3 repository - Using the Perl repository
7 First, we assume here that you have already decided that you will
8 need B<write> access to the repository. If all you need is B<read>
9 access, there are much better ways to access the most current state of
10 the perl repository, or explore individual files and patches therein.
11 See L<perlhack> for details.
13 This document describes what a Perl Porter needs to do to start using
18 You'll need to get hold of the following software.
24 Download a perforce client from:
26 http://www.perforce.com/perforce/loadprog.html
28 You'll probably also want to look at:
30 http://www.perforce.com/perforce/technical.html
32 where you can look at or download its documentation.
36 If you don't already have access to an ssh client, then look at its
37 home site C<http://www.cs.hut.fi/ssh> which mentions ftp sites from
38 which it's available. You only need to build the client parts (ssh
39 and ssh-keygen should suffice).
41 If you're on Windows then you might like to obtain Cygwin from:
45 which contains an ssh client. (MSYS also contains an ssh client
46 but it seems to time-out and disconnect from the server and doesn't
47 understand the ServerAliveInterval setting described later that can
48 be used to stop Cygwin's ssh client from doing this.)
50 Alternatively, the "plink" program, part of PuTTY:
52 http://www.chiark.greenend.org.uk/~sgtatham/putty/
54 should also work fine for Windows users.
58 =head1 Creating an SSH Key Pair
60 If you already use ssh and want to use the same key pair for perl
61 repository access then you can skip the rest of this section.
62 Otherwise, generate an ssh key pair for use with the repository
67 After generating a key pair and testing it, ssh-keygen will ask you
68 to enter a filename in which to save the key. The default it offers
69 will be the file F<~/.ssh/identity> which is suitable unless you
70 particularly want to keep separate ssh identities for some reason.
71 If so, you could save the perl repository private key in the file
72 F<~/.ssh/perl>, for example, but I will use the standard filename
73 in the remainder of the examples of this document.
75 After typing in the filename, it will prompt you to type in a
76 passphrase. The private key will itself be encrypted so that it is
77 usable only when that passphrase is typed. (When using ssh, you will
78 be prompted when it requires a pass phrase to unlock a private key.)
79 If you provide a blank passphrase then no passphrase will be needed
80 to unlock the key and, as a consequence, anyone who gains access to
81 the key file gains access to accounts protected with that key
82 (barring additional configuration to restrict access by IP address).
84 When you have typed the passphrase in twice, ssh-keygen will confirm
85 where it has saved the private key (in the filename you gave and
86 with permissions set to be only readable by you), what your public
87 key is (don't worry: you don't need to memorise it) and where it
88 has saved the corresponding public key. The public key is saved in
89 a filename corresponding to your private key's filename but with
90 ".pub" appended, usually F<~/.ssh/identity.pub>. That public key
91 can be (but need not be) world readable. It is not used by your
94 Note that the above process creates a key pair for ssh protocol 1.
95 You can request ssh protocol 2 (RSA) instead if you prefer (if your
96 particular ssh client supports it), via the command
100 This will create private/public identity files called F<~/.ssh/id_rsa>
101 and F<~/.ssh/id_rsa.pub> respectively. Protocol 2 offers a higher
102 level of security than protocol 1. This is not required for access to
103 the Perl repository -- ssh is used for authentication rather than
104 encryption (the Perl sources are open anyway) -- but either protocol
105 is supported by the server.
107 B<IMPORTANT NOTE FOR CYGWIN USERS:> In order to make the private key
108 files only readable by you you must include the string "ntea" in the
109 "CYGWIN" environment variable in the shell used to run C<chmod(1)>,
110 and in the shell used to run the ssh client itself later. If "CYGWIN"
111 doesn't contain "ntea" then it will appear to the ssh client that the
112 file permissions are not set correctly, in which case the files will be
113 ignored and you won't be able to connect.
115 =head1 Notifying the Repository Keeper
117 Mail the contents of that public key file to the keeper of the perl
118 repository (see L</Contact Information> below).
119 When the key is added to the repository host's configuration file,
120 you will be able to connect to it with ssh by using the corresponding
121 private key file (after unlocking it with your chosen passphrase).
123 There is no harm in creating both protocol 1 and protocol 2 keys and
124 mailing them both in. That way you'll be able to connect using either
125 protocol, which may be useful if you later find yourself using a client
126 that only supports one or the other protocol.
128 =head1 Connecting to the Repository
130 Connections to the repository are made by using ssh to provide a
131 TCP "tunnel" rather than by using ssh to login to or invoke any
132 ordinary commands on the repository.
