X-Git-Url: https://www.chiark.greenend.org.uk/ucgi/~ianmdlvl/git?a=blobdiff_plain;f=dgit-repos-server;h=5055de63bc44b939dbd44e4bc683056507f9b4c7;hb=b1f5b0b214e6f21145627e78e662c370754c1aff;hp=677e3d71f27444afb578db245267d747dbd7ef35;hpb=86b0a275600e7e40a5cda380797163dc661f903d;p=dgit.git diff --git a/dgit-repos-server b/dgit-repos-server index 677e3d71..5055de63 100644 --- a/dgit-repos-server +++ b/dgit-repos-server @@ -2,8 +2,7 @@ # dgit-repos-push-receiver # # usages: -# .../dgit-repos-push-receiver KEYRING-AUTH-SPEC DGIT-REPOS-DIR --ssh -# .../dgit-repos-push-receiver KEYRING-AUTH-SPEC DGIT-REPOS-DIR PACKAGE +# .../dgit-repos-push-receiver SUITES KEYRING-AUTH-SPEC DGIT-REPOS-DIR --ssh # internal usage: # .../dgit-repos-push-receiver --pre-receive-hook PACKAGE # @@ -11,6 +10,9 @@ # # Works like git-receive-pack # +# SUITES is the name of a file which lists the permissible suites +# one per line (#-comments and blank lines ignored) +# # KEYRING-AUTH-SPEC is a :-separated list of # KEYRING.GPG,AUTH-SPEC # where AUTH-SPEC is one of @@ -20,43 +22,93 @@ use strict; # What we do is this: -# - extract the destination repo name somehow +# - extract the destination repo name # - make a hardlink clone of the destination repo # - provide the destination with a stunt pre-receive hook # - run actual git-receive-pack with that new destination -# as a result of this the stunt pre-receive hook runs; it does this -# find the keyring(s) to use for verification -# verify the signed tag -# check that the signed tag has a suitable name -# parse the signed tag body to extract the intended -# distro and suite -# check that the distro is right -# check that the suite is the same as the branch we are -# supposed to update -# check that the signed tag refers to the same commit -# as the new suite -# check that the signer was correct -# push the signed tag to the actual repo -# push the new dgit branch head to the actual repo +# as a result of this the stunt pre-receive hook runs; it does this: +# + understand what refs we are allegedly updating and +# check some correspondences: +# * we are updating only refs/tags/debian/* and refs/dgit/* +# * and only one of each +# * and the tag does not already exist +# and +# * recover the suite name from the destination refs/dgit/ ref +# + disassemble the signed tag into its various fields and signature +# including: +# * parsing the first line of the tag message to recover +# the package name, version and suite +# * checking that the package name corresponds to the dest repo name +# * checking that the suite name is as recovered above +# + verify the signature on the signed tag +# and if necessary check that the keyid and package are listed in dm.txt +# + check various correspondences: +# * the suite is one of those permitted +# * the signed tag must refer to a commit +# * the signed tag commit must be the refs/dgit value +# * the name in the signed tag must correspond to its ref name +# * the tag name must be debian/ (massaged as needed) +# * the signed tag has a suitable name +# * the commit is a fast forward +# + push the signed tag and new dgit branch to the actual repo +# +# If the destination repo does not already exist, we need to make +# sure that we create it reasonably atomically, and also that +# we don't every have a destination repo containing no refs at all +# (because such a thing causes git-fetch-pack to barf). So then we +# do as above, except: +# - before starting, we take out our own lock for the destination repo +# - we create a prospective new destination repo by