virtio-devices: Port devices over to new read_config_from_slice() helper

Using this helper removes lots of duplicated code across the devices.

Signed-off-by: Rob Bradford <robert.bradford@intel.com>

virtio-devices/src/balloon.rs

@@ -20,9 +20,8 @@ use super::{
 use crate::vm_memory::GuestMemory;
 use crate::{VirtioInterrupt, VirtioInterruptType};
 use libc::EFD_NONBLOCK;
-use std::cmp;
 use std::fs::File;
-use std::io::{self, Write};
+use std::io;
 use std::mem::size_of;
 use std::os::unix::io::{AsRawFd, FromRawFd};
 use std::result;
@@ -471,19 +470,8 @@ impl VirtioDevice for Balloon {
         self.acked_features |= v;
     }
 
-    fn read_config(&self, offset: u64, mut data: &mut [u8]) {
+    fn read_config(&self, offset: u64, data: &mut [u8]) {
-        let config = self.config.lock().unwrap();
+        self.read_config_from_slice(self.config.lock().unwrap().as_slice(), offset, data);
-        let config_slice = config.as_slice();
-        let config_len = config_slice.len() as u64;
-        if offset >= config_len {
-            error!("Failed to read config space");
-            return;
-        }
-        if let Some(end) = offset.checked_add(data.len() as u64) {
-            // This write can't fail, offset and end are checked against config_len.
-            data.write_all(&config_slice[offset as usize..cmp::min(end, config_len) as usize])
-                .unwrap();
-        }
     }
 
     fn activate(

virtio-devices/src/block.rs

@@ -17,7 +17,6 @@ use crate::VirtioInterrupt;
 use anyhow::anyhow;
 use block_util::{build_disk_image_id, Request, RequestType, VirtioBlockConfig};
 use libc::EFD_NONBLOCK;
-use std::cmp;
 use std::collections::HashMap;
 use std::fs::File;
 use std::io::{self, Read, Seek, SeekFrom, Write};
@@ -504,18 +503,8 @@ impl<T: 'static + DiskFile + Send> VirtioDevice for Block<T> {
         self.acked_features |= v;
     }
 
-    fn read_config(&self, offset: u64, mut data: &mut [u8]) {
+    fn read_config(&self, offset: u64, data: &mut [u8]) {
-        let config_slice = self.config.as_slice();
+        self.read_config_from_slice(self.config.as_slice(), offset, data);
-        let config_len = config_slice.len() as u64;
-        if offset >= config_len {
-            error!("Failed to read config space");
-            return;
-        }
-        if let Some(end) = offset.checked_add(data.len() as u64) {
-            // This write can't fail, offset and end are checked against config_len.
-            data.write_all(&config_slice[offset as usize..cmp::min(end, config_len) as usize])
-                .unwrap();
-        }
     }
 
     fn write_config(&mut self, offset: u64, data: &[u8]) {

virtio-devices/src/console.rs

@@ -505,20 +505,8 @@ impl VirtioDevice for Console {
         self.acked_features |= v;
     }
 
-    fn read_config(&self, offset: u64, mut data: &mut [u8]) {
+    fn read_config(&self, offset: u64, data: &mut [u8]) {
-        let config = self.config.lock().unwrap();
+        self.read_config_from_slice(self.config.lock().unwrap().as_slice(), offset, data);
-        let config_slice = config.as_slice();
-        let config_len = config_slice.len() as u64;
-        if offset >= config_len {
-            error!("Failed to read config space");
-            return;
-        }
-
-        if let Some(end) = offset.checked_add(data.len() as u64) {
-            // This write can't fail, offset and end are checked against config_len.
-            data.write_all(&config_slice[offset as usize..cmp::min(end, config_len) as usize])
-                .unwrap();
-        }
     }
 
     fn activate(

virtio-devices/src/iommu.rs

@@ -10,11 +10,10 @@ use super::{
 use crate::{DmaRemapping, VirtioInterrupt, VirtioInterruptType};
 use anyhow::anyhow;
 use libc::EFD_NONBLOCK;
-use std::cmp;
 use std::collections::BTreeMap;
 use std::fmt::{self, Display};
 use std::fs::File;
-use std::io::{self, Write};
+use std::io;
 use std::mem::size_of;
 use std::ops::Bound::Included;
 use std::os::unix::io::{AsRawFd, FromRawFd};
@@ -968,26 +967,16 @@ impl VirtioDevice for Iommu {
         self.acked_features |= v;
     }
 
