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  • Re-use aliased field in SQL SELECT STATEMENT

    - by Bad Display Name
    Hi, the question is hard to define without giving an example, e.g. I'd like to achieve something like this : SELECT (CASE WHEN ...) AS FieldA, 20 + FieldA AS FieldB FROM Tbl Assuming that by "..." I've replaced a long and complex CASE statement, hence I don't want to repeat it when selecting FieldB and use the aliased FieldA instead. IS THIS EVEN POSSIBLE? What could be a workaround? Note, that this will return multiple rows , hence the DECLARE/SET outside the SELECT statement is no good in my case. PLEASE HELP. P.S. I am using SQL 2008

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  • Redirecting http to https for a directory, via .htaccess, using mod_alias only

    - by Belinda
    I have the common problem of wanting to redirect requests for a certain restricted access directory from http to https, so that users' login credentials are sent in a secure way. However, I do not have mod_rewrite enabled on my server. I only have mod_alias. This means I have to use the RedirectMatch command. I can't use the usual solutions that use RewriteCond and RewriteRule. (A note on the politics: I am a small-fry subsite maintainer in a very large organisation, so the server admins are unlikely to be willing to change the server config for me!) The following line works, but forms an infinite loop (because the rewritten URL is still caught by the initial regular expression): RedirectMatch permanent ^/intranet(.*)$ https://example.com/intranet$1 One of my internal IT guys has suggested I avoid the infinite loop by moving the files to a new directory with a new name (eg /intranet2/). That seems pretty ugly to me. And people could still accidentally/deliberately revert to an insecure connection by visiting http://example.com/intranet2/ directly. Then I tried this, but it didn't work: RedirectMatch permanent ^http:(.*)/intranet(.*)$ https://example.com/intranet$1 I suspect it didn't work because the first argument must be a file path from the root directory, so it can't start with "http:". So: any better ideas how to do this?

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  • Is it possible to get anti-alias for Font in Rebol Graphics VID ?

    - by Rebol Tutorial
    Anti-alias works for Draw but I can't see how to get anti-alias for font : is it possible anywhow (including hacking rebol vid ...) because font in the picture generated below is not nice: view layout [ box 278x185 effect [ ; default box face size is 100x100 draw [ anti-alias on ; information for the next draw element (not required) line-width 2.5 ; number of pixels in width of the border pen black ; color of the edge of the next draw element fill-pen radial 100x50 5 55 5 10 10 71.0.6 30.10.10 71.0.6 ; the draw element box ; another box drawn as an effect 15 ; size of rounding in pixels 0x0 ; upper left corner 278x170 ; lower right corner ] ] pad 30x-150 Text "Experiment" font [name: "Impact" size: 24 color: white] image http://www.rebol.com/graphics/reb-logo.gif ]

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  • Ops Center 12c - Provisioning Solaris Using a Card-Based NIC

