use idiomatic syscall error wrappers

A simplified version of the function used in std which aren’t
made public.

1 files changed, 48 insertions, 24 deletions

diff --git a/src/lib.rs b/src/lib.rs
index f8bef99..4030884 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -5,6 +5,29 @@ use std::{convert::TryFrom,
           os::unix::io::{AsRawFd, RawFd},
           path::{Path, PathBuf}};
 
+/** Convenience syscall wrapper based on its namesake found in the sadly
+private ``std::sys::unix`` library. */
+fn cvt(t: libc::c_int) -> io::Result<libc::c_int>
+{
+    if t == -1 {
+        Err(Error::last_os_error())
+    } else {
+        Ok(t)
+    }
+}
+
+/** Convenience syscall wrapper based on its namesake found in the sadly
+private ``std::sys::unix`` library. */
+fn cvt_r(f: &mut dyn FnMut() -> libc::c_int) -> io::Result<libc::c_int>
+{
+    loop {
+        match cvt((*f)()) {
+            Err(ref e) if e.kind() == io::ErrorKind::Interrupted => {},
+            other => return other,
+        }
+    }
+}
+
 #[derive(Debug)]
 pub struct Fd(libc::c_int);
 
@@ -515,34 +538,35 @@ impl From<&RawPalette<'_>> for Palette
 
 pub fn ioctl_pio_cmap<F: AsRawFd>(fd: &F, pal: &Palette) -> io::Result<()>
 {
-    if unsafe {
-        ioctl(
-            fd.as_raw_fd(),
-            PIO_CMAP,
-            std::mem::transmute::<&Palette, *const libc::c_void>(&pal),
-        )
-    } < 0
-    {
-        Err(Error::last_os_error())
-    } else {
-        Ok(())
-    }
+    /* cvt_r because technically it can’t be ruled out that we hit EINTR. */
+    cvt_r(&mut || {
+        unsafe {
+            ioctl(
+                fd.as_raw_fd(),
+                PIO_CMAP,
+                std::mem::transmute::<&Palette, *const libc::c_void>(&pal),
+            )
+        }
+    })
+    .map(|_| ())
 }
 
 pub fn ioctl_gio_cmap<F: AsRawFd>(fd: &F) -> io::Result<Palette>
 {
     let mut pal = Palette::new();
 
-    if unsafe {
-        ioctl(
-            fd.as_raw_fd(),
-            GIO_CMAP,
-            std::mem::transmute::<&mut Palette, *mut libc::c_void>(&mut pal),
-        )
-    } < 0
-    {
-        Err(Error::last_os_error())
-    } else {
-        Ok(pal)
-    }
+    /* cvt_r because technically it can’t be ruled out that we hit EINTR. */
+    cvt_r(&mut || {
+        unsafe {
+            ioctl(
+                fd.as_raw_fd(),
+                GIO_CMAP,
+                std::mem::transmute::<&mut Palette, *mut libc::c_void>(
+                    &mut pal,
+                ),
+            )
+        }
+    })
+    .map(|_| ())?;
+    Ok(pal)
 }