checkpoint regression test demonstrating failure of rust issue 101913.

Cargo.toml

@@ -130,3 +130,8 @@ edition = '2018'
 name = "concurrent-panics"
 required-features = ["std"]
 harness = false
+
+[[test]]
+name = "current-exe-mismatch"
+required-features = ["std"]
+harness = false

tests/common/mod.rs

@@ -0,0 +1,14 @@
+/// Some tests only make sense in contexts where they can re-exec the test
+/// itself. Not all contexts support this, so you can call this method to find
+/// out which case you are in.
+pub fn cannot_reexec_the_test() -> bool {
+    // These run in docker containers on CI where they can't re-exec the test,
+    // so just skip these for CI. No other reason this can't run on those
+    // platforms though.
+    // Miri does not have support for re-execing a file
+    cfg!(unix)
+        && (cfg!(target_arch = "arm")
+            || cfg!(target_arch = "aarch64")
+            || cfg!(target_arch = "s390x"))
+        || cfg!(miri)
+}

tests/concurrent-panics.rs

@@ -9,16 +9,11 @@ const PANICS: usize = 100;
 const THREADS: usize = 8;
 const VAR: &str = "__THE_TEST_YOU_ARE_LUKE";
 
+mod common;
+
 fn main() {
-    // These run in docker containers on CI where they can't re-exec the test,
-    // so just skip these for CI. No other reason this can't run on those
-    // platforms though.
-    // Miri does not have support for re-execing a file
-    if cfg!(unix)
-        && (cfg!(target_arch = "arm")
-            || cfg!(target_arch = "aarch64")
-            || cfg!(target_arch = "s390x"))
-        || cfg!(miri)
+    // If we cannot re-exec this test, there's no point in trying to do it.
+    if common::cannot_reexec_the_test()
     {
         println!("test result: ok");
         return;

tests/current-exe-mismatch.rs

@@ -0,0 +1,133 @@
+// rust-lang/rust#101913: when you run your program explicitly via `ld.so`,
+// `std::env::current_exe` will return the path of *that* program, and not
+// the Rust program itself.
+
+use std::process::Command;
+use std::path::{Path, PathBuf};
+use std::io::{BufRead, BufReader};
+
+mod common;
+
+fn main() {
+    if std::env::var(VAR).is_err() {
+        // the parent waits for the child; then we then handle either printing
+        // "test result: ok", "test result: ignored", or panicking.
+        match parent() {
+            Ok(()) => {
+                println!("test result: ok");
+            }
+            Err(EarlyExit::IgnoreTest(_)) => {
+                println!("test result: ignored");
+            }
+            Err(EarlyExit::IoError(e)) => {
+                println!("{} parent encoutered IoError: {:?}", file!(), e);
+                panic!();
+            }
+        }
+    } else {
+        // println!("{} running child", file!());
+        child().unwrap();
+    }
+}
+
+const VAR: &str = "__THE_TEST_YOU_ARE_LUKE";
+
+#[derive(Debug)]
+enum EarlyExit {
+    IgnoreTest(String),
+    IoError(std::io::Error),
+}
+
+impl From<std::io::Error> for EarlyExit {
+    fn from(e: std::io::Error) -> Self {
+        EarlyExit::IoError(e)
+    }
+}
+
+fn parent() -> Result<(), EarlyExit> {
+    // If we cannot re-exec this test, there's no point in trying to do it.
+    if common::cannot_reexec_the_test()
+    {
+        return Err(EarlyExit::IgnoreTest("(cannot reexec)".into()));
+    }
+
+    let me = std::env::current_exe().unwrap();
+    let ld_so = find_interpreter(&me)?;
+
+    // use interp to invoke current exe, yielding child test.
+    //
+    // (if you're curious what you might compare this against, you can try
+    // swapping in the below definition for `result`, which is the easy case of
+    // not using the ld.so interpreter directly that Rust handled fine even
+    // prior to resolution of rust-lang/rust#101913.)
+    //
+    // let result = Command::new(me).env(VAR, "1").output()?;
+    let result = Command::new(ld_so).env(VAR, "1").arg(&me).output().unwrap();
+
+    if result.status.success() {
+        return Ok(());
+    }
+    println!("stdout:\n{}", String::from_utf8_lossy(&result.stdout));
+    println!("stderr:\n{}", String::from_utf8_lossy(&result.stderr));
+    println!("code: {}", result.status);
+    panic!();
+}
+
+fn child() -> Result<(), EarlyExit> {
+    let bt = backtrace::Backtrace::new();
+    println!("{:?}", bt);
+
+    let mut found_my_name = false;
+
+    let my_filename = file!();
+    'frames: for frame in bt.frames() {
+        let symbols = frame.symbols();
+        if symbols.is_empty() {
+            continue;
+        }
+
+        for sym in symbols {
+            if let Some(filename) = sym.filename() {
+                if filename.ends_with(my_filename) {
+                    // huzzah!
+                    found_my_name = true;
+                    break 'frames;
+                }
+            }
+        }
+    }
+
+    assert!(found_my_name);
+
+    Ok(())
+}
+
+// we use the `readelf` command to extract the path to the interpreter requested
+// by our binary.
+//
+// if we cannot `readelf` for some reason, or if we fail to parse its output,
+// then we will just give up on this test (and not treat it as a test failure).
+fn find_interpreter(me: &Path) -> Result<PathBuf, EarlyExit> {
+    let result = Command::new("readelf")
+        .arg("-l")
+        .arg(me)
+        .output()
+        .unwrap();
+    if result.status.success() {
+        let r = BufReader::new(&result.stdout[..]);
+        for line in r.lines() {
+            let line = line?;
+            let line = line.trim();
+            let prefix = "[Requesting program interpreter: ";
+            if let Some((_, suffix)) = line.split_once(prefix) {
+                if let Some((found_path, _ignore_suffix)) = suffix.rsplit_once("]") {
+                    return Ok(found_path.into());
+                }
+            }
+        }
+
+        Err(EarlyExit::IgnoreTest("could not find interpreter from readelf output".into()))
+    } else {
+        Err(EarlyExit::IgnoreTest("readelf invocation failed".into()))
+    }
+}