-    fn read_config(&self, offset: u64, mut data: &mut [u8]) {
+    fn read_config(&self, offset: u64, data: &mut [u8]) {
         let mut config: Vec<u8> = Vec::new();
         config.extend_from_slice(self.config.as_slice());
         for config_topo_pci_range in self.config_topo_pci_ranges.iter() {
             config.extend_from_slice(config_topo_pci_range.as_slice());
         }
 
-        let config_slice = config.as_slice();
+        self.read_config_from_slice(config.as_slice(), offset, data);
-        let config_len = config_slice.len() as u64;
-        if offset >= config_len {
-            error!("Failed to read config space");
-            return;
-        }
-
-        if let Some(end) = offset.checked_add(data.len() as u64) {
-            // This write can't fail, offset and end are checked against config_len.
-            data.write_all(&config_slice[offset as usize..cmp::min(end, config_len) as usize])
-                .unwrap();
-        }
     }
+
     fn activate(
         &mut self,
         mem: GuestMemoryAtomic<GuestMemoryMmap>,

virtio-devices/src/mem.rs

@@ -21,7 +21,7 @@ use crate::{VirtioInterrupt, VirtioInterruptType};
 use libc::EFD_NONBLOCK;
 use std::cmp;
 use std::fs::File;
-use std::io::{self, Write};
+use std::io;
 use std::mem::size_of;
 use std::os::unix::io::{AsRawFd, FromRawFd, RawFd};
 use std::result;
@@ -870,19 +870,8 @@ impl VirtioDevice for Mem {
         self.acked_features |= v;
     }
 
-    fn read_config(&self, offset: u64, mut data: &mut [u8]) {
+    fn read_config(&self, offset: u64, data: &mut [u8]) {
-        let config = self.config.lock().unwrap();
+        self.read_config_from_slice(self.config.lock().unwrap().as_slice(), offset, data);
-        let config_slice = config.as_slice();
-        let config_len = config_slice.len() as u64;
-        if offset >= config_len {
-            error!("Failed to read config space");
-            return;
-        }
-        if let Some(end) = offset.checked_add(data.len() as u64) {
-            // This write can't fail, offset and end are checked against config_len.
-            data.write_all(&config_slice[offset as usize..cmp::min(end, config_len) as usize])
-                .unwrap();
-        }
     }
 
     fn activate(

virtio-devices/src/net.rs

@@ -20,10 +20,9 @@ use net_util::{
     open_tap, MacAddr, NetCounters, NetQueuePair, OpenTapError, RxVirtio, Tap, TxVirtio,
     RX_QUEUE_EVENT, RX_TAP_EVENT, TX_QUEUE_EVENT,
 };
-use std::cmp;
 use std::collections::HashMap;
 use std::fs::File;
-use std::io::{self, Write};
+use std::io;
 use std::net::Ipv4Addr;
 use std::num::Wrapping;
 use std::os::unix::io::{AsRawFd, FromRawFd};
@@ -413,18 +412,8 @@ impl VirtioDevice for Net {
         self.acked_features |= v;
     }
 
-    fn read_config(&self, offset: u64, mut data: &mut [u8]) {
+    fn read_config(&self, offset: u64, data: &mut [u8]) {
-        let config_slice = self.config.as_slice();
+        self.read_config_from_slice(self.config.as_slice(), offset, data);
-        let config_len = config_slice.len() as u64;
-        if offset >= config_len {
-            error!("Failed to read config space");
-            return;
-        }
-        if let Some(end) = offset.checked_add(data.len() as u64) {
-            // This write can't fail, offset and end are checked against config_len.
-            data.write_all(&config_slice[offset as usize..cmp::min(end, config_len) as usize])
-                .unwrap();
-        }
     }
 
     fn activate(

virtio-devices/src/pmem.rs

@@ -15,10 +15,9 @@ use crate::{VirtioInterrupt, VirtioInterruptType};
 use anyhow::anyhow;
 use libc::EFD_NONBLOCK;
 use serde::ser::{Serialize, SerializeStruct, Serializer};
-use std::cmp;
 use std::fmt::{self, Display};
 use std::fs::File;
-use std::io::{self, Write};
+use std::io;
 use std::mem::size_of;
 use std::os::unix::io::{AsRawFd, FromRawFd};
 use std::result;
@@ -463,19 +462,8 @@ impl VirtioDevice for Pmem {
         self.acked_features |= v;
     }
 
