libsmbclient - Thread Saftey
Derrell Lipman
derrell.lipman at unwireduniverse.com
Sat Oct 4 01:49:10 GMT 2008
On Fri, Oct 3, 2008 at 9:15 PM, David Collier-Brown <davecb at sun.com> wrote:
> Ok, in GIT/v4-0-test/examples/libsmbclient there is a copy of smbclient,
> so I reran port on it instead, and indeed found some additional
> and/or differnt data.
>
Ok, well it's good to see that all of these that you found are in test
programs or in smbwrapper which is an example application that uses
libsmbclient. None of these are in the libsmbclient library code, so that's
good. However, I'm still not sure what code you're looking at since I don't
see a top-level examples directory in my git tree for v4-0-test, and no
smbclient directory anyplace in the tree:
{dworkin} /home/derrell/=/samba.git/samba4 ---> git branch
* v4-0-test
{dworkin} /home/derrell/=/samba.git/samba4 ---> find . -name examples -print
./source/lib/ldb/examples
./source/lib/zlib/examples
./source/lib/netapi/examples
./source/scripting/python/examples
{dworkin} /home/derrell/=/samba.git/samba4 ---> find . -name '*smbclient*'
-print
./source/bin/smbclient
./source/pkgconfig/smbclient.pc
./source/client/tests/test_smbclient.sh
{dworkin} /home/derrell/=/samba.git/samba4 --->
libsmbclient is current in branch v3-2-test in source/libsmb, and in branch
master insource3/libsmb.
What utility are you running to generate this report? It looks like a
useful tool to have available...
Derrell
lib
> froggy> more mtcheck.report
> ctermid - generate path name for controlling terminal
> MT-Level: The ctermid() function is unsafe in multithreaded
> applications.
> The ctermid_r() function is MT-Safe, and should be used
> instead. When compiling multithreaded applications, the
> _REENTRANT flag must be defined on the compile line. This
> flag should be used only
> with multithreaded applications.
>
> Found in:
> "/opt/csw/gcc3/lib/gcc/sparc-sun-solaris2.8/3.4.5/include/stdio.h",
> 284:
>
> ctime - convert date and time to string
> MT-Level: MT-Safe with exceptions
> use ctime_r
>
> Found in:
> "./testsmbc.c",
> 254:
> 257:
> "./tree.c",
> 285:
>
> getopt - get option letter from argument vector
> MT-Level: MT-Unsafe
>
> Found in:
> "./smbwrapper/smbsh.c",
> 66:
> "/opt/csw/gcc3/lib/gcc/sparc-sun-solaris2.8/3.4.5/include/stdio.h",
> 319:
>
> getpass - read a string of characters without echo
> MT-Level: MT-Unsafe
>
> Found in:
> "./smbwrapper/smbsh.c",
> 119:
>
>
> pclose - initiate a pipe to or from a process
> MT-Level: MT-Unsafe
>
> Found in:
> "/opt/csw/gcc3/lib/gcc/sparc-sun-solaris2.8/3.4.5/include/stdio.h",
> 311:
>
> popen - initiate a pipe to or from a process
> MT-Level: MT-Unsafe
>
> Found in:
> "/opt/csw/gcc3/lib/gcc/sparc-sun-solaris2.8/3.4.5/include/stdio.h",
> 309:
>
> readdir - read directory
> MT-Level: When compiling multithreaded programs, see Intro 3 , Notes
> On Multithreaded Applications . The readdir() function is unsafe in
> multithreaded applications. The readdir_r() function is safe, and
> should be used instead.
>
> Found in:
> "./smbwrapper/opendir_smbsh.c",
> 36:
> "./smbwrapper/wrapper.c",
> 1209:
> 311:
>
> popen - initiate a pipe to or from a process
> MT-Level: MT-Unsafe
>
> Found in:
> "/opt/csw/gcc3/lib/gcc/sparc-sun-solaris2.8/3.4.5/include/stdio.h",
> 309:
>
> readdir - read directory
> MT-Level: When compiling multithreaded programs, see Intro 3 , Notes
> On Multithreaded Applications . The readdir() function is unsafe in
> multithreaded applications. The readdir_r() function is safe, and
> should be used instead.
>
> Found in:
> "./smbwrapper/opendir_smbsh.c",
> 36:
> "./smbwrapper/wrapper.c",
> 1209:
> 1222: NC
> "./smbwrapper/wrapper.h",
> 132:
>
> --dave
>
>
>
> David Collier-Brown wrote:
>
>> I did a scan from a copy of v4-0-test after a git-fetch. I'll clean my
>> directory and refetch it and 3.2-test, unless there is
>> a specific tree I should use...
>>
>> --dave
>>
>> Derrell Lipman wrote:
>>
>> On Fri, Oct 3, 2008 at 5:40 PM, David Collier-Brown <davec-b at rogers.com<mailto:
>>> davec-b at rogers.com>> wrote:
>>>
>>> I did a check for MT-safe versus merely async-signal-safe functions
>>> in
>>> the samba4 libsmbclient, and found a number that need attention:
>>>
>>>
>>> Hi David, thanks for reporting these!
