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Top Forums Programming System calls and C language low-level qualities??? Post 302622555 by gabam on Thursday 12th of April 2012 10:21:20 AM
Old 04-12-2012
System calls and C language low-level qualities???

Hi friends,
I hope everyone is fine and doing well. I queried in my previous thread about the low-level qualities of C/C++ languages.I really thank you people for explaining, it was really helpful. One more ambiquity that I have in my mind is regarding the unix system calls like open, creat, write, read etc. The system calls that I have mentioned are all used for file manipulation. We also have functions like fopen, fclose in C language for the same purpose. Java, C++/C# also provide classes for file manipulation. Could you please tell me what is the difference between handling files using system calls in c language, and java/C++/C# classes and c functions like fopen etc. Isn't it that the system calls are one of the low-level properties of c language. And is it right to say that Java/C# depend on c language system calls to do their file manipulation jobs, that's why they are considered high-level languages. Unix operating systems provide different system calls, is it possible to use those system calls from languages other than C. Please don't think that I am posting some kind of homework etc, I just want to learn. One more thing which I need your guidance for, I have the intention to build a disk defragmenting and disk filesystem checking software someday. I got know from my previous post, thanks to you people, that these types of software are written in C/C++. Coud you please guide me to some direction i.e. books, source code or anything else, which would help me build such a software. I am looking forward to your wonderful replies.

Thanks in advance!
 

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SGETMASK(2)						     Linux Programmer's Manual						       SGETMASK(2)

NAME
sgetmask, ssetmask - manipulation of signal mask (obsolete) SYNOPSIS
long sgetmask(void); long ssetmask(long newmask); Note: There are no glibc wrappers for these system calls; see NOTES. DESCRIPTION
These system calls are obsolete. Do not use them; use sigprocmask(2) instead. sgetmask() returns the signal mask of the calling process. ssetmask() sets the signal mask of the calling process to the value given in newmask. The previous signal mask is returned. The signal masks dealt with by these two system calls are plain bit masks (unlike the sigset_t used by sigprocmask(2)); use sigmask(3) to create and inspect these masks. RETURN VALUE
sgetmask() always successfully returns the signal mask. ssetmask() always succeeds, and returns the previous signal mask. ERRORS
These system calls always succeed. VERSIONS
Since Linux 3.16, support for these system calls is optional, depending on whether the kernel was built with the CONFIG_SGETMASK_SYSCALL option. CONFORMING TO
These system calls are Linux-specific. NOTES
Glibc does not provide wrappers for these obsolete system calls; in the unlikely event that you want to call them, use syscall(2). These system calls are unaware of signal numbers greater than 31 (i.e., real-time signals). These system calls do not exist on x86-64. It is not possible to block SIGSTOP or SIGKILL. SEE ALSO
sigprocmask(2), signal(7) COLOPHON
This page is part of release 4.15 of the Linux man-pages project. A description of the project, information about reporting bugs, and the latest version of this page, can be found at https://www.kernel.org/doc/man-pages/. Linux 2017-09-15 SGETMASK(2)
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