From 6dadc8bf0c996385531af6729361751b47b8926b Mon Sep 17 00:00:00 2001
From: Pavel Tikhomirov <ptikhomirov@virtuozzo.com>
Date: Fri, 22 Oct 2021 17:56:37 +0300
Subject: [PATCH 029/120] util: use nftw in rmrf helper

This simplifies the code by removing excess recursion and reusing
standard function to walk over file-tree instead of opencoding it.

This addresses problem mentioned in my review comment:
https://github.com/checkpoint-restore/criu/pull/1495#discussion_r677554523

Fixes: 0db135ac4 ("util: add rm -rf function")

Signed-off-by: Pavel Tikhomirov <ptikhomirov@virtuozzo.com>
---
 criu/apparmor.c     |  2 +-
 criu/include/util.h |  4 ++--
 criu/util.c         | 46 ++++++++++++++-------------------------------
 3 files changed, 17 insertions(+), 35 deletions(-)

diff --git a/criu/apparmor.c b/criu/apparmor.c
index 328fc606b..f9ad79619 100644
--- a/criu/apparmor.c
+++ b/criu/apparmor.c
@@ -630,7 +630,7 @@ int suspend_aa(void)
 	}
 
 	ret = do_suspend(true);
-	if (rm_rf(policydir) < 0)
+	if (rmrf(policydir) < 0)
 		pr_err("failed removing policy dir %s\n", policydir);
 
 	return ret;
diff --git a/criu/include/util.h b/criu/include/util.h
index a2dac2233..19d378fc5 100644
--- a/criu/include/util.h
+++ b/criu/include/util.h
@@ -284,8 +284,8 @@ int setup_tcp_server(char *type, char *addr, unsigned short *port);
 int run_tcp_server(bool daemon_mode, int *ask, int cfd, int sk);
 int setup_tcp_client(char *hostname);
 
-/* *dir should be writable and at least PATH_MAX long */
-int rm_rf(char *dir);
+/* path should be writable and no more than PATH_MAX long */
+int rmrf(char *path);
 
 #define LAST_PID_PATH "sys/kernel/ns_last_pid"
 #define PID_MAX_PATH  "sys/kernel/pid_max"
diff --git a/criu/util.c b/criu/util.c
index 06124c220..414879971 100644
--- a/criu/util.c
+++ b/criu/util.c
@@ -1,4 +1,4 @@
-#define _XOPEN_SOURCE
+#define _XOPEN_SOURCE 500
 
 #include <stdio.h>
 #include <stdarg.h>
@@ -26,6 +26,7 @@
 #include <netinet/in.h>
 #include <netinet/tcp.h>
 #include <sched.h>
+#include <ftw.h>
 
 #include "linux/mount.h"
 
@@ -1613,44 +1614,25 @@ ssize_t write_all(int fd, const void *buf, size_t size)
 	return n;
 }
 
-int rm_rf(char *target)
+static int remove_one(const char *fpath, const struct stat *sb, int tflag, struct FTW *ftwbuf)
 {
-	int offset = strlen(target);
-	DIR *dir = NULL;
-	struct dirent *de;
-	int ret = -1;
+	int ret;
 
-	dir = opendir(target);
-	if (!dir) {
-		pr_perror("unable to open %s", target);
+	ret = remove(fpath);
+	if (ret) {
+		pr_perror("rmrf: unable to remove %s", fpath);
 		return -1;
 	}
 
-	while ((de = readdir(dir))) {
-		int n;
-
-		if (dir_dots(de))
-			continue;
-
-		n = snprintf(target + offset, PATH_MAX - offset, "/%s", de->d_name);
-		if (n < 0 || n >= PATH_MAX) {
-			pr_err("snprintf failed\n");
-			goto out;
-		}
-
-		if (de->d_type == DT_DIR && rm_rf(target))
-			goto out;
+	return 0;
+}
 
-		if (remove(target) < 0) {
-			pr_perror("unable to remove %s", target);
-			goto out;
-		}
-	}
+#define NFTW_FD_MAX 64
 
-	ret = 0;
-out:
-	target[offset] = 0;
-	return ret;
+int rmrf(char *path)
+{
+	pr_debug("rmrf: removing %s\n", path);
+	return nftw(path, remove_one, NFTW_FD_MAX, FTW_DEPTH | FTW_PHYS);
 }
 
 __attribute__((returns_twice)) static pid_t raw_legacy_clone(unsigned long flags, int *pidfd)
-- 
2.34.1