Load libcurl.so at runtime.

Loading libcurl at runtime instead of linking it at compile time makes
things a lot easier and more reliable on Windows. On other platform
libcurl can be installed as optional dependency instead as an hard one.

Makefile

@@ -352,6 +352,10 @@ build/client/%.o: %.c
 
 release/yquake2.exe : LDFLAGS += -mwindows
 
+ifeq ($(WITH_CURL),yes)
+release/quake2 : CFLAGS += -DUSE_CURL
+endif
+
 ifeq ($(WITH_OPENAL),yes)
 release/yquake2.exe : CFLAGS += -DUSE_OPENAL -DDEFAULT_OPENAL_DRIVER='"openal32.dll"'
 endif
@@ -379,7 +383,6 @@ release/quake2 : CFLAGS += -Wno-unused-result
 
 ifeq ($(WITH_CURL),yes)
 release/quake2 : CFLAGS += -DUSE_CURL
-release/quake2 : LDFLAGS += -lcurl
 endif
 
 ifeq ($(WITH_OPENAL),yes)
@@ -690,6 +693,7 @@ CLIENT_OBJS_ := \
 	src/client/cl_screen.o \
 	src/client/cl_tempentities.o \
 	src/client/cl_view.o \
+	src/client/curl/qcurl.o \
 	src/client/input/sdl.o \
 	src/client/menu/menu.o \
 	src/client/menu/qmenu.o \

src/client/cl_http.c

@@ -27,6 +27,7 @@
 
 #include <ctype.h>
 #include "header/client.h"
+#include "curl/header/qcurl.h"
 
 #ifdef USE_CURL
 
@@ -66,7 +67,7 @@ static size_t CL_HTTP_Recv(void *ptr, size_t size, size_t nmemb, void *stream)
 	{
 		double length = 0;
 
-		curl_easy_getinfo(dl->curl, CURLINFO_CONTENT_LENGTH_DOWNLOAD, &length);
+		qcurl_easy_getinfo(dl->curl, CURLINFO_CONTENT_LENGTH_DOWNLOAD, &length);
 
 		// Mkay, the remote file should be at least one byte long.
 		// Since this is used for paclists only we assume that the
@@ -198,33 +199,33 @@ static void CL_StartHTTPDownload (dlqueue_t *entry, dlhandle_t *dl)
 	// Setup and configure the CURL part of our download handle.
 	if (!dl->curl)
 	{
-		dl->curl = curl_easy_init();
+		dl->curl = qcurl_easy_init();
 	}
 
 	Com_sprintf(dl->URL, sizeof(dl->URL), "%s%s", cls.downloadServer, escapedFilePath);
 
-	curl_easy_setopt(dl->curl, CURLOPT_ENCODING, "");
+	qcurl_easy_setopt(dl->curl, CURLOPT_ENCODING, "");
 
 	if (dl->file)
 	{
-		curl_easy_setopt(dl->curl, CURLOPT_WRITEDATA, dl->file);
+		qcurl_easy_setopt(dl->curl, CURLOPT_WRITEDATA, dl->file);
-		curl_easy_setopt(dl->curl, CURLOPT_WRITEFUNCTION, NULL);
+		qcurl_easy_setopt(dl->curl, CURLOPT_WRITEFUNCTION, NULL);
 	}
 	else
 	{
-		curl_easy_setopt(dl->curl, CURLOPT_WRITEDATA, dl);
+		qcurl_easy_setopt(dl->curl, CURLOPT_WRITEDATA, dl);
-		curl_easy_setopt(dl->curl, CURLOPT_WRITEFUNCTION, CL_HTTP_Recv);
+		qcurl_easy_setopt(dl->curl, CURLOPT_WRITEFUNCTION, CL_HTTP_Recv);
 	}
 
