From 4420284125c7be582ff81799069d29e8a2429735 Mon Sep 17 00:00:00 2001
From: Andreas Kling <kling@serenityos.org>
Date: Sat, 22 Feb 2020 11:01:37 +0100
Subject: [PATCH] profile: Allow launching a command with profiling enabled

You can now profile a program from start to finish by doing:

    $ profile -c "cat /etc/passwd"

The old "enable or disable profiling for a PID" mode is accessible via:

    $ profile -p <PID> -e    # Enable profiling for PID
    $ profile -p <PID> -d    # Disable profiling for PID

The generated profile is available via /proc/profile like before.
This is far from perfect, but it at least makes profiling a lot nicer
to use since you don't have to hurry and attach to something when you
want to profile the whole thing anyway.
---
 Userland/profile.cpp | 59 ++++++++++++++++++++++++++++++++++++--------
 1 file changed, 49 insertions(+), 10 deletions(-)

diff --git a/Userland/profile.cpp b/Userland/profile.cpp
index 15031555835..cff8a5b7b8a 100644
--- a/Userland/profile.cpp
+++ b/Userland/profile.cpp
@@ -24,6 +24,7 @@
  * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  */
 
+#include <LibCore/ArgsParser.h>
 #include <serenity.h>
 #include <stdio.h>
 #include <stdlib.h>
@@ -31,25 +32,63 @@
 
 int main(int argc, char** argv)
 {
-    if (argc != 3) {
-        printf("usage: profile <pid> <on|off>\n");
+    Core::ArgsParser args_parser;
+
+    const char* pid_argument = nullptr;
+    const char* cmd_argument = nullptr;
+    bool enable = false;
+    bool disable = false;
+
+    args_parser.add_option(pid_argument, "Target PID", nullptr, 'p', "PID");
+    args_parser.add_option(enable, "Enable", nullptr, 'e');
+    args_parser.add_option(disable, "Disable", nullptr, 'd');
+    args_parser.add_option(cmd_argument, "Command", nullptr, 'c', "command");
+
+    args_parser.parse(argc, argv);
+
+    if (!pid_argument && !cmd_argument) {
+        args_parser.print_usage(stdout, argv[0]);
         return 0;
     }
 
-    pid_t pid = atoi(argv[1]);
-    bool enabled = !strcmp(argv[2], "on");
-
-    if (enabled) {
-        if (profiling_enable(pid) < 0) {
-            perror("profiling_enable");
+    if (pid_argument) {
+        if (!(enable ^ disable)) {
+            fprintf(stderr, "-p <PID> requires -e xor -d.\n");
             return 1;
         }
+
+        pid_t pid = atoi(pid_argument);
+
+        if (enable) {
+            if (profiling_enable(pid) < 0) {
+                perror("profiling_enable");
+                return 1;
+            }
+            return 0;
+        }
+
+        if (profiling_disable(pid) < 0) {
+            perror("profiling_disable");
+            return 1;
+        }
+
         return 0;
     }
 
-    if (profiling_disable(pid) < 0) {
-        perror("profiling_disable");
+    auto cmd_parts = String(cmd_argument).split(' ');
+    Vector<const char*> cmd_argv;
+
+    for (auto& part : cmd_parts)
+        cmd_argv.append(part.characters());
+
+    cmd_argv.append(nullptr);
+
+    dbg() << "Enabling profiling for PID " << getpid();
+    profiling_enable(getpid());
+    if (execvp(cmd_argv[0], const_cast<char**>(cmd_argv.data())) < 0) {
+        perror("execv");
         return 1;
     }
+
     return 0;
 }