From fcb318b9c5158ab66ca1d5797b197237eae7d5c3 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Barnab=C3=A1s=20P=C5=91cze?= <pobrn@protonmail.com>
Date: Wed, 23 Jul 2025 18:18:52 +0200
Subject: [PATCH] pwtest: is_debugger_attached(): rework test

Check if the "TracerPid" field in `/proc/self/status` is non-zero. This does
not need libcap, and does not depend on capabilities, and it also works under
qemu user emulation.
---
 meson.build      |  3 ---
 test/meson.build |  1 -
 test/pwtest.c    | 43 +++++++++++--------------------------------
 3 files changed, 11 insertions(+), 36 deletions(-)

diff --git a/meson.build b/meson.build
index 307f1155c..0a01a8f37 100644
--- a/meson.build
+++ b/meson.build
@@ -381,9 +381,6 @@ libusb_dep = dependency('libusb-1.0', required : get_option('libusb'))
 summary({'libusb (Bluetooth quirks)': libusb_dep.found()}, bool_yn: true, section: 'Backend')
 cdata.set('HAVE_LIBUSB', libusb_dep.found())
 
-cap_lib = dependency('libcap', required : false)
-cdata.set('HAVE_LIBCAP', cap_lib.found())
-
 glib2_dep = dependency('glib-2.0', required : get_option('flatpak'))
 summary({'GLib-2.0 (Flatpak support)': glib2_dep.found()}, bool_yn: true, section: 'Misc dependencies')
 flatpak_support = glib2_dep.found()
diff --git a/test/meson.build b/test/meson.build
index b4f24cf1b..c5671149d 100644
--- a/test/meson.build
+++ b/test/meson.build
@@ -9,7 +9,6 @@ pwtest_deps = [
   pipewire_dep,
   mathlib,
   dl_lib,
-  cap_lib,
   epoll_shim_dep
 ]
 
diff --git a/test/pwtest.c b/test/pwtest.c
index 7094a59e1..89a385f53 100644
--- a/test/pwtest.c
+++ b/test/pwtest.c
@@ -19,9 +19,6 @@
 #ifdef HAVE_PIDFD_OPEN
 #include <sys/syscall.h>
 #endif
-#ifdef HAVE_LIBCAP
-#include <sys/capability.h>
-#endif
 #include <sys/epoll.h>
 #include <sys/ptrace.h>
 #include <sys/resource.h>
@@ -33,6 +30,7 @@
 #include <valgrind/valgrind.h>
 
 #include "spa/utils/ansi.h"
+#include "spa/utils/cleanup.h"
 #include "spa/utils/string.h"
 #include "spa/utils/defs.h"
 #include "spa/utils/list.h"
@@ -1298,39 +1296,20 @@ static void list_tests(struct pwtest_context *ctx)
 
 static bool is_debugger_attached(void)
 {
-	bool rc = false;
-#ifdef HAVE_LIBCAP
-	int status;
-	int pid = fork();
+	spa_autofree char *line = NULL;
+	size_t length = 0;
 
-	if (pid == -1)
-		return 0;
+	spa_autoptr(FILE) f = fopen("/proc/self/status", "re");
+	if (!f)
+		return false;
 
-	if (pid == 0) {
-		int ppid = getppid();
-		cap_t caps = cap_get_pid(ppid);
-		cap_flag_value_t cap_val;
-
-		if (cap_get_flag(caps, CAP_SYS_PTRACE, CAP_EFFECTIVE, &cap_val) == -1 ||
-		    cap_val != CAP_SET)
-			_exit(false);
-
-		if (ptrace(PTRACE_ATTACH, ppid, NULL, 0) == 0) {
-			waitpid(ppid, NULL, 0);
-			ptrace(PTRACE_CONT, ppid, NULL, 0);
-			ptrace(PTRACE_DETACH, ppid, NULL, 0);
-			rc = false;
-		} else {
-			rc = true;
-		}
-		_exit(rc);
-	} else {
-		waitpid(pid, &status, 0);
-		rc = WEXITSTATUS(status);
+	while (getline(&line, &length, f) >= 0) {
+		unsigned int tracer_pid;
+		if (sscanf(line, "TracerPid: %u", &tracer_pid) == 1)
+			return tracer_pid > 0;
 	}
 
-#endif
-	return !!rc;
+	return false;
 }
 
 static void usage(FILE *fp, const char *progname)