    - by scottdickson
    It's been a long time since last I added something here, but having some conversations this last week, I got inspired to update things. I've been spending a lot of time with Ops Center for managing and installing systems these days.  So, I suspect a number of my upcoming posts will be in that area. Today, I want to look at how to provision Solaris using Ops Center when your network is not connected to one of the built-in NICs.  We'll talk about how this can work for both Solaris 10 and Solaris 11, since they are pretty similar.  In both cases, WANboot is a key piece of the story. Here's what I want to do:  I have a Sun Fire T2000 server with a Quad-GbE nxge card installed.  The only network is connected to port 2 on that card rather than the built-in network interfaces.  I want to install Solaris on it across the network, either Solaris 10 or Solaris 11.  I have met with a lot of customers lately who have a similar architecture.  Usually, they have T4-4 servers with the network connected via 10GbE connections. Add to this mix the fact that I use Ops Center to manage the systems in my lab, so I really would like to add this to Ops Center.  If possible, I would like this to be completely hands free.  I can't quite do that yet. Close, but not quite. WANBoot or Old-Style NetBoot? When a system is installed from the network, it needs some help getting the process rolling.  It has to figure out what its network configuration (IP address, gateway, etc.) ought to be.  It needs to figure out what server is going to help it boot and install, and it needs the instructions for the installation.  There are two different ways to bootstrap an installation of Solaris on SPARC across the network.   The old way uses a broadcast of RARP or more recently DHCP to obtain the IP configuration and the rest of the information needed.  The second is to explicitly configure this information in the OBP and use WANBoot for installation WANBoot has a number of benefits over broadcast-based installation: it is not restricted to a single subnet; it does not require special DHCP configuration or DHCP helpers; it uses standard HTTP and HTTPS protocols which traverse firewalls much more easily than NFS-based package installation.  But, WANBoot is not available on really old hardware and WANBoot requires the use o Flash Archives in Solaris 10.  Still, for many people, this is a great approach. As it turns out, WANBoot is necessary if you plan to install using a NIC on a card rather than a built-in NIC. Identifying Which Network Interface to Use One of the trickiest aspects to this process, and the one that actually requires manual intervention to set up, is identifying how the OBP and Solaris refer to the NIC that we want to use to boot.  The OBP already has device aliases configured for the built-in NICs called net, net0, net1, net2, net3.  The device alias net typically points to net0 so that when you issue the command  "boot net -v install", it uses net0 for the boot.  Our task is to figure out the network instance for the NIC we want to use.  We will need to get to the OBP console of the system we want to install in order to figure out what the network should be called.  I will presume you know how to get to the ok prompt.  Once there, we have to see what networks the OBP sees and identify which one is associated with our NIC using the OBP command show-nets. SunOS Release 5.11 Version 11.0 64-bit Copyright (c) 1983, 2011, Oracle and/or its affiliates. All rights reserved. {4} ok banner Sun Fire T200, No Keyboard Copyright (c) 1998, 2010, Oracle and/or its affiliates. All rights reserved. OpenBoot 4.30.4.b, 32640 MB memory available, Serial #69057548. Ethernet address 0:14:4f:1d:bc:c, Host ID: 841dbc0c. {4} ok show-nets a) /pci@7c0/pci@0/pci@2/network@0,1 b) /pci@7c0/pci@0/pci@2/network@0 c) /pci@780/pci@0/pci@8/network@0,3 d) /pci@780/pci@0/pci@8/network@0,2 e) /pci@780/pci@0/pci@8/network@0,1 f) /pci@780/pci@0/pci@8/network@0 g) /pci@780/pci@0/pci@1/network@0,1 h) /pci@780/pci@0/pci@1/network@0 q) NO SELECTION Enter Selection, q to quit: d /pci@780/pci@0/pci@8/network@0,2 has been selected. Type ^Y ( Control-Y ) to insert it in the command line. e.g. ok nvalias mydev ^Y for creating devalias mydev for /pci@780/pci@0/pci@8/network@0,2 {4} ok devalias ... net3 /pci@7c0/pci@0/pci@2/network@0,1 net2 /pci@7c0/pci@0/pci@2/network@0 net1 /pci@780/pci@0/pci@1/network@0,1 net0 /pci@780/pci@0/pci@1/network@0 net /pci@780/pci@0/pci@1/network@0 ... name aliases By looking at the devalias and the show-nets output, we can see that our Quad-GbE card must be the device nodes starting with  /pci@780/pci@0/pci@8/network@0.  The cable for our network is plugged into the 3rd slot, so the device address for our network must be /pci@780/pci@0/pci@8/network@0,2. With that, we can create a device alias for our network interface.  Naming the device alias may take a little bit of trial and error, especially in Solaris 11 where the device alias seems to matter more with the new virtualized network stack. So far in my testing, since this is the "next" network interface to be used, I have found success in naming it net4, even though it's a NIC in the middle of a card that might, by rights, be called net6 (assuming the 0th interface on the card is the next interface identified by Solaris and this is the 3rd interface on the card).  So, we will call it net4.  We need to assign a device alias to it: {4} ok nvalias net4 /pci@780/pci@0/pci@8/network@0,2 {4} ok devalias net4 /pci@780/pci@0/pci@8/network@0,2 ... We also may need to have the MAC for this particular interface, so let's get it, too.  To do this, we go to the device and interrogate its properties. {4} ok cd /pci@780/pci@0/pci@8/network@0,2 {4} ok .properties assigned-addresses 82060210 00000000 03000000 00000000 01000000 82060218 00000000 00320000 00000000 00008000 82060220 00000000 00328000 00000000 00008000 82060230 00000000 00600000 00000000 00100000 local-mac-address 00 21 28 20 42 92 phy-type mif ... From this, we can see that the MAC for this interface is  00:21:28:20:42:92.  We will need this later. This is all we need to do at the OBP.  Now, we can configure Ops Center to use this interface. Network Boot in Solaris 10 Solaris 10 turns out to be a little simpler than Solaris 11 for this sort of a network boot.  Since WANBoot in Solaris 10 fetches a specified In order to install the system using Ops Center, it is necessary to create a OS Provisioning profile and its corresponding plan.  I am going to presume that you already know how to do this within Ops Center 12c and I will just cover the differences between a regular profile and a profile that can use an alternate interface. Create a OS Provisioning profile for Solaris 10 as usual.  However, when you specify the network resources for the primary network, click on the name of the NIC, probably GB_0, and rename it to GB_N/netN, where N is the instance number you used previously in creating the device alias.  This is where the trial and error may come into play.  You may need to try a few instance numbers before you, the OBP, and Solaris all agree on the instance number.  Mark this as the boot network. For Solaris 10, you ought to be able to then apply the OS Provisioning profile to the server and it should install using that interface.  