set_impl uses raii helper

include/boost/http_proto/fields_base.hpp

@@ -18,6 +18,10 @@
 namespace boost {
 namespace http_proto {
 
+namespace detail {
+struct prefix_op;
+} // detail
+
 /** Mixin for modifiable HTTP fields
 
     @par Iterators
@@ -32,6 +36,8 @@ class BOOST_SYMBOL_VISIBLE
     fields_base
     : public virtual fields_view_base
 {
+    friend struct detail::prefix_op;
+
     detail::header h_;
 
     class op_t;

include/boost/http_proto/message_base.hpp

@@ -1,5 +1,6 @@
 //
 // Copyright (c) 2021 Vinnie Falco ([email protected])
+// Copyright (c) 2024 Christian Mazakas
 //
 // Distributed under the Boost Software License, Version 1.0. (See accompanying
 // file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
@@ -11,9 +12,12 @@
 #define BOOST_HTTP_PROTO_MESSAGE_BASE_HPP
 
 #include <boost/http_proto/detail/config.hpp>
+#include <boost/http_proto/detail/header.hpp>
 #include <boost/http_proto/fields_base.hpp>
 #include <boost/http_proto/message_view_base.hpp>
+#include <boost/http_proto/detail/except.hpp>
 #include <boost/core/detail/string_view.hpp>
+#include <boost/core/span.hpp>
 
 namespace boost {
 namespace http_proto {
@@ -93,9 +97,6 @@ class BOOST_SYMBOL_VISIBLE
     BOOST_HTTP_PROTO_DECL
     void
     set_keep_alive(bool value);
-
-private:
-    char* set_prefix_impl(std::size_t);
 };
 
 } // http_proto

src/detail/header.hpp

@@ -0,0 +1,111 @@
+//
+// Copyright (c) 2024 Christian Mazakas
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+// Official repository: https://github.com/CPPAlliance/http_proto
+//
+
+#ifndef BOOST_HTTP_PROTO_SRC_DETAIL_HEADER_HPP
+#define BOOST_HTTP_PROTO_SRC_DETAIL_HEADER_HPP
+
+#include <boost/http_proto/message_base.hpp>
+#include <boost/http_proto/detail/header.hpp>
+#include <boost/core/span.hpp>
+#include <cstddef>
+
+namespace boost {
+namespace http_proto {
+namespace detail {
+
+struct prefix_op {
+    message_base& mb_;
+    span<char> prefix_;
+    char* buf_ = nullptr;
+    std::size_t n_ = 0;
+
+    prefix_op(
+        message_base& mb,
+        std::size_t n)
+    : mb_{mb}
+    , n_{n}
+    {
+        auto& h = mb_.h_;
+        if( h.buf && n <= h.prefix )
+        {
+            prefix_ = {h.buf, n};
+            return;
+        }
+
+        // allocate or grow
+        if( n > h.prefix &&
+            static_cast<std::size_t>(
+                n - h.prefix) >
+            static_cast<std::size_t>(
+                max_offset - h.size))
+            detail::throw_length_error();
+
+        auto n0 = detail::header::bytes_needed(
+            n + h.size - h.prefix,
+            h.count);
+
+        auto p = new char[n0];
+        if( h.buf != nullptr )
+        {
+            std::memcpy(
+                p + n,
+                h.buf + h.prefix,
+                h.size - h.prefix);
+
+            h.copy_table(p + n0);
+        }
+        else
+        {
+            std::memcpy(
+                p + n,
+                h.cbuf + h.prefix,
+                h.size - h.prefix);
+        }
+
+        prefix_ = {p, n};
+        buf_ = h.buf;
+
+        h.buf = p;
+        h.cbuf = p;
+        h.size = static_cast<
+            offset_type>(h.size +
+                n - h.prefix);
+        h.prefix = static_cast<
+            offset_type>(n);
+        h.cap = n0;
+    }
+
+    prefix_op(prefix_op&&) = delete;
+    prefix_op(prefix_op const&) = delete;
+
+    ~prefix_op()
+    {
+        auto& h = mb_.h_;
+        if( n_ < h.prefix )
+        {
+            std::memmove(
+                h.buf + n_,
+                h.buf + h.prefix,
+                h.size - h.prefix);
+
+            h.size = static_cast<
+                offset_type>(h.size -
+                    h.prefix + n_);
+            h.prefix = static_cast<
+                offset_type>(n_);
+        }
+        delete[] buf_;
+    }
+};
+
+} // detail
+} // http_proto
+} // boost
+
+#endif // BOOST_HTTP_PROTO_SRC_DETAIL_HEADER_HPP

