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digitalmars.D.learn - Where is "open" in "core.sys.linux.unistd"?

reply rempas <rempas tutanota.com> writes:
The file can be found quickly 
[here](https://github.com/dlang/druntime/blob/master/src/core
sys/posix/unistd.d) or in your system if you want. Now the question is, why
isn't there an "open" function for the equivalent system call? "close",
"write", "read" etc. all exist. Anyone knows what's going on with open?
Jul 09 2021
next sibling parent reply rikki cattermole <rikki cattermole.co.nz> writes:
On 10/07/2021 2:51 AM, rempas wrote:

 The file can be found quickly 
 [here](https://github.com/dlang/druntime/blob/master/src/core
sys/posix/unistd.d) 
 or in your system if you want. Now the question is, why isn't there an 
 "open" function for the equivalent system call? "close", "write", "read" 
 etc. all exist. Anyone knows what's going on with open?


This is easily explained.

open is not declared to be defined in unist.h[0]

You may be wanting fopen from stdio.h[1]

Or open from fcntl.h[2]

[0] https://man7.org/linux/man-pages/man0/unistd.h.0p.html
[1] https://man7.org/linux/man-pages/man0/stdio.h.0p.html
[2] https://man7.org/linux/man-pages/man0/fcntl.h.0p.html
Jul 09 2021
parent rempas <rempas tutanota.com> writes:
On Friday, 9 July 2021 at 15:04:32 UTC, rikki cattermole wrote:

 On 10/07/2021 2:51 AM, rempas wrote:

 The file can be found quickly 
 [here](https://github.com/dlang/druntime/blob/master/src/core
sys/posix/unistd.d) or in your system if you want. Now the question is, why
isn't there an "open" function for the equivalent system call? "close",
"write", "read" etc. all exist. Anyone knows what's going on with open?


 This is easily explained.

 open is not declared to be defined in unist.h[0]

 You may be wanting fopen from stdio.h[1]

 Or open from fcntl.h[2]

 [0] https://man7.org/linux/man-pages/man0/unistd.h.0p.html
 [1] https://man7.org/linux/man-pages/man0/stdio.h.0p.html
 [2] https://man7.org/linux/man-pages/man0/fcntl.h.0p.html


Thanks man, have a nice day
Jul 09 2021
prev sibling parent reply Steven Schveighoffer <schveiguy gmail.com> writes:
On 7/9/21 10:51 AM, rempas wrote:

 The file can be found quickly 
 [here](https://github.com/dlang/druntime/blob/master/src/core
sys/posix/unistd.d) 
 or in your system if you want. Now the question is, why isn't there an 
 "open" function for the equivalent system call? "close", "write", "read" 
 etc. all exist. Anyone knows what's going on with open?


Because file descriptors are created in different ways.

For example, `open` exists for files 
[here](https://github.com/dlang/druntime/blob/master/src/core/sys/posix/fcntl.d)

But opening a socket is done via the `socket` system call 
[here](https://github.com/dlang/druntime/blob/master/src/core/sys/posix/sys/socket.d)

They don't take the same arguments (nor should they).

But reading/writing, closing these file descriptors is always the same.

-Steve
Jul 09 2021
next sibling parent reply Dennis <dkorpel gmail.com> writes:
On Friday, 9 July 2021 at 15:11:38 UTC, Steven Schveighoffer 
wrote:

 But reading/writing, closing these file descriptors is always 
 the same.


For sockets you'd typically use `recv` and `send` instead or 
`read` and `write` because the former give extra options and the 
latter don't work on Windows. But yeah, on Linux `read` and 
`write` should work universally among file descriptors.
Jul 09 2021
next sibling parent rempas <rempas tutanota.com> writes:
On Friday, 9 July 2021 at 15:31:50 UTC, Dennis wrote:

 On Friday, 9 July 2021 at 15:11:38 UTC, Steven Schveighoffer 
 wrote:

 But reading/writing, closing these file descriptors is always 
 the same.


 For sockets you'd typically use `recv` and `send` instead or 
 `read` and `write` because the former give extra options and 
 the latter don't work on Windows. But yeah, on Linux `read` and 
 `write` should work universally among file descriptors.


That's very important! Thanks a lot for the info!
Jul 09 2021
prev sibling parent Steven Schveighoffer <schveiguy gmail.com> writes:
On 7/9/21 11:31 AM, Dennis wrote:

 On Friday, 9 July 2021 at 15:11:38 UTC, Steven Schveighoffer wrote:

 But reading/writing, closing these file descriptors is always the same.


 
 For sockets you'd typically use `recv` and `send` instead or `read` and 
 `write` because the former give extra options and the latter don't work 
 on Windows. But yeah, on Linux `read` and `write` should work 
 universally among file descriptors.
 


I typically only use `send` and `recv` for for connectionless sockets. 
For TCP sockets, it's generally `read` and `write` for me (and it works 
fine).

Windows is a different story, they have different i/o routines for 
system calls (yes, there's the shims for Posix file descriptors, but I 
wouldn't use those anyway).

The larger point is that the reason `read`/`write` are separate from 
descriptor creation is because they are universal, while creation is not.

-Steve
Jul 09 2021
prev sibling parent reply rempas <rempas tutanota.com> writes:
On Friday, 9 July 2021 at 15:11:38 UTC, Steven Schveighoffer 
wrote:

 On 7/9/21 10:51 AM, rempas wrote:

 The file can be found quickly 
 [here](https://github.com/dlang/druntime/blob/master/src/core
sys/posix/unistd.d) or in your system if you want. Now the question is, why
isn't there an "open" function for the equivalent system call? "close",
"write", "read" etc. all exist. Anyone knows what's going on with open?


 Because file descriptors are created in different ways.

 For example, `open` exists for files 
 [here](https://github.com/dlang/druntime/blob/master/src/core/sys/posix/fcntl.d)

 But opening a socket is done via the `socket` system call 
 [here](https://github.com/dlang/druntime/blob/master/src/core/sys/posix/sys/socket.d)

 They don't take the same arguments (nor should they).

 But reading/writing, closing these file descriptors is always 
 the same.

 -Steve


If I tell you that I searched "fnctl" in the repo and didn't find 
anything will you believe me? Probably made a typo idk... Anyway 
thanks a lot your help and I wish you to have an amazing day!
Jul 09 2021
parent reply =?UTF-8?Q?Ali_=c3=87ehreli?= <acehreli yahoo.com> writes:
On 7/9/21 8:31 AM, rempas wrote:


 I searched "fnctl" in the repo [...] Probably made a typo


Yes, the typo should be obvious to the non-dyslexic among us. :)

fnctl <-- wrong
fcntl <-- correct

Ali
Jul 09 2021
parent rempas <rempas tutanota.com> writes:
On Friday, 9 July 2021 at 15:37:41 UTC, Ali Çehreli wrote:

 On 7/9/21 8:31 AM, rempas wrote:


 I searched "fnctl" in the repo [...] Probably made a typo


 Yes, the typo should be obvious to the non-dyslexic among us. :)

 fnctl <-- wrong
 fcntl <-- correct

 Ali


Lol, I'm not dyslexic (or at least I haven't find out) but still 
some times I just miss those small details. Its probably that in 
my mind, I never really noticed how it's typed in the first 
place. I thought "fn" then "ctl" for "control" so "function 
control" or something idk.... Anyway yeah nice catch ;)
Jul 09 2021