linux-kernel - [PATCH 1/3] init/main.c: introduce function ramdisk_exec

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Date:   Sat, 22 May 2021 19:31:53 +0800
From:   menglong8.dong@...il.com
To:     mcgrof@...nel.org
Cc:     viro@...iv.linux.org.uk, keescook@...omium.org,
        samitolvanen@...gle.com, johan@...nel.org, ojeda@...nel.org,
        jeyu@...nel.org, joe@...ches.com, dong.menglong@....com.cn,
        masahiroy@...nel.org, jack@...e.cz, axboe@...nel.dk, hare@...e.de,
        gregkh@...uxfoundation.org, tj@...nel.org, song@...nel.org,
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        f.fainelli@...il.com, wangkefeng.wang@...wei.com, arnd@...db.de,
        linux@...musvillemoes.dk, mhiramat@...nel.org, rostedt@...dmis.org,
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        ebiederm@...ssion.com, jojing64@...il.com,
        linux-fsdevel@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: [PATCH 1/3] init/main.c: introduce function ramdisk_exec_exist()

From: Menglong Dong <dong.menglong@....com.cn>

Introduce the function ramdisk_exec_exist, which is used to check
the exist of 'ramdisk_execute_command'.

It can do absolute path and relative path check. For relative path,
it will ignore '/' and '.' in the start of
'ramdisk_execute_command'.

Signed-off-by: Menglong Dong <dong.menglong@....com.cn>
---
 init/main.c | 17 ++++++++++++++++-
 1 file changed, 16 insertions(+), 1 deletion(-)

diff --git a/init/main.c b/init/main.c
index eb01e121d2f1..95cab17046e0 100644
--- a/init/main.c
+++ b/init/main.c
@@ -1522,6 +1522,21 @@ void __init console_on_rootfs(void)
 	fput(file);
 }
 
+bool __init ramdisk_exec_exist(bool absolute)
+{
+	char *tmp_command = ramdisk_execute_command;
+
+	if (!tmp_command)
+		return false;
+
+	if (!absolute) {
+		while (*tmp_command == '/' || *tmp_command == '.')
+			tmp_command++;
+	}
+
+	return init_eaccess(tmp_command) == 0;
+}
+
 static noinline void __init kernel_init_freeable(void)
 {
 	/*
@@ -1568,7 +1583,7 @@ static noinline void __init kernel_init_freeable(void)
 	 * check if there is an early userspace init.  If yes, let it do all
 	 * the work
 	 */
-	if (init_eaccess(ramdisk_execute_command) != 0) {
+	if (!ramdisk_exec_exist(true)) {
 		ramdisk_execute_command = NULL;
 		prepare_namespace();
 	}
-- 
2.31.1