util/SPrintf: wrapper for snprintf()

src/KeyDefPage.cxx

@@ -16,6 +16,7 @@
 #include "GlobalBindings.hxx"
 #include "screen_utils.hxx"
 #include "Options.hxx"
+#include "util/SPrintf.hxx"
 
 #include <assert.h>
 #include <errno.h>
@@ -211,18 +212,14 @@ CommandKeysPage::GetListItemText(std::span<char> buffer,
 	if (idx == GetLeavePosition())
 		return "[..]"sv;
 
-	if (idx == GetAddPosition()) {
-		std::size_t length = snprintf(buffer.data(), buffer.size(), "%d. %s", idx, _("Add new key"));
-		return {buffer.data(), length};
-	}
+	if (idx == GetAddPosition())
+		return SPrintf(buffer, "%d. %s", idx, _("Add new key"));
 
 	assert(IsKeyPosition(idx));
 
-	std::size_t length = snprintf(buffer.data(), buffer.size(),
-				      "%d. %-20s   (%d) ", idx,
-				      GetLocalizedKeyName(binding->keys[PositionToKeyIndex(idx)]),
-				      binding->keys[PositionToKeyIndex(idx)]);
-	return {buffer.data(), length};
+	return SPrintf(buffer, "%d. %-20s   (%d) ", idx,
+		       GetLocalizedKeyName(binding->keys[PositionToKeyIndex(idx)]),
+		       binding->keys[PositionToKeyIndex(idx)]);
 }
 
 void
@@ -434,9 +431,8 @@ CommandListPage::GetListItemText(std::span<char> buffer,
 	if (len < get_cmds_max_name_width())
 		memset(buffer.data() + len, ' ', get_cmds_max_name_width() - len);
 
-	std::size_t length = snprintf(buffer.data() + get_cmds_max_name_width(),
-				      buffer.size() - get_cmds_max_name_width(),
-				      " - %s", my_gettext(get_command_definitions()[idx].description));
+	std::size_t length = SPrintf(buffer.subspan(get_cmds_max_name_width()),
+				     " - %s", my_gettext(get_command_definitions()[idx].description)).size();
 
 	return {buffer.data(), get_cmds_max_name_width() + length};
 }

src/SearchPage.cxx

@@ -14,6 +14,7 @@
 #include "screen_utils.hxx"
 #include "FileListPage.hxx"
 #include "filelist.hxx"
+#include "util/SPrintf.hxx"
 #include "util/StringAPI.hxx"
 
 #include <iterator>
@@ -129,24 +130,16 @@ class SearchHelpText final : public ListText {
 					 unsigned idx) const noexcept override {
 		assert(idx < std::size(help_text));
 
-		if (idx == 0) {
-			std::size_t length =
-				snprintf(buffer.data(), buffer.size(),
-					 " %s : %s",
-					 GetGlobalKeyBindings().GetKeyNames(Command::SCREEN_SEARCH).c_str(),
-					 "New search");
-			return {buffer.data(), length};
-		}
+		if (idx == 0)
+			return SPrintf(buffer, " %s : %s",
+				       GetGlobalKeyBindings().GetKeyNames(Command::SCREEN_SEARCH).c_str(),
+				       "New search");
 
-		if (idx == 1) {
-			std::size_t length =
-				snprintf(buffer.data(), buffer.size(),
-					 " %s : %s [%s]",
-					 GetGlobalKeyBindings().GetKeyNames(Command::SEARCH_MODE).c_str(),
-					 get_key_description(Command::SEARCH_MODE),
-					 my_gettext(mode[options.search_mode].label));
-			return {buffer.data(), length};
-		}
+		if (idx == 1)
+			return SPrintf(buffer, " %s : %s [%s]",
+				       GetGlobalKeyBindings().GetKeyNames(Command::SEARCH_MODE).c_str(),
+				       get_key_description(Command::SEARCH_MODE),
+				       my_gettext(mode[options.search_mode].label));
 
 		return help_text[idx];
 	}

src/util/SPrintf.hxx

@@ -0,0 +1,19 @@
+// SPDX-License-Identifier: BSD-2-Clause
+// author: Max Kellermann <[email protected]>
+
+#pragma once
+
+#include <span>
+
+#include <stdio.h>
+
+template<typename... Args>
+static inline std::string_view
+SPrintf(std::span<char> buffer, const char *fmt, Args&&... args) noexcept
+{
+	int length = snprintf(buffer.data(), buffer.size(), fmt, args...);
+	if (length < 0)
+		return {};
+
+	return {buffer.data(), static_cast<std::size_t>(length)};
+}