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Syscall Used by fopen()

Question Text​

Use strace to determine the syscall called by fopen() to access the file. Which one is it?

Question Answers​

  • read()
  • openat()

  • write()

  • fstat()

Feedback​

student@os:~/.../lab/support/simple-file-handling$ strace ./file_operations
[...]
openat(AT_FDCWD, "file.txt", O_RDONLY)  = 3
fstat(3, {st_mode=S_IFREG|0664, st_size=11, ...}) = 0
read(3, "C was here!", 4096)            = 11
[...]

So fopen()'s (main) underlying syscall is openat().