Podcast
Questions and Answers
What is the primary role of the System Call Interface (SCI)?
What is the primary role of the System Call Interface (SCI)?
- Manages memory allocation for user programs.
- Acts as an intermediary, allowing programs to interact with the kernel without directly invoking system calls. (correct)
- Provides a direct pathway for user applications to access hardware components.
- Handles all network communication for the operating system.
User mode has direct access to hardware, while kernel mode does not.
User mode has direct access to hardware, while kernel mode does not.
False (B)
In assembly language, the syscall instruction is used to ______ a system call.
In assembly language, the syscall instruction is used to ______ a system call.
invoke
Which of the following statements is correct regarding the use of system calls?
Which of the following statements is correct regarding the use of system calls?
Match the following Windows system calls with their equivalent Unix system calls:
Match the following Windows system calls with their equivalent Unix system calls:
Explain the role of the C standard library in the context of system calls.
Explain the role of the C standard library in the context of system calls.
System calls are executed in user mode.
System calls are executed in user mode.
Which of the following is NOT a typical function of system calls?
Which of the following is NOT a typical function of system calls?
The fopen() function in C is an example of a library call that may eventually invoke the ______ system call.
The fopen() function in C is an example of a library call that may eventually invoke the ______ system call.
Which of the following is the correct order of steps when a user application invokes a system call?
Which of the following is the correct order of steps when a user application invokes a system call?
What is the purpose of the message_len equ $ - message line in the assembly language example?
What is the purpose of the message_len equ $ - message line in the assembly language example?
The Windows API provides a direct interface to system calls, bypassing the kernel.
The Windows API provides a direct interface to system calls, bypassing the kernel.
In the C standard library example, which function is responsible for writing data to a file?
In the C standard library example, which function is responsible for writing data to a file?
The CreateFile() function in Windows is analogous to the ______ system call in Unix-like operating systems.
The CreateFile() function in Windows is analogous to the ______ system call in Unix-like operating systems.
Which of the following system calls is used for terminating a process in UNIX?
Which of the following system calls is used for terminating a process in UNIX?
Why is it generally discouraged for user-level programs to directly execute system calls?
Why is it generally discouraged for user-level programs to directly execute system calls?
System calls are architecture-independent, meaning the same system call will always have the same implementation across different operating systems.
System calls are architecture-independent, meaning the same system call will always have the same implementation across different operating systems.
Which of the following actions requires a system call?
Which of the following actions requires a system call?
In the assembly code example, the mov rax, 1 instruction sets the system call number for ______.
In the assembly code example, the mov rax, 1 instruction sets the system call number for ______.
Match the Windows function with its description.
Match the Windows function with its description.
Flashcards
System Call Interface (SCI)
System Call Interface (SCI)
An API provided by operating systems that allows programs to interact with the kernel.
System Call
System Call
A programming interface that allows a user-level process to request services from the kernel
sys_write
sys_write
A system call to output data to the console or a file. Requires specifying the file descriptor, message and the message length.
sys_exit
sys_exit
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Standard C library
Standard C library
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CreateProcess() vs fork()
CreateProcess() vs fork()
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ExitProcess() vs exit()
ExitProcess() vs exit()
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WaitForSingleObject() vs wait()
WaitForSingleObject() vs wait()
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CreateFile() vs open()
CreateFile() vs open()
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ReadFile() vs read()
ReadFile() vs read()
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WriteFile() vs write()
WriteFile() vs write()
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CloseHandle() vs close()
CloseHandle() vs close()
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Study Notes
- System calls allow user applications to interact with the kernel.
- Assembly-language instructions use
syscallto invoke system calls.
Assembly example:
raxholds the system call number.rdiis the file descriptor.rsipoints to the message.rdxis the message length.- Sys_write writes to standard output.
- Sys_exit terminates the program.
C Standard example:
- A C program can use standard library functions like
fopen,printf,freadetc. fopenopens a file.printfprints to the console.freadreads data.fclosecloses a file.
System Call Interface (SCI)
- The System Call Interface (SCI) is the API provided by operating systems to allow programs to interact with the kernel directly.
- Examples: Windows API and POSIX API.
- The standard C library provides a portion of the system-call interface for many versions of UNIX and Linux.
- The C library intercepts the
printf()call and invokes thewrite()system call, then passes the value returned bywrite()back to the program.
Windows and UNIX System Calls
- Windows CreateProcess() is equivalent to Unix fork().
- Windows ExitProcess() is equivalent to Unix exit().
- Windows WaitForSingleObject() is equivalent to Unix wait().
- Windows CreateFile() is equivalent to Unix open().
- Windows ReadFile() is equivalent to Unix read().
- Windows WriteFile() is equivalent to Unix write().
- Windows CloseHandle() is equivalent to Unix close().
- Windows SetConsoleMode() is equivalent to Unix ioctl().
- Windows ReadConsole() is equivalent to Unix read().
- Windows WriteConsole() is equivalent to Unix write().
- Windows GetCurrentProcessID() is equivalent to Unix getpid().
- Windows SetTimer() is equivalent to Unix alarm().
- Windows Sleep() is equivalent to Unix sleep().
- Windows CreatePipe() is equivalent to Unix pipe().
- Windows CreateFileMapping() is equivalent to Unix shm_open().
- Windows MapViewOfFile() is equivalent to Unix mmap().
- Windows SetFileSecurity() is equivalent to Unix chmod().
- Windows InitializeSecurityDescriptor() is equivalent to Unix umask().
- Windows SetSecurityDescriptorGroup() is equivalent to Unix chown().
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