Pass PacketBuf as an argument of API

examples/armv4t/gdb/host_io.rs

@@ -262,7 +262,11 @@ impl target::ext::host_io::HostIoReadlink for Emu {
             .to_str()
             .ok_or(HostIoError::Errno(HostIoErrno::ENOENT))?
             .as_bytes();
-        Ok(copy_range_to_buf(data, 0, data.len(), buf))
+        if data.len() <= buf.len() {
+            Ok(copy_range_to_buf(data, 0, data.len(), buf))
+        } else {
+            Err(HostIoError::Errno(HostIoErrno::ENAMETOOLONG))
+        }
     }
 }
 

examples/armv4t/gdb/mod.rs

@@ -1,4 +1,4 @@
-use core::convert::TryInto;
+use core::convert::{TryFrom, TryInto};
 
 use armv4t_emu::{reg, Memory};
 use gdbstub::target;
@@ -37,12 +37,16 @@ fn cpu_reg_id(id: ArmCoreRegId) -> Option<u8> {
 }
 
 /// Copy a range of `data` (start at `offset` with a size of `length`) to `buf`.
-/// Return the size of data copied. Return 0 if encounter EOF.
+/// Return the size of data copied. Returns 0 if `offset >= buf.len()`.
 ///
 /// Mainly used by qXfer:_object_:read commands.
 pub fn copy_range_to_buf(data: &[u8], offset: u64, length: usize, buf: &mut [u8]) -> usize {
+    let offset = match usize::try_from(offset) {
+        Ok(v) => v,
+        Err(_) => return 0,
+    };
     let len = data.len();
-    let data = &data[len.min(offset as usize)..len.min(offset as usize + length)];
+    let data = &data[len.min(offset)..len.min(offset + length)];
     let buf = &mut buf[..data.len()];
     buf.copy_from_slice(data);
     data.len()