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libc: Implement memfd on top of tmpfs

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https://man7.org/linux/man-pages/man2/memfd_create.2.html

Signed-off-by: Xiang Xiao <xiaoxiang@xiaomi.com>
This commit is contained in:
Xiang Xiao 2022-08-08 00:17:41 +08:00 committed by Petro Karashchenko
parent 08b8234e9e
commit fa2e1897ea
5 changed files with 141 additions and 1 deletions
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10
include/fcntl.h
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@ -97,6 +97,8 @@
#define F_SETOWN 13 /* Set pid that will receive SIGIO and SIGURG signals for fd */
#define F_SETSIG 14 /* Set the signal to be sent */
#define F_GETPATH 15 /* Get the path of the file descriptor(BSD/macOS) */
#define F_ADD_SEALS 16 /* Add the bit-mask argument arg to the set of seals of the inode */
#define F_GET_SEALS 17 /* Get (as the function result) the current set of seals of the inode */
/* For posix fcntl() and lockf() */
@ -117,6 +119,14 @@
#define DN_RENAME 4 /* A file was renamed */
#define DN_ATTRIB 5 /* Attributes of a file were changed */
/* Types of seals */
#define F_SEAL_SEAL 0x0001 /* Prevent further seals from being set */
#define F_SEAL_SHRINK 0x0002 /* Prevent file from shrinking */
#define F_SEAL_GROW 0x0004 /* Prevent file from growing */
#define F_SEAL_WRITE 0x0008 /* Prevent writes */
#define F_SEAL_FUTURE_WRITE 0x0010 /* Prevent future writes while mapped */
/* int creat(const char *path, mode_t mode);
*
* is equivalent to open with O_WRONLY|O_CREAT|O_TRUNC.

72
include/sys/memfd.h Normal file
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@ -0,0 +1,72 @@
/****************************************************************************
* include/sys/memfd.h
*
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership. The
* ASF licenses this file to you under the Apache License, Version 2.0 (the
* "License"); you may not use this file except in compliance with the
* License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
* WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
* License for the specific language governing permissions and limitations
* under the License.
*
****************************************************************************/
#ifndef __INCLUDE_SYS_MEMFD_H
#define __INCLUDE_SYS_MEMFD_H
/****************************************************************************
* Included Files
****************************************************************************/
#include <fcntl.h>
/****************************************************************************
* Pre-processor Definitions
****************************************************************************/
#define MFD_CLOEXEC O_CLOEXEC
#define MFD_ALLOW_SEALING (1 << 16)
#define MFD_HUGETLB (1 << 17)
#define MFD_HUGE_SHIFT 26
#define MFD_HUGE_MASK 0x3f
#define MFD_HUGE_64KB (16 << MFD_HUGE_SHIFT)
#define MFD_HUGE_512KB (19 << MFD_HUGE_SHIFT)
#define MFD_HUGE_1MB (20 << MFD_HUGE_SHIFT)
#define MFD_HUGE_2MB (21 << MFD_HUGE_SHIFT)
#define MFD_HUGE_8MB (23 << MFD_HUGE_SHIFT)
#define MFD_HUGE_16MB (24 << MFD_HUGE_SHIFT)
#define MFD_HUGE_32MB (25 << MFD_HUGE_SHIFT)
#define MFD_HUGE_256MB (28 << MFD_HUGE_SHIFT)
#define MFD_HUGE_512MB (29 << MFD_HUGE_SHIFT)
#define MFD_HUGE_1GB (30 << MFD_HUGE_SHIFT)
#define MFD_HUGE_2GB (31 << MFD_HUGE_SHIFT)
#define MFD_HUGE_16GB (34 << MFD_HUGE_SHIFT)
/****************************************************************************
* Public Function Prototypes
****************************************************************************/
#ifdef __cplusplus
#define EXTERN extern "C"
extern "C"
{
#else
#define EXTERN extern
#endif
int memfd_create(FAR const char *name, unsigned int flags);
#undef EXTERN
#ifdef __cplusplus
}
#endif
#endif /* __INCLUDE_SYS_MEMFD_H */

7
libs/libc/misc/Kconfig
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@ -62,6 +62,13 @@ config LIBC_ENVPATH
Use the contents of the common environment variable to locate executable
or library files. Default: n
config MEM_FD_VFS_PATH
string "Relative path to memfd storage"
default "memfd"
depends on FS_TMPFS
---help---
The relative path to where memfd will exist in the tmpfs namespace.
config LIBC_ERR
bool "Support err() verr() verrx() warn() vwarn() vwarnx()"
default y

2
libs/libc/misc/Make.defs
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@ -22,7 +22,7 @@
CSRCS += lib_mknod.c lib_umask.c lib_utsname.c lib_getrandom.c
CSRCS += lib_xorshift128.c lib_tea_encrypt.c lib_tea_decrypt.c
CSRCS += lib_cxx_initialize.c lib_impure.c
CSRCS += lib_cxx_initialize.c lib_impure.c lib_memfd.c
# Support for platforms that do not have long long types

51
libs/libc/misc/lib_memfd.c Normal file
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@ -0,0 +1,51 @@
/****************************************************************************
* libs/libc/misc/lib_memfd.c
*
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership. The
* ASF licenses this file to you under the Apache License, Version 2.0 (the
* "License"); you may not use this file except in compliance with the
* License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
* WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
* License for the specific language governing permissions and limitations
* under the License.
*
****************************************************************************/
/****************************************************************************
* Included Files
****************************************************************************/
#include <sys/memfd.h>
#include <errno.h>
#include <stdio.h>
#include <unistd.h>
/****************************************************************************
* Pre-processor Definitions
****************************************************************************/
#define MEM_FD_VFS_PATH CONFIG_LIBC_TMPDIR "/" CONFIG_MEM_FD_VFS_PATH "/%s"
/****************************************************************************
* Public Functions
****************************************************************************/
int memfd_create(FAR const char *name, unsigned int flags)
{
#ifdef CONFIG_FS_TMPFS
char path[PATH_MAX];
snprintf(path, sizeof(path), MEM_FD_VFS_PATH, name);
return open(path, O_RDWR | flags);
#else
set_errno(ENOSYS);
return -1;
#endif
}