134 The ssh (secure shell) protocol runs over port number 22, so if you
135 have a firewall installed at the client end then you must ensure that
136 it is configured to allow you to make an outgoing connection to port 22
137 on sickle.activestate.com.
139 When you want to start a session using the repository, use the command:
141 ssh -l perlrep -f -q -x -L 1666:127.0.0.1:1666 sickle.activestate.com foo
143 If you are not using the default filename of F<~/.ssh/identity> or
144 F<~/.ssh/id_rsa> to hold your perl repository private key then you'll
145 need to add the option B<-i filename> to tell ssh where it is. Unless
146 you chose a blank passphrase for that private key, ssh will prompt you
147 for the passphrase to unlock that key. Then ssh will fork and put itself
148 in the background, returning you (silently) to your shell prompt.
150 Note that the first time you connect you may see a message like
151 "The authenticity of host 'sickle.activestate.com' can't be established,"
152 and asking you if you want to continue. Just answer yes and sickle's
153 details will be cached in a F<known_hosts> or F<known_hosts2> file. You
154 will not see that message again unless you delete the cache file.
156 The tunnel for repository access is now ready for use.
158 For the sake of completeness (and for the case where the chosen
159 port of 1666 is already in use on your machine), I'll briefly
160 describe what all those ssh arguments are for.
166 Use a remote username of perlrep. (The account on the repository which
167 provides the end-point of the ssh tunnel is named "perlrep".)
171 Tells ssh to fork and remain running in the background. Since ssh
172 is only being used for its tunnelling capabilities, the command
173 that ssh runs never does any I/O and can sit silently in the
178 Tells ssh to be quiet. Without this option, ssh will output a
179 message each time you use a p4 command (since each p4 command
180 tunnels over the ssh connection to reach the repository).
184 Tells ssh not to bother to set up a tunnel for X11 connections.
185 The repository doesn't allow this anyway.
187 =item B<-L 1666:127.0.0.1:1666>
189 This is the important option. It tells ssh to listen out for
190 connections made to port 1666 on your local machine. When such
191 a connection is made, the ssh client tells the remote side
192 (the corresponding ssh daemon on the repository) to make a
193 connection to IP address 127.0.0.1, port 1666. Data flowing
194 along that connection is tunnelled over the ssh connection
195 (encrypted). The perforce daemon running on the repository
196 only accepts connections from localhost and that is exactly
197 where ssh-tunnelled connections appear to come from.
199 If port 1666 is already in use on your machine then you can
200 choose any non-privileged port (a number between 1024 and 65535)
201 which happens to be free on your machine. It's the first of the
202 three colon separated values that you should change. Picking
203 port 2345 would mean changing the option to
204 B<-L 2345:127.0.0.1:1666>. Whatever port number you choose should
205 be used for the value of the P4PORT environment variable (q.v.).
207 =item sickle.activestate.com
209 This is the canonical name of the host on which the perl repository
214 This is a dummy place holder argument. Without an argument
215 here, ssh will try to perform an interactive login to the
216 repository which is not allowed. Ordinarily, this argument
217 is for the one-off command which is to be executed on the
218 remote host. However, the repository's ssh configuration
219 file uses the "command=" option to force a particular
220 command to run so the actual value of the argument is
221 ignored. The command that's actually run merely pauses and
222 waits for the ssh connection to drop, then exits.
228 You should normally get a prompt that asks for the passphrase
229 for your RSA key when you connect with the ssh command shown
230 above. If you see a prompt that looks like:
232 perlrep@sickle.activestate.com's password:
234 Then you either don't have a F<~/.ssh/identity> or F<~/.ssh/id_rsa>
235 file corresponding to your public key, or that file is not readable.
236 Fix the problem and try again. Alternatively, some ssh implementations
237 will fail to verify your RSA key if the key if readable by others.
238 Just lower the permissions to make the key readable to yourself.
240 If you only had the public key file for one protocol installed at the
241 server end then make sure your client is using the corresponding
242 protocol. An ssh client that supports protocol 2 will probably choose
243 that by default, which will fail if the server end only has your public
244 key file for protocol 1. Some ssh clients have "-1" and "-2" arguments
245 to force which protocol to use.
247 The "-v" (verbose) flag can be useful for seeing what protocol your
248 client is actually trying to connect with, and for spotting any other
249 problems. The flag can be specified multiple times to increase
250 verbosity. Note that specifying the "-q" flag as well might override
251 your request for verbose output, so drop the "-q" flag when trying this.
253 If you're using the Cygwin ssh client on Windows then you will probably
254 find that the connection times out after a short period of inactivity.