src/message_base.cpp

@@ -1,5 +1,6 @@
 //
 // Copyright (c) 2021 Vinnie Falco ([email protected])
+// Copyright (c) 2024 Christian Mazakas
 //
 // Distributed under the Boost Software License, Version 1.0. (See accompanying
 // file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
@@ -185,69 +186,5 @@ set_keep_alive(bool value)
     }
 }
 
-//------------------------------------------------
-
-char*
-message_base::
-set_prefix_impl(
-    std::size_t n)
-{
-    if( n > h_.prefix ||
-        h_.buf == nullptr)
-    {
-        // allocate or grow
-        if( n > h_.prefix &&
-            static_cast<std::size_t>(
-                n - h_.prefix) >
-            static_cast<std::size_t>(
-                max_offset - h_.size))
-            detail::throw_length_error();
-
-        auto n0 = detail::header::bytes_needed(
-            n + h_.size - h_.prefix,
-            h_.count);
-        auto buf = new char[n0];
-        if(h_.buf != nullptr)
-        {
-            std::memcpy(
-                buf + n,
-                h_.buf + h_.prefix,
-                h_.size - h_.prefix);
-            detail::header::table ft(
-                h_.buf + h_.cap);
-            h_.copy_table(buf + n0);
-            delete[] h_.buf;
-        }
-        else
-        {
-            std::memcpy(
-                buf + n,
-                h_.cbuf + h_.prefix,
-                h_.size - h_.prefix);
-        }
-        h_.buf = buf;
-        h_.cbuf = buf;
-        h_.size = static_cast<
-            offset_type>(h_.size +
-                n - h_.prefix);
-        h_.prefix = static_cast<
-            offset_type>(n);
-        h_.cap = n0;
-        return h_.buf;
-    }
-
-    // shrink
-    std::memmove(
-        h_.buf + n,
-        h_.buf + h_.prefix,
-        h_.size - h_.prefix);
-    h_.size = static_cast<
-        offset_type>(h_.size -
-            h_.prefix + n);
-    h_.prefix = static_cast<
-        offset_type>(n);
-    return h_.buf;
-}
-
 } // http_proto
 } // boost

src/request.cpp

@@ -10,9 +10,12 @@
 
 #include <boost/http_proto/request.hpp>
 #include <boost/http_proto/request_view.hpp>
-#include "detail/copied_strings.hpp"
+
+#include <cstring>
 #include <utility>
 
+#include "detail/header.hpp"
+
 namespace boost {
 namespace http_proto {
 
@@ -145,25 +148,25 @@ set_impl(
     core::string_view t,
     http_proto::version v)
 {
-    detail::copied_strings cs(
-        this->buffer());
-    ms = cs.maybe_copy(ms);
-    t = cs.maybe_copy(t);
-
     auto const vs =
         to_string(v);
     auto const n =
+        // method SP
         ms.size() + 1 +
+        // request-target SP
         t.size() + 1 +
+        // HTTP-version CRLF
         vs.size() + 2;
-    auto dest = set_prefix_impl(n);
-    std::memcpy(
+
+    detail::prefix_op op(*this, n);
+    auto dest = op.prefix_.data();
+    std::memmove(
         dest,
         ms.data(),
         ms.size());
     dest += ms.size();
     *dest++ = ' ';
-    std::memcpy(
+    std::memmove(
         dest,
         t.data(),
         t.size());

src/response.cpp

@@ -14,6 +14,8 @@
 
 #include <utility>
 
+#include "detail/header.hpp"
+
 namespace boost {
 namespace http_proto {
 
@@ -109,7 +111,9 @@ set_impl(
         3 + 1 +
         rs.size() +
         2;
-    auto dest = set_prefix_impl(n);
+
+    detail::prefix_op op(*this, n);
+    auto dest = op.prefix_.data();
 
     h_.version = v;
     vs.copy(dest, vs.size());