Clean up and fix file_length_impl for blockdevs on linux

Only try BLKGETSIZE on blockdevs,
use BLKGETSIZE64 instead of BLKGETSIZE,
store BLKGETSIZE64 a u64 and then "as _" at point-of-use (musl).

Closes: #155

build.rs

@@ -23,8 +23,8 @@ BLKGETSIZE
 /// Replace `{}` with the `BLKGETSIZE` expression from `IOCTL_CHECK_SOURCE`
 #[cfg(not(any(target_os = "windows", target_os = "macos")))]
 static IOCTL_INCLUDE_SKELETON: &str = r#"
-/// Return `device size / 512` (`long *` arg)
-static BLKGETSIZE: {type} = {expr} as {type};
+/// Return size of blockdev (`u64 *` arg)
+static BLKGETSIZE64: u64 = {expr} as _;
 "#;
 
 
@@ -51,14 +51,9 @@ fn get_ioctl_data() {
     let ioctl_preprocessed = String::from_utf8(cc::Build::new().file(ioctl_source).expand()).unwrap();
     let blkgetsize_expr = ioctl_preprocessed.lines().next_back().unwrap().replace("U", "");
 
-    let ioctl_request_type = match &env::var("CARGO_CFG_TARGET_ENV").expect("CARGO_CFG_TARGET_ENV")[..] {
-        "musl" => "libc::c_int",
-        _ => "libc::c_ulong",
-    };
-
     let ioctl_include = ioctl_dir.join("ioctl.rs");
     File::create(&ioctl_include)
         .unwrap()
-        .write_all(IOCTL_INCLUDE_SKELETON.replace("{type}", ioctl_request_type).replace("{expr}", &blkgetsize_expr).as_bytes())
+        .write_all(IOCTL_INCLUDE_SKELETON.replace("{expr}", &blkgetsize_expr).as_bytes())
         .unwrap();
 }

src/util/os/non_windows_non_macos.rs

@@ -1,5 +1,5 @@
 use std::os::unix::fs::{PermissionsExt, FileTypeExt};
-use libc::{O_RDONLY, c_ulong, close, ioctl, open};
+use libc::{O_CLOEXEC, O_RDONLY, close, ioctl, open};
 use std::os::unix::ffi::OsStrExt;
 use std::fs::{FileType, Metadata};
 use std::ffi::CString;
@@ -9,15 +9,6 @@ use std::path::Path;
 include!(concat!(env!("OUT_DIR"), "/ioctl-data/ioctl.rs"));
 
 
-// Stolen from https://unix.superglobalmegacorp.com/Net2/newsrc/sys/stat.h.html
-/// X for owner
-const S_IXUSR: u32 = 0o000100;
-/// X for group
-const S_IXGRP: u32 = 0o000010;
-/// X for other
-const S_IXOTH: u32 = 0o000001;
-
-
 /// OS-specific check for fileness
 pub fn is_device(tp: &FileType) -> bool {
     tp.is_block_device() || tp.is_char_device() || tp.is_fifo() || tp.is_socket()
@@ -30,17 +21,16 @@ pub fn file_length<P: AsRef<Path>>(meta: &Metadata, path: &P) -> u64 {
 }
 
 fn file_length_impl(meta: &Metadata, path: &Path) -> u64 {
-    if is_device(&meta.file_type()) {
-        let mut block_count: c_ulong = 0;
-
+    if meta.file_type().is_block_device() {
         let path_c = CString::new(path.as_os_str().as_bytes()).unwrap();
-        let dev_file = unsafe { open(path_c.as_ptr(), O_RDONLY) };
-        if dev_file >= 0 {
-            let ok = unsafe { ioctl(dev_file, BLKGETSIZE, &mut block_count as *mut c_ulong) } == 0;
+        let dev_file = unsafe { open(path_c.as_ptr(), O_RDONLY | O_CLOEXEC) };
+        if dev_file != -1 {
+            let mut size: u64 = 0;
+            let ok = unsafe { ioctl(dev_file, BLKGETSIZE64 as _, &mut size as *mut _) } == 0;
             unsafe { close(dev_file) };
 
             if ok {
-                return block_count as u64 * 512;
+                return size;
             }
         }
     }
@@ -50,5 +40,5 @@ fn file_length_impl(meta: &Metadata, path: &Path) -> u64 {
 
 /// Check if file is marked executable
 pub fn file_executable(meta: &Metadata) -> bool {
-    (meta.permissions().mode() & (S_IXUSR | S_IXGRP | S_IXOTH)) != 0
+    (meta.permissions().mode() & 0o111) != 0
 }