input/curl: use new class HttpStatusError

This way, IsFileNotFound() can detect status 404.

Makefile.am

@@ -234,6 +234,7 @@ libmpd_a_SOURCES += \
 endif
 
 CURL_SOURCES = \
+	src/lib/curl/Error.hxx \
 	src/lib/curl/Version.cxx src/lib/curl/Version.hxx \
 	src/lib/curl/Global.cxx src/lib/curl/Global.hxx \
 	src/lib/curl/Request.cxx src/lib/curl/Request.hxx \

src/input/Error.cxx

@@ -21,6 +21,10 @@
 #include "Error.hxx"
 #include "system/Error.hxx"
 
+#ifdef ENABLE_CURL
+#include "lib/curl/Error.hxx"
+#endif
+
 #ifdef ENABLE_NFS
 #include "lib/nfs/Error.hxx"
 #include <nfsc/libnfs-raw-nfs.h>
@@ -33,6 +37,10 @@ IsFileNotFound(std::exception_ptr ep)
 		std::rethrow_exception(ep);
 	} catch (const std::system_error &e) {
 		return IsFileNotFound(e);
+#ifdef ENABLE_CURL
+	} catch (const HttpStatusError &e) {
+		return e.GetStatus() == 404;
+#endif
 #ifdef ENABLE_NFS
 	} catch (const NfsClientError &e) {
 		return e.GetCode() == NFS3ERR_NOENT;

src/input/plugins/CurlInputPlugin.cxx

@@ -19,6 +19,7 @@
 
 #include "config.h"
 #include "CurlInputPlugin.hxx"
+#include "lib/curl/Error.hxx"
 #include "lib/curl/Easy.hxx"
 #include "lib/curl/Global.hxx"
 #include "lib/curl/Request.hxx"
@@ -188,7 +189,9 @@ CurlInputStream::OnHeaders(unsigned status,
 	assert(!postponed_exception);
 
 	if (status < 200 || status >= 300)
-		throw FormatRuntimeError("got HTTP status %ld", status);
+		throw HttpStatusError(status,
+				      StringFormat<40>("got HTTP status %u",
+						       status).c_str());
 
 	const std::lock_guard<Mutex> protect(mutex);
 

src/lib/curl/Error.hxx

@@ -0,0 +1,42 @@
+/*
+ * Copyright 2003-2018 The Music Player Daemon Project
+ * http://www.musicpd.org
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ */
+
+#ifndef CURL_ERROR_HXX
+#define CURL_ERROR_HXX
+
+#include <stdexcept>
+
+/**
+ * Thrown when an unsuccessful status was received from the HTTP
+ * server.
+ */
+class HttpStatusError : public std::runtime_error {
+	unsigned status;
+
+public:
+	template<typename M>
+	explicit HttpStatusError(unsigned _status, M &&_msg) noexcept
+		:std::runtime_error(std::forward<M>(_msg)), status(_status) {}
+
+	unsigned GetStatus() const noexcept {
+		return status;
+	}
+};
+
+#endif