-	curl_easy_setopt(dl->curl, CURLOPT_PROXY, cl_http_proxy->string);
+	qcurl_easy_setopt(dl->curl, CURLOPT_PROXY, cl_http_proxy->string);
-	curl_easy_setopt(dl->curl, CURLOPT_FOLLOWLOCATION, 1);
+	qcurl_easy_setopt(dl->curl, CURLOPT_FOLLOWLOCATION, 1);
-	curl_easy_setopt(dl->curl, CURLOPT_MAXREDIRS, 5);
+	qcurl_easy_setopt(dl->curl, CURLOPT_MAXREDIRS, 5);
-	curl_easy_setopt(dl->curl, CURLOPT_PROGRESSDATA, dl);
+	qcurl_easy_setopt(dl->curl, CURLOPT_PROGRESSDATA, dl);
-	curl_easy_setopt(dl->curl, CURLOPT_USERAGENT, Cvar_VariableString ("version"));
+	qcurl_easy_setopt(dl->curl, CURLOPT_USERAGENT, Cvar_VariableString ("version"));
-	curl_easy_setopt(dl->curl, CURLOPT_REFERER, cls.downloadReferer);
+	qcurl_easy_setopt(dl->curl, CURLOPT_REFERER, cls.downloadReferer);
-	curl_easy_setopt(dl->curl, CURLOPT_URL, dl->URL);
+	qcurl_easy_setopt(dl->curl, CURLOPT_URL, dl->URL);
 
-	if (curl_multi_add_handle (multi, dl->curl) != CURLM_OK)
+	if (qcurl_multi_add_handle(multi, dl->curl) != CURLM_OK)
 	{
 		Com_Printf("HTTP download: cURL error\n");
 		dl->queueEntry->state = DLQ_STATE_DONE;
@@ -473,7 +474,7 @@ static void CL_FinishHTTPDownload(void)
 	do
 	{
 		// Get a message from CURL.
-		CURLMsg *msg = curl_multi_info_read(multi, &msgs_in_queue);
+		CURLMsg *msg = qcurl_multi_info_read(multi, &msgs_in_queue);
 
 		if (!msg)
 		{
@@ -551,7 +552,7 @@ static void CL_FinishHTTPDownload(void)
 		{
 			case CURLE_HTTP_RETURNED_ERROR:
 			case CURLE_OK:
-				curl_easy_getinfo(curl, CURLINFO_RESPONSE_CODE, &responseCode);
+				qcurl_easy_getinfo(curl, CURLINFO_RESPONSE_CODE, &responseCode);
 
 				if (responseCode == 404)
 				{
@@ -564,7 +565,7 @@ static void CL_FinishHTTPDownload(void)
 					}
 
 					// ...and remove it from the CURL multihandle.
-					curl_multi_remove_handle(multi, dl->curl);
+					qcurl_multi_remove_handle(multi, dl->curl);
 
 					Com_Printf("HTTP download: %s - File Not Found\n", dl->queueEntry->quakePath);
 
@@ -597,7 +598,7 @@ static void CL_FinishHTTPDownload(void)
 				}
 
 				// ...and the handle from CURLs mutihandle.
-				curl_multi_remove_handle (multi, dl->curl);
+				qcurl_multi_remove_handle(multi, dl->curl);
 
 				// Special case: We're already aborting HTTP downloading,
 				// so we can't just kill everything. Otherwise we'll get
@@ -614,7 +615,7 @@ static void CL_FinishHTTPDownload(void)
 				break;
 
 			default:
-				Com_Printf ("HTTP download: cURL error - %s\n", curl_easy_strerror(result));
+				Com_Printf ("HTTP download: cURL error - %s\n", qcurl_easy_strerror(result));
 
 				i = strlen(dl->queueEntry->quakePath);
 
@@ -625,7 +626,7 @@ static void CL_FinishHTTPDownload(void)
 				}
 
 				// ...and the handle from CURLs mutihandle.
-				curl_multi_remove_handle (multi, dl->curl);
+				qcurl_multi_remove_handle (multi, dl->curl);
 
 				continue;
 				break;
@@ -651,7 +652,7 @@ static void CL_FinishHTTPDownload(void)
 		}
 
 		// Remove the file fo CURLs multihandle.
-		curl_multi_remove_handle (multi, dl->curl);
+		qcurl_multi_remove_handle (multi, dl->curl);
 
 	} while (msgs_in_queue > 0);
 
