IkiWiki/Wrapper.pm

   1 #!/usr/bin/perl
   2
   3 package IkiWiki;
   4
   5 use warnings;
   6 use strict;
   7 use File::Spec;
   8 use Data::Dumper;
   9 use IkiWiki;
  10
  11 sub gen_wrappers () {
  12         debug(gettext("generating wrappers.."));
  13         my %origconfig=(%config);
  14         foreach my $wrapper (@{$config{wrappers}}) {
  15                 %config=(%origconfig, %{$wrapper});
  16                 $config{verbose}=$config{setupverbose}
  17                         if exists $config{setupverbose};
  18                 $config{syslog}=$config{setupsyslog}
  19                         if exists $config{setupsyslog};
  20                 delete @config{qw(setupsyslog setupverbose wrappers genwrappers rebuild)};
  21                 checkconfig();
  22                 if (! $config{cgi} && ! $config{post_commit} &&
  23                     ! $config{test_receive}) {
  24                         $config{post_commit}=1;
  25                 }
  26                 gen_wrapper();
  27         }
  28         %config=(%origconfig);
  29 }
  30
  31 sub gen_wrapper () {
  32         $config{srcdir}=File::Spec->rel2abs($config{srcdir});
  33         $config{destdir}=File::Spec->rel2abs($config{destdir});
  34         my $this=File::Spec->rel2abs($0);
  35         if (! -x $this) {
  36                 error(sprintf(gettext("%s doesn't seem to be executable"), $this));
  37         }
  38
  39         if ($config{setup}) {
  40                 error(gettext("cannot create a wrapper that uses a setup file"));
  41         }
  42         my $wrapper=possibly_foolish_untaint($config{wrapper});
  43         if (! defined $wrapper || ! length $wrapper) {
  44                 error(gettext("wrapper filename not specified"));
  45         }
  46         delete $config{wrapper};
  47
  48         my @envsave;
  49         push @envsave, qw{REMOTE_ADDR QUERY_STRING REQUEST_METHOD REQUEST_URI
  50                        CONTENT_TYPE CONTENT_LENGTH GATEWAY_INTERFACE
  51                        HTTP_COOKIE REMOTE_USER HTTPS REDIRECT_STATUS
  52                        HTTP_HOST SERVER_PORT HTTPS
  53                        REDIRECT_URL} if $config{cgi};
  54         my $envsave="";
  55         foreach my $var (@envsave) {
  56                 $envsave.=<<"EOF";
  57         if ((s=getenv("$var")))
  58                 addenv("$var", s);
  59 EOF
  60         }
  61
  62         my @wrapper_hooks;
  63         run_hooks(genwrapper => sub { push @wrapper_hooks, shift->() });
  64
  65         my $check_commit_hook="";
  66         my $pre_exec="";
  67         if ($config{post_commit}) {
  68                 # Optimise checking !commit_hook_enabled() ,
  69                 # so that ikiwiki does not have to be started if the
  70                 # hook is disabled.
  71                 #
  72                 # Note that perl's flock may be implemented using fcntl
  73                 # or lockf on some systems. If so, and if there is no
  74                 # interop between the locking systems, the true C flock will
  75                 # always succeed, and this optimisation won't work.
  76                 # The perl code will later correctly check the lock,
  77                 # so the right thing will still happen, though without
  78                 # the benefit of this optimisation.
  79                 $check_commit_hook=<<"EOF";
  80         {
  81                 int fd=open("$config{wikistatedir}/commitlock", O_CREAT | O_RDWR, 0666);
  82                 if (fd != -1) {
  83                         if (flock(fd, LOCK_SH | LOCK_NB) != 0)
  84                                 exit(0);
  85                         close(fd);
  86                 }
  87         }
  88 EOF
  89         }
  90         elsif ($config{cgi}) {
  91                 # Avoid more than one ikiwiki cgi running at a time by
  92                 # taking a cgi lock. Since ikiwiki uses several MB of
  93                 # memory, a pile up of processes could cause thrashing
  94                 # otherwise. The fd of the lock is stored in
  95                 # IKIWIKI_CGILOCK_FD so unlockwiki can close it.