making a copy +# of _template +# - we use the prospective new destination repo instead of the +# actual new destination repo (since the latter doesn't exist) +# - we set up a post-receive hook as well, which +# + touches a stamp file +# - after git-receive-pack exits, we +# + check that the prospective repo contains a tag and head +# + rename the prospective destination repo into place +# +# Cleanup strategy: +# - We are crash-only +# - Temporary working trees and their locks are cleaned up +# opportunistically by a program which tries to take each lock and +# if successful deletes both the tree and the lockfile +# - Prospective working trees and their locks are cleaned up by +# a program which tries to take each lock and if successful +# deletes any prospective working tree and the lock (but not +# of course any actual tree) +# - It is forbidden to _remove_ the lockfile without removing +# the corresponding temporary tree, as the lockfile is also +# a stampfile whose presence indicates that there may be +# cleanup to do use POSIX; use Fcntl qw(:flock); +use File::Path qw(rmtree); our $package_re = '[0-9a-z][-+.0-9a-z]+'; +our $func; our $dgitrepos; our $pkg; +our $suitesfile; +our $realdestrepo; our $destrepo; our $workrepo; our @keyrings; +our @lockfhs; + +#----- utilities ----- sub acquirelock ($$) { my ($lock, $must) = @_; + my $fh; for (;;) { - my $fh = new IO::File, ">", $lock or die "open $lock: $!"; + close $fh if $fh; + $fh = new IO::File, ">", $lock or die "open $lock: $!"; my $ok = flock $fh, $must ? LOCK_EX : (LOCK_EX|LOCK_NB); if (!$ok) { - return unless $must; + return undef unless $must; die "flock $lock: $!"; } if (!stat $lock) { @@ -66,21 +118,38 @@ sub acquirelock ($$) { my $want = (stat _)[1]; stat $fh or die $!; my $got = (stat _)[1]; - return $fh if $got == $want; + last if $got == $want; + } + return $fh; +} + +sub acquiretree ($$) { + my ($tree, $must) = @_; + my $fh = acquirelock("$tree.lock", $must); + if ($fh) { + push @lockfhs, $fh; + rmtree $tree; } + return $fh; +} + +sub reject ($) { + die "dgit-repos-server: reject: $_[0]\n"; +} + +#----- git-receive-pack ----- + +sub fixmissing__git_receive_pack () { + $destrepo = "$dgitrepos/_tmp/${pkg}_prospective"; + acquiretree($destrepo, 1); + my $r = system qw(cp -a --), "$dgitrepos/_template", "$destrepo"; + !$r or die "create new repo failed failed: $r $!"; } sub makeworkingclone () { $workrepo = "$dgitrepos/_tmp/${pkg}_incoming$$"; - my $lock = "$workrepo.lock"; - my $lockfh = acquirelock($lock, 1); - if (!stat $destrepo) { - $! == ENOENT or die "stat dest repo $destrepo: $!"; - mkdir $workrepo or die "create work repo $workrepo: $!"; - runcmd qw(git init --bare), $workrepo; - } else { - runcmd qw(git clone -l -q --mirror), $destrepo, $workrepo; - } + acquiretree($workrepo, 1); + runcmd qw(git clone -l -q --mirror), $destrepo, $workrepo; } sub setupstunthook () { @@ -97,6 +166,40 @@ END $ENV{'DGIT_RPR_DEST'}= $destrepo; } +sub maybeinstallprospective () { + return if $destrepo eq $realdestrepo; + + my $child = open SR, "-|"; + defined $child or die $!; + if (!$child) { + chdir $destrepo or die $!; + exec qw(git show-ref); + die $!; + } + my %got = qw(tag 0 head 0); + while () { + chomp or die; + s/^\S*[1-9a-f]\S* (\S+)$/$1/ or die; + my $wh = + m{^refs/tags/} ? 'tag' : + m{^refs/dgit/} ? 'head' : + die; + die if $got{$wh}++; + } + die if grep { !$_ } values %got; + $!=0; $?