sbrk system call in unix
I studied like malloc uses the sbrk system call. But, some one says, the sbrk is deprecated one. Now a days malloc using the mmap2 system call to allocate memory. So, Is there any commands like (ls,cat, grep, sed) using the sbrk system call. For Ex:
mohanraj@ltsp63:~/Development/chap8$ strace -c ls
a.out files flush.c fopen.c ld.c lld.c malloc.c opendir1.c t2.c t3.c t.c test.c
% time seconds usecs/call calls errors syscall
------ ----------- ----------- --------- --------- ----------------
-nan 0.000000 0 12 read
-nan 0.000000 0 1 write
-nan 0.000000 0 13 open
-nan 0.000000 0 16 close
-nan 0.000000 0 1 execve
-nan 0.000000 0 1 time
-nan 0.000000 0 9 8 access
-nan 0.000000 0 3 brk
-nan 0.000000 0 3 ioctl
-nan 0.000000 0 1 readlink
-nan 0.000000 0 5 munmap
-nan 0.000000 0 1 uname
-nan 0.000000 0 11 mprotect
-nan 0.000000 0 1 _llseek
-nan 0.000000 0 1 getsid
-nan 0.000000 0 2 rt_sigaction
-nan 0.000000 0 1 rt_sigprocmask
-nan 0.000000 0 1 getcwd
-nan 0.000000 0 1 getrlimit
-nan 0.000000 0 28 mmap2
-nan 0.000000 0 1 stat64
-nan 0.000000 0 16 fstat64
-nan 0.000000 0 1 getuid32
-nan 0.000000 0 2 getdents64
-nan 0.000000 0 1 1 futex
-nan 0.000000 0 1 set_thread_area
-nan 0.000000 0 1 set_tid_address
-nan 0.000000 0 1 statfs64
-nan 0.000000 0 1 openat
-nan 0.000000 0 1 set_robust_list
-nan 0.000000 0 1 socket
-nan 0.000000 0 1 connect
-nan 0.000000 0 1 send
------ ----------- ----------- --------- --------- ----------------
100.00 0.000000 141 9 total
mohanraj@ltsp63:~/Development/chap8$
The above output shows that the ls command using the above syscall to execute the output. Likewise any command using the sbrk system call, Is there any what is that?
Thanks in Advance.
sbrk is not a system call in linux. It's a library function implemented in libc which uses the brk system call. Your strace shows brk being used.
If in libc a malloc implementation is redirecited to mmap instead of sbrk . Then every call to malloc will result in mmap. And you can find sbrk only if it is explicitly used in user level application (normally malloc is used)
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