>>>
>>> I'm not sure which libsmbclient you're basing this on. There is no
>>> libsmbclient in samba4 unless it's something ancient from the early days of
>>> samba4, and I can't find any calls to getpass -- one of the issues you raise
>>> -- anyplace in samba3 (master) libsmb_*.c. I did find one call to it in
>>> clidfs.c but I'm not sure if/when that's called by libsmbclient code.
>>>
>>> Please let me know what source tree you were looking at in locating
>>> these. I'm going to create a bug report to keep track of these things so
>>> that I can fix them when I have some time.
>>>
>>> Thanks again,
>>>
>>> Derrell
>>>
>>>
>>>
>>> 1) The MT-safe (or unsafe!) ones were:
>>>
>>> atof - convert string to double-precision number
>>> MT-Level: MT-Safe as long as setlocale(3C) is not
>>> called to change the locale.
>>>
>>> Found in:
>>> "./libsmbclient.c",
>>> 4697: 4730:
>>> ctime - convert date and time to string
>>> MT-Level: MT-Safe , but note that the return values for
>>> asctime(), ctime(), gmtime(), and
>>> localtime() point to thread-specific data whose content is
>>> overwritten by each call by the same thread.
>>>
>>> Found in:
>>> "./libsmbclient.c",
>>> 4044: 4050: getpass - read a string of characters
>>> without echo
>>> MT-Level: MT-Unsafe
>>> This one needs a buffer and a semaphore to protect it,
>>> and make it, in effect, a getpass_r
>>> Found in:
>>> "./clidfs.c",
>>> 203: inet_ntoa - Internet address manipulation
>>> MT-Level: MT-Unsafe, static buffer is overwritten on
>>> each call. Linux and Solaris *may* make this per-thread
>>> of the compiler is told to generate MT code...
>>>
>>> Found in:
>>> "./namequery.c",
>>> 716: 723: 1083: "./nmblib.c",
>>> 112: 802: 824: 839: readdir -
>>> read directory
>>> The readdir() function is unsafe in
>>> multithreaded applications. The readdir_r() function is safe, and
>>> should be used instead.
>>> Found in:
>>> "./libsmb_compat.c",
>>> 256: 2) The merely Async-Signal-Safe ones follow: as the
>>> change something
>>> external,
>>> two competing threads can fight over the results. If you really need
>>> to protect these, you need a semaphore that's visible to all callers
>>> of the library. In general, that's too much work for too little
>>> value (;-))
>>>
>>> chmod - change access permission mode of file
>>> close - close a file descriptor
>>> creat - create a new file or rewrite an existing one
>>> fstat - get file status
>>> geteuid - get real user, effective user, real group, and effective
>>> group IDs
>>> getuid - get real user, effective user, real group, and effective
>>> group IDs
>>> kill - send a signal to a process or a group of processes
>>> lseek - move read/write file pointer
>>> mkdir - make a directory
>>> open - open a file
>>> read - read from file
>>> rename - change the name of a file
>>> rmdir - remove a directory
>>> stat - get file status
>>> time - get time
>>> unlink - remove directory entry
>>> write - write on a file
>>>
>>> --dave
>>>
>>>
>>>
>>>
>>>
>>> Jeremy Allison wrote:
>>>
>>> On Fri, Oct 03, 2008 at 10:46:14AM -0400, Derrell Lipman wrote:
>>>
>>> On Fri, Oct 3, 2008 at 10:14 AM, Pane, Chris
>>> <cpane at vanteon.com <mailto:cpane at vanteon.com>> wrote:
>>>
>>>
>>> I have been using libsmbclient to do some smb share
>>> browsing in an
>>> application. I have read that it is currently not thread
>>> safe in samba-3.x.
>>> Anyone know if there are plans for it to be made
>>> thread-safe in samba4?
>>>
>>>
>>>
>>> Hi Chris,
>>>
>>> I believe I've eliminated all non-thread-safe issues from
>>> within
>>> libsmbclient itself (although that will require a thorough
>>> inspection to
>>> confirm), but the core functions within samba that
>>> libsmbclient calls have
>>> not been thread-safe. Samba4 interfaces are, I think,
>>> inherently
>>> thread-safe. Therefore, although no work has begun yet on
>>> creating a samba4
>>> version of libsmbclient (and it's not yet scheduled), I
>>> don't believe
>>> there's any reason why a samba4 libsmbclient can't or won't
>>> be thread-safe.
>>>
>>>
>>>
>>> The easiest thing to do at the moment is wrap the libsmbclient
>>> functions in a mutex. I'm looking at making the underlying
>>> functions thread safe, but that's a longer term job.
>>>
>>> Jeremy.
>>>
>>>
>>> -- David Collier-Brown, | Always do right. This will
>>> gratify
>>> System Programmer and Author | some people and astonish the rest
>>> davecb at spamcop.net <mailto:davecb at spamcop.net> |
>>> -- Mark Twain
>>> (416) 223-5943
>>>
>>>
>>>
>>
> --
> David Collier-Brown | Always do right. This will gratify
> Sun Microsystems, Toronto | some people and astonish the rest
> davecb at sun.com | -- Mark Twain
> cell: (647) 833-9377, bridge: (877) 385-4099 code: 506 9191#
>
More information about the samba-technical
mailing list