132 lines
4.1 KiB
C
132 lines
4.1 KiB
C
/****************************************************************************
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* libs/libc/misc/lib_fdcheck.c
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*
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* Licensed to the Apache Software Foundation (ASF) under one or more
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* contributor license agreements. See the NOTICE file distributed with
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* this work for additional information regarding copyright ownership. The
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* ASF licenses this file to you under the Apache License, Version 2.0 (the
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* "License"); you may not use this file except in compliance with the
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* License. You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
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* WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
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* License for the specific language governing permissions and limitations
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* under the License.
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*
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****************************************************************************/
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/****************************************************************************
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* Included Files
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****************************************************************************/
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#include <nuttx/fdcheck.h>
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#include <nuttx/lib/math32.h>
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#include <nuttx/sched.h>
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#include <debug.h>
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#include <stdio.h>
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#ifdef CONFIG_FDCHECK
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/****************************************************************************
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* Pre-processor Definitions
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****************************************************************************/
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#define FD_SHIFT 0
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#define FD_BITS LOG2_CEIL(OPEN_MAX)
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#define FD_MASK ((1 << FD_BITS) - 1)
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#define PID_SHIFT (FD_BITS + FD_SHIFT)
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#define PID_BITS (8 * sizeof(int) - 1 - PID_SHIFT)
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#define PID_MASK ((1 << PID_BITS) - 1)
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/****************************************************************************
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* Public Functions
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****************************************************************************/
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/****************************************************************************
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* Name: fdcheck_restore
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*
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* Description: Obtain original fd information
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*
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* Val carries the pid and fd information.
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* The original fd information is stored in low bit of val.
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* The pid information is stored in the high bit of val.
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* For ease of understanding, let's give an example where
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* the following information is represented in 32-bit binary format
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*
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* val 00000000 00000000 01010101 10001010
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* fd 00000000 00000000 00000000 10001010
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* pid 00000000 00000000 00000000 01010101
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*
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* In this function, we also check if the pid information is correct.
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* If there is an error, it will panic.
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*
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* Input Parameters:
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* val - this val carrying pid and original fd information
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*
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* Returned Value: none
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*
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****************************************************************************/
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int fdcheck_restore(int val)
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{
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int pid_expect;
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int pid_now;
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int ppid_now;
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if (val <= 2)
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{
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return val;
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}
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pid_expect = (val >> PID_SHIFT);
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pid_now = (_SCHED_GETPID() & PID_MASK);
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ppid_now = (_SCHED_GETPPID() & PID_MASK);
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if (pid_expect != pid_now && pid_expect != ppid_now && pid_expect != 0)
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{
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ferr("pid_expect %d pid_now %d ppid_now %d\n",
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pid_expect, pid_now, ppid_now);
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PANIC();
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}
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return val & FD_MASK;
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}
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/****************************************************************************
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* Name: fdcheck_protect
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*
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* Description: Obtain the combined value of fd and pid
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*
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* the return value carries the pid and fd information.
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* The original fd information is stored in low bit of val.
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* The pid information is stored in high bit of val.
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* For ease of understanding, let's give an example where
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* the following information is represented in 32-bit binary format
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*
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* fd 00000000 00000000 00000000 10001010
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* pid 00000000 00000000 00000000 01010101
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* val 00000000 00000000 01010101 10001010
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*
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* Input Parameters:
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* fd - original fd
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*
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* Returned Value: the combined value of fd and pid
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*
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****************************************************************************/
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int fdcheck_protect(int fd)
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{
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if (fd <= 2)
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{
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return fd;
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}
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return (fd & FD_MASK) | ((_SCHED_GETPID() & PID_MASK) << PID_SHIFT);
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}
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#endif
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