From 79365da15181db2e7d9622db834c4c0b84f1e060 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Maciej=20=C5=BBenczykowski?= <maze@google.com>
Date: Fri, 17 Jan 2020 19:07:37 -0800
Subject: [PATCH] BpfMap/Utils - fix const-ness of key & value
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When accessing maps keys are always const/read-only.
Similarly for the value when it is being stored in the map.

This eliminates four const_casts.

Test: build, atest
Signed-off-by: Maciej Żenczykowski <maze@google.com>
Change-Id: Icc57b46a8e9e81b5b06264260bfbf34a4ba9105d
---
 libbpf_android/include/bpf/BpfMap.h   | 8 ++++----
 libbpf_android/include/bpf/BpfUtils.h | 8 ++++----
 2 files changed, 8 insertions(+), 8 deletions(-)

diff --git a/libbpf_android/include/bpf/BpfMap.h b/libbpf_android/include/bpf/BpfMap.h
index a894b57..80ae62b 100644
--- a/libbpf_android/include/bpf/BpfMap.h
+++ b/libbpf_android/include/bpf/BpfMap.h
@@ -79,7 +79,7 @@ class BpfMap {
 
     netdutils::StatusOr<Key> getNextKey(const Key& key) const {
         Key nextKey;
-        if (getNextMapKey(mMapFd, const_cast<Key*>(&key), &nextKey)) {
+        if (getNextMapKey(mMapFd, &key, &nextKey)) {
             return netdutils::statusFromErrno(
                 errno, base::StringPrintf("Get next key of map %d failed", mMapFd.get()));
         }
@@ -87,7 +87,7 @@ class BpfMap {
     }
 
     netdutils::Status writeValue(const Key& key, const Value& value, uint64_t flags) {
-        if (writeToMapEntry(mMapFd, const_cast<Key*>(&key), const_cast<Value*>(&value), flags)) {
+        if (writeToMapEntry(mMapFd, &key, &value, flags)) {
             return netdutils::statusFromErrno(
                 errno, base::StringPrintf("write to map %d failed", mMapFd.get()));
         }
@@ -96,7 +96,7 @@ class BpfMap {
 
     netdutils::StatusOr<Value> readValue(const Key key) const {
         Value value;
-        if (findMapEntry(mMapFd, const_cast<Key*>(&key), &value)) {
+        if (findMapEntry(mMapFd, &key, &value)) {
             return netdutils::statusFromErrno(
                 errno, base::StringPrintf("read value of map %d failed", mMapFd.get()));
         }
@@ -104,7 +104,7 @@ class BpfMap {
     }
 
     netdutils::Status deleteValue(const Key& key) {
-        if (deleteMapEntry(mMapFd, const_cast<Key*>(&key))) {
+        if (deleteMapEntry(mMapFd, &key)) {
             return netdutils::statusFromErrno(
                 errno, base::StringPrintf("delete entry from map %d failed", mMapFd.get()));
         }
diff --git a/libbpf_android/include/bpf/BpfUtils.h b/libbpf_android/include/bpf/BpfUtils.h
index 4d3e155..cf6e1ac 100644
--- a/libbpf_android/include/bpf/BpfUtils.h
+++ b/libbpf_android/include/bpf/BpfUtils.h
@@ -85,7 +85,7 @@ static inline int createMap(bpf_map_type map_type, uint32_t key_size, uint32_t v
                                });
 }
 
-static inline int writeToMapEntry(const base::unique_fd& map_fd, void* key, void* value,
+static inline int writeToMapEntry(const base::unique_fd& map_fd, const void* key, const void* value,
                                   uint64_t flags) {
     return bpf(BPF_MAP_UPDATE_ELEM, {
                                             .map_fd = static_cast<__u32>(map_fd.get()),
@@ -95,7 +95,7 @@ static inline int writeToMapEntry(const base::unique_fd& map_fd, void* key, void
                                     });
 }
 
-static inline int findMapEntry(const base::unique_fd& map_fd, void* key, void* value) {
+static inline int findMapEntry(const base::unique_fd& map_fd, const void* key, void* value) {
     return bpf(BPF_MAP_LOOKUP_ELEM, {
                                             .map_fd = static_cast<__u32>(map_fd.get()),
                                             .key = ptr_to_u64(key),
@@ -103,14 +103,14 @@ static inline int findMapEntry(const base::unique_fd& map_fd, void* key, void* v
                                     });
 }
 
-static inline int deleteMapEntry(const base::unique_fd& map_fd, void* key) {
+static inline int deleteMapEntry(const base::unique_fd& map_fd, const void* key) {
     return bpf(BPF_MAP_DELETE_ELEM, {
                                             .map_fd = static_cast<__u32>(map_fd.get()),
                                             .key = ptr_to_u64(key),
                                     });
 }
 
-static inline int getNextMapKey(const base::unique_fd& map_fd, void* key, void* next_key) {
+static inline int getNextMapKey(const base::unique_fd& map_fd, const void* key, void* next_key) {
     return bpf(BPF_MAP_GET_NEXT_KEY, {
                                              .map_fd = static_cast<__u32>(map_fd.get()),
                                              .key = ptr_to_u64(key),