[Bug 220273] New: syslog(2): conflict between "The symbolic names [...] are not exported to user space" and "Definition of SYSLOG_* constants"?

[Bug 220273] New: syslog(2): conflict between "The symbolic names [...] are not exported to user space" and "Definition of SYSLOG_* constants"?

[bugzilla-daemon]

https://bugzilla.kernel.org/show_bug.cgi?id=220273

            Bug ID: 220273
           Summary: syslog(2): conflict between "The symbolic names [...]
                    are not exported to user space" and "Definition of
                    SYSLOG_* constants"?
           Product: Documentation
           Version: unspecified
          Hardware: All
                OS: Linux
            Status: NEW
          Severity: normal
          Priority: P3
         Component: man-pages
          Assignee: documentation_man-pages@kernel-bugs.osdl.org
          Reporter: nathaniel@google.com
        Regression: No

Over at syslog(2) we see both

```
#include <sys/klog.h>        /* Definition of SYSLOG_* constants */
```

and

```
The symbolic names
are defined in the kernel source, but are not exported to user
space; you will either need to use the numbers, or define the
names yourself.
```

Is there a conflict between these two? After reading the first one I spent a
while trying to figure out why I wasn't able to use the constants in my code
despite having the include; only much later did I notice the second one.

If there's no conflict between the two, what might I be misunderstanding about
the first one?

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[Bug 220273] syslog(2): conflict between "The symbolic names [...] are not exported to user space" and "Definition of SYSLOG_* constants"?

[bugzilla-daemon]

https://bugzilla.kernel.org/show_bug.cgi?id=220273

--- Comment #1 from Alejandro Colomar (alx@kernel.org) ---
Hi Nathaniel,

On Thu, Jun 26, 2025 at 02:54:59PM +0000, bugzilla-daemon@kernel.org wrote:
> Over at syslog(2) we see both
> 
> ```
> #include <sys/klog.h>        /* Definition of SYSLOG_* constants */
> ```
> 
> and
> 
> ```
> The symbolic names
> are defined in the kernel source, but are not exported to user
> space; you will either need to use the numbers, or define the
> names yourself.
> ```
> 
> Is there a conflict between these two? After reading the first one I spent a
> while trying to figure out why I wasn't able to use the constants in my code
> despite having the include; only much later did I notice the second one.
> 
> If there's no conflict between the two, what might I be misunderstanding
> about
> the first one?

The first one is a mistake introduced by me.  Sorry!  I've fixed it with
this commit:

        commit 3d3ffae8774c89d9e0b099dba18441c459fec2c2
        Author: Alejandro Colomar <alx@kernel.org>
        Date:   Mon Aug 18 08:39:51 2025 +0200

            man/man2/syslog.2: SYNOPSIS: Remove incorrect include

            It doesn't provide any macros, as said later in the page.  The
            programmer must either define the macros itself, or use the raw
values.

            Fixes: e5a173829179 (2021-06-20; "syslog.2: Use syscall(SYS_...);
for raw system calls")
            Closes: <https://bugzilla.kernel.org/show_bug.cgi?id=220273>
            Reported-by: Nathaniel Manista <nathaniel@google.com>
            Signed-off-by: Alejandro Colomar <alx@kernel.org>

        diff --git a/man/man2/syslog.2 b/man/man2/syslog.2
        index ad15f4942..1b3ba8926 100644
        --- a/man/man2/syslog.2
        +++ b/man/man2/syslog.2
        @@ -12,7 +12,6 @@ .SH LIBRARY
         .RI ( libc ,\~ \-lc )
         .SH SYNOPSIS
         .nf
        -.BR "#include <sys/klog.h>" "        /* Definition of " SYSLOG_* "
constants */"
         .BR "#include <sys/syscall.h>" "     /* Definition of " SYS_* "
constants */"
         .B #include <unistd.h>
         .P


Thanks for the report!


Have a lovely day!
Alex

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