255 You will have to keep re-entering your passphrase to reconnect, which
256 gets annoying after a while. In order to prevent these time-outs from
257 happening place the following two lines in the file F<~/.ssh/config>:
259 Host sickle.activestate.com
260 ServerAliveInterval 120
262 This causes the ssh client to send a message to the server every 120
263 seconds to check that the server is still alive. The client will not
264 disconnect unless "ServerAliveCountMax" many of these messages go
265 unanswered. Run C<man ssh_config> for more details. Note also that
266 this option applies to protocol version 2 only.
268 =head1 Using the Perforce Client
270 Remember to read the documentation for Perforce. You need
271 to make sure that three environment variable are set
272 correctly before using the p4 client with the perl repository.
278 Set this to localhost:1666 (the port for your ssh client to listen on)
279 unless that port is already in use on your host. If it is, see
280 the section above on the B<-L 1666:127.0.0.1:1666> option to ssh.
284 The value of this is the name by which Perforce knows your
285 host's workspace. You need to pick a name (normally, your
286 Perforce username, a dash, and your host's short name)
287 when you first start using the perl repository and then
290 Perforce keeps track of the files you have on your machine. It
291 does this through your client. When you first sync a version of a
292 file, the file comes from the server to your machine. If you sync
293 the same file again the server does nothing because it
294 knows you already have the file.
296 You should NOT use the same client on different machines. If you do
297 you probably won't get the files you expect, and may end up with
298 nasty corruption. Perforce allows you to have as many clients as
299 you want. For example, sally-home, sally-openbsd, sally-laptop.
301 Also, never change the client's root and view at the same time.
302 See C<http://www.perforce.com/perforce/doc.002/manuals/p4guide/04_details.html#1048341>
304 If you have multiple hosts sharing the same directory structure
305 via NFS then you may be able to get away with only one client name,
308 The C<p4 clients> command lists all currently known clients.
312 This is the username by which perforce knows you. Use your
313 username if you have a well known or obvious one or else pick
314 a new one which other perl5-porters will recognise. There is
315 a licence limit on the number of these usernames, so be sure not
316 to use more than one.
318 It is very important to set a password for your Perforce username,
319 or else anyone can impersonate you. Use the C<p4 passwd> command
320 to do this. Once a password is set for your account, you'll need
321 to tell Perforce what it is. You can do this by setting the
322 environment variable P4PASSWD, or you can use the C<-P> flag
323 with the C<p4> command.
325 There are a few techniques you can use to avoid having to either
326 set an environment variable or type the password on every command.
327 One is to create a shell alias, for example, in bash, add something like
328 alias p4='p4 -P secret'
329 to your F<.bash_profile> file. Another way is to create a small shell
333 And use this instead of running C<p4> directly.
335 With either of these, be sure the file containing your password
336 (the F<.bash_profile> or shell script file) is only readable by you.
338 The C<p4 users> command lists all currently known users.
342 Note that on Windows P4PORT and P4USER are requested when installing
343 Perforce. They are stored in the registry, so they do not need to be
344 set in the environment.
346 Once these three environment variables are set, you can use the
347 perforce p4 client exactly as described in its documentation.
349 After setting these variables and connecting to the repository
350 for the first time, you should use the C<p4 user> command to
351 set a valid email address for yourself. Messages to the commit list
352 are sent (faked) from whatever email address you set here.
354 Also use the C<p4 client> command to specify your workspace
355 specifications for each individual client from which you will interact
356 with the repository. The P4CLIENT environment variable, of course,
357 needs to be set to one of these client workspace names.
359 =head1 Ending a Repository Session
361 When you have finished a session using the repository, you
362 should kill off the ssh client process to break the tunnel.
363 Since ssh forked itself into the background, you'll need to use
364 something like ps with the appropriate options to find the ssh
365 process and then kill it manually. The default signal of
368 =head1 Overview of the Repository
370 Please read at least the introductory sections of the Perforce
371 User Guide (and perhaps the Quick Start Guide as well) before
372 reading this section.
374 Every repository user typically "owns" a "branch" of the mainline
375 code in the repository. They hold the "pumpkin" for things in this
376 area, and are usually the only user who will modify files there.
377 This is not strictly enforced in order to allow the flexibility
378 of other users stealing the pumpkin for short periods with the
381 Here is (part of) the current structure of the repository:
383 /----+-----perl - Mainline development (bleadperl)
384 +-----perlio - PerlIO Pumpkin's Perl
385 +-----vmsperl - VMS Pumpkin's Perl
386 +-----maint-5.004------perl - Maintenance branches
387 +-----maint-5.005------perl
388 +-----maint-5.6--------perl
389 +-----maint-5.8--------perl
390 +-----pureperl---------pureperl
392 Perforce uses a branching model that simply tracks relationships
393 between files. It does not care about directories at all, so
394 any file can be a branch of any other file--the fully qualified
395 depot path name (of the form //depot/foo/bar.c) uniquely determines
396 a file for the purpose of establishing branching relationships.
