Import TryInto

src/hermit.rs

@@ -1,5 +1,5 @@
 use crate::Error;
-use core::{cmp::min, mem::MaybeUninit, num::NonZeroU32};
+use core::{convert::TryInto, mem::MaybeUninit, num::NonZeroU32};
 
 extern "C" {
     fn sys_read_entropy(buffer: *mut u8, length: usize, flags: u32) -> isize;
@@ -17,8 +17,7 @@ pub fn getrandom_inner(mut dest: &mut [MaybeUninit<u8>]) -> Result<(), Error> {
                 .unwrap_or(Error::UNEXPECTED);
             return Err(err);
         }
-        let len = min(res as usize, dest.len());
-        dest = dest.get_mut(len..).ok_or(Error::UNEXPECTED)?;
+        dest = dest.get_mut(res as usize..).ok_or(Error::UNEXPECTED)?;
     }
     Ok(())
 }

src/util_libc.rs

@@ -8,7 +8,6 @@
 #![allow(dead_code)]
 use crate::Error;
 use core::{
-    cmp::min,
     mem::MaybeUninit,
     num::NonZeroU32,
     ptr::NonNull,
@@ -70,17 +69,18 @@ pub fn sys_fill_exact(
 ) -> Result<(), Error> {
     while !buf.is_empty() {
         let res = sys_fill(buf);
-        if res < 0 {
+        if res > 0 {
+            buf = buf.get_mut(res as usize..).ok_or(Error::UNEXPECTED)?;
+        } else if res < 0 {
             let err = last_os_error();
             // We should try again if the call was interrupted.
             if err.raw_os_error() != Some(libc::EINTR) {
                 return Err(err);
             }
         } else {
-            // We don't check for EOF (ret = 0) as the data we are reading
+            // EOF (ret = 0) should be impossible, as the data we are reading
             // should be an infinite stream of random bytes.
-            let len = min(res as usize, buf.len());
-            buf = buf.get_mut(len..).ok_or(Error::UNEXPECTED)?;
+            return Err(Error::UNEXPECTED);
         }
     }
     Ok(())