From: Dmitry V. Levin <ldv@altlinux.org>
Date: Sat, 18 Nov 2017 00:19:31 +0000 (+0000)
Subject: Print the first argument of memfd_create syscall as a path
X-Git-Tag: v4.21~305
X-Git-Url: https://granicus.if.org/sourcecode?a=commitdiff_plain;h=c75392f67a6518b8a55f0ed72de97172643bf20e;p=strace

Print the first argument of memfd_create syscall as a path

The limit imposed by the kernel on the length of memfd_create first
argument is NAME_MAX - strlen("memfd:").

* memfd_create.c (SYS_FUNC(memfd_create)): Print the first argument
using printpathn.
* tests/memfd_create.c: Check it.
---

diff --git a/memfd_create.c b/memfd_create.c
index 1691352c..12949706 100644
--- a/memfd_create.c
+++ b/memfd_create.c
@@ -32,7 +32,7 @@
 
 SYS_FUNC(memfd_create)
 {
-	printstr(tcp, tcp->u_arg[0]);
+	printpathn(tcp, tcp->u_arg[0], 255 - (sizeof("memfd:") - 1));
 	tprints(", ");
 	printflags(memfd_create_flags, tcp->u_arg[1], "MFD_???");
 
diff --git a/tests/memfd_create.c b/tests/memfd_create.c
index 4559b426..3daa8c9c 100644
--- a/tests/memfd_create.c
+++ b/tests/memfd_create.c
@@ -1,3 +1,32 @@
+/*
+ * Check decoding of memfd_create syscall.
+ *
+ * Copyright (c) 2015-2017 Dmitry V. Levin <ldv@altlinux.org>
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ * 3. The name of the author may not be used to endorse or promote products
+ *    derived from this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
+ * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
+ * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
+ * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
+ * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+ * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
+ * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
 #include "tests.h"
 #include <asm/unistd.h>
 #include "scno.h"
@@ -5,17 +34,33 @@
 #ifdef __NR_memfd_create
 
 # include <stdio.h>
+# include <stdint.h>
 # include <unistd.h>
 
+static const char *errstr;
+
+static long
+k_memfd_create(const kernel_ulong_t name, const kernel_ulong_t flags)
+{
+	const long rc = syscall(__NR_memfd_create, name, flags);
+	errstr = sprintrc(rc);
+	return rc;
+}
+
 int
 main(void)
 {
-	static const char text[] = "strace";
-	int rc = syscall(__NR_memfd_create, text, 0xf);
+	const size_t size = 255 - (sizeof("memfd:") - 1) + 1;
+	char *const pattern = tail_alloc(size);
+	fill_memory_ex(pattern, size, '0', 10);
+
+	const kernel_ulong_t flags = (kernel_ulong_t) 0xfacefeed0000000fULL;
+	k_memfd_create((uintptr_t) pattern, flags);
 
-	printf("memfd_create(\"%s\", %s) = %s\n",
-	       text, "MFD_CLOEXEC|MFD_ALLOW_SEALING|MFD_HUGETLB|0x8",
-	       sprintrc(rc));
+	printf("memfd_create(\"%.*s\"..., %s) = %s\n",
+	       (int) size - 1, pattern,
+	       "MFD_CLOEXEC|MFD_ALLOW_SEALING|MFD_HUGETLB|0x8",
+	       errstr);
 
 	puts("+++ exited with 0 +++");
 	return 0;