  96                 $pre_exec=<<"EOF";
  97         lockfd=open("$config{wikistatedir}/cgilock", O_CREAT | O_RDWR, 0666);
  98         if (lockfd != -1 && flock(lockfd, LOCK_EX) == 0) {
  99                 char *fd_s=malloc(8);
 100                 sprintf(fd_s, "%i", lockfd);
 101                 setenv("IKIWIKI_CGILOCK_FD", fd_s, 1);
 102         }
 103 EOF
 104         }
 105
 106         my $set_background_command='';
 107         if (defined $config{wrapper_background_command} &&
 108             length $config{wrapper_background_command}) {
 109                 my $background_command=delete $config{wrapper_background_command};
 110                 $set_background_command=~s/"/\\"/g;
 111                 $set_background_command='#define BACKGROUND_COMMAND "'.$background_command.'"';
 112         }
 113
 114         $Data::Dumper::Indent=0; # no newlines
 115         my $configstring=Data::Dumper->Dump([\%config], ['*config']);
 116         $configstring=~s/\\/\\\\/g;
 117         $configstring=~s/"/\\"/g;
 118         $configstring=~s/\n/\\n/g;
 119
 120         writefile(basename("$wrapper.c"), dirname($wrapper), <<"EOF");
 121 /* A wrapper for ikiwiki, can be safely made suid. */
 122 #include <stdio.h>
 123 #include <sys/types.h>
 124 #include <sys/stat.h>
 125 #include <fcntl.h>
 126 #include <unistd.h>
 127 #include <stdlib.h>
 128 #include <string.h>
 129 #include <sys/file.h>
 130
 131 extern char **environ;
 132 char *newenviron[$#envsave+7];
 133 int i=0;
 134
 135 void addenv(char *var, char *val) {
 136         char *s=malloc(strlen(var)+1+strlen(val)+1);
 137         if (!s)
 138                 perror("malloc");
 139         sprintf(s, "%s=%s", var, val);
 140         newenviron[i++]=s;
 141 }
 142
 143 int main (int argc, char **argv) {
 144         int lockfd=-1;
 145         char *s;
 146
 147 $check_commit_hook
 148 @wrapper_hooks
 149 $envsave
 150         newenviron[i++]="HOME=$ENV{HOME}";
 151         newenviron[i++]="PATH=$ENV{PATH}";
 152         newenviron[i++]="WRAPPED_OPTIONS=$configstring";
 153
 154 #ifdef __TINYC__
 155         /* old tcc versions do not support modifying environ directly */
 156         if (clearenv() != 0) {
 157                 perror("clearenv");
 158                 exit(1);
 159         }
 160         for (; i>0; i--)
 161                 putenv(newenviron[i-1]);
 162 #else
 163         newenviron[i]=NULL;
 164         environ=newenviron;
 165 #endif
 166
 167         if (setregid(getegid(), -1) != 0 &&
 168             setregid(getegid(), -1) != 0) {
 169                 perror("failed to drop real gid");
 170                 exit(1);
 171         }
 172         if (setreuid(geteuid(), -1) != 0 &&
 173             setreuid(geteuid(), -1) != 0) {
 174                 perror("failed to drop real uid");
 175                 exit(1);
 176         }
 177
 178 $pre_exec
 179
 180 $set_background_command
 181 #ifdef BACKGROUND_COMMAND
 182         if (lockfd != -1) {
 183                 close(lockfd);
 184         }
 185
 186         pid_t pid=fork();
 187         if (pid == -1) {
 188                 perror("fork");
 189                 exit(1);
 190         }
 191         else if (pid == 0) {
 192                 execl("$this", "$this", NULL);
 193                 perror("exec $this");
 194                 exit(1);
 195         }
 196         else {
 197                 waitpid(pid, NULL, 0);
 198
 199                 if (daemon(1, 0) == 0) {
 200                         system(BACKGROUND_COMMAND);
 201                         exit(0);
 202                 }
 203                 else {
 204                         perror("daemon");
 205                         exit(1);
 206                 }
 207         }
 208 #else
 209         execl("$this", "$this", NULL);
 210         perror("exec $this");
 211         exit(1);
 212 #endif
 213 }
 214 EOF
 215
 216         my @cc=exists $ENV{CC} ? possibly_foolish_untaint($ENV{CC}) : 'cc';
 217         push @cc, possibly_foolish_untaint($ENV{CFLAGS}) if exists $ENV{CFLAGS};
 218         if (system(@cc, "$wrapper.c", "-o", "$wrapper.new") != 0) {
 219                 #translators: The parameter is a C filename.
 220                 error(sprintf(gettext("failed to compile %s"), "$wrapper.c"));
 221         }
 222         unlink("$wrapper.c");
 223         if (defined $config{wrappergroup}) {
 224                 my $gid=(getgrnam($config{wrappergroup}))[2];
 225                 if (! defined $gid) {
 226                         error(sprintf("bad wrappergroup"));
 227                 }
 228                 if (! chown(-1, $gid, "$wrapper.new")) {
 229                         error("chown $wrapper.new: $!");
 230                 }
 231         }
 232         if (defined $config{wrappermode} &&
 233             ! chmod(oct($config{wrappermode}), "$wrapper.new")) {
 234                 error("chmod $wrapper.new: $!");
 235         }
 236         if (! rename("$wrapper.new", $wrapper)) {
 237                 error("rename $wrapper.new $wrapper: $!");
 238         }
 239         #translators: The parameter is a filename.
 240         printf(gettext("successfully generated %s"), $wrapper);
 241         print "\n";
 242 }
 243
 244 1