397 Since a branch usually involves hundreds of files, such relationships
398 are typically specified en masse using a branch map (try `p4 help branch`).
399 `p4 branches` lists the existing branches that have been set up.
400 `p4 branch -o branchname` can be used to view the map for a particular
401 branch, if you want to determine the ancestor for a particular set of
404 The mainline (aka "trunk") code in the Perl repository is under
405 "//depot/perl/...". Most branches typically map its entire
406 contents under a directory that goes by the same name as the branch
407 name. Thus the contents of the perlio branch are to be found
410 Run `p4 client` to specify how the repository contents should map to
411 your local disk. Most users will typically have a client map that
412 includes at least their entire branch and the contents of the mainline.
414 Run `p4 changes -l -m10` to check on the activity in the repository.
415 //depot/perl/Porting/genlog is useful to get an annotated changelog
416 that shows files and branches. You can use this listing to determine
417 if there are any changes in the mainline that you need to merge into
418 your own branch. A typical merging session looks like this:
421 % p4 integrate -b perlio # to bring parent changes into perlio
422 % p4 resolve -am ./... # auto merge the changes
423 % p4 resolve ./... # manual merge conflicting changes
424 % p4 submit ./... # check in
426 If the owner of the mainline wants to bring the changes in perlio
427 back into the mainline, they do:
429 % p4 integrate -r -b perlio
432 Generating a patch for change#42 is done as follows:
434 % p4genpatch 42 > change-42.patch
436 F<p4genpatch> is to be found in //depot/perl/Porting/.
438 The usual routine to apply a patch is
440 % p4 edit file.c file.h
443 (any necessary, re-Configure, make regen_headers, make clean, etc, here)
447 (preferably make all test in several platforms and under several
448 different Configurations)
457 Other useful Perforce commands
459 % p4 describe -du 12345 # show change 12345
461 Note: the output of "p4 describe" is not in proper diff format, use
462 the F<Porting/p4genpatch> to get a diff-compatible format.
463 (Note that it may be easier to get one already prepared: grep
464 L<perlhack> for APC, and append eg "/diffs/12345.gz" to one of the
465 URLs to get a usable patch.)
467 % p4 diff -se ./... # have I modified something but forgotten
468 # to "p4 edit", easy faux pas with autogenerated
469 # files like proto.h, or if one forgets to
470 # look carefully which files a patch modifies
471 % p4 sync file.h # if someone else has modified file.h
472 % p4 opened # which files are opened (p4 edit) by me
473 % p4 opened -a # which files are opened by anybody
474 % p4 diff -du file.c # what changes have I done
475 % p4 revert file.h # never mind my changes
476 % p4 sync -f argh.c # forcibly synchronize your file
477 # from the repository
478 % p4 diff -sr | p4 -x - revert
479 # throw away (opened but) unchanged files
480 # (in Perforce it's a little bit too easy
481 # to checkin unchanged files)
483 Integrate patch 12345 from the mainline to the maint-5.6 branch:
484 (you have to in the directory that has both the mainline and
485 the maint-5.6/perl as subdirectories)
487 % p4 integrate -d perl/...@12345,12345 maint-5.6/perl/...
489 Integrate patches 12347-12350 from the perlio branch to the mainline:
491 % p4 integrate -d perlio/...@12347,12350 perl/...
493 =head1 Contact Information
495 The mail alias E<lt>perl-repository-keepers@perl.orgE<gt> can be used to reach
496 all current users of the repository.
498 The repository keeper is currently Philippe M. Chiasson
499 E<lt>gozer@ActiveState.comE<gt>.
503 Malcolm Beattie, E<lt>mbeattie@sable.ox.ac.ukE<gt>, 24 June 1997.
505 Gurusamy Sarathy, E<lt>gsar@activestate.comE<gt>, 8 May 1999.
507 Slightly updated by Simon Cozens, E<lt>simon@brecon.co.ukE<gt>, 3 July 2000.
509 More updates by Jarkko Hietaniemi, E<lt>jhi@iki.fiE<gt>, 28 June 2001.
511 Perforce clarifications by Randall Gellens, E<lt>rcg@users.sourceforge.netE<gt>, 12 July 2001.
513 Windows-related updates by Steve Hay E<lt>shay@cpan.orgE<gt>, 23 July 2004