_dir.into(); | ||
path.push("Platforms"); | ||
path.push(sdk_name); | ||
path.set_extension("platform"); | ||
path.push("Developer"); | ||
path.push("SDKs"); | ||
path.push(sdk_name); | ||
path.set_extension("sdk"); | ||
path | ||
} | ||
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/// Find a SDK root from the user's environment for the given SDK name. | ||
/// | ||
/// We do this by searching (purely by names in the filesystem, without reading SDKSettings.json) | ||
/// for a matching SDK in the following places: | ||
/// - `DEVELOPER_DIR` | ||
/// - `/var/db/xcode_select_link` | ||
/// - `/Applications/Xcode.app` | ||
/// - `/Library/Developer/CommandLineTools` | ||
/// | ||
/// This does roughly the same thing as `xcrun -sdk $sdk_name -show-sdk-path` (see `man xcrun` for | ||
/// a few details on the search algorithm). | ||
/// | ||
/// The reason why we implement this logic ourselves is: | ||
/// - Reading these directly is faster than spawning a new process. | ||
/// - `xcrun` can be fairly slow to start up after a reboot. | ||
/// - In the future, we will be able to integrate this better with the compiler's change tracking | ||
/// mechanisms, allowing rebuilds when the involved env vars and paths here change. See #118204. | ||
/// - It's easier for us to emit better error messages. | ||
/// | ||
/// Though a downside is that `xcrun` might be expanded in the future to check more places, and then | ||
/// `rustc` would have to be changed to keep up. Furthermore, `xcrun`'s exact algorithm is | ||
/// undocumented, so it might be doing more things than we do here. | ||
pub(crate) fn find_sdk_root(sdk_name: &'static str) -> Result<PathBuf, AppleSdkError> { | ||
// Only try this if host OS is macOS. | ||
if !cfg!(target_os = "macos") { | ||
return Err(AppleSdkError::MissingCrossCompileNonMacOS { sdk_name }); | ||
} | ||
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// NOTE: We could consider walking upwards in `SDKROOT` assuming Xcode directory structure, but | ||
// that isn't what `xcrun` does, and might still not yield the desired result (e.g. if using an | ||
// old SDK to compile for an old ARM iOS arch, we don't want `rustc` to pick a macOS SDK from | ||
// the old Xcode). | ||
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// Try reading from `DEVELOPER_DIR` on all hosts. | ||
if let Some(dir) = std::env::var_os("DEVELOPER_DIR") { | ||
let dir = PathBuf::from(dir); | ||
let sdkroot = sdk_root_in_developer_dir(&dir, sdk_name); | ||
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if try_exists(&sdkroot)? { | ||
return Ok(sdkroot); | ||
} else { | ||
let sdkroot_bare = sdk_root_in_sdks_dir(&dir, sdk_name); | ||
if try_exists(&sdkroot_bare)? { | ||
return Ok(sdkroot_bare); | ||
} else { | ||
return Err(AppleSdkError::MissingDeveloperDir { dir, sdkroot, sdkroot_bare }); | ||
} | ||
} | ||
} | ||
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// Next, try to read the link that `xcode-select` sets. | ||
// | ||
// FIXME(madsmtm): Support cases where `/var/db/xcode_select_link` contains a relative path? | ||
let path = PathBuf::from("/var/db/xcode_select_link"); | ||
match fs::read_link(&path) { | ||
Ok(dir) => { | ||
let sdkroot = sdk_root_in_developer_dir(&dir, sdk_name); | ||
if try_exists(&sdkroot)? { | ||
return Ok(sdkroot); | ||
} else { | ||
let sdkroot_bare = sdk_root_in_sdks_dir(&dir, sdk_name); | ||
if try_exists(&sdkroot_bare)? { | ||
return Ok(sdkroot_bare); | ||
} else { | ||
return Err(AppleSdkError::MissingXcodeSelect { dir, sdkroot, sdkroot_bare }); | ||
} | ||
} | ||
} | ||
