nixpkgs/pkgs/build-support/buildenv/builder.pl
José Romildo Malaquias 4a1ef63c55 buildenv: paths to link resolving to the same absolute path is not a conflict
When building an environment if two paths conflict but one or both are
symbolic links and they resolve to the same real path, the conflict is
discarded because the contents of both paths are the same. One of them
is chosen and there is no need to recur into them in order to build
deeper symbolic links.
2020-06-10 06:42:48 -03:00

252 lines
7.2 KiB
Perl
Executable file

#! @perl@ -w
use strict;
use Cwd 'abs_path';
use IO::Handle;
use File::Path;
use File::Basename;
use File::Compare;
use JSON::PP;
STDOUT->autoflush(1);
my $out = $ENV{"out"};
my @pathsToLink = split ' ', $ENV{"pathsToLink"};
sub isInPathsToLink {
my $path = shift;
$path = "/" if $path eq "";
foreach my $elem (@pathsToLink) {
return 1 if
$elem eq "/" ||
(substr($path, 0, length($elem)) eq $elem
&& (($path eq $elem) || (substr($path, length($elem), 1) eq "/")));
}
return 0;
}
# Returns whether a path in one of the linked packages may contain
# files in one of the elements of pathsToLink.
sub hasPathsToLink {
my $path = shift;
foreach my $elem (@pathsToLink) {
return 1 if
$path eq "" ||
(substr($elem, 0, length($path)) eq $path
&& (($path eq $elem) || (substr($elem, length($path), 1) eq "/")));
}
return 0;
}
# Similar to `lib.isStorePath`
sub isStorePath {
my $path = shift;
my $storePath = "@storeDir@";
return substr($path, 0, 1) eq "/" && dirname($path) eq $storePath;
}
# For each activated package, determine what symlinks to create.
my %symlinks;
# Add all pathsToLink and all parent directories.
#
# For "/a/b/c" that will include
# [ "", "/a", "/a/b", "/a/b/c" ]
#
# That ensures the whole directory tree needed by pathsToLink is
# created as directories and not symlinks.
$symlinks{""} = ["", 0];
for my $p (@pathsToLink) {
my @parts = split '/', $p;
my $cur = "";
for my $x (@parts) {
$cur = $cur . "/$x";
$cur = "" if $cur eq "/";
$symlinks{$cur} = ["", 0];
}
}
sub findFiles;
sub findFilesInDir {
my ($relName, $target, $ignoreCollisions, $checkCollisionContents, $priority) = @_;
opendir DIR, "$target" or die "cannot open `$target': $!";
my @names = readdir DIR or die;
closedir DIR;
foreach my $name (@names) {
next if $name eq "." || $name eq "..";
findFiles("$relName/$name", "$target/$name", $name, $ignoreCollisions, $checkCollisionContents, $priority);
}
}
sub checkCollision {
my ($path1, $path2) = @_;
my $stat1 = (stat($path1))[2];
my $stat2 = (stat($path2))[2];
if ($stat1 != $stat2) {
warn "different permissions in `$path1' and `$path2': "
. sprintf("%04o", $stat1 & 07777) . " <-> "
. sprintf("%04o", $stat2 & 07777);
return 0;
}
return compare($path1, $path2) == 0;
}
sub findFiles {
my ($relName, $target, $baseName, $ignoreCollisions, $checkCollisionContents, $priority) = @_;
# The store path must not be a file
if (-f $target && isStorePath $target) {
die "The store path $target is a file and can't be merged into an environment using pkgs.buildEnv!";
}
# Urgh, hacky...
return if
$relName eq "/propagated-build-inputs" ||
$relName eq "/nix-support" ||
$relName =~ /info\/dir/ ||
( $relName =~ /^\/share\/mime\// && !( $relName =~ /^\/share\/mime\/packages/ ) ) ||
$baseName eq "perllocal.pod" ||
$baseName eq "log" ||
! (hasPathsToLink($relName) || isInPathsToLink($relName));
my ($oldTarget, $oldPriority) = @{$symlinks{$relName} // [undef, undef]};
