From: Ian Rogers <irogers@google.com>
Date: Fri, 3 Oct 2025 17:56:12 +0000 (-0700)
Subject: perf namespaces: Avoid get_current_dir_name dependency
X-Git-Url: https://www.infradead.org/git/?a=commitdiff_plain;h=062d02a96d810d55afdc594ceeb52223d8b36b5c;p=users%2Fhch%2Fmisc.git

perf namespaces: Avoid get_current_dir_name dependency

get_current_dir_name is a GNU extension not supported on, for example,
Android. There is only one use of it so let's just switch to getcwd to
avoid build and other complexity.

Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
---

diff --git a/tools/perf/Makefile.config b/tools/perf/Makefile.config
index 481e7fe26f3b..76b92608a24e 100644
--- a/tools/perf/Makefile.config
+++ b/tools/perf/Makefile.config
@@ -417,10 +417,6 @@ ifeq ($(feature-eventfd), 1)
   CFLAGS += -DHAVE_EVENTFD_SUPPORT
 endif
 
-ifeq ($(feature-get_current_dir_name), 1)
-  CFLAGS += -DHAVE_GET_CURRENT_DIR_NAME
-endif
-
 ifeq ($(feature-gettid), 1)
   CFLAGS += -DHAVE_GETTID
 endif
diff --git a/tools/perf/util/Build b/tools/perf/util/Build
index d31f5f252fa8..e6b396d919bb 100644
--- a/tools/perf/util/Build
+++ b/tools/perf/util/Build
@@ -23,7 +23,6 @@ perf-util-y += evsel_fprintf.o
 perf-util-y += perf_event_attr_fprintf.o
 perf-util-y += evswitch.o
 perf-util-y += find_bit.o
-perf-util-y += get_current_dir_name.o
 perf-util-y += levenshtein.o
 perf-util-$(CONFIG_LIBBFD) += libbfd.o
 perf-util-y += llvm.o
diff --git a/tools/perf/util/get_current_dir_name.c b/tools/perf/util/get_current_dir_name.c
deleted file mode 100644
index e68935e9ac8c..000000000000
--- a/tools/perf/util/get_current_dir_name.c
+++ /dev/null
@@ -1,18 +0,0 @@
-// SPDX-License-Identifier: LGPL-2.1
-// Copyright (C) 2018, 2019 Red Hat Inc, Arnaldo Carvalho de Melo <acme@redhat.com>
-//
-#ifndef HAVE_GET_CURRENT_DIR_NAME
-#include "get_current_dir_name.h"
-#include <limits.h>
-#include <string.h>
-#include <unistd.h>
-
-/* Android's 'bionic' library, for one, doesn't have this */
-
-char *get_current_dir_name(void)
-{
-	char pwd[PATH_MAX];
-
-	return getcwd(pwd, sizeof(pwd)) == NULL ? NULL : strdup(pwd);
-}
-#endif // HAVE_GET_CURRENT_DIR_NAME
diff --git a/tools/perf/util/get_current_dir_name.h b/tools/perf/util/get_current_dir_name.h
deleted file mode 100644
index 69f7d5537d32..000000000000
--- a/tools/perf/util/get_current_dir_name.h
+++ /dev/null
@@ -1,8 +0,0 @@
-// SPDX-License-Identifier: LGPL-2.1
-// Copyright (C) 2018, 2019 Red Hat Inc, Arnaldo Carvalho de Melo <acme@redhat.com>
-//
-#ifndef __PERF_GET_CURRENT_DIR_NAME_H
-#ifndef HAVE_GET_CURRENT_DIR_NAME
-char *get_current_dir_name(void);
-#endif // HAVE_GET_CURRENT_DIR_NAME
-#endif // __PERF_GET_CURRENT_DIR_NAME_H
diff --git a/tools/perf/util/namespaces.c b/tools/perf/util/namespaces.c
index 68f5de2d79c7..01502570b32d 100644
--- a/tools/perf/util/namespaces.c
+++ b/tools/perf/util/namespaces.c
@@ -6,7 +6,6 @@
 
 #include "namespaces.h"
 #include "event.h"
-#include "get_current_dir_name.h"
 #include <sys/types.h>
 #include <sys/stat.h>
 #include <fcntl.h>
@@ -293,14 +292,14 @@ void nsinfo__mountns_enter(struct nsinfo *nsi,
 	if (!nsi || !nsinfo__need_setns(nsi))
 		return;
 
-	if (snprintf(curpath, PATH_MAX, "/proc/self/ns/mnt") >= PATH_MAX)
+	if (!getcwd(curpath, sizeof(curpath)))
 		return;
 
-	oldcwd = get_current_dir_name();
+	oldcwd = strdup(curpath);
 	if (!oldcwd)
 		return;
 
-	oldns = open(curpath, O_RDONLY);
+	oldns = open("/proc/self/ns/mnt", O_RDONLY);
 	if (oldns < 0)
 		goto errout;