From 5c8f70a17c2eea3e04f0b41a8ac59e4c60ccd8c3 Mon Sep 17 00:00:00 2001
From: Jan Beich <jbeich@FreeBSD.org>
Date: Fri, 27 Jan 2023 09:55:33 +0000
Subject: [PATCH] os: Use KERN_PROC_ARGS to determine client command on
 DragonFly and FreeBSD

---
 os/client.c | 57 ++++++++++++++++++++++++++++++++++++++++++++++++++++-
 1 file changed, 56 insertions(+), 1 deletion(-)

diff --git a/os/client.c b/os/client.c
index 953431bd9..3295949a4 100644
--- a/os/client.c
+++ b/os/client.c
@@ -73,6 +73,11 @@
 #include <limits.h>
 #endif
 
+#if defined(__DragonFly__) || defined(__FreeBSD__)
+#include <sys/sysctl.h>
+#include <errno.h>
+#endif
+
 #ifdef __APPLE__
 #include <dispatch/dispatch.h>
 #include <errno.h>
@@ -136,7 +141,7 @@ DetermineClientPid(struct _Client * client)
 void
 DetermineClientCmd(pid_t pid, const char **cmdname, const char **cmdargs)
 {
-#if !defined(__APPLE__)
+#if !defined(__APPLE__) && !defined(__DragonFly__) && !defined(__FreeBSD__)
     char path[PATH_MAX + 1];
     int totsize = 0;
     int fd = 0;
@@ -248,6 +253,56 @@ DetermineClientCmd(pid_t pid, const char **cmdname, const char **cmdargs)
             *cmdargs = strdup(args);
         }
 
+        free(procargs);
+    }
+#elif defined(__DragonFly__) || defined(__FreeBSD__)
+    /* on DragonFly and FreeBSD use KERN_PROC_ARGS */
+    {
+        int mib[] = {
+            CTL_KERN,
+            KERN_PROC,
+            KERN_PROC_ARGS,
+            pid,
+        };
+
+        /* Determine exact size instead of relying on kern.argmax */
+        size_t len;
+        if (sysctl(mib, ARRAY_SIZE(mib), NULL, &len, NULL, 0) != 0) {
+            ErrorF("Failed to query KERN_PROC_ARGS length for PID %d: %s\n", pid, strerror(errno));
+            return;
+        }
+
+        /* Read KERN_PROC_ARGS contents. Similar to /proc/pid/cmdline
+         * the process name and each argument are separated by NUL byte. */
+        char *const procargs = malloc(len);
+        if (sysctl(mib, ARRAY_SIZE(mib), procargs, &len, NULL, 0) != 0) {
+            ErrorF("Failed to get KERN_PROC_ARGS for PID %d: %s\n", pid, strerror(errno));
+            free(procargs);
+            return;
+        }
+
+        /* Construct the process name without arguments. */
+        if (cmdname) {
+            *cmdname = strdup(procargs);
+        }
+
+        /* Construct the arguments for client process. */
+        if (cmdargs) {
+            size_t cmdsize = strlen(procargs) + 1;
+            size_t argsize = len - cmdsize;
+            char *args = NULL;
+
+            if (argsize > 0)
+                args = procargs + cmdsize;
+            if (args) {
+                /* Replace NUL with space except terminating NUL */
+                for (size_t i = 0; i < (argsize - 1); i++) {
+                    if (args[i] == '\0')
+                        args[i] = ' ';
+                }
+                *cmdargs = strdup(args);
+            }
+        }
         free(procargs);
     }
 #elif defined(__OpenBSD__)