X-Recipient: archive-cygwin AT delorie DOT com X-SWARE-Spam-Status: No, hits=1.6 required=5.0 tests=AWL,BAYES_00,BOTNET,KHOP_THREADED,RCVD_IN_DNSWL_NONE,RCVD_IN_HOSTKARMA_NO,RCVD_IN_HOSTKARMA_YE,TW_RW X-Spam-Check-By: sourceware.org MIME-version: 1.0 Content-transfer-encoding: 8BIT Content-type: text/plain; charset=UTF-8; format=flowed Message-id: <4F91A392.7070108@cygwin.com> Date: Fri, 20 Apr 2012 13:57:38 -0400 From: "Larry Hall (Cygwin)" Reply-to: cygwin AT cygwin DOT com User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:11.0) Gecko/20120327 Thunderbird/11.0.1 To: cygwin AT cygwin DOT com Subject: Re: Why /usr/bin/*.dll must be executable? References: <4F915E65 DOT 8070608 AT gmail DOT com> <4F918C2A DOT 2080300 AT gmail DOT com> <20120420162718 DOT GK22155 AT calimero DOT vinschen DOT de> <4F919DA6 DOT 7000700 AT gmail DOT com> <4F919F9C DOT 1080307 AT cygwin DOT com> <4F91A11C DOT 5000300 AT gmail DOT com> In-reply-to: <4F91A11C.5000300@gmail.com> Mailing-List: contact cygwin-help AT cygwin DOT com; run by ezmlm List-Id: List-Subscribe: List-Archive: List-Post: List-Help: , Sender: cygwin-owner AT cygwin DOT com Mail-Followup-To: cygwin AT cygwin DOT com Delivered-To: mailing list cygwin AT cygwin DOT com On 4/20/2012 1:47 PM, De-Jian Zhao wrote: > On 2012-4-21 1:40, Larry Hall (Cygwin) wrote: >> On 4/20/2012 1:32 PM, De-Jian Zhao wrote: >>> On 2012-4-21 0:27, Corinna Vinschen wrote: >>>> On Apr 21 00:17, De-Jian Zhao wrote: >>>>> On 2012-4-20 21:07, Václav Zeman wrote: >>>>>> On 20 April 2012 15:02, De-Jian Zhao wrote: >>>>>>> Hi, >>>>>>> >>>>>>> When I type "cyg" and Tab, many executables starting with "cyg" are >>>>>>> listed >>>>>>> (Display all 262 possibilities? (y or n) y). I find that many of them >>>>>>> are >>>>>>> *.dll libraries under /usr/bin/. This is inconvenient to find the real >>>>>>> executable applications (*.exe). Since *.dll files are only libraries, >>>>>>> they >>>>>>> are not necessary to have the attribute of "x". Thus, I run the command >>>>>>> "chmod a-x /usr/bin/*.dll". Unexpectedly, cygwin is corrupted. I closed >>>>>>> the >>>>>>> terminal and failed to restart Cygwin. I started my older version of >>>>>>> Cygwin >>>>>>> (I did not deleted it after installing a new version), and added "x" to >>>>>>> the >>>>>>> previous *.dll files. The dead Cygwin revived. >>>>>>> >>>>>>> I am confused why /usr/bin/*.dll should be executable. I thought they >>>>>>> were >>>>>>> only library files. When I tried to run a dll file, bash says "cannot >>>>>>> execute binary file". Are there some hidden stories? >>>>>> DLLs are executables thus they need the +x bit. This is a Windows thing. >>>>>> >>>>> If this is a windows thing, removing the x bit should not affect >>>>> Cygwin. Instead, Cygwin is corrupted after removing the x bit. >>>> Windows requires the x bit for DLLs to be loadable as executable code >>>> into the address space of a process. As Václav wrote, it's a Windows >>>> thing. >>> >>> Can Windows see the rwx bits assigned by Cygwin to the files? I tried >>> removing the x bit of an executable file blastall.exe (chmod a-x >>> blastall.exe); the file can not be executed under Cygwin, but still can be >>> executed under cmd console of Windows. It seems that Windows does not honor >>> the rwx bits assigned by Cygwin. >>> >>> Is there a detailed description of the starting process of Cygwin system? >>> Or, how does Cygwin interact with *.dll files? >>> >>> After starting Cygwin, I ran "chmod a-x /usr/bin/cygperl5_10.dll" and perl >>> could not be started any more. This could be cured by ran "chmod a+x >>> /usr/bin/cygperl5_10.dll". It seems to me that the Cygwin binary executables >>> will communicate with their corresponding *.dll files when executed. The >>> *.dll provide the required functions and subroutines and that's enough. >>> There is no need to mark *.dll with an x bit. >>> >>> I have no strong background of computer science. Maybe there is some basic >>> knowledge beyond my imagination. Hope you can help disclose it to me. >>> Thanks. >> >> Cygwin DLLs are no different than native Windows DLLs when it comes to >> loading them. The Windows loader is responsible for loading them. So >> we're stuck with whatever restrictions the Windows loader imposes on >> Windows apps. >> > > Yes. But does Windows loader can see the x bit assigned by Cygwin, a quite > different OS? Cygwin is not an O/S. The basis for Cygwin is the emulation _DLL_, cygwin1.dll. Cygwin executables and DLLs are Windows binaries, subject to whatever limitations the Windows loader has. That's it. If you're not happy about that, you should complain to MS about it. -- Larry _____________________________________________________________________ A: Yes. > Q: Are you sure? >> A: Because it reverses the logical flow of conversation. >>> Q: Why is top posting annoying in email? -- Problem reports: http://cygwin.com/problems.html FAQ: http://cygwin.com/faq/ Documentation: http://cygwin.com/docs.html Unsubscribe info: http://cygwin.com/ml/#unsubscribe-simple