@@ -736,7 +737,11 @@ static void CL_StartNextHTTPDownload(void)
  */
 void CL_InitHTTPDownloads (void)
 {
-	curl_global_init (CURL_GLOBAL_NOTHING);
+	// We're initializing the cURL backend here because
+	// currently we're the only user. As soon as there
+	// are other users this must be moved up into the
+	// global client intialization.
+	qcurlInit();
 }
 
 /*
@@ -771,8 +776,11 @@ void CL_HTTP_Cleanup(qboolean fullShutdown)
 		if (dl->curl)
 		{
 			if (multi)
-				curl_multi_remove_handle (multi, dl->curl);
+			{
-			curl_easy_cleanup (dl->curl);
+				qcurl_multi_remove_handle(multi, dl->curl);
+			}
+
+			qcurl_easy_cleanup(dl->curl);
 			dl->curl = NULL;
 		}
 
@@ -782,14 +790,17 @@ void CL_HTTP_Cleanup(qboolean fullShutdown)
 	// Cleanup CURL multihandle.
 	if (multi)
 	{
-		curl_multi_cleanup(multi);
+		qcurl_multi_cleanup(multi);
 		multi = NULL;
 	}
 
 	// Shutdown CURL.
 	if (fullShutdown)
 	{
-		curl_global_cleanup ();
+		// This must be moved up into the generic
+		// client shutdown as soon as there're
+		// other users of the cURL backend.
+		qcurlShutdown();
 		httpDown = true;
 	}
 }
@@ -807,6 +818,16 @@ void CL_SetHTTPServer (const char *URL)
 	dlqueue_t *last = NULL;
 	dlqueue_t *q = &cls.downloadQueue;
 
+	// This code abuses the download server setting to
+	// determine if HTTP downloads are possible. So if
+	// we don't set a download server, no downloads are
+	// queued and run. :)
+	if (!qcurlInitialized)
+	{
+		cls.downloadServer[0] = 0;
+		return;
+	}
+
 	CL_HTTP_Cleanup(false);
 
 	// Cleanup download queues.
@@ -841,7 +862,7 @@ void CL_SetHTTPServer (const char *URL)
 		Com_Error(ERR_DROP, "HTTP download: Still have old handle?!");
 	}
 
-	multi = curl_multi_init();
+	multi = qcurl_multi_init();
 }
 
 /*
@@ -984,7 +1005,7 @@ void CL_RunHTTPDownloads(void)
 	int	newHandleCount;
 	CURLMcode ret;
 
-	// No HTTP server given.
+	// No HTTP server given or not initialized.
 	if (!cls.downloadServer[0])
 	{
 		return;
@@ -993,7 +1014,7 @@ void CL_RunHTTPDownloads(void)
 	// Kick CURL into action.
 	do
 	{
-		ret = curl_multi_perform(multi, &newHandleCount);
+		ret = qcurl_multi_perform(multi, &newHandleCount);
 
 		if (newHandleCount < handleCount)
 		{

src/client/curl/header/qcurl.h

@@ -0,0 +1,70 @@
+/*
+ * Copyright (C) 2018 Yamagi
+ *
+ * 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., 59 Temple Place - Suite 330, Boston, MA
+ * 02111-1307, USA.
+ *
+ * =======================================================================
+ *
+ * CURL backend for Quake II.
+ *
+ * =======================================================================
+ */
+
+#ifdef USE_CURL
+
+#ifndef QCURL_H
+#define QCURL_H
+
+// --------
+
+#include <curl/curl.h>
+#include "../../../common/header/common.h"
+
+// --------
+
+// True if cURL is initialized.
+extern qboolean qcurlInitialized;
+
+// Function pointers to cURL.
+extern void (*qcurl_easy_cleanup)(CURL *curl);
+extern CURL *(*qcurl_easy_init)(void);
+extern CURLcode (*qcurl_easy_getinfo)(CURL *curl, CURLINFO info, ...);
+extern CURLcode (*qcurl_easy_setopt)(CURL *curl, CURLoption option, ...);
+extern const char *(*qcurl_easy_strerror)(CURLcode);
+
+extern void (*qcurl_global_cleanup)(void);
+extern CURLcode (*qcurl_global_init)(long flags);
+
+extern CURLMcode (*qcurl_multi_add_handle)(CURLM *multi_handle, CURL *curl_handle);
+extern CURLMcode (*qcurl_multi_cleanup)(CURLM *multi_handle);
+extern CURLMsg *(*qcurl_multi_info_read)(CURLM *multi_handle, int *msgs_in_queue);
+extern CURLM *(*qcurl_multi_init)(void);
+extern CURLMcode (*qcurl_multi_perform)(CURLM *multi_handle, int *running_handles);
+extern CURLMcode (*qcurl_multi_remove_handle)(CURLM *multi_handle, CURL *curl_handle);
+
+// --------
+
+// Loads and initialized cURL.
+qboolean qcurlInit(void);
+
+// Shuts cURL down and unloads it.
+void qcurlShutdown(void);
+
+// --------
+
+#endif // QCURL_H
+#endif // USE_CURL