And if you put your cards in the same slots and plug the networks into the same NICs, this profile is reusable across multiple servers. Why This Works If you watch the console as Solaris boots during the OSP process, Ops Center is going to look for the device alias netN.  Since WANBoot requires a device alias called just net, Ops Center uses the value of your netN device alias and assigns that device to the net alias.  That means that boot net will automatically use this device.  Very cool!  Here's a trace from the console as Ops Center provisions a server: Sun Sun Fire T200, No KeyboardCopyright (c) 1998, 2010, Oracle and/or its affiliates. All rights reserved.OpenBoot 4.30.4.b, 32640 MB memory available, Serial #69057548.Ethernet address 0:14:4f:1d:bc:c, Host ID: 841dbc0c.auto-boot? =            false{0} ok  {0} ok printenv network-boot-argumentsnetwork-boot-arguments =  host-ip=10.140.204.234,router-ip=10.140.204.1,subnet-mask=255.255.254.0,hostname=atl-sewr-52,client-id=0100144F1DBC0C,file=http://10.140.204.22:5555/cgi-bin/wanboot-cgi{0} ok {0} ok devalias net net                      /pci@780/pci@0/pci@1/network@0{0} ok devalias net4 net4                     /pci@780/pci@0/pci@8/network@0,2{0} ok devalias net /pci@780/pci@0/pci@8/network@0,2{0} ok setenv network-boot-arguments host-ip=10.140.204.234,router-ip=10.140.204.1,subnet-mask=255.255.254.0,hostname=atl-sewr-52,client-id=0100144F1DBC0C,file=http://10.140.204.22:8004/cgi-bin/wanboot-cginetwork-boot-arguments =  host-ip=10.140.204.234,router-ip=10.140.204.1,subnet-mask=255.255.254.0,hostname=atl-sewr-52,client-id=0100144F1DBC0C,file=http://10.140.204.22:8004/cgi-bin/wanboot-cgi{0} ok {0} ok boot net - installBoot device: /pci@780/pci@0/pci@8/network@0,2  File and args: - install/pci@780/pci@0/pci@8/network@0,2: 1000 Mbps link up<time unavailable> wanboot info: WAN boot messages->console<time unavailable> wanboot info: configuring /pci@780/pci@0/pci@8/network@0,2 See what happened?  Ops Center looked for the network device alias called net4 that we specified in the profile, took the value from it, and made it the net device alias for the boot.  Pretty cool! WANBoot and Solaris 11 Solaris 11 requires an additional step since the Automated Installer in Solaris 11 uses the MAC address of the network to figure out which manifest to use for system installation.  In order to make sure this is available, we have to take an extra step to associate the MAC of the NIC on the card with the host.  So, in addition to creating the device alias like we did above, we also have to declare to Ops Center that the host has this new MAC. Declaring the NIC Start out by discovering the hardware as usual.  Once you have discovered it, take a look under the Connectivity tab to see what networks it has discovered.  In the case of this system, it shows the 4 built-in networks, but not the networks on the additional cards.  These are not directly visible to the system controller.  In order to add the additional network interface to the hardware asset, it is necessary to Declare it.  We will declare that we have a server with this additional NIC, but we will also  specify the existing GB_0 network so that Ops Center can associate the right resources together.  The GB_0 acts as sort of a key to tie our new declaration to the old system already discovered.  Go to the Assets tab, select All Assets, and then in the Actions tab, select Add Asset.  Rather than going through a discovery this time, we will manually declare a new asset. When we declare it, we will give the hostname, IP address, system model that match those that have already been discovered.  Then, we will declare both GB_0 with its existing MAC and the new GB_4 with its MAC.  Remember that we collected the MAC for GB_4 when we created its device alias. After you declare the asset, you will see the new NIC in the connectivity tab for the asset.  You will notice that only the NICs you listed when you declared it are seen now.  If you want Ops Center to see all of the existing NICs as well as the additional one, declare them as well.  Add the other GB_1, GB_2, GB_3 links and their MACs just as you did GB_0 and GB_4.  Installing the OS  Once you have declared the asset, you can create an OS Provisioning profile for Solaris 11 in the same way that you did for Solaris 10.  The only difference from any other provisioning profile you might have created already is the network to use for installation.  Again, use GB_N/netN where N is the interface number you used for your device alias and in your declaration.  And away you go.  When the system boots from the network, the automated installer (AI) is able to see which system manifest to use, based on the new MAC that was associated, and the system gets installed. {0} ok {0} ok printenv network-boot-argumentsnetwork-boot-arguments =  host-ip=10.140.204.234,router-ip=10.140.204.1,subnet-mask=255.255.254.0,hostname=atl-sewr-52,client-id=01002128204292,file=http://10.140.204.22:5555/cgi-bin/wanboot-cgi{0} ok {0} ok devalias net net                      /pci@780/pci@0/pci@1/network@0{0} ok devalias net4 net4                     /pci@780/pci@0/pci@8/network@0,2{0} ok devalias net /pci@780/pci@0/pci@8/network@0,2{0} ok setenv network-boot-arguments host-ip=10.140.204.234,router-ip=10.140.204.1,subnet-mask=255.255.254.0,hostname=atl-sewr-52,client-id=01002128204292,file=http://10.140.204.22:5555/cgi-bin/wanboot-cginetwork-boot-arguments =  host-ip=10.140.204.234,router-ip=10.140.204.1,subnet-mask=255.255.254.0,hostname=atl-sewr-52,client-id=01002128204292,file=http://10.140.204.22:5555/cgi-bin/wanboot-cgi{0} ok {0} ok boot net - installBoot device: /pci@780/pci@0/pci@8/network@0,2  File and args: - install/pci@780/pci@0/pci@8/network@0,2: 1000 Mbps link up<time unavailable> wanboot info: WAN boot messages->console<time unavailable> wanboot info: configuring /pci@780/pci@0/pci@8/network@0,2...SunOS Release 5.11 Version 11.0 64-bitCopyright (c) 1983, 2011, Oracle and/or its affiliates. All rights reserved.Remounting root read/writeProbing for device nodes ...Preparing network image for useDownloading solaris.zlib--2012-02-17 15:10:17--  http://10.140.204.22:5555/var/js/AI/sparc//solaris.zlibConnecting to 10.140.204.22:5555... connected.HTTP request sent, awaiting response... 200 OKLength: 126752256 (121M) [text/plain]Saving to: `/tmp/solaris.zlib'100%[======================================>] 126,752,256 28.6M/s   in 4.4s    2012-02-17 15:10:21 (27.3 MB/s) - `/tmp/solaris.zlib' saved [126752256/126752256] Conclusion So, why go to all of this trouble?  More and more, I find that customers are wiring their data center to only use higher speed networks - 10GbE only to the hosts.  Some customers are moving aggressively toward consolidated networks combining storage and network on CNA NICs.  All of this means that network-based provisioning cannot rely exclusively on the built-in network interfaces.  So, it's important to be able to provision a system using other than the built-in networks.  Turns out, that this is pretty straight-forward for both Solaris 10 and Solaris 11 and fits into the Ops Center deployment process quite nicely. Hopefully, you will be able to use this as you build out your own private cloud solutions with Ops Center.

