From 5f33647fb392c2d4f71af94a223bc1a9abb80643 Mon Sep 17 00:00:00 2001 From: Ben Kimock Date: Wed, 20 Sep 2023 19:26:04 -0400 Subject: [PATCH] Add unit tests based on files that return odd sizes to stat --- compiler/rustc_span/src/source_map/tests.rs | 27 +++++++++++++++++++++ 1 file changed, 27 insertions(+) diff --git a/compiler/rustc_span/src/source_map/tests.rs b/compiler/rustc_span/src/source_map/tests.rs index e393db02064..a12f50c87a2 100644 --- a/compiler/rustc_span/src/source_map/tests.rs +++ b/compiler/rustc_span/src/source_map/tests.rs @@ -567,3 +567,30 @@ fn test_next_point() { assert_eq!(span.hi().0, 6); assert!(sm.span_to_snippet(span).is_err()); } + +#[cfg(target_os = "linux")] +#[test] +fn read_binary_file_handles_lying_stat() { + // read_binary_file tries to read the contents of a file into an Lrc<[u8]> while + // never having two copies of the data in memory at once. This is an optimization + // to support include_bytes! with large files. But since Rust allocators are + // sensitive to alignment, our implementation can't be bootstrapped off calling + // std::fs::read. So we test that we have the same behavior even on files where + // fs::metadata lies. + + // stat always says that /proc/self/cmdline is length 0, but it isn't. + let cmdline = Path::new("/proc/self/cmdline"); + let len = std::fs::metadata(cmdline).unwrap().len() as usize; + let real = std::fs::read(cmdline).unwrap(); + assert!(len < real.len()); + let bin = RealFileLoader.read_binary_file(cmdline).unwrap(); + assert_eq!(&real[..], &bin[..]); + + // stat always says that /sys/devices/system/cpu/kernel_max is the size of a block. + let kernel_max = Path::new("/sys/devices/system/cpu/kernel_max"); + let len = std::fs::metadata(kernel_max).unwrap().len() as usize; + let real = std::fs::read(kernel_max).unwrap(); + assert!(len > real.len()); + let bin = RealFileLoader.read_binary_file(kernel_max).unwrap(); + assert_eq!(&real[..], &bin[..]); +}