src/client/curl/qcurl.c

@@ -0,0 +1,221 @@
+/*
+ * Copyright (C) 2018 Yamagi
+ *
+ * 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., 59 Temple Place - Suite 330, Boston, MA
+ * 02111-1307, USA.
+ *
+ * =======================================================================
+ *
+ * CURL backend for Quake II.
+ *
+ * =======================================================================
+ */
+
+#ifdef USE_CURL
+
+// --------
+
+#include <curl/curl.h>
+
+#include "header/qcurl.h"
+#include "../../common/header/common.h"
+
+// --------
+
+// True if cURL is initialized.
+qboolean qcurlInitialized;
+
+// Pointer to the dynamic library.
+static void *curlhandle;
+
+// CVars
+static cvar_t *cl_libcurl;
+
+// Function pointers to cURL.
+void (*qcurl_easy_cleanup)(CURL *curl);
+CURL *(*qcurl_easy_init)(void);
+CURLcode (*qcurl_easy_getinfo)(CURL *curl, CURLINFO info, ...);
+CURLcode (*qcurl_easy_setopt)(CURL *curl, CURLoption option, ...);
+const char *(*qcurl_easy_strerror)(CURLcode);
+
+void (*qcurl_global_cleanup)(void);
+CURLcode (*qcurl_global_init)(long flags);
+
+CURLMcode (*qcurl_multi_add_handle)(CURLM *multi_handle, CURL *curl_handle);
+CURLMcode (*qcurl_multi_cleanup)(CURLM *multi_handle);
+CURLMsg *(*qcurl_multi_info_read)(CURLM *multi_handle, int *msgs_in_queue);
+CURLM *(*qcurl_multi_init)(void);
+CURLMcode (*qcurl_multi_perform)(CURLM *multi_handle, int *running_handles);
+CURLMcode (*qcurl_multi_remove_handle)(CURLM *multi_handle, CURL *curl_handle);
+
+// --------
+
+/*
+ * Load libcurl, connect the function pointer
+ * and call cURLs global init function.
+ */
+qboolean qcurlInit(void)
+{
+	Com_Printf("------- curl initialization -------\n");
+
+	assert(!qcurlInitialized && "cURL already initialized?!");
+
+	// Most systems have only one distinct name for the
+	// libcurl, loading that one will be successfull in
+	// at least 99% of all cases. But Linux, the mother
+	// of chaos, is more complicated. Debian / Ubuntu
+	// alone has 6 possible names... So:
+	//  - Let's try whatever the user has written into
+	//    the cl_libcurl cvar first.
+	//  - If that fails try all possible names until we
+	//    find a working one.
+	//  - If we found one put it into cl_libcurl, so we
+	//    don't need to iterate trought the whole list
+	//    the next time the game is started.
+	//  - If we found none error out.
+#ifdef __APPLE__
+	const char *libcurl[] = { "libcurl.dylib", NULL };
+#elif __linux__
+	const char *libcurl[] = { "libcurl.so", "libcurl.so.3", "libcurl.so.4", "libcurl-gnutls.so.3",
+		"libcurl-gnutls.so.4", "libcurl-nss.so.3", "libcurl-nss.so.4", NULL };
+#elif _WIN32
+	const char *libcurl[] = { "curl.dll", NULL };
+#else
+	const char *libcurl[] = { "libcurl.so", NULL };
+#endif
+
+	// Mkay, let's try to find a working libcurl.
