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 our $program_to_wrap = $0;
  32 sub gen_wrapper () {
  33         $config{srcdir}=File::Spec->rel2abs($config{srcdir});
  34         $config{destdir}=File::Spec->rel2abs($config{destdir});
  35         my $this=File::Spec->rel2abs($program_to_wrap);
  36         if (! -x $this) {
  37                 error(sprintf(gettext("%s doesn't seem to be executable"), $this));
  38         }
  39
  40         if ($config{setup}) {
  41                 error(gettext("cannot create a wrapper that uses a setup file"));
  42         }
  43         my $wrapper=possibly_foolish_untaint($config{wrapper});
  44         if (! defined $wrapper || ! length $wrapper) {
  45                 error(gettext("wrapper filename not specified"));
  46         }
  47         delete $config{wrapper};
  48
  49         my @envsave;
  50         push @envsave, qw{REMOTE_ADDR QUERY_STRING REQUEST_METHOD REQUEST_URI
  51                        CONTENT_TYPE CONTENT_LENGTH GATEWAY_INTERFACE
  52                        HTTP_COOKIE REMOTE_USER HTTPS REDIRECT_STATUS
  53                        HTTP_HOST SERVER_PORT HTTPS HTTP_ACCEPT
  54                        REDIRECT_URL} if $config{cgi};
  55         my $envsize=$#envsave;
  56         my $envsave="";
  57         foreach my $var (@envsave) {
  58                 $envsave.=<<"EOF";
  59         if ((s=getenv("$var")))
  60                 addenv("$var", s);
  61 EOF
  62         }
  63         if (ref $config{ENV} eq 'HASH') {
  64                 foreach my $key (keys %{$config{ENV}}) {
  65                         my $val=$config{ENV}{$key};
  66                         $val =~ s/([\\"])/\\$1/g;
  67                         $envsize += 1;
  68                         $envsave.=<<"EOF";
  69         addenv("$key", "$val");
  70 EOF
  71                 }
  72                 delete $config{ENV};
  73         }
  74
  75         my @wrapper_hooks;
  76         run_hooks(genwrapper => sub { push @wrapper_hooks, shift->() });
  77
  78         my $check_commit_hook="";
  79         my $pre_exec="";
  80         if ($config{post_commit}) {
  81                 # Optimise checking !commit_hook_enabled() ,
  82                 # so that ikiwiki does not have to be started if the
  83                 # hook is disabled.
  84                 #
  85                 # Note that perl's flock may be implemented using fcntl
  86                 # or lockf on some systems. If so, and if there is no
  87                 # interop between the locking systems, the true C flock will
  88                 # always succeed, and this optimisation won't work.
  89                 # The perl code will later correctly check the lock,
  90                 # so the right thing will still happen, though without
  91                 # the benefit of this optimisation.
  92                 $check_commit_hook=<<"EOF";
  93         {
  94                 int fd=open("$config{wikistatedir}/commitlock", O_CREAT | O_RDWR, 0666);
  95                 if (fd != -1) {
  96                         if (flock(fd, LOCK_SH | LOCK_NB) != 0)
  97                                 exit(0);
  98                         close(fd);
  99                 }
 100         }
 101 EOF
 102         }
 103         elsif ($config{cgi}) {
 104                 # Avoid more than one ikiwiki cgi running at a time by
 105                 # taking a cgi lock. Since ikiwiki uses several MB of
 106                 # memory, a pile up of processes could cause thrashing
 107                 # otherwise. The fd of the lock is stored in
 108                 # IKIWIKI_CGILOCK_FD so unlockwiki can close it.
 109                 #
 110                 # A lot of cgi wrapper processes can potentially build
 111                 # up and clog an otherwise unloaded web server. To
 112                 # partially avoid this, when a GET comes in and the lock
 113                 # is already held, rather than blocking a html page is
 114                 # constructed that retries. This is enabled by setting
 115                 # cgi_overload_delay.
 116                 if (defined $config{cgi_overload_delay} &&
 117                     $config{cgi_overload_delay} =~/^[0-9]+/) {
 118                         my $i=int($config{cgi_overload_delay});
 119                         $pre_exec.="#define CGI_OVERLOAD_DELAY $i\n"
 120                                 if $i > 0;
 121                         my $msg=gettext("Please wait");
 122                         $msg=~s/"/\\"/g;
 123                         $pre_exec.='#define CGI_PLEASE_WAIT_TITLE "'.$msg."\"\n";
 124                         if (defined $config{cgi_overload_message} && length $config{cgi_overload_message}) {
 125                                 $msg=$config{cgi_overload_message};
 126                                 $msg=~s/"/\\"/g;
 127                         }
 128                         $pre_exec.='#define CGI_PLEASE_WAIT_BODY "'.$msg."\"\n";
 129                 }
 130                 $pre_exec.=<<"EOF";
 131         lockfd=open("$config{wikistatedir}/cgilock", O_CREAT | O_RDWR, 0666);
 132         if (lockfd != -1) {
 133 #ifdef CGI_OVERLOAD_DELAY
 134                 char *request_method = getenv("REQUEST_METHOD");
 135                 if (request_method && strcmp(request_method, "GET") == 0) {
 136                         if (lockf(lockfd, F_TLOCK, 0) == 0) {
 137                                 set_cgilock_fd(lockfd);
 138                         }
 139                         else {
 140                                 printf("Content-Type: text/html\\nRefresh: %i; URL=%s\\n\\n<html><head><title>%s</title><head><body><p>%s</p></body></html>",
