When running a 32-bit rustup on an aarch64 CPU, select a 32-bit toolc…

…hain

this mirrors a similar check that exists in rustup-init.sh

fixes #3307

src/dist/dist.rs

@@ -1,7 +1,8 @@
 use std::collections::HashSet;
 use std::env;
 use std::fmt;
-use std::io::Write;
+use std::fs;
+use std::io::{self, Read, Write};
 use std::ops::Deref;
 use std::path::Path;
 use std::str::FromStr;
@@ -219,6 +220,26 @@ impl Deref for TargetTriple {
  }
 }
 
+fn is_32bit_userspace() -> bool {
+ // Check if /bin/sh is a 32-bit binary. If it doesn't exist, fall back to
+ // checking if _we_ are a 32-bit binary.
+ // rustup-init.sh also relies on checking /bin/sh for bitness.
+
+ // inner function is to simplify error handling.
+ fn inner() -> io::Result<bool> {
+ let mut f = fs::File::open("/bin/sh")?;
+ let mut buf = [0; 5];
+ f.read_exact(&mut buf)?;
+
+ // ELF files start out "\x7fELF", and the following byte is
+ // 0x01 for 32-bit and
+ // 0x02 for 64-bit.
+ Ok(&buf == b"\x7fELF\x01")
+ }
+
+ inner().unwrap_or(cfg!(target_pointer_width = "32"))
+}
+
 impl TargetTriple {
  pub fn new(name: &str) -> Self {
  Self(name.to_string())
@@ -346,7 +367,11 @@ impl TargetTriple {
  (b"Linux", b"arm") => Some("arm-unknown-linux-gnueabi"),
  (b"Linux", b"armv7l") => Some("armv7-unknown-linux-gnueabihf"),
  (b"Linux", b"armv8l") => Some("armv7-unknown-linux-gnueabihf"),
- (b"Linux", b"aarch64") => Some(TRIPLE_AARCH64_UNKNOWN_LINUX),
+ (b"Linux", b"aarch64") => Some(if is_32bit_userspace() {
+ "armv7-unknown-linux-gnueabihf"
+ } else {
+ TRIPLE_AARCH64_UNKNOWN_LINUX
+ }),
  (b"Darwin", b"x86_64") => Some("x86_64-apple-darwin"),
  (b"Darwin", b"i686") => Some("i686-apple-darwin"),
  (b"FreeBSD", b"x86_64") => Some("x86_64-unknown-freebsd"),