=0; close SR or die "$? $!"; + + rename $destrepo, $realdestrepo or die $!; + remove "$destrepo.lock" or die $!; +} + +sub main__git_receive_pack () { + makeworkingclone(); + setupstunthook(); + runcmd qw(git receive-pack), $destdir; + maybeinstallprospective(); +} + #----- stunt post-receive hook ----- our ($tagname, $tagval, $suite, $oldcommit, $commit); @@ -132,7 +235,6 @@ sub parsetag () { open PT, ">dgit-tmp/plaintext" or die $!; open DS, ">dgit-tmp/plaintext.asc" or die $!; open T, "-|", qw(git cat-file tag), $tagval or die $!; - my %tagh; for (;;) { $!=0; $_=; defined or die $!; print PT or die $!; @@ -241,9 +343,23 @@ sub verifytag () { reject "key not found in keyrings"; } -sub checktag () { - tagh1('object') eq $commit or die; +sub checksuite () { + open SUITES, "<", $suitesfile or die $!; + while () { + chomp; + next unless m/\S/; + next if m/^\#/; + s/\s+$//; + return if $_ eq $suite; + } + die $! if SUITES->error; + reject "unknown suite"; +} + +sub checks () { + checksuite(); tagh1('type') eq 'commit' or die; + tagh1('object') eq $commit or die; tagh1('tag') eq $tagname or die; my $v = $version; @@ -273,19 +389,27 @@ sub stunthook () { readupdates(); parsetag(); verifytag(); - checktag(); + checks(); onwardpush(); } #----- arg parsing and main program ----- -sub parseargs () { +sub argval () { + die unless @ARGV; + my $v = shift @ARGV; + die if $v =~ m/^-/; + return $v; +} + +sub parseargsdispatch () { die unless @ARGV; if ($ARGV[0] eq '--pre-receive-hook') { shift @ARGV; @ARGV == 1 or die; $pkg = shift @ARGV; + defined($suitesfile = $ENV{'DGIT_RPR_SUITES'}) or die; defined($workrepo = $ENV{'DGIT_RPR_WORK'}) or die; defined($destrepo = $ENV{'DGIT_RPR_DEST'}) or die; defined($keyrings = $ENV{'DGIT_RPR_KEYRINGS'}) or die $!; @@ -294,48 +418,59 @@ sub parseargs () { exit 0; } - die unless @ARGV>=2; - - die if $ARGV[0] =~ m/^-/; - $ENV{'DGIT_RPR_KEYRINGS'} = shift @ARGV; - die if $ARGV[0] =~ m/^-/; - $dgitrepos = shift @ARGV; - - die unless @ARGV; - if ($ARGV[0] != m/^-/) { - @ARGV == 1 or die; - $pkg = shift @ARGV; - } elsif ($ARGV[0] eq '--ssh') { - shift @ARGV; - !@ARGV or die; - my $cmd = $ENV{'SSH_ORIGINAL_COMMAND'}; - $cmd =~ m{ - ^ - (?:\S*/)? - (git-receive-pack|git-upload-pack) - \s+ - (?:\S*/)? - ($package_re)\.git - $ - }ox - or die "requested command $cmd not understood"; - $method = $1; - $pkg = $2; - my $func = $method; - $func =~ y/-/_/; - $func = $main::{"main__$func"}; - &$func; + $ENV{'DGIT_RPR_SUITES'} = argval(); + $ENV{'DGIT_RPR_KEYRINGS'} = argval(); + $dgitrepos = argval(); + + die unless @ARGV==1 && $ARGV[0] eq '--ssh'; + + my $cmd = $ENV{'SSH_ORIGINAL_COMMAND'}; + $cmd =~ m{ + ^ + (?:\S*/)? + ([-0-9a-z]+) + \s+ + (?:\S*/)? + ($package_re)\.git + $ + }ox + or reject "command string not understood"; + $method = $1; + $pkg = $2; + $realdestrepo = "$dgitrepos/$pkg.git"; + + my $funcn = $method; + $funcn =~ y/-/_/; + my $mainfunc = $main::{"main__$funcn"}; + + reject "unknown method" unless $mainfunc; + + if (stat $realdestrepo) { + $destrepo = $realdestrepo; } else { - die; + $! == ENOENT or die "stat dest repo $destrepo: $!"; + my $fixfunc = $main::{"fixmissing__$funcn"}; + &$fixfunc; } - $destrepo = "$dgitrepos/$pkg.git"; + &$mainfunc; } -sub main__git_receive_pack () { - parseargs(); -fixme check method; - makeworkingclone(); - setupstunthook(); - runcmd qw(git receive-pack), $destdir; +sub unlockall () { + while (my $fh = pop $lockfhs) { close $fh; } +} + +sub cleanup () { + unlockall(); + chdir "$dgitrepos/_tmp" or die $!; + foreach my $lock (<*.lock>) { + my $tree = $lf; + $tree =~ s/\.lock$//; + next unless acquiretree($tree, 0); + remove $lock or warn $!; + unlockall(); + } } + +parseargsdispatch(); +cleanup();