+	cl_libcurl = Cvar_Get("cl_libcurl", (char *)libcurl[0], CVAR_ARCHIVE);
+
+	Com_Printf("LoadLibrary(%s)\n", cl_libcurl->string);
+	Sys_LoadLibrary(cl_libcurl->string, NULL, &curlhandle);
+
+	if (!curlhandle)
+	{
+		Com_Printf("Loading %s failed!\n", cl_libcurl->string);
+
+		for (int i = 0; libcurl[i] != NULL; i++)
+		{
+			// Tried that one already.
+			if (!strcmp(cl_libcurl->string, libcurl[i]))
+			{
+				continue;
+			}
+
+			Com_Printf("LoadLibrary(%s)\n", libcurl[i]);
+			Sys_LoadLibrary(libcurl[i], NULL, &curlhandle);
+
+			if (!curlhandle)
+			{
+				// No luck with this one.
+				Com_Printf("Loading %s failed!\n", libcurl[i]);
+				continue;
+			}
+			else
+			{
+				// Got one!
+				Cvar_Set("cl_libcurl", (char *)libcurl[i]);
+				break;
+			}
+		}
+
+		if (!curlhandle)
+		{
+			goto error;
+		}
+	}
+
+	// libcurl loaded sucessfully, connect the pointers.
+	#define CONCURL(var, sym) do { \
+		var = Sys_GetProcAddress(curlhandle, sym); \
+		if (!var) goto error; \
+	} while(0)
+	
+	CONCURL(qcurl_easy_cleanup, "curl_easy_cleanup");
+	CONCURL(qcurl_easy_init, "curl_easy_init");
+	CONCURL(qcurl_easy_getinfo, "curl_easy_getinfo");
+	CONCURL(qcurl_easy_setopt, "curl_easy_setopt");
+	CONCURL(qcurl_easy_strerror, "curl_easy_strerror");
+
+	CONCURL(qcurl_global_cleanup, "curl_global_cleanup");
+	CONCURL(qcurl_global_init, "curl_global_init");
+
+	CONCURL(qcurl_multi_add_handle, "curl_multi_add_handle");
+	CONCURL(qcurl_multi_cleanup, "curl_multi_cleanup");
+	CONCURL(qcurl_multi_info_read, "curl_multi_info_read");
+	CONCURL(qcurl_multi_init, "curl_multi_init");
+	CONCURL(qcurl_multi_perform, "curl_multi_perform");
+	CONCURL(qcurl_multi_remove_handle, "curl_multi_remove_handle");
+
+	#undef CONCURL
+
+	// And finally the global cURL initialization.
+	qcurl_global_init(CURL_GLOBAL_NOTHING);
+	qcurlInitialized = true;
+
+	Com_Printf("------------------------------------\n\n");
+
+	return true;
+
+error:
+	qcurlShutdown();
+
+	Com_Printf("------------------------------------\n\n");
+
+	return false;
+}
+
+/*
+ * Calls cURLs global shutdown funtion,
+ * unloads libcurl and set the function
+ * pointers to NULL.
+ */
+void qcurlShutdown(void)
+{
+	if (qcurlInitialized)
+	{
+		Com_Printf("Shutting down curl.\n");
+
+		qcurl_global_cleanup();
+		qcurlInitialized = false;
+	}
+
+	qcurl_easy_cleanup = NULL;
+	qcurl_easy_init = NULL;
+	qcurl_easy_getinfo = NULL;
+	qcurl_easy_setopt = NULL;
+	qcurl_easy_strerror = NULL;
+
+	qcurl_global_cleanup = NULL;
+	qcurl_global_init = NULL;
+
+    qcurl_multi_add_handle = NULL;
+	qcurl_multi_cleanup = NULL;
+	qcurl_multi_info_read = NULL;
+	qcurl_multi_init = NULL;
+	qcurl_multi_perform = NULL;
+	qcurl_multi_remove_handle = NULL;
+
+	if (curlhandle)
+	{
+		Sys_FreeLibrary(curlhandle);
+		curlhandle = NULL;
+	}
+}
+
+// --------
+
+#endif // USE_CURL