Declare read-only pointers as const

sysprog21 · Jan 23, 2024 · 35517a0 · 35517a0
1 parent 78ec6f7
commit 35517a0
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Showing 2 changed files with 14 additions and 13 deletions.
diff --git a/virtio-blk.c b/virtio-blk.c
@@ -106,7 +106,7 @@ static void virtio_blk_write_handler(virtio_blk_state_t *vblk,
                                      uint32_t len)
 {
     void *dest = (void *) ((uintptr_t) vblk->disk + sector * DISK_BLK_SIZE);
-    void *src = (void *) ((uintptr_t) vblk->ram + desc_addr);
+    const void *src = (void *) ((uintptr_t) vblk->ram + desc_addr);
     memcpy(dest, src, len);
 }
 
@@ -116,7 +116,8 @@ static void virtio_blk_read_handler(virtio_blk_state_t *vblk,
                                     uint32_t len)
 {
     void *dest = (void *) ((uintptr_t) vblk->ram + desc_addr);
-    void *src = (void *) ((uintptr_t) vblk->disk + sector * DISK_BLK_SIZE);
+    const void *src =
+        (void *) ((uintptr_t) vblk->disk + sector * DISK_BLK_SIZE);
     memcpy(dest, src, len);
 }
 
@@ -140,7 +141,7 @@ static int virtio_blk_desc_handler(virtio_blk_state_t *vblk,
     /* Collect the descriptors */
     for (int i = 0; i < 3; i++) {
         /* The size of the `struct virtq_desc` is 4 words */
-        uint32_t *desc = &vblk->ram[queue->QueueDesc + desc_idx * 4];
+        const uint32_t *desc = &vblk->ram[queue->QueueDesc + desc_idx * 4];
 
         /* Retrieve the fields of current descriptor */
         vq_desc[i].addr = desc[0];
@@ -162,7 +163,7 @@ static int virtio_blk_desc_handler(virtio_blk_state_t *vblk,
     }
 
     /* Process the header */
-    struct vblk_req_header *header =
+    const struct vblk_req_header *header =
         (struct vblk_req_header *) ((uintptr_t) vblk->ram + vq_desc[0].addr);
     uint32_t type = header->type;
     uint64_t sector = header->sector;

diff --git a/virtio-net.c b/virtio-net.c
@@ -116,15 +116,15 @@ static bool vnet_iovec_read(struct iovec **vecs,
 /* Require existing 'desc_idx' to use as iteration variable, and input
  * 'buffer_idx'.
  */
-#define VNET_ITERATE_BUFFER(checked, body)                      \
-    desc_idx = buffer_idx;                                      \
-    while (1) {                                                 \
-        if (checked && desc_idx >= queue->QueueNum)             \
-            return virtio_net_set_fail(vnet);                   \
-        uint32_t *desc = &ram[queue->QueueDesc + desc_idx * 4]; \
-        uint16_t desc_flags = desc[3];                          \
-        body if (!(desc_flags & VIRTIO_DESC_F_NEXT)) break;     \
-        desc_idx = desc[3] >> 16;                               \
+#define VNET_ITERATE_BUFFER(checked, body)                            \
+    desc_idx = buffer_idx;                                            \
+    while (1) {                                                       \
+        if (checked && desc_idx >= queue->QueueNum)                   \
+            return virtio_net_set_fail(vnet);                         \
+        const uint32_t *desc = &ram[queue->QueueDesc + desc_idx * 4]; \
+        uint16_t desc_flags = desc[3];                                \
+        body if (!(desc_flags & VIRTIO_DESC_F_NEXT)) break;           \
+        desc_idx = desc[3] >> 16;                                     \
     }
 
 /* Input: 'buffer_idx'.