aboutsummaryrefslogtreecommitdiff
path: root/IkiWiki/Wrapper.pm
blob: f175b4a0ba168242ebb8396d6608cdb001cb0b34 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
#!/usr/bin/perl

package IkiWiki;

use warnings;
use strict;
use File::Spec;
use Data::Dumper;
use IkiWiki;

sub gen_wrapper () {
	$config{srcdir}=File::Spec->rel2abs($config{srcdir});
	$config{destdir}=File::Spec->rel2abs($config{destdir});
	my $this=File::Spec->rel2abs($0);
	if (! -x $this) {
		error(sprintf(gettext("%s doesn't seem to be executable"), $this));
	}

	if ($config{setup}) {
		error(gettext("cannot create a wrapper that uses a setup file"));
	}
	my $wrapper=possibly_foolish_untaint($config{wrapper});
	if (! defined $wrapper || ! length $wrapper) {
		error(gettext("wrapper filename not specified"));
	}
	delete $config{wrapper};
	
	my @envsave;
	push @envsave, qw{REMOTE_ADDR QUERY_STRING REQUEST_METHOD REQUEST_URI
	               CONTENT_TYPE CONTENT_LENGTH GATEWAY_INTERFACE
		       HTTP_COOKIE REMOTE_USER HTTPS REDIRECT_STATUS
		       REDIRECT_URL} if $config{cgi};
	my $envsave="";
	foreach my $var (@envsave) {
		$envsave.=<<"EOF";
	if ((s=getenv("$var")))
		addenv("$var", s);
EOF
	}
	
	my @wrapper_hooks;
	run_hooks(genwrapper => sub { push @wrapper_hooks, shift->() });

	my $check_commit_hook="";
	my $pre_exec="";
	if ($config{post_commit}) {
		# Optimise checking !commit_hook_enabled() , 
		# so that ikiwiki does not have to be started if the
		# hook is disabled.
		#
		# Note that perl's flock may be implemented using fcntl
		# or lockf on some systems. If so, and if there is no
		# interop between the locking systems, the true C flock will
		# always succeed, and this optimisation won't work.
		# The perl code will later correctly check the lock,
		# so the right thing will still happen, though without
		# the benefit of this optimisation.
		$check_commit_hook=<<"EOF";
	{
		int fd=open("$config{wikistatedir}/commitlock", O_CREAT | O_RDWR, 0666);
		if (fd != -1) {
			if (flock(fd, LOCK_SH | LOCK_NB) != 0)
				exit(0);
			close(fd);
		}
	}
EOF
	}
	elsif ($config{cgi}) {
		# Avoid more than one ikiwiki cgi running at a time by
		# taking a cgi lock. Since ikiwiki uses several MB of
		# memory, a pile up of processes could cause thrashing
		# otherwise. The fd of the lock is stored in
		# IKIWIKI_CGILOCK_FD so unlockwiki can close it.
		$pre_exec=<<"EOF";
	{
		int fd=open("$config{wikistatedir}/cgilock", O_CREAT | O_RDWR, 0666);
		if (fd != -1 && flock(fd, LOCK_EX) == 0) {
			char *fd_s=malloc(8);
			sprintf(fd_s, "%i", fd);
			setenv("IKIWIKI_CGILOCK_FD", fd_s, 1);
		}
	}
EOF
	}

	$Data::Dumper::Indent=0; # no newlines
	my $configstring=Data::Dumper->Dump([\%config], ['*config']);
	$configstring=~s/\\/\\\\/g;
	$configstring=~s/"/\\"/g;
	$configstring=~s/\n/\\n/g;
	
	writefile(basename("$wrapper.c"), dirname($wrapper), <<"EOF");
/* A wrapper for ikiwiki, can be safely made suid. */
#include <stdio.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <unistd.h>
#include <stdlib.h>
#include <string.h>
#include <sys/file.h>

char *newenviron[$#envsave+6];
int i=0;

void addenv(char *var, char *val) {
	char *s=malloc(strlen(var)+1+strlen(val)+1);
	if (!s)
		perror("malloc");
	sprintf(s, "%s=%s", var, val);
	newenviron[i++]=s;
}

int main (int argc, char **argv) {
	char *s;

$check_commit_hook
@wrapper_hooks
$envsave
	newenviron[i++]="HOME=$ENV{HOME}";
	newenviron[i++]="WRAPPED_OPTIONS=$configstring";

	if (clearenv() != 0) {
		perror("clearenv");
		exit(1);
	}
	for (; i>0; i--)
		putenv(newenviron[i-1]);

	if (setregid(getegid(), -1) != 0 &&
	    setregid(getegid(), -1) != 0) {
		perror("failed to drop real gid");
		exit(1);
	}
	if (setreuid(geteuid(), -1) != 0 &&
	    setreuid(geteuid(), -1) != 0) {
		perror("failed to drop real uid");
		exit(1);
	}

$pre_exec
	execl("$this", "$this", NULL);
	perror("exec $this");
	exit(1);
}
EOF

	my @cc=exists $ENV{CC} ? possibly_foolish_untaint($ENV{CC}) : 'cc';
	push @cc, possibly_foolish_untaint($ENV{CFLAGS}) if exists $ENV{CFLAGS};
	if (system(@cc, "$wrapper.c", "-o", "$wrapper.new") != 0) {
		#translators: The parameter is a C filename.
		error(sprintf(gettext("failed to compile %s"), "$wrapper.c"));
	}
	unlink("$wrapper.c");
	if (defined $config{wrappergroup}) {
		my $gid=(getgrnam($config{wrappergroup}))[2];
		if (! defined $gid) {
			error(sprintf("bad wrappergroup"));
		}
		if (! chown(-1, $gid, "$wrapper.new")) {
			error("chown $wrapper.new: $!");
		}
	}
	if (defined $config{wrappermode} &&
	    ! chmod(oct($config{wrappermode}), "$wrapper.new")) {
		error("chmod $wrapper.new: $!");
	}
	if (! rename("$wrapper.new", $wrapper)) {
		error("rename $wrapper.new $wrapper: $!");
	}
	#translators: The parameter is a filename.
	printf(gettext("successfully generated %s"), $wrapper);
	print "\n";
}

1