Bump RLIMIT_NOFILE

Wayland compositors handle many file descriptors: client
connections, DMA-BUFs, sync_files, wl_data_device pipes, and so
on. Bump the limit to the max.

Closes: https://github.com/swaywm/sway/issues/6285

1 files changed, 31 insertions, 0 deletions

diff --git a/sway/main.c b/sway/main.c
index 264fa847..2c760524 100644
--- a/sway/main.c
+++ b/sway/main.c
@@ -6,6 +6,7 @@
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
+#include <sys/resource.h>
 #include <sys/stat.h>
 #include <sys/types.h>
 #include <sys/wait.h>
@@ -27,6 +28,7 @@
 
 static bool terminate_request = false;
 static int exit_value = 0;
+static struct rlimit original_nofile_rlimit = {0};
 struct sway_server server = {0};
 struct sway_debug debug = {0};
 
@@ -169,6 +171,33 @@ static bool drop_permissions(void) {
         return true;
 }
 
+static void increase_nofile_limit(void) {
+        if (getrlimit(RLIMIT_NOFILE, &original_nofile_rlimit) != 0) {
+                sway_log_errno(SWAY_ERROR, "Failed to bump max open files limit: "
+                        "getrlimit(NOFILE) failed");
+                return;
+        }
+
+        struct rlimit new_rlimit = original_nofile_rlimit;
+        new_rlimit.rlim_cur = new_rlimit.rlim_max;
+        if (setrlimit(RLIMIT_NOFILE, &new_rlimit) != 0) {
+                sway_log_errno(SWAY_ERROR, "Failed to bump max open files limit: "
+                        "setrlimit(NOFILE) failed");
+                sway_log(SWAY_INFO, "Running with %d max open files",
+                        (int)original_nofile_rlimit.rlim_cur);
+        }
+}
+
+void restore_nofile_limit(void) {
+        if (original_nofile_rlimit.rlim_cur == 0) {
+                return;
+        }
+        if (setrlimit(RLIMIT_NOFILE, &original_nofile_rlimit) != 0) {
+                sway_log_errno(SWAY_ERROR, "Failed to restore max open files limit: "
+                        "setrlimit(NOFILE) failed");
+        }
+}
+
 void enable_debug_flag(const char *flag) {
         if (strcmp(flag, "damage=highlight") == 0) {
                 debug.damage = DAMAGE_HIGHLIGHT;
@@ -349,6 +378,8 @@ int main(int argc, char **argv) {
                 exit(EXIT_FAILURE);
         }
 
+        increase_nofile_limit();
+
         // handle SIGTERM signals
         signal(SIGTERM, sig_handler);
         signal(SIGINT, sig_handler);