security study guide

function:View man page, command mode, put the cursor on the function name, press "K" can directly see man page.Several settings:: Set NU Displays line number: Set AI automatically indents rows: Set ts=4 sets a TAB key equal to several spacesTo move the cursor:[[Go to Previous ' {' in first column]]] to go to the next "{" In the first column{Go to previous empty row} go to the next empty lineGD goes to the definition of the local variable referred to by the current cursor20135234 Ma Qiyang-—— In

autowrite(aw) set AutoArchive, default not open Enter or in command line :set background=dark mode light , set the background style Command line mode input :set backup(bk) set automatic backup, default not open Command line mode input : set cindent(cin) set C language style indent 3.Linux System Programming(1) Use of GCCcompiler use of GCC Second, the problems encountered and sentiment:Early groping vim time with too much, followed the tutorial done two times, think some instru

networks, graphical interface systems (X window), and Linux also attracted many industry concerns. Some small companies developed and distributed Linux, and dozens of Linux user communities were established. In the 1994, Linux magazine also began to release.Compared to Windows, Linux is free, the platform is more secure, mostly open source free software, users can modify the customization and redistribution, but some software quality and experience is deficient, but can be customized, more free

values③ floating-Point arithmetic: addition: does not have the binding law, satisfies the monotonicityFloating-point numbers for ④c languages: float, doubleProblems encountered:There are some areas where the overflow is not clear.Do not know abelian group is the Exchange group, forgotten the concept of exchange group and nature, through Baidu re-familiar with the previous knowledge.The operator is not familiar with the formula, do not know whether the need for memory, hope that in the future wi

-feeling bad, read a lot of confusion, code execution is also less. This week's code package gives me a good chance to practice understanding! So I just took the code out of the video in handy. The feeling learned a lot of content. In particular, the function of fork such functions are in the execution of the code to feel its principle. It was really touching when I finished it!!!Because there is also a recent project of this course, the internet also searched a lot of communication between the

1234 AOKHLKAdrIns Normal operationProcessor execution Halt instructionsIllegal address encounteredEncounter illegal instructions 4.2 Logic Design and seal Control Language HCl4.2.1 Logic GateAnd,or,not,| |,!4.2.2 Combination Circuit and HCl Boolean expressionBy combining a lot of logic gates into a network, you can form a computational block called a combinational circuit.Multiplexer: According to the value of the input control model, choose a different set o

any timing or control. This is a reasonable assumption for smaller memory (such as a register file), and for larger circuits, a special clock circuit can be used to simulate this effect. Since instruction memory is used only for reading instructions, we can consider this unit as a combinatorial logic.4 Implementation of the SEQ phaseThe register file has four ports, it supports simultaneous two reads (on ports A and B) and two writes (on Ports E and M). Each port has an address connection and a

expressed in the desired floating-point form.1. Rounding to even numbersRounds a number up or down so that the lowest effective number of the result is even.2. Rounding to 03. Rounding up4. Rounding Down34 you can see the upper bound.Rounding to even gets the closest match.4. Floating-point arithmeticFloating-point addition: exchangeable, non-associative, satisfying monotonicityFloating-point multiplication: exchangeable, non-associative, non-assignable, satisfies the following monotonicityFloa

, can be divided into three cases: condition One: Normalized value (when the Order field is not all 0 or(3) Rounding of floating-point numbersThere are four scenarios: rounding to even numbers (default), rounding to 0, rounding down, rounding up.(4) floating point arithmeticFloating-point addition: does not satisfy the binding, satisfies the monotonic floating-point multiplication: does not satisfy the binding, satisfies the monotonicity, does not satisfy the distributive in the additionAll is 1

descriptor table entry OLDFD to the Descriptor table entry NEWFD, overwriting the previous contents of the Descriptor Sheet table entry newfd. If the NEWFD is already open, Dup2 will close NEWFD before copying the OLDFD.#include int dup2(int oldfd,int newfd);8 Standard I/OThe standard I/O library models an open file as a stream, which is a pointer to the structure of the file type.#include *stdin; /*标准输入，文件描述符为0*/extern FILE *stdout; /*标准输出，文件描述符为1*/extern FILE *stderr; /*标准错误，文件描述符为2*/A strea