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  • How can I make zsh completion behave like Bash completion?

    - by Nate
    I switched to zsh, but I dislike the completion. If I have 20 files, each with a shared prefix, on pressing tab, zsh will fully complete the first file, then continue going through the list with each press of tab. If I want one near the end, I would have to press tab many times. In bash, this was simple - press tab and I would get the prefix. If I continued typing (and pressing tab), bash would complete as far as it could be certain of. I find this behavior to be much more intuitive but prefer the other features of zsh to bash. Is there a way to get this style of completion? Google suggested setopt bash_autolist, but this had no effect for me (and no error message was printed upon starting my shell). Thanks.

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  • Apache: Isn't chmod 755 enough to set up symlink or alias on Apache httpd on Mac OS 10.5?

    - by eed3si9n
    On my Mac OS 10.5 machine, I would like to set up a subfolder of ~/Documents like ~/Documents/foo/html to be http://localhost/foo. The first thing I thought of doing is using Alias as follows: Alias /foo /Users/someone/Documents/foo/html <Directory "/Users/someone/Documents/foo/html"> Options Indexes FollowSymLinks MultiViews Order allow,deny Allow from all </Directory> This got me 403 Forbidden. In the error_log I got: [error] [client ::1] (13)Permission denied: access to /foo denied The subfolder in question has chmod 755 access. I've tried specifying likes like http://localhost/foo/test.php, but that didn't work either. Next, I tried the symlink route. Went into /Library/WebServer/Documents and made a symlink to ~/Documents/foo/html. The document root has Options Indexes FollowSymLinks MultiViews This still got me 403 Forbidden: Symbolic link not allowed or link target not accessible: /Library/WebServer/Documents/foo What else do I need to set this up? Solution: $ chmod 755 ~/Documents In general, the folder to be shared and all of its ancestor folder needs to be viewable by the www service user.

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  • How do I setup an Alias on Apache with XAMPP on Linux ? (Permission problem)

    - by knarf
    XAMPP works fine but I want to have http://localhost/f to point to /home/knarf/prog/php/fwyxz. I've chmod -R 777 /home/knarf/prog/php/fwyxz I've added Alias /f /home/knarf/prog/php/fwyxz at the end of the httpd.conf And when I try to access it, I get a 403. From the apache error_log: [error] [client 127.0.0.1] (13)Permission denied: access to /f denied. I've already tried several solutions (userdir and symlinks) but they both failed with the same error. I've also tried to add this after the Alias: <Directory "/home/knarf/prog/php/fwyxz"> Order allow,deny Allow from all </Directory> But again, permission denied. Now if I change the User/Group under which apache runs from nobody to knarf, it seems to work (static files are ok) but PHP can't use/initialize sessions : [error] [client 127.0.0.1] PHP Warning: session_start() [function.session-start]: open(/tmp/sess_r5nrmu4ugqguqqe83rs53lq6k0, O_RDWR) failed: Permission denied (13) in /home/knarf/prog/php/fwyxz/index.php on line 3 [error] [client 127.0.0.1] PHP Warning: Unknown: open(/tmp/sess_r5nrmu4ugqguqqe83rs53lq6k0, O_RDWR) failed: Permission denied (13) in Unknown on line 0 [error] [client 127.0.0.1] PHP Warning: Unknown: Failed to write session data (files). Please verify that the current setting of session.save_path is correct () in Unknown on line 0 This is really frustrating.

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  • 'sudo su -' vs 'sudo -i' vs 'sudo /bin/bash' - when does it matter which is used, or does it matter at all?

    - by Paul
    When I'm doing something that requires root be typed in dozens of times in a row, I prefer to switch my session to a root session. In the various tutorials and instructions I have used on the Internet, I see sudo su, sudo su -, sudo -i and sudo /bin/bash being used to open a root session, but I'm not clear on the difference between these and when or if that difference matters. Can someone clear this up for me?

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  • Can tomcat perform ssl redirection by filtering host alias?

    - by Stephen
    Hi, We have a tomcat server (6.0.20) running one web application behind two urls, e.g. www.foo and secure.foo This is configured in the server.xml as one host with a single alias: <Host name="www.foo" appBase="webapps"> <Context docBase="foo" path=""></Context> <Alias>secure.foo</Alias> </Host> Ideally we'd like any requests to secure.foo on port 80 to be automatically redirected to use ssl. However, I can only find instructions for redirecting based on the path after the hostname, so I could add a /* security constraint but then this would apply to both urls. Does anyone know if it's possible to apply the redirection by filtering on hostname requested? (We've already got the ssl connector, certificate, etc. working ok). I know we could do it by sticking an apache server in front of tomcat and handling the redirection there, but I'm curious to know if tomcat can do this on its own. Thanks

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  • How to get git-completion.bash to work on Mac OS X?

