rgw/common: Get rid of VLAs in rgw_(un)escape_str

Signed-off-by: Adam C. Emerson <aemerson@redhat.com>

diff --git a/src/rgw/rgw_common.cc b/src/rgw/rgw_common.cc
index 99a7b2599914c2f02a216c896c8711094b7f42d4..5fe9f3647614a80777a0f4ee9a9b1352e695c724 100644 (file)
--- a/src/rgw/rgw_common.cc
+++ b/src/rgw/rgw_common.cc
@@ -2178,10 +2178,12 @@ bool RGWUserCaps::is_valid_cap_type(const string& tp)
 
 void rgw_pool::from_str(const string& s)
 {
-  size_t pos = rgw_unescape_str(s, 0, '\\', ':', &name);
-  if (pos != string::npos) {
-    pos = rgw_unescape_str(s, pos, '\\', ':', &ns);
-    /* ignore return; if pos != string::npos it means that we had a colon
+  name.clear();
+  auto sr = rgw_unescape_str(s, '\\', ':', std::back_inserter(name));
+  if (sr) {
+    ns.clear();
+    rgw_unescape_str(sr, '\\', ':', std::back_inserter(ns));
+    /* ignore return; if nonempty, it means that we had a colon
      * in the middle of ns that wasn't escaped, we're going to stop there
      */
   }
@@ -2190,12 +2192,12 @@ void rgw_pool::from_str(const string& s)
 string rgw_pool::to_str() const
 {
   string esc_name;
-  rgw_escape_str(name, '\\', ':', &esc_name);
+  rgw_escape_str(name, '\\', ':', std::back_inserter(esc_name));
   if (ns.empty()) {
     return esc_name;
   }
   string esc_ns;
-  rgw_escape_str(ns, '\\', ':', &esc_ns);
+  rgw_escape_str(ns, '\\', ':', std::back_inserter(esc_ns));
   return esc_name + ":" + esc_ns;
 }
 

diff --git a/src/rgw/rgw_common.h b/src/rgw/rgw_common.h
index ff8549b9892308ebfc20a296820758dece856817..90e4d36c6afe9ceb6bb147e2a4de38899cebbb30 100644 (file)
--- a/src/rgw/rgw_common.h
+++ b/src/rgw/rgw_common.h
@@ -2143,52 +2143,71 @@ uppercase_dash_transform(
 void rgw_setup_saved_curl_handles();
 void rgw_release_all_curl_handles();
 
-static inline void rgw_escape_str(const std::string& s, char esc_char,
-                                 char special_char, std::string *dest)
+/// Escape one character with another
+///
+/// \note This function appends, it does not clear its output.
+///
+/// \param[in] in Input string
+/// \param[in] esc_char Character with which to escape
+/// \param[in] special_char Character to be escaped
+/// \param[in] out Output iterator to append
+///
+/// \return New output iterator
+inline auto
+rgw_escape_str(
+    std::ranges::input_range auto&& in,
+    char esc_char,
+    char special_char,
+    std::output_iterator<char> auto out)
 {
-  const char *src = s.c_str();
-  char dest_buf[s.size() * 2 + 1];
-  char *destp = dest_buf;
-
-  for (size_t i = 0; i < s.size(); i++) {
-    char c = src[i];
+  for (const auto c : std::forward<decltype(in)>(in)) {
     if (c == esc_char || c == special_char) {
-      *destp++ = esc_char;
+      *out++ = esc_char;
     }
-    *destp++ = c;
+    *out++ = c;
   }
-  *destp++ = '\0';
-  *dest = dest_buf;
+  return out;
 }
 
-static inline ssize_t rgw_unescape_str(const std::string& s, ssize_t ofs,
-                                      char esc_char, char special_char,
-                                      std::string *dest)
+/// Unescapes an escaped character
+///
+/// \note This function appends, it does not clear its output.
+///
+/// \param[in] in Input string
+/// \param[in] esc_char Character with which we escaped
+/// \param[in] special_char Character which was to be escaped
+/// \param[in] out Output iterator to append
+///
+/// \return If we encounter `special_char` not preceded by `esc_char`,
+///         return a subrange beginning with the next character,
+///         otherwise an empty subrange.
+template <std::ranges::input_range In>
+  requires std::ranges::borrowed_range<In> || std::is_lvalue_reference_v<In&&>
+inline auto
+rgw_unescape_str(
+    In&& in,
+    char esc_char,
+    char special_char,
+    std::output_iterator<char> auto out)
 {
-  const char *src = s.c_str();
-  char dest_buf[s.size() + 1];
-  char *destp = dest_buf;
   bool esc = false;
 
-  dest_buf[0] = '\0';
-
-  for (size_t i = ofs; i < s.size(); i++) {
-    char c = src[i];
+  auto it = std::ranges::begin(in);
+  auto end = std::ranges::end(in);
+  while (it != end) {
+    const char c = *it;
+    ++it;
     if (!esc && c == esc_char) {
       esc = true;
       continue;
     }
     if (!esc && c == special_char) {
-      *destp = '\0';
-      *dest = dest_buf;
-      return (ssize_t)i + 1;
+      break;
     }
-    *destp++ = c;
+    *out++ = c;
     esc = false;
   }
-  *destp = '\0';
-  *dest = dest_buf;
-  return std::string::npos;
+  return std::ranges::subrange{it, end};
 }
 
 /// Return a string copy of the given bufferlist with trailing nulls removed