shared. 10.7 redirectsI/O redirection: Use the DUP2 function:#include int dup2(int OIDFD,int newfd); Returns: a non-negative descriptor if successful, or1 if an error occurs10.8 Standard I/OStandard I/O library (LIBC): Advanced input-Output functions#include extern FILE *stdin;/* standard input, file descriptor 0*/ extern FILE *stdout;/* Standard output, file descriptor 1*/ extern file *STDERR;/* standard error, file descriptor 2*/ The standard I/O library m

function, which can be seen as a buffer version of the UNIX read function. When calling Rio_read requires reading n bytes, there are rp->rio_cnt unread bytes in the read buffer. If the buffer is empty, the read system function is called to fill the buffer. This read call is not an error if it receives an insufficient value, except that the read buffer is partially populated. Once the buffer is non-empty, Rio_read copies N and rp->rio_cnt from the read buffer to the user buffer, and returns the

document descriptor and stream buffer. To reduce system overhead.10.9 synthesis: What should be used I/O functionMost of the time, you can use standard I/O.Use the Rio function when using a network socket. You need to format the output, use the sprintf function to format a string, and then use Rio_writen to send it to the socket interface. Format the input, use Rio_readlineb to read a complete line of text, and then use scanf to extract the different fields from the line of text.Summary:The con

not many, mainly is mastering the process and its control function use, the signal sends the function, the reception function and the processing function. The most rewarding part of the learning process in this chapter is the understanding of the general concept of the process, which is learning the process scheduling mechanism recently, allowing me to supplement the vacancy on the process.Resources:"In-depth understanding of computer Systems" Chapter 8th, chapter 10th I/O redirectionPipe pipe:

, stack pointer, program counter, and general purpose register value. Each thread shares other parts of the process context with other threads. This includes the entire user virtual address space, which consists of read-only text (code), read-write data, heaps, and all shared library code and data regions. Threads also share the same set of open files. Registers are never shared.mapping variables to storageIn threaded C programs, variables are mapped to virtual storage according to their storage

between the WEB client and the server is a text-based application-level protocol called HTTP (hypertext Transfer Protocol, Hypertext Transfer Protocol). HTTP is a simple protocol. A WEB client (that is, a browser) opens an Internet connection to the server and requests some content. The server responds to the requested content, and then closes the connection. The browser reads the content and displays it on the screen.2. Web ContentEach content returned by the WEB server is associated with a fi

the screen output, the rest will be output to the redirected file.10:testsystem called the system functionHeader file: #include 11:waitdemo1Call the Wait function: header file: #include Define function: pid_t wait (int* status);Return value: Success returns the child process PID, the failure returns 1, the reason is stored in errno.Waitdemo2: Similar to Waitdemo1, the difference is that the end state value of the child process is printed in three parts.12:mkfifo function header file: #include d

0000 */low_7 = Child_status 0x7F; /* 0000 0000 0111 1111 */bit_7 = Child_status 0x80; /* 0000 0000 1000 0000 */printf ("status:exit=%d, sig=%d, core=%d\n", High_8, Low_7, bit_7);}int main (){int newpid;printf ("Before:mypid is%d\n", getpid ()); Number of processes?if ((Newpid = fork ()) = = =-1)Perror ("fork");else if (Newpid = = 0)Child_code (DELAY);ElseParent_code (NEWPID);} Testsystem #include int main (int argc, char *argv[]){System (argv[1]);System (argv[2]);return exit_suc

("fork");else if (Newpid = = 0)Child_code (DELAY);ElseParent_code (NEWPID);}Operation diagram:Shows that the wait function tells the parent process that the child process is the same as and ends with the arguments passed to the wait. When the parent process calls wait, an integer variable address is passed to the function, and the kernel saves the child process's exit state in the variable.V. Problems encountered and Solutions1. Virtual machine can not run, a virtual machine computer on the car

(1) Function definition: #include #include #include int open(char *filename, int flags, mode_t mode); (2) Parameter analysis: return value: Type int, returns a descriptor number, always the smallest descriptor that is not currently open in the process. If an error occurs, the return value is-1. FileName: File name Flags: Indicates how the process intends to access this file, the values that can be taken are shown below: O_RDONLY：只读 O_WRONLY：只写 O