    - by n179911
    Hi, I have followed http://blog.bitfluent.com/page/3 to add git-completion.bash to my /opt/local/etc/bash_completion.d/git-completion and I put PS1='\h:\W$(__git_ps1 "(%s)") \u\$ ' in my .bashrc_profile But now I am getting this -bash: __git_ps1: command not found everything I do a cd. Can you please tell me what am I missing?

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  • MySQL: Combining multiple where conditions

    - by Karl
    I'm working on a menu system that takes a url and then queries the db to build the menu. My menu table is: +---------+--------------+------+-----+---------+----------------+ | Field | Type | Null | Key | Default | Extra | +---------+--------------+------+-----+---------+----------------+ | id | int(11) | NO | PRI | NULL | auto_increment | | node_id | int(11) | YES | | NULL | | | parent | int(11) | YES | | NULL | | | weight | int(11) | YES | | NULL | | | title | varchar(250) | YES | | NULL | | | alias | varchar(250) | YES | | NULL | | | exclude | int(11) | YES | | NULL | | +---------+--------------+------+-----+---------+----------------+ The relevant columns for my question are alias, parent and node_id. So for a url like: http://example.com/folder1/folder2/filename Alias would potentially = "filename", "folder1", "folder2" Parent = the node_id of the parent folder. What I know is how to split the url up into an array and check the alias for a match to each part. What I don't know is how to have it then filter by parent whose alias matches "folder2" and whose parent alias matches "folder1". I'm imagining a query like so: select * from menu where alias='filename' and where parent = node_id where alias='folder2' and parent = node_id where alias='folder1' Except I know that the above is wrong. I'm hoping this can be done in a single query. Thanks for any help in advance!

