4 files changed, 62 insertions, 27 deletions
diff --git a/library/std/src/sys/unix/cmath.rs b/library/std/src/sys/unix/cmath.rs
index f327b69fc75..2bf80d7a4cb 100644
--- a/library/std/src/sys/unix/cmath.rs
+++ b/library/std/src/sys/unix/cmath.rs
@@ -1,32 +1,33 @@
 #![cfg(not(test))]
 
-use libc::{c_double, c_float};
+// These symbols are all defined by `libm`,
+// or by `compiler-builtins` on unsupported platforms.
 
 extern "C" {
-    pub fn acos(n: c_double) -> c_double;
-    pub fn acosf(n: c_float) -> c_float;
-    pub fn asin(n: c_double) -> c_double;
-    pub fn asinf(n: c_float) -> c_float;
-    pub fn atan(n: c_double) -> c_double;
-    pub fn atan2(a: c_double, b: c_double) -> c_double;
-    pub fn atan2f(a: c_float, b: c_float) -> c_float;
-    pub fn atanf(n: c_float) -> c_float;
-    pub fn cbrt(n: c_double) -> c_double;
-    pub fn cbrtf(n: c_float) -> c_float;
-    pub fn cosh(n: c_double) -> c_double;
-    pub fn coshf(n: c_float) -> c_float;
-    pub fn expm1(n: c_double) -> c_double;
-    pub fn expm1f(n: c_float) -> c_float;
-    pub fn fdim(a: c_double, b: c_double) -> c_double;
-    pub fn fdimf(a: c_float, b: c_float) -> c_float;
-    pub fn hypot(x: c_double, y: c_double) -> c_double;
-    pub fn hypotf(x: c_float, y: c_float) -> c_float;
-    pub fn log1p(n: c_double) -> c_double;
-    pub fn log1pf(n: c_float) -> c_float;
-    pub fn sinh(n: c_double) -> c_double;
-    pub fn sinhf(n: c_float) -> c_float;
-    pub fn tan(n: c_double) -> c_double;
-    pub fn tanf(n: c_float) -> c_float;
-    pub fn tanh(n: c_double) -> c_double;
-    pub fn tanhf(n: c_float) -> c_float;
+    pub fn acos(n: f64) -> f64;
+    pub fn acosf(n: f32) -> f32;
+    pub fn asin(n: f64) -> f64;
+    pub fn asinf(n: f32) -> f32;
+    pub fn atan(n: f64) -> f64;
+    pub fn atan2(a: f64, b: f64) -> f64;
+    pub fn atan2f(a: f32, b: f32) -> f32;
+    pub fn atanf(n: f32) -> f32;
+    pub fn cbrt(n: f64) -> f64;
+    pub fn cbrtf(n: f32) -> f32;
+    pub fn cosh(n: f64) -> f64;
+    pub fn coshf(n: f32) -> f32;
+    pub fn expm1(n: f64) -> f64;
+    pub fn expm1f(n: f32) -> f32;
+    pub fn fdim(a: f64, b: f64) -> f64;
+    pub fn fdimf(a: f32, b: f32) -> f32;
+    pub fn hypot(x: f64, y: f64) -> f64;
+    pub fn hypotf(x: f32, y: f32) -> f32;
+    pub fn log1p(n: f64) -> f64;
+    pub fn log1pf(n: f32) -> f32;
+    pub fn sinh(n: f64) -> f64;
+    pub fn sinhf(n: f32) -> f32;
+    pub fn tan(n: f64) -> f64;
+    pub fn tanf(n: f32) -> f32;
+    pub fn tanh(n: f64) -> f64;
+    pub fn tanhf(n: f32) -> f32;
 }
diff --git a/library/std/src/sys/unix/ext/fs.rs b/library/std/src/sys/unix/ext/fs.rs
index 9a982a4acd9..9cf51be2836 100644
--- a/library/std/src/sys/unix/ext/fs.rs
+++ b/library/std/src/sys/unix/ext/fs.rs
@@ -884,3 +884,29 @@ impl DirBuilderExt for fs::DirBuilder {
         self
     }
 }
+
+/// Change the root directory of the current process to the specified path.
+///
+/// This typically requires privileges, such as root or a specific capability.
+///
+/// This does not change the current working directory; you should call
+/// [`std::env::set_current_dir`][`crate::env::set_current_dir`] afterwards.
+///
+/// # Examples
+///
+/// ```no_run
+/// #![feature(unix_chroot)]
+/// use std::os::unix::fs;
+///
+/// fn main() -> std::io::Result<()> {
+///     fs::chroot("/sandbox")?;
+///     std::env::set_current_dir("/")?;
+///     // continue working in sandbox
+///     Ok(())
+/// }
+/// ```
+#[unstable(feature = "unix_chroot", issue = "84715")]
+#[cfg(not(target_os = "fuchsia"))]
+pub fn chroot<P: AsRef<Path>>(dir: P) -> io::Result<()> {
+    sys::fs::chroot(dir.as_ref())
+}
diff --git a/library/std/src/sys/unix/fs.rs b/library/std/src/sys/unix/fs.rs
index 16a7f727696..45bae25a0c3 100644
--- a/library/std/src/sys/unix/fs.rs
+++ b/library/std/src/sys/unix/fs.rs
@@ -1328,3 +1328,10 @@ pub fn copy(from: &Path, to: &Path) -> io::Result<u64> {
     })?;
     Ok(bytes_copied as u64)
 }
+
+#[cfg(not(target_os = "fuchsia"))]
+pub fn chroot(dir: &Path) -> io::Result<()> {
+    let dir = cstr(dir)?;
+    cvt(unsafe { libc::chroot(dir.as_ptr()) })?;
+    Ok(())
+}
diff --git a/library/std/src/sys/unix/mod.rs b/library/std/src/sys/unix/mod.rs
index a0ee69c2f72..6c4fbaf2734 100644
--- a/library/std/src/sys/unix/mod.rs
+++ b/library/std/src/sys/unix/mod.rs
@@ -11,6 +11,7 @@ pub mod weak;
 pub mod alloc;
 pub mod android;
 pub mod args;
+#[path = "../unix/cmath.rs"]
 pub mod cmath;
 pub mod condvar;
 pub mod env;