Err(err) if err.kind() == ErrorKind::NotFound => { | ||
// Intentionally ignore not found errors, if `xcode-select --reset` is called the | ||
// link will not exist. | ||
} | ||
Err(error) => return Err(AppleSdkError::FailedReading { path, error }), | ||
} | ||
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// Next, fall back to reading from `/Applications/Xcode.app`. | ||
let dir = PathBuf::from("/Applications/Xcode.app/Contents/Developer"); | ||
if try_exists(&dir)? { | ||
let sdkroot = sdk_root_in_developer_dir(&dir, sdk_name); | ||
if try_exists(&sdkroot)? { | ||
return Ok(sdkroot); | ||
} else { | ||
return Err(AppleSdkError::MissingXcode { sdkroot, sdk_name }); | ||
} | ||
} | ||
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// Finally, fall back to reading from `/Library/Developer/CommandLineTools`. | ||
let dir = PathBuf::from("/Library/Developer/CommandLineTools"); | ||
if try_exists(&dir)? { | ||
let sdkroot = sdk_root_in_sdks_dir(&dir, sdk_name); | ||
if try_exists(&sdkroot)? { | ||
return Ok(sdkroot); | ||
} else { | ||
return Err(AppleSdkError::MissingCommandlineTools { sdkroot, sdk_name }); | ||
} | ||
} | ||
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Err(AppleSdkError::Missing { sdk_name }) | ||
} |
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Original file line number | Diff line number | Diff line change |
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use std::io; | ||
use std::path::PathBuf; | ||
use std::process::Command; | ||
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use super::find_sdk_root; | ||
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fn find_sdk_root_xcrun(sdk_name: &str) -> io::Result<PathBuf> { | ||
let output = Command::new("xcrun") | ||
.arg("-sdk") | ||
.arg(sdk_name.to_lowercase()) | ||
.arg("-show-sdk-path") | ||
.output()?; | ||
if output.status.success() { | ||
// FIXME(madsmtm): If using this for real, we should not error on non-UTF-8 paths. | ||
let output = String::from_utf8(output.stdout).unwrap(); | ||
Ok(PathBuf::from(output.trim())) | ||
} else { | ||
let error = String::from_utf8(output.stderr); | ||
let error = format!("process exit with error: {}", error.unwrap()); | ||
Err(io::Error::new(io::ErrorKind::Other, &error[..])) | ||
} | ||
} | ||
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/// Ensure that our `find_sdk_root` matches `xcrun`'s behaviour. | ||
/// | ||
/// `xcrun` is quite slow the first time it's run after a reboot, so this test may take some time. | ||
#[test] | ||
#[cfg_attr(not(target_os = "macos"), ignore = "xcrun is only available on macOS")] | ||
fn test_find_sdk_root() { | ||
let sdks = [ | ||
"MacOSX", | ||
"AppleTVOS", | ||
"AppleTVSimulator", | ||
"iPhoneOS", | ||
"iPhoneSimulator", | ||
"WatchOS", | ||
"WatchSimulator", | ||
"XROS", | ||
"XRSimulator", | ||
]; | ||
for sdk_name in sdks { | ||
if let Ok(expected) = find_sdk_root_xcrun(sdk_name) { | ||
// `xcrun` prefers `MacOSX14.0.sdk` over `MacOSX.sdk`, so let's compare canonical paths. | ||
let expected = std::fs::canonicalize(expected).unwrap(); | ||
let actual = find_sdk_root(sdk_name).unwrap(); | ||
let actual = std::fs::canonicalize(actual).unwrap(); | ||
assert_eq!(expected, actual); | ||
} else { | ||
// The macOS SDK must always be findable in Rust's CI. | ||
// | ||
// The other SDKs are allowed to not be found in the current developer directory when | ||
// running this test. | ||
if sdk_name == "MacOSX" { | ||
panic!("Could not find macOS SDK with `xcrun -sdk macosx -show-sdk-path`"); | ||
} | ||
} | ||
} | ||
} |
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