Fix ICE caused by seeking past i64::MAX

Author: adwinwhite

src/shims/unix/fs.rs

@@ -395,7 +395,9 @@ pub trait EvalContextExt<'tcx>: crate::MiriInterpCxExt<'tcx> {
         // Isolation check is done via `FileDescriptor` trait.
 
         let seek_from = if whence == this.eval_libc_i32("SEEK_SET") {
-            SeekFrom::Start(u64::try_from(offset).unwrap())
+            // Be consistent with standard library.
+            #[allow(clippy::cast_sign_loss)]
+            SeekFrom::Start(i64::try_from(offset).unwrap() as u64)
         } else if whence == this.eval_libc_i32("SEEK_CUR") {
             SeekFrom::Current(i64::try_from(offset).unwrap())
         } else if whence == this.eval_libc_i32("SEEK_END") {

tests/pass/issues/issue-miri-3680.rs

@@ -0,0 +1,24 @@
+//@ignore-target-windows: File handling is not implemented yet
+//@compile-flags: -Zmiri-disable-isolation
+
+use std::fs::remove_file;
+use std::io::Seek;
+use std::panic::catch_unwind;
+
+#[path = "../../utils/mod.rs"]
+mod utils;
+
+fn main() {
+    let path = utils::prepare("miri_test_fs_seek_i64_max_plus_1.txt");
+
+    let result = catch_unwind(|| {
+        let mut f = std::fs::File::create(&path).unwrap();
+        f.seek(std::io::SeekFrom::Start(i64::MAX as u64 + 1)).unwrap();
+    });
+
+    // Make sure it panics.
+    assert!(result.is_err());
+
+    // Cleanup
+    remove_file(&path).unwrap();
+}

tests/pass/issues/issue-miri-3680.stderr

@@ -0,0 +1,24 @@
+thread 'main' panicked at $DIR/issue-miri-3680.rs:LL:CC:
+called `Result::unwrap()` on an `Err` value: Os { code: 22, kind: InvalidInput, message: "invalid input parameter" }
+stack backtrace:
+   0: std::panicking::begin_panic_handler
+ at RUSTLIB/std/src/panicking.rs:LL:CC
+   1: core::panicking::panic_fmt
+ at RUSTLIB/core/src/panicking.rs:LL:CC
+   2: std::result::unwrap_failed
+ at RUSTLIB/core/src/result.rs:LL:CC
+   3: std::result::Result::unwrap
+ at RUSTLIB/core/src/result.rs:LL:CC
+   4: main::{closure#0}
+ at $DIR/issue-miri-3680.rs:LL:CC
+   5: std::panicking::r#try::do_call
+ at RUSTLIB/std/src/panicking.rs:LL:CC
+   6: std::panicking::r#try
+ at RUSTLIB/std/src/panicking.rs:LL:CC
+   7: std::panic::catch_unwind
+ at RUSTLIB/std/src/panic.rs:LL:CC
+   8: main
+ at $DIR/issue-miri-3680.rs:LL:CC
+   9: <fn() as std::ops::FnOnce<()>>::call_once - shim(fn())
+ at RUSTLIB/core/src/ops/function.rs:LL:CC
+note: Some details are omitted, run with `RUST_BACKTRACE=full` for a verbose backtrace.