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  • Using Stub Objects

    - by user9154181
    Having told the long and winding tale of where stub objects came from and how we use them to build Solaris, I'd like to focus now on the the nuts and bolts of building and using them. The following new features were added to the Solaris link-editor (ld) to support the production and use of stub objects: -z stub This new command line option informs ld that it is to build a stub object rather than a normal object. In this mode, it accepts the same command line arguments as usual, but will quietly ignore any objects and sharable object dependencies. STUB_OBJECT Mapfile Directive In order to build a stub version of an object, its mapfile must specify the STUB_OBJECT directive. When producing a non-stub object, the presence of STUB_OBJECT causes the link-editor to perform extra validation to ensure that the stub and non-stub objects will be compatible. ASSERT Mapfile Directive All data symbols exported from the object must have an ASSERT symbol directive in the mapfile that declares them as data and supplies the size, binding, bss attributes, and symbol aliasing details. When building the stub objects, the information in these ASSERT directives is used to create the data symbols. When building the real object, these ASSERT directives will ensure that the real object matches the linking interface presented by the stub. Although ASSERT was added to the link-editor in order to support stub objects, they are a general purpose feature that can be used independently of stub objects. For instance you might choose to use an ASSERT directive if you have a symbol that must have a specific address in order for the object to operate properly and you want to automatically ensure that this will always be the case. The material presented here is derived from a document I originally wrote during the development effort, which had the dual goals of providing supplemental materials for the stub object PSARC case, and as a set of edits that were eventually applied to the Oracle Solaris Linker and Libraries Manual (LLM). The Solaris 11 LLM contains this information in a more polished form. Stub Objects A stub object is a shared object, built entirely from mapfiles, that supplies the same linking interface as the real object, while containing no code or data. Stub objects cannot be used at runtime. However, an application can be built against a stub object, where the stub object provides the real object name to be used at runtime, and then use the real object at runtime. When building a stub object, the link-editor ignores any object or library files specified on the command line, and these files need not exist in order to build a stub. Since the compilation step can be omitted, and because the link-editor has relatively little work to do, stub objects can be built very quickly. Stub objects can be used to solve a variety of build problems: Speed Modern machines, using a version of make with the ability to parallelize operations, are capable of compiling and linking many objects simultaneously, and doing so offers significant speedups. However, it is typical that a given object will depend on other objects, and that there will be a core set of objects that nearly everything else depends on. It is necessary to impose an ordering that builds each object before any other object that requires it. This ordering creates bottlenecks that reduce the amount of parallelization that is possible and limits the overall speed at which the code can be built. Complexity/Correctness In a large body of code, there can be a large number of dependencies between the various objects. The makefiles or other build descriptions for these objects can become very complex and difficult to understand or maintain. The dependencies can change as the system evolves. This can cause a given set of makefiles to become slightly incorrect over time, leading to race conditions and mysterious rare build failures. Dependency Cycles It might be desirable to organize code as cooperating shared objects, each of which draw on the resources provided by the other. Such cycles cannot be supported in an environment where objects must be built before the objects that use them, even though the runtime linker is fully capable of loading and using such objects if they could be built. Stub shared objects offer an alternative method for building code that sidesteps the above issues. Stub objects can be quickly built for all the shared objects produced by the build. Then, all the real shared objects and executables can be built in parallel, in any order, using the stub objects to stand in for the real objects at link-time. Afterwards, the executables and real shared objects are kept, and the stub shared objects are discarded. Stub objects are built from a mapfile, which must satisfy the following requirements. The mapfile must specify the STUB_OBJECT directive. This directive informs the link-editor that the object can be built as a stub object, and as such causes the link-editor to perform validation and sanity checking intended to guarantee that an object and its stub will always provide identical linking interfaces. All function and data symbols that make up the external interface to the object must be explicitly listed in the mapfile. The mapfile must use symbol scope reduction ('*'), to remove any symbols not explicitly listed from the external interface. All global data exported from the object must have an ASSERT symbol attribute in the mapfile to specify the symbol type, size, and bss attributes. In the case where there are multiple symbols that reference the same data, the ASSERT for one of these symbols must specify the TYPE and SIZE attributes, while the others must use the ALIAS attribute to reference this primary symbol. Given such a mapfile, the stub and real versions of the shared object can be built using the same command line for each, adding the '-z stub' option to the link for the stub object, and omiting the option from the link for the real object. To demonstrate these ideas, the following code implements a shared object named idx5, which exports data from a 5 element array of integers, with each element initialized to contain its zero-based array index. This data is available as a global array, via an alternative alias data symbol with weak binding, and via a functional interface. % cat idx5.c int _idx5[5] = { 0, 1, 2, 3, 4 }; #pragma weak idx5 = _idx5 int idx5_func(int index) { if ((index 4)) return (-1); return (_idx5[index]); } A mapfile is required to describe the interface provided by this shared object. % cat mapfile $mapfile_version 2 STUB_OBJECT; SYMBOL_SCOPE { _idx5 { ASSERT { TYPE=data; SIZE=4[5] }; }; idx5 { ASSERT { BINDING=weak; ALIAS=_idx5 }; }; idx5_func; local: *; }; The following main program is used to print all the index values available from the idx5 shared object. % cat main.c #include <stdio.h> extern int _idx5[5], idx5[5], idx5_func(int); int main(int argc, char **argv) { int i; for (i = 0; i The following commands create a stub version of this shared object in a subdirectory named stublib. elfdump is used to verify that the resulting object is a stub. The command used to build the stub differs from that of the real object only in the addition of the -z stub option, and the use of a different output file name. This demonstrates the ease with which stub generation can be added to an existing makefile. % cc -Kpic -G -M mapfile -h libidx5.so.1 idx5.c -o stublib/libidx5.so.1 -zstub % ln -s libidx5.so.1 stublib/libidx5.so % elfdump -d stublib/libidx5.so | grep STUB [11] FLAGS_1 0x4000000 [ STUB ] The main program can now be built, using the stub object to stand in for the real shared object, and setting a runpath that will find the real object at runtime. However, as we have not yet built the real object, this program cannot yet be run. Attempts to cause the system to load the stub object are rejected, as the runtime linker knows that stub objects lack the actual code and data found in the real object, and cannot execute. % cc main.c -L stublib -R '$ORIGIN/lib' -lidx5 -lc % ./a.out ld.so.1: a.out: fatal: libidx5.so.1: open failed: No such file or directory Killed % LD_PRELOAD=stublib/libidx5.so.1 ./a.out ld.so.1: a.out: fatal: stublib/libidx5.so.1: stub shared object cannot be used at runtime Killed We build the real object using the same command as we used to build the stub, omitting the -z stub option, and writing the results to a different file. % cc -Kpic -G -M mapfile -h libidx5.so.1 idx5.c -o lib/libidx5.so.1 Once the real object has been built in the lib subdirectory, the program can be run. % ./a.out [0] 0 0 0 [1] 1 1 1 [2] 2 2 2 [3] 3 3 3 [4] 4 4 4 Mapfile Changes The version 2 mapfile syntax was extended in a number of places to accommodate stub objects. Conditional Input The version 2 mapfile syntax has the ability conditionalize mapfile input using the $if control directive. As you might