[Bug manual/27207] New: mount examples don't match the mount function signature

[Bug manual/27207] New: mount examples don't match the mount function signature

[john at mccabe dot org.uk]

https://sourceware.org/bugzilla/show_bug.cgi?id=27207

            Bug ID: 27207
           Summary: mount examples don't match the mount function
                    signature
           Product: glibc
           Version: 2.32
            Status: UNCONFIRMED
          Severity: normal
          Priority: P2
         Component: manual
          Assignee: unassigned at sourceware dot org
          Reporter: john at mccabe dot org.uk
                CC: mtk.manpages at gmail dot com
  Target Milestone: ---

In section 31.3.2, "Mount, Unmount, Remount", the signature of the mount
function is declared as:

  int mount (const char *special_file, const char *dir, const char *fstype,
unsigned long int options, const void *data)

Later in the documentation, the following examples are provided:

  Example:

    #include <sys/mount.h>

    mount("/dev/hdb", "/cdrom", MS_MGC_VAL | MS_RDONLY | MS_NOSUID, "");

    mount("/dev/hda2", "/mnt", MS_MGC_VAL | MS_REMOUNT, "");

Both of these examples have the options flags as the 3rd parameter, with an
empty string as the 4th. As these are MS_REMOUNT examples, it looks like the
4th parameter in the examples is meant to represent the filesystem type, so the
3rd and 4th parameters are the wrong way round.

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[Bug manual/27207] mount examples don't match the mount function signature

[john at mccabe dot org.uk]

https://sourceware.org/bugzilla/show_bug.cgi?id=27207

John McCabe <john at mccabe dot org.uk> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |john at mccabe dot org.uk

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[Bug manual/27207] mount examples don't match the mount function signature

[john at mccabe dot org.uk]

https://sourceware.org/bugzilla/show_bug.cgi?id=27207

--- Comment #1 from John McCabe <john at mccabe dot org.uk> ---
More details:

Contained in sysinfo.texi:

This section:

----
@smallexample
@group
#include <sys/mount.h>

mount("/dev/hdb", "/cdrom", MS_MGC_VAL | MS_RDONLY | MS_NOSUID, "");

mount("/dev/hda2", "/mnt", MS_MGC_VAL | MS_REMOUNT, "");

@end group
@end smallexample
----

Probably needs to change to:

----
@smallexample
@group
#include <sys/mount.h>

mount("/dev/hdb", "/cdrom",  "", MS_MGC_VAL | MS_RDONLY | MS_NOSUID);

mount("/dev/hda2", "/mnt", "", MS_MGC_VAL | MS_REMOUNT);

@end group
@end smallexample
----

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[Bug manual/27207] mount examples don't match the mount function signature

[mtk.manpages at gmail dot com]

https://sourceware.org/bugzilla/show_bug.cgi?id=27207

--- Comment #2 from Michael Kerrisk <mtk.manpages at gmail dot com> ---
I confirm this bug.

However, since mount(2) is not variadic, the change should probably be:

----
@smallexample
@group
#include <sys/mount.h>

mount("/dev/hdb", "/cdrom",  "", MS_MGC_VAL | MS_RDONLY | MS_NOSUID, NULL);

mount("/dev/hda2", "/mnt", "", MS_MGC_VAL | MS_REMOUNT, NULL);

@end group
@end smallexample
----

(That is, add the fifth argument in each call.)

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[Bug manual/27207] mount examples don't match the mount function signature

[john at mccabe dot org.uk]

https://sourceware.org/bugzilla/show_bug.cgi?id=27207

--- Comment #3 from John McCabe <john at mccabe dot org.uk> ---
Good call; that's correct!

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[Bug manual/27207] mount examples don't match the mount function signature

[john at mccabe dot org.uk]

https://sourceware.org/bugzilla/show_bug.cgi?id=27207

--- Comment #4 from John McCabe <john at mccabe dot org.uk> ---
Created attachment 13138
  --> https://sourceware.org/bugzilla/attachment.cgi?id=13138&action=edit
Proposed patch to fix it

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