 141                                         CGI_OVERLOAD_DELAY,
 142                                         getenv("REQUEST_URI"),
 143                                         CGI_PLEASE_WAIT_TITLE,
 144                                         CGI_PLEASE_WAIT_BODY);
 145                                 exit(0);
 146                         }
 147                 }
 148                 else if (lockf(lockfd, F_LOCK, 0) == 0) {
 149                         set_cgilock_fd(lockfd);
 150                 }
 151 #else
 152                 if (lockf(lockfd, F_LOCK, 0) == 0) {
 153                         set_cgilock_fd(lockfd);
 154                 }
 155 #endif
 156         }
 157 EOF
 158         }
 159
 160         my $set_background_command='';
 161         if (defined $config{wrapper_background_command} &&
 162             length $config{wrapper_background_command}) {
 163                 my $background_command=delete $config{wrapper_background_command};
 164                 $set_background_command=~s/"/\\"/g;
 165                 $set_background_command='#define BACKGROUND_COMMAND "'.$background_command.'"';
 166         }
 167
 168         $Data::Dumper::Indent=0; # no newlines
 169         my $configstring=Data::Dumper->Dump([\%config], ['*config']);
 170         $configstring=~s/\\/\\\\/g;
 171         $configstring=~s/"/\\"/g;
 172         $configstring=~s/\n/\\n/g;
 173
 174         writefile(basename("$wrapper.c"), dirname($wrapper), <<"EOF");
 175 /* A wrapper for ikiwiki, can be safely made suid. */
 176 #include <stdio.h>
 177 #include <sys/types.h>
 178 #include <sys/stat.h>
 179 #include <fcntl.h>
 180 #include <unistd.h>
 181 #include <stdlib.h>
 182 #include <string.h>
 183 #include <sys/file.h>
 184
 185 extern char **environ;
 186 char *newenviron[$envsize+7];
 187 int i=0;
 188
 189 void addenv(char *var, char *val) {
 190         char *s=malloc(strlen(var)+1+strlen(val)+1);
 191         if (!s)
 192                 perror("malloc");
 193         sprintf(s, "%s=%s", var, val);
 194         newenviron[i++]=s;
 195 }
 196
 197 void set_cgilock_fd (int lockfd) {
 198         char *fd_s=malloc(8);
 199         sprintf(fd_s, "%i", lockfd);
 200         setenv("IKIWIKI_CGILOCK_FD", fd_s, 1);
 201 }
 202
 203 int main (int argc, char **argv) {
 204         int lockfd=-1;
 205         char *s;
 206
 207 $check_commit_hook
 208 @wrapper_hooks
 209 $envsave
 210         newenviron[i++]="HOME=$ENV{HOME}";
 211         newenviron[i++]="PATH=$ENV{PATH}";
 212         newenviron[i++]="WRAPPED_OPTIONS=$configstring";
 213
 214 #ifdef __TINYC__
 215         /* old tcc versions do not support modifying environ directly */
 216         if (clearenv() != 0) {
 217                 perror("clearenv");
 218                 exit(1);
 219         }
 220         for (; i>0; i--)
 221                 putenv(newenviron[i-1]);
 222 #else
 223         newenviron[i]=NULL;
 224         environ=newenviron;
 225 #endif
 226
 227         if (setregid(getegid(), -1) != 0 &&
 228             setregid(getegid(), -1) != 0) {
 229                 perror("failed to drop real gid");
 230                 exit(1);
 231         }
 232         if (setreuid(geteuid(), -1) != 0 &&
 233             setreuid(geteuid(), -1) != 0) {
 234                 perror("failed to drop real uid");
 235                 exit(1);
 236         }
 237
 238 $pre_exec
 239
 240 $set_background_command
 241 #ifdef BACKGROUND_COMMAND
 242         if (lockfd != -1) {
 243                 close(lockfd);
 244         }
 245
 246         pid_t pid=fork();
 247         if (pid == -1) {
 248                 perror("fork");
 249                 exit(1);
 250         }
 251         else if (pid == 0) {
 252                 execl("$this", "$this", NULL);
 253                 perror("exec $this");
 254                 exit(1);
 255         }
 256         else {
 257                 waitpid(pid, NULL, 0);
 258
 259                 if (daemon(1, 0) == 0) {
 260                         system(BACKGROUND_COMMAND);
 261                         exit(0);
 262                 }
 263                 else {
 264                         perror("daemon");
 265                         exit(1);
 266                 }
 267         }
 268 #else
 269         execl("$this", "$this", NULL);
 270         perror("exec $this");
 271         exit(1);
 272 #endif
 273 }
 274 EOF
 275
 276         my @cc=exists $ENV{CC} ? possibly_foolish_untaint($ENV{CC}) : 'cc';
 277         push @cc, split(' ', possibly_foolish_untaint($ENV{CFLAGS})) if exists $ENV{CFLAGS};
 278         if (system(@cc, "$wrapper.c", "-o", "$wrapper.new") != 0) {
 279                 #translators: The parameter is a C filename.
 280                 error(sprintf(gettext("failed to compile %s"), "$wrapper.c"));
 281         }
 282         unlink("$wrapper.c");
 283         if (defined $config{wrappergroup}) {
 284                 my $gid=(getgrnam($config{wrappergroup}))[2];
 285                 if (! defined $gid) {
 286                         error(sprintf("bad wrappergroup"));
 287                 }
 288                 if (! chown(-1, $gid, "$wrapper.new")) {
 289                         error("chown $wrapper.new: $!");
 290                 }
 291         }
 292         if (defined $config{wrappermode} &&
 293             ! chmod(oct($config{wrappermode}), "$wrapper.new")) {
 294                 error("chmod $wrapper.new: $!");
 295         }
 296         if (! rename("$wrapper.new", $wrapper)) {
 297                 error("rename $wrapper.new $wrapper: $!");
 298         }
 299         #translators: The parameter is a filename.
 300         debug(sprintf(gettext("successfully generated %s"), $wrapper));
 301 }
 302
 303 1