imagine, these directives are used frequently with ASSERT directives for data, because a given data symbol will frequently have a different size in 32 or 64-bit code, or on differing hardware such as x86 versus sparc. The link-editor maintains an internal table of names that can be used in the logical expressions evaluated by $if and $elif. At startup, this table is initialized with items that describe the class of object (_ELF32 or _ELF64) and the type of the target machine (_sparc or _x86). We found that there were a small number of cases in the Solaris code base in which we needed to know what kind of object we were producing, so we added the following new predefined items in order to address that need: NameMeaning ...... _ET_DYNshared object _ET_EXECexecutable object _ET_RELrelocatable object ...... STUB_OBJECT Directive The new STUB_OBJECT directive informs the link-editor that the object described by the mapfile can be built as a stub object. STUB_OBJECT; A stub shared object is built entirely from the information in the mapfiles supplied on the command line. When the -z stub option is specified to build a stub object, the presence of the STUB_OBJECT directive in a mapfile is required, and the link-editor uses the information in symbol ASSERT attributes to create global symbols that match those of the real object. When the real object is built, the presence of STUB_OBJECT causes the link-editor to verify that the mapfiles accurately describe the real object interface, and that a stub object built from them will provide the same linking interface as the real object it represents. All function and data symbols that make up the external interface to the object must be explicitly listed in the mapfile. The mapfile must use symbol scope reduction ('*'), to remove any symbols not explicitly listed from the external interface. All global data in the object is required to have an ASSERT attribute that specifies the symbol type and size. If the ASSERT BIND attribute is not present, the link-editor provides a default assertion that the symbol must be GLOBAL. If the ASSERT SH_ATTR attribute is not present, or does not specify that the section is one of BITS or NOBITS, the link-editor provides a default assertion that the associated section is BITS. All data symbols that describe the same address and size are required to have ASSERT ALIAS attributes specified in the mapfile. If aliased symbols are discovered that do not have an ASSERT ALIAS specified, the link fails and no object is produced. These rules ensure that the mapfiles contain a description of the real shared object's linking interface that is sufficient to produce a stub object with a completely compatible linking interface. SYMBOL_SCOPE/SYMBOL_VERSION ASSERT Attribute The SYMBOL_SCOPE and SYMBOL_VERSION mapfile directives were extended with a symbol attribute named ASSERT. The syntax for the ASSERT attribute is as follows: ASSERT { ALIAS = symbol_name; BINDING = symbol_binding; TYPE = symbol_type; SH_ATTR = section_attributes; SIZE = size_value; SIZE = size_value[count]; }; The ASSERT attribute is used to specify the expected characteristics of the symbol. The link-editor compares the symbol characteristics that result from the link to those given by ASSERT attributes. If the real and asserted attributes do not agree, a fatal error is issued and the output object is not created. In normal use, the link editor evaluates the ASSERT attribute when present, but does not require them, or provide default values for them. The presence of the STUB_OBJECT directive in a mapfile alters the interpretation of ASSERT to require them under some circumstances, and to supply default assertions if explicit ones are not present. See the definition of the STUB_OBJECT Directive for the details. When the -z stub command line option is specified to build a stub object, the information provided by ASSERT attributes is used to define the attributes of the global symbols provided by the object. ASSERT accepts the following: ALIAS Name of a previously defined symbol that this symbol is an alias for. An alias symbol has the same type, value, and size as the main symbol. The ALIAS attribute is mutually exclusive to the TYPE, SIZE, and SH_ATTR attributes, and cannot be used with them. When ALIAS is specified, the type, size, and section attributes are obtained from the alias symbol. BIND Specifies an ELF symbol binding, which can be any of the STB_ constants defined in <sys/elf.h>, with the STB_ prefix removed (e.g. GLOBAL, WEAK). TYPE Specifies an ELF symbol type, which can be any of the STT_ constants defined in <sys/elf.h>, with the STT_ prefix removed (e.g. OBJECT, COMMON, FUNC). In addition, for compatibility with other mapfile usage, FUNCTION and DATA can be specified, for STT_FUNC and STT_OBJECT, respectively. TYPE is mutually exclusive to ALIAS, and cannot be used in conjunction with it. SH_ATTR Specifies attributes of the section associated with the symbol. The section_attributes that can be specified are given in the following table: Section AttributeMeaning BITSSection is not of type SHT_NOBITS NOBITSSection is of type SHT_NOBITS SH_ATTR is mutually exclusive to ALIAS, and cannot be used in conjunction with it. SIZE Specifies the expected symbol size. SIZE is mutually exclusive to ALIAS, and cannot be used in conjunction with it. The syntax for the size_value argument is as described in the discussion of the SIZE attribute below. SIZE The SIZE symbol attribute existed before support for stub objects was introduced. It is used to set the size attribute of a given symbol. This attribute results in the creation of a symbol definition. Prior to the introduction of the ASSERT SIZE attribute, the value of a SIZE attribute was always numeric. While attempting to apply ASSERT SIZE to the objects in the Solaris ON consolidation, I found that many data symbols have a size based on the natural machine wordsize for the class of object being produced. Variables declared as long, or as a pointer, will be 4 bytes in size in a 32-bit object, and 8 bytes in a 64-bit object. Initially, I employed the conditional $if directive to handle these cases as follows: $if _ELF32 foo { ASSERT { TYPE=data; SIZE=4 } }; bar { ASSERT { TYPE=data; SIZE=20 } }; $elif _ELF64 foo { ASSERT { TYPE=data; SIZE=8 } }; bar { ASSERT { TYPE=data; SIZE=40 } }; $else $error UNKNOWN ELFCLASS $endif I found that the situation occurs frequently enough that this is cumbersome. To simplify this case, I introduced the idea of the addrsize symbolic name, and of a repeat count, which together make it simple to specify machine word scalar or array symbols. Both the SIZE, and ASSERT SIZE attributes support this syntax: The size_value argument can be a numeric value, or it can be the symbolic name addrsize. addrsize represents the size of a machine word capable of holding a memory address. The link-editor substitutes the value 4 for addrsize when building 32-bit objects, and the value 8 when building 64-bit objects. addrsize is useful for representing the size of pointer variables and C variables of type long, as it automatically adjusts for 32 and 64-bit objects without requiring the use of conditional input. The size_value argument can be optionally suffixed with a count value, enclosed in square brackets. If count is present, size_value and count are multiplied together to obtain the final size value. Using this feature, the example above can be written more naturally as: foo { ASSERT { TYPE=data; SIZE=addrsize } }; bar { ASSERT { TYPE=data; SIZE=addrsize[5] } }; Exported Global Data Is Still A Bad Idea As you can see, the additional plumbing added to the Solaris link-editor to support stub objects is minimal. Furthermore, about 90% of that plumbing is dedicated to handling global data. We have long advised against global data exported from shared objects. There are many ways in which global data does not fit well with dynamic linking. Stub objects simply provide one more reason to avoid this practice. It is always better to export all data via a functional interface. You should always hide your data, and make it available to your users via a function that they can call to acquire the address of the data item. However, If you do have to support global data for a stub, perhaps because you are working with an already existing object, it is still easilily done, as shown above. Oracle does not like us to discuss hypothetical new features that don't exist in shipping product, so I'll end this section with a speculation. It might be possible to do more in this area to ease the difficulty of dealing with objects that have global data that the users of the library don't need. Perhaps someday... Conclusions It is easy to create stub objects for most objects. If your library only exports function symbols, all you have to do to build a faithful stub object is to add STUB_OBJECT; and then to use the same link command you're currently using, with the addition of the -z stub option. Happy Stubbing!