-    fn read_config(&self, offset: u64, mut data: &mut [u8]) {
+    fn read_config(&self, offset: u64, data: &mut [u8]) {
-        let config_slice = self.config.as_slice();
+        self.read_config_from_slice(self.config.as_slice(), offset, data);
-        let config_len = config_slice.len() as u64;
-        if offset >= config_len {
-            error!("Failed to read config space");
-            return;
-        }
-
-        if let Some(end) = offset.checked_add(data.len() as u64) {
-            // This write can't fail, offset and end are checked against config_len.
-            data.write_all(&config_slice[offset as usize..cmp::min(end, config_len) as usize])
-                .unwrap();
-        }
     }
 
     fn activate(

virtio-devices/src/vhost_user/blk.rs

@@ -9,8 +9,6 @@ use super::{Error, Result};
 use crate::VirtioInterrupt;
 use block_util::VirtioBlockConfig;
 use libc::EFD_NONBLOCK;
-use std::cmp;
-use std::io::Write;
 use std::mem;
 use std::os::unix::io::AsRawFd;
 use std::result;
@@ -188,18 +186,8 @@ impl VirtioDevice for Blk {
         self.acked_features |= v;
     }
 
-    fn read_config(&self, offset: u64, mut data: &mut [u8]) {
+    fn read_config(&self, offset: u64, data: &mut [u8]) {
-        let config_slice = self.config.as_slice();
+        self.read_config_from_slice(self.config.as_slice(), offset, data);
-        let config_len = config_slice.len() as u64;
-        if offset >= config_len {
-            error!("Failed to read config space");
-            return;
-        }
-        if let Some(end) = offset.checked_add(data.len() as u64) {
-            // This write can't fail, offset and end are checked against config_len.
-            data.write_all(&config_slice[offset as usize..cmp::min(end, config_len) as usize])
-                .unwrap();
-        }
     }
 
     fn write_config(&mut self, offset: u64, data: &[u8]) {

virtio-devices/src/vhost_user/fs.rs

@@ -10,9 +10,7 @@ use crate::{
     VirtioInterrupt, VirtioSharedMemoryList, VIRTIO_F_VERSION_1,
 };
 use libc::{self, c_void, off64_t, pread64, pwrite64, EFD_NONBLOCK};
-use std::cmp;
 use std::io;
-use std::io::Write;
 use std::os::unix::io::{AsRawFd, RawFd};
 use std::result;
 use std::sync::atomic::{AtomicBool, Ordering};
@@ -407,18 +405,8 @@ impl VirtioDevice for Fs {
         self.acked_features |= v;
     }
 
-    fn read_config(&self, offset: u64, mut data: &mut [u8]) {
+    fn read_config(&self, offset: u64, data: &mut [u8]) {
-        let config_slice = self.config.as_slice();
+        self.read_config_from_slice(self.config.as_slice(), offset, data);
-        let config_len = config_slice.len() as u64;
-        if offset >= config_len {
-            error!("Failed to read config space");
-            return;
-        }
-        if let Some(end) = offset.checked_add(data.len() as u64) {
-            // This write can't fail, offset and end are checked against config_len.
-            data.write_all(&config_slice[offset as usize..cmp::min(end, config_len) as usize])
-                .unwrap();
-        }
     }
 
     fn activate(

virtio-devices/src/vhost_user/net.rs

@@ -13,8 +13,6 @@ use super::{Error, Result};
 use crate::VirtioInterrupt;
 use libc::EFD_NONBLOCK;
 use net_util::MacAddr;
-use std::cmp;
-use std::io::Write;
 use std::os::unix::io::AsRawFd;
 use std::result;
 use std::sync::atomic::{AtomicBool, Ordering};
@@ -194,18 +192,8 @@ impl VirtioDevice for Net {
         self.acked_features |= v;
     }
 
-    fn read_config(&self, offset: u64, mut data: &mut [u8]) {
+    fn read_config(&self, offset: u64, data: &mut [u8]) {
-        let config_slice = self.config.as_slice();
+        self.read_config_from_slice(self.config.as_slice(), offset, data);
-        let config_len = config_slice.len() as u64;
-        if offset >= config_len {
-            error!("Failed to read config space");
-            return;
-        }
-        if let Some(end) = offset.checked_add(data.len() as u64) {
-            // This write can't fail, offset and end are checked against config_len.
-            data.write_all(&config_slice[offset as usize..cmp::min(end, config_len) as usize])
-                .unwrap();
-        }
     }
 
     fn activate(