compositor: implement wayland socket handover

This commit implements the compositor side of the Wayland socket handover protocol as described in the [KDE Wiki]. The CLI options are chosen so that they are compatible with Kwin. [KDE Wiki]: https://invent.kde.org/plasma/kwin/-/wikis/Restarting
hyprwm · Jul 19, 2024 · 94d994c · 94d994c
1 parent 300228b
commit 94d994c
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Showing 3 changed files with 45 additions and 11 deletions.
diff --git a/src/Compositor.cpp b/src/Compositor.cpp
@@ -27,6 +27,7 @@
 #include <hyprutils/string/String.hpp>
 using namespace Hyprutils::String;
 
+#include <fcntl.h>
 #include <sys/types.h>
 #include <sys/stat.h>
 #include <sys/resource.h>
@@ -533,19 +534,30 @@ void CCompositor::prepareFallbackOutput() {
     wlr_headless_add_output(headless, 1920, 1080);
 }
 
-void CCompositor::startCompositor() {
+void CCompositor::startCompositor(std::string socketName, int socketFd) {
     initAllSignals();
 
-    // get socket, avoid using 0
-    for (int candidate = 1; candidate <= 32; candidate++) {
-        const auto CANDIDATESTR = ("wayland-" + std::to_string(candidate));
-        const auto RETVAL       = wl_display_add_socket(m_sWLDisplay, CANDIDATESTR.c_str());
+    if (!socketName.empty() && socketFd != -1) {
+        fcntl(socketFd, F_SETFD, FD_CLOEXEC);
+        const auto RETVAL = wl_display_add_socket_fd(m_sWLDisplay, socketFd);
         if (RETVAL >= 0) {
-            m_szWLDisplaySocket = CANDIDATESTR;
-            Debug::log(LOG, "wl_display_add_socket for {} succeeded with {}", CANDIDATESTR, RETVAL);
-            break;
+            m_szWLDisplaySocket = socketName;
+            Debug::log(LOG, "wl_display_add_socket_fd for {} succeeded with {}", socketName, RETVAL);
         } else {
-            Debug::log(WARN, "wl_display_add_socket for {} returned {}: skipping candidate {}", CANDIDATESTR, RETVAL, candidate);
+            Debug::log(WARN, "wl_display_add_socket_fd for {} returned {}: skipping", socketName, RETVAL);
+        }
+    } else {
+        // get socket, avoid using 0
+        for (int candidate = 1; candidate <= 32; candidate++) {
+            const auto CANDIDATESTR = ("wayland-" + std::to_string(candidate));
+            const auto RETVAL       = wl_display_add_socket(m_sWLDisplay, CANDIDATESTR.c_str());
+            if (RETVAL >= 0) {
+                m_szWLDisplaySocket = CANDIDATESTR;
+                Debug::log(LOG, "wl_display_add_socket for {} succeeded with {}", CANDIDATESTR, RETVAL);
+                break;
+            } else {
+                Debug::log(WARN, "wl_display_add_socket for {} returned {}: skipping candidate {}", CANDIDATESTR, RETVAL, candidate);
+            }
         }
     }
 

diff --git a/src/Compositor.hpp b/src/Compositor.hpp
@@ -78,7 +78,7 @@ class CCompositor {
     std::unordered_map<std::string, uint64_t> m_mMonitorIDMap;
 
     void                                      initServer();
-    void                                      startCompositor();
+    void                                      startCompositor(std::string socketName, int socketFd);
     void                                      cleanup();
     void                                      createLockFile();
     void                                      removeLockFile();

diff --git a/src/main.cpp b/src/main.cpp
@@ -16,6 +16,8 @@ void help() {
     std::cout << "\nArguments:\n";
     std::cout << "  --help              -h       - Show this message again\n";
     std::cout << "  --config FILE       -c FILE  - Specify config file to use\n";
+    std::cout << "  --socket NAME                - Sets the Wayland socket name (for crash-recovery)\n";
+    std::cout << "  --wayland-fd FD              - Sets the Wayland socket fd (for crash-recovery)\n";
     std::cout << "  --i-am-really-stupid         - Omits root user privileges check (why would you do that?)\n";
 }
 
@@ -37,6 +39,8 @@ int main(int argc, char** argv) {
 
     // parse some args
     std::string              configPath;
+    std::string              socketName;
+    int                      socketFd = -1;
     bool                     ignoreSudo = false;
 
     std::vector<std::string> args{argv + 1, argv + argc};
@@ -46,6 +50,24 @@ int main(int argc, char** argv) {
             std::cout << "[ WARNING ] Running Hyprland with superuser privileges might damage your system\n";
 
             ignoreSudo = true;
+        } else if (it->compare("--socket") == 0) {
+            if (std::next(it) == args.end()) {
+                help();
+
+                return 1;
+            }
+
+            socketName = *std::next(it);
+            it++;
+        } else if (it->compare("--wayland-fd") == 0) {
+            if (std::next(it) == args.end()) {
+                help();
+
+                return 1;
+            }
+
+            socketFd = std::atoi(std::next(it)->c_str());
+            it++;
         } else if (it->compare("-c") == 0 || it->compare("--config") == 0) {
             if (std::next(it) == args.end()) {
                 help();
@@ -113,7 +135,7 @@ int main(int argc, char** argv) {
     Debug::log(LOG, "Hyprland init finished.");
 
     // If all's good to go, start.
-    g_pCompositor->startCompositor();
+    g_pCompositor->startCompositor(socketName, socketFd);
 
     g_pCompositor->m_bIsShuttingDown = true;