# If target doesn't exist, create it. If it already exists as a
# symlink to a file (not a directory) in a lower-priority package,
# overwrite it.
if (!defined $oldTarget || ($priority < $oldPriority && ($oldTarget ne "" && ! -d $oldTarget))) {
$symlinks{$relName} = [$target, $priority];
return;
}
# If target already exists and both targets resolves to the same path, skip
if (defined $oldTarget && $oldTarget ne "" && abs_path($target) eq abs_path($oldTarget)) {
# Prefer the target that is not a symlink, if any
if (-l $oldTarget && ! -l $target) {
$symlinks{$relName} = [$target, $priority];
}
return;
}
# If target already exists as a symlink to a file (not a
# directory) in a higher-priority package, skip.
if (defined $oldTarget && $priority > $oldPriority && $oldTarget ne "" && ! -d $oldTarget) {
return;
}
unless (-d $target && ($oldTarget eq "" || -d $oldTarget)) {
if ($ignoreCollisions) {
warn "collision between `$target' and `$oldTarget'\n" if $ignoreCollisions == 1;
return;
} elsif ($checkCollisionContents && checkCollision($oldTarget, $target)) {
return;
} else {
die "collision between `$target' and `$oldTarget'\n";
}
}
findFilesInDir($relName, $oldTarget, $ignoreCollisions, $checkCollisionContents, $oldPriority) unless $oldTarget eq "";
findFilesInDir($relName, $target, $ignoreCollisions, $checkCollisionContents, $priority);
$symlinks{$relName} = ["", $priority]; # denotes directory
}
my %done;
my %postponed;
sub addPkg {
my ($pkgDir, $ignoreCollisions, $checkCollisionContents, $priority) = @_;
return if (defined $done{$pkgDir});
$done{$pkgDir} = 1;
findFiles("", $pkgDir, "", $ignoreCollisions, $checkCollisionContents, $priority);
my $propagatedFN = "$pkgDir/nix-support/propagated-user-env-packages";
if (-e $propagatedFN) {
open PROP, "<$propagatedFN" or die;
my $propagated = <PROP>;
close PROP;
my @propagated = split ' ', $propagated;
foreach my $p (@propagated) {
$postponed{$p} = 1 unless defined $done{$p};
}
}
}
# Read packages list.
my $pkgs;
if (exists $ENV{"pkgsPath"}) {
open FILE, $ENV{"pkgsPath"};
$pkgs = <FILE>;
close FILE;
} else {
$pkgs = $ENV{"pkgs"}
}
# Symlink to the packages that have been installed explicitly by the
# user.
for my $pkg (@{decode_json $pkgs}) {
for my $path (@{$pkg->{paths}}) {
addPkg($path,
$ENV{"ignoreCollisions"} eq "1",
$ENV{"checkCollisionContents"} eq "1",
$pkg->{priority})
if -e $path;
}
}
# Symlink to the packages that have been "propagated" by packages
# installed by the user (i.e., package X declares that it wants Y
# installed as well). We do these later because they have a lower
# priority in case of collisions.
my $priorityCounter = 1000; # don't care about collisions
while (scalar(keys %postponed) > 0) {
my @pkgDirs = keys %postponed;
%postponed = ();
foreach my $pkgDir (sort @pkgDirs) {
addPkg($pkgDir, 2, $ENV{"checkCollisionContents"} eq "1", $priorityCounter++);
}
}
# Create the symlinks.
my $extraPrefix = $ENV{"extraPrefix"};
my $nrLinks = 0;
foreach my $relName (sort keys %symlinks) {
my ($target, $priority) = @{$symlinks{$relName}};
my $abs = "$out" . "$extraPrefix" . "/$relName";
next unless isInPathsToLink $relName;
if ($target eq "") {
#print "creating directory $relName\n";
mkpath $abs or die "cannot create directory `$abs': $!";
} else {
#print "creating symlink $relName to $target\n";
symlink $target, $abs ||
die "error creating link `$abs': $!";
$nrLinks++;
}
}
print STDERR "created $nrLinks symlinks in user environment\n";
my $manifest = $ENV{"manifest"};
if ($manifest) {
symlink($manifest, "$out/manifest") or die "cannot create manifest";
}