From 4ce24269bb498b799ad14bd1fe3fb11900c1ce64 Mon Sep 17 00:00:00 2001 From: Tobias Bucher Date: Sat, 12 May 2018 02:31:38 +0200 Subject: [PATCH] Do not silently truncate offsets for `read_at`/`write_at` on emscripten Generate an IO error if the offset is out of bounds for the system call. --- src/libstd/sys/unix/fd.rs | 18 ++++++++++++++++-- 1 file changed, 16 insertions(+), 2 deletions(-) diff --git a/src/libstd/sys/unix/fd.rs b/src/libstd/sys/unix/fd.rs index 5dafc3251e755..67546d06b4e55 100644 --- a/src/libstd/sys/unix/fd.rs +++ b/src/libstd/sys/unix/fd.rs @@ -75,8 +75,15 @@ impl FileDesc { unsafe fn cvt_pread64(fd: c_int, buf: *mut c_void, count: usize, offset: i64) -> io::Result { + use convert::TryInto; use libc::pread64; - cvt(pread64(fd, buf, count, offset as i32)) + // pread64 on emscripten actually takes a 32 bit offset + if let Ok(o) = offset.try_into() { + cvt(pread64(fd, buf, count, o)) + } else { + Err(io::Error::new(io::ErrorKind::InvalidInput, + "cannot pread >2GB")) + } } #[cfg(not(any(target_os = "android", target_os = "emscripten")))] @@ -116,8 +123,15 @@ impl FileDesc { unsafe fn cvt_pwrite64(fd: c_int, buf: *const c_void, count: usize, offset: i64) -> io::Result { + use convert::TryInto; use libc::pwrite64; - cvt(pwrite64(fd, buf, count, offset as i32)) + // pwrite64 on emscripten actually takes a 32 bit offset + if let Ok(o) = offset.try_into() { + cvt(pwrite64(fd, buf, count, o)) + } else { + Err(io::Error::new(io::ErrorKind::InvalidInput, + "cannot pwrite >2GB")) + } } #[cfg(not(any(target_os = "android", target_os = "emscripten")))]