Kernel+AK: Eliminate a couple of temporary String allocations

Author: https://github.com/BertalanD
Commit: https://github.com/SerenityOS/serenity/commit/1d2f78682b8
Pull-request: https://github.com/SerenityOS/serenity/pull/11501

AK/StringBuilder.cpp

@@ -184,7 +184,7 @@ void StringBuilder::append_escaped_for_json(StringView string)
             break;
         default:
             if (ch >= 0 && ch <= 0x1f)
-                append(String::formatted("\\u{:04x}", ch));
+                appendff("\\u{:04x}", ch);
             else
                 append(ch);
         }

Kernel/GlobalProcessExposed.cpp

@@ -131,7 +131,7 @@ private:
         JsonArraySerializer array { builder };
         LocalSocket::for_each([&array](auto& socket) {
             auto obj = array.add_object();
-            obj.add("path", String(socket.socket_path()));
+            obj.add("path", socket.socket_path());
             obj.add("origin_pid", socket.origin_pid().value());
             obj.add("origin_uid", socket.origin_uid().value());
             obj.add("origin_gid", socket.origin_gid().value());
@@ -463,7 +463,7 @@ private:
                 ENUMERATE_PLEDGE_PROMISES
 #undef __ENUMERATE_PLEDGE_PROMISE
 
-                process_object.add("pledge", pledge_builder.to_string());
+                process_object.add("pledge", pledge_builder.string_view());
 
                 switch (process.veil_state()) {
                 case VeilState::None:
@@ -756,7 +756,7 @@ private:
     {
         if (!Process::current().is_superuser())
             return EPERM;
-        return builder.append(String::number(kernel_load_base));
+        return builder.appendff("{}", kernel_load_base);
     }
 };
 

Kernel/KBufferBuilder.cpp

@@ -121,7 +121,7 @@ ErrorOr<void> KBufferBuilder::append_escaped_for_json(StringView string)
             break;
         default:
             if (ch >= 0 && ch <= 0x1f)
-                TRY(append(String::formatted("\\u{:04x}", ch)));
+                TRY(appendff("\\u{:04x}", ch));
             else
                 TRY(append(ch));
         }

Kernel/Net/IPv4Socket.cpp

@@ -497,7 +497,7 @@ ErrorOr<NonnullOwnPtr<KString>> IPv4Socket::pseudo_path(const OpenFileDescriptio
         VERIFY_NOT_REACHED();
     }
 
-    return KString::try_create(builder.to_string());
+    return KString::try_create(builder.string_view());
 }
 
 ErrorOr<void> IPv4Socket::setsockopt(int level, int option, Userspace<const void*> user_value, socklen_t user_value_size)

Kernel/Net/LocalSocket.cpp

@@ -378,7 +378,7 @@ ErrorOr<NonnullOwnPtr<KString>> LocalSocket::pseudo_path(const OpenFileDescripti
         break;
     }
 
-    return KString::try_create(builder.to_string());
+    return KString::try_create(builder.string_view());
 }
 
 ErrorOr<void> LocalSocket::getsockopt(OpenFileDescription& description, int level, int option, Userspace<void*> value, Userspace<socklen_t*> value_size)

Kernel/ProcessSpecificExposed.cpp

@@ -159,7 +159,7 @@ ErrorOr<void> Process::procfs_get_unveil_stats(KBufferBuilder& builder) const
             permissions_builder.append('c');
         if (unveiled_path.permissions() & UnveilAccess::Browse)
             permissions_builder.append('b');
-        obj.add("permissions", permissions_builder.to_string());
+        obj.add("permissions", permissions_builder.string_view());
     }
     array.finish();
     return {};
@@ -255,7 +255,7 @@ ErrorOr<void> Process::procfs_get_virtual_memory_stats(KBufferBuilder& builder)
                 else
                     pagemap_builder.append('P');
             }
-            region_object.add("pagemap", pagemap_builder.to_string());
+            region_object.add("pagemap", pagemap_builder.string_view());
         }
     }
     array.finish();

Kernel/Syscalls/mmap.cpp

@@ -520,7 +520,7 @@ ErrorOr<FlatPtr> Process::sys$allocate_tls(Userspace<const char*> initial_data,
         return EINVAL;
 
     auto range = TRY(address_space().try_allocate_range({}, size));
-    auto* region = TRY(address_space().allocate_region(range, String("Master TLS"), PROT_READ | PROT_WRITE));
+    auto* region = TRY(address_space().allocate_region(range, "Master TLS"sv, PROT_READ | PROT_WRITE));
 
     m_master_tls_region = region->make_weak_ptr();
     m_master_tls_size = size;