omhacks FTBFS: open O_CREAT needs 3 arguments

[Kamal Mostafa]

http://launchpadlibrarian.net/39017735/buildlog_ubuntu-lucid-i386.omhacks_0.8-1_FAILEDTOBUILD.txt.gz

cd /build/buildd/omhacks-0.8/obj-i486-linux-gnu/omhacks && /usr/bin/gcc -Domhacks_EXPORTS -g -O2 -fPIC -I/build/buildd/omhacks-0.8/omhacks/.. -Wall -Werror -o CMakeFiles/omhacks.dir/sysfs.c.o -c /build/buildd/omhacks-0.8/omhacks/sysfs.c
In file included from /usr/include/fcntl.h:205,
                 from /build/buildd/omhacks-0.8/omhacks/sysfs.c:28:
In function 'open',
    inlined from 'om_sysfs_writefile' at /build/buildd/omhacks-0.8/omhacks/sysfs.c:194:
/usr/include/bits/fcntl2.h:51: error: call to '__open_missing_mode' declared with attribute error: open with O_CREAT in second argument needs 3 arguments
make[3]: *** [omhacks/CMakeFiles/omhacks.dir/sysfs.c.o] Error 1

[Kamal Mostafa (kamalmostafa)]

Attached branch fixes the FTBFS by adding the required standard 3rd argument to the open-with-O_CREAT call. Patch has been forwarded to Debian.

[StefanPotyra (sistpoty)]

Hi,

patch looks good, but why do you set S_IWGRP|S_IWOTH? (looking at entries in /sys, these don't have group/others write permissions).

Cheers,
    Stefan.

[Kamal Mostafa (kamalmostafa)]

Hi Stefan-

The "mode" argument for open() with O_CREAT does not directly set the permissions of the file being created -- it just specifies the mode bits before modification by the process umask setting (see the open(2) man page). So enabling the read and write bits for all three 'classes' (user, group, and other) in the open() call allows the umask setting to control the permissions. The normal default umask (0022) will "strip away" the two permissions bits you questioned (group-write and other-write), so newly created files actually *will* get created with the permissions "-rw-r--r--" you're expecting... Unless, that is, the user has explicitly set their umask to something else, (say 0002, to allow other members of their group write-access to their files) in which case that same open() call will create a file with "-rw-rw-r--" which is just what the use wanted.

Specifying all six of the read/write user/group/other mode bits is the standard way to address source code which omits it.

[Launchpad Janitor (janitor)]

This bug was fixed in the package omhacks - 0.8-1ubuntu1

---------------
omhacks (0.8-1ubuntu1) lucid; urgency=low

  * Fix FTBFS: sysfs.c open with O_CREAT needs 3 arguments (LP: #521164)
 -- Kamal Mostafa <email address hidden> Fri, 12 Feb 2010 12:40:17 -0800