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  • How-To define an Alias-Name for a given Fileserver?

    - by Ice
    Hi, I'm building a testsystem and want to use the servernames like in the productive environment. For tcp-traffic i made an entry in the hosts-file but that seems not to work for fileservers (smb). How may i define an Alias-Name like (\Filer) for my fileserver with IP:192.168.1.2 and Name \testshare in our test-domain? Peace Ice

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  • Alias a linked Server in SQL server management studio?

    - by absentmindeduk
    Hoping someone can help - is there a way in SQL server management studio 2008 R2 that I can alias a linked SQL server? I have a server, added by IP address, to which I do not have the login credentials - however as the connection is already setup I can login ok. Issue is that, this is a dev environment, prior to a live deployment and the IP I have as a linked server needs to be 'accessible' by my stored procs under a different name, eg 'myserver' not 192.168.xxx.xxx... Any help much appreciated.

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  • How can I create (or do I even need to create) an alias of a DNS MX record?

    - by AKWF
    I am in the process of moving my DNS records from Network Solutions to the Amazon Route 53 service. While I know and understand a little about the basic kinds of records, I am stumped on how to create the record that will point to the MX record on Network Solutions (if I'm even saying that right). On Network Solutions I have this: Mail Servers (MX Records) Note: Mail Servers are listed in rank order myapp.net Add Sub-Domain MXMailServer(Preference) TTL inbound.myapp.net.netsolmail.net.(10) 7200 Network Solutions E-mail I have read that the payload for an MX record state that it must point to an existing A record in the DNS. Yet in the example above, that inbound.myapp... record only has the words "Network Solutions E-mail" next to it. Our email is hosted at Network Solutions. I have already created the CNAME records that look like this: mail.myapp.net 7200 mail.mycarparts.net.netsolmail.net. smtp.myapp.net 7100 smtp.mycarparts.net.netsolmail.net. Since I am only using Amazon as the DNS, do I even need to do anything with that MX record? I appreciate your help, I googled and researched this before I posted, this is my first post on webmasters although I've been on SO for a few years.

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  • How can I add a bash script to the Unity launcher?

    - by hippyjim
    I open my favourite IDE (PhpStorm) using a custom bash script. I would like to add the script to the Unity launcher. I thought I could add it by clicking the "keep in launcher" option, and sure enough, the icon stays on the launcher after I close the app. But clicking the icon doesn't reopen the IDE - the launcher just sits there, flashing. When I relogin in, the launcher icon is gone. Anyone got any ideas how I can make this work?

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  • Sortie de Debian 6.0.0, alias « Squeeze » : Kernel 2.6.32, Tomcat 6.0.28, Apache 2.2.16, MySQL 5.1.49 ou PHP 5.3.2 au menu

    Sortie de Debian 6.0.0 Squeeze Le Debian Project l'avait annoncé ce 31 janvier 2011, la sortie officielle de Debian 6.0, plus connue sous le nom de Squeeze l'extraterrestre à 3 yeux, était iminente. Et bien, c'est chose faite ! Le passage en version stable de Squeeze a eu lieu ce week-end et pour l'occasion, le site web du projet a subi un rajeunissement. Citation: Envoyé par [email protected] Release Manage...

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  • How to anti-alias the fonts in visual studio in windows forms application?

    - by user1781077
    i want my font to be anti aliased like this so that it looks more professionalenter link description heredoes any one know the code to anti alias the fonts so that the project looks more professional.tell me the code and where to insert it in the project.As of now the fonts looks jaggy the programming language is visual C# 4.0 .net and IDE is VS 2010 for example this is a label1 what do I need to insert to anti alias this.label1.AutoSize = true; this.label1.Font = new System.Drawing.Font("Segoe UI", 8.25F, System.Drawing.FontStyle.Regular, System.Drawing.GraphicsUnit.Point, ((byte)(0))); this.label1.Location = new System.Drawing.Point(189, 187); this.label1.Name = "label1"; this.label1.Size = new System.Drawing.Size(31, 13); this.label1.TabIndex = 0; this.label1.Text = "from";

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  • Access Java based keystore directly on Sun ONE Webserver 6.1

    - by George Bailey
    The keystore seems to reside in one of /opt/SUNWwbsvr/alias/https-sub.domain.ext-hostname-cert8.db /opt/SUNWwbsvr/alias/https-sub.domain.ext-hostname-key3.db What tool would I use to access this file? I have tried these commands which did not work. /opt/SUNWwbsvr/bin/https/jdk/bin/keytool -certreq -keyalg RSA -file /tmp/test.csr -keystore /opt/SUNWwbsvr/alias/https-sub.domain.ext-hostname-cert8.db /opt/SUNWwbsvr/bin/https/jdk/bin/keytool -certreq -keyalg RSA -file /tmp/test.csr -keystore /opt/SUNWwbsvr/alias/https-sub.domain.ext-hostname-key3.db /opt/SUNWwbsvr/bin/https/jdk/bin/keytool -list -storepass password -keystore /opt/SUNWwbsvr/alias/https-sub.domain.ext-hostname-cert8.db /opt/SUNWwbsvr/bin/https/jdk/bin/keytool -list -storepass password -keystore /opt/SUNWwbsvr/alias/https-sub.domain.ext-hostname-key3.db They all gave me the error message keytool error: java.io.IOException: Invalid keystore format

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