From e411b8a63d4a44ac191b5ca032c4639b12d4b838 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?=C3=89rico=20Rolim?= <erico.erc@gmail.com>
Date: Wed, 18 Nov 2020 14:07:10 -0300
Subject: [PATCH] lib/procutils: add proc_is_procfs helper.

Also add missing include in procutils.h for the definition of pid_t.
---
 include/procutils.h |  3 +++
 lib/procutils.c     | 19 +++++++++++++++++++
 2 files changed, 22 insertions(+)

diff --git a/include/procutils.h b/include/procutils.h
index 9f8dd76ec..c9f5bb552 100644
--- a/include/procutils.h
+++ b/include/procutils.h
@@ -2,6 +2,7 @@
 #define UTIL_LINUX_PROCUTILS
 
 #include <dirent.h>
+#include <sys/types.h>
 
 struct proc_tasks {
 	DIR *dir;
@@ -31,4 +32,6 @@ extern int proc_next_pid(struct proc_processes *ps, pid_t *pid);
 extern char *proc_get_command(pid_t pid);
 extern char *proc_get_command_name(pid_t pid);
 
+extern int proc_is_procfs(int fd);
+
 #endif /* UTIL_LINUX_PROCUTILS */
diff --git a/lib/procutils.c b/lib/procutils.c
index cf660ea5d..4436f38fa 100644
--- a/lib/procutils.c
+++ b/lib/procutils.c
@@ -13,11 +13,13 @@
 #include <string.h>
 #include <errno.h>
 #include <sys/stat.h>
+#include <sys/vfs.h>
 #include <sys/types.h>
 #include <dirent.h>
 #include <ctype.h>
 
 #include "procutils.h"
+#include "statfs_magic.h"
 #include "fileutils.h"
 #include "all-io.h"
 #include "c.h"
@@ -235,6 +237,23 @@ int proc_next_pid(struct proc_processes *ps, pid_t *pid)
 	return 0;
 }
 
+/* checks if fd is file in a procfs;
+ * returns 1 if true, 0 if false or couldn't determine */
+int proc_is_procfs(int fd)
+{
+	struct statfs st;
+	int ret;
+
+	do {
+		ret = fstatfs(fd, &st);
+	} while (ret == -1 && errno == EINTR);
+
+	if (ret == 0)
+		return st.f_type == STATFS_PROC_MAGIC;
+	else
+		return 0;
+}
+
 #ifdef TEST_PROGRAM_PROCUTILS
 
 static int test_tasks(int argc, char *argv[])