Handle out of memory errors in io:Read::read_to_end()

Author: kornelski

library/std/src/fs.rs

@@ -772,14 +772,14 @@ impl Read for &File {
     // Reserves space in the buffer based on the file size when available.
     fn read_to_end(&mut self, buf: &mut Vec<u8>) -> io::Result<usize> {
         let size = buffer_capacity_required(self);
-        buf.reserve(size.unwrap_or(0));
+        buf.try_reserve(size.unwrap_or(0)).map_err(|_| io::ErrorKind::OutOfMemory)?;
         io::default_read_to_end(self, buf, size)
     }
 
     // Reserves space in the buffer based on the file size when available.
     fn read_to_string(&mut self, buf: &mut String) -> io::Result<usize> {
         let size = buffer_capacity_required(self);
-        buf.reserve(size.unwrap_or(0));
+        buf.try_reserve(size.unwrap_or(0)).map_err(|_| io::ErrorKind::OutOfMemory)?;
         io::default_read_to_string(self, buf, size)
     }
 }

library/std/src/io/mod.rs

@@ -418,7 +418,8 @@ pub(crate) fn default_read_to_end<R: Read + ?Sized>(
     let mut initialized = 0; // Extra initialized bytes from previous loop iteration
     loop {
         if buf.len() == buf.capacity() {
-            buf.reserve(32); // buf is full, need more space
+            // buf is full, need more space
+            buf.try_reserve(32).map_err(|_| ErrorKind::OutOfMemory)?;
         }
 
         let mut spare = buf.spare_capacity_mut();
@@ -464,6 +465,7 @@ pub(crate) fn default_read_to_end<R: Read + ?Sized>(
                 match r.read(&mut probe) {
                     Ok(0) => return Ok(buf.len() - start_len),
                     Ok(n) => {
+                        buf.try_reserve(n).map_err(|_| ErrorKind::OutOfMemory)?;
                         buf.extend_from_slice(&probe[..n]);
                         break;
                     }