www-cgi/: Decentralize the whitelist of environment variables.

[userv-utils] / www-cgi / ucgicommon.c

/*
 * Copyright (C) 1998-1999,2003 Ian Jackson
 *
 * This is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful, but
 * WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with userv-utils; if not, write to the Free Software
 * Foundation, 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
 *
 * $Id$
 */

#include <stdio.h>
#include <string.h>
#include <errno.h>

#include <unistd.h>

#include "ucgi.h"

int debugmode= 0;

static void outerror(void) {
  perror("stdout");
  exit(debugmode ? 0 : -1);
}

void syserror(const char *m) {
  if (printf("Content-Type: text/plain\n\n"
	     "ucgi: system call error:\n"
	     "%s: %s\n",
	     m,strerror(errno))==EOF || fflush(stdout)) outerror();
  exit(0);
}

void error(const char *m) {
  if (printf("Content-Type: text/plain\n\n"
	     "ucgi: error:\n"
	     "%s\n",
	     m)==EOF || fflush(stdout)) outerror();
  exit(0);
}

void *xmalloc(size_t sz) {
  void *r;

  r= malloc(sz);
  if (!r) syserror("malloc failed");
  return r;
}

void *xrealloc(void *ptr, size_t sz) {
  void *r;

  r= realloc(ptr,sz);
  if (!r) syserror("realloc failed");
  return r;
}

void xsetenv(const char *en, const char *ev, int overwrite) {
  if (setenv(en,ev,overwrite)) syserror("setenv");
}

void filter_environment(unsigned flags, const char *prefix_in,
			const char *const *patv,
			void (*foundone)(const char *fulln,
					 const char *en, const char *ev,
					 void *p),
			void *p)
{
  char *const *ep;
  const char *const *patp;
  const char *en, *ev, *pat, *q;
  char enbuf[MAX_ENVVAR_NAME];
  size_t n, pn = strlen(prefix_in);
  int acceptp;

  D( if (debugmode) printf(";; filter_environment...\n"); )
  for (ep= environ; (en= *ep); ep++) {
    D( if (debugmode) printf(";;   consider env-var `%s'\n", en); )
    if (strncmp(en, prefix_in, pn) != 0 || !en[pn]) {
      D( if (debugmode) printf(";;     doesn't match prefix\n"); )
      goto next_ev;
    }
    for (patp= patv; (pat= *patp); patp++) {
      q= en + pn;
      acceptp= 1;
      if (*pat == '!' && (flags & FILTF_WILDCARD)) {
	acceptp= 0; pat++;
      }
      for (;;) {
	if (!*pat) {
	  if (*q != '=') {
	    D( if (debugmode)
		 printf(";;     mismatch `%s' (prefix)\n", *patp); )
	    goto next_pat;
	  }
	  D( if (debugmode) printf(";;     matched `%s'\n", *patp); )
	  ev = q + 1;
	  break;
	} else if (*pat == '*' && (flags & FILTF_WILDCARD)) {
	  q = strchr(q, '=');
	  if (!q) {
	    D( if (debugmode)
		 printf(";;     mismatch `%s' (discard: no `=')\n", *patp); )
	    goto next_ev;
	  }
	  D( if (debugmode)
	       printf(";;     wildcard match for `%s'\n", *patp); )
	  ev = q + 1;
	  break;
	} else
	  if (*pat++ != *q++) {
	    D( if (debugmode) printf(";;     mismatch `%s'\n", *patp); )
	    goto next_pat;
	  }
      }
      if (acceptp) {
	n= q - en;
	if (n >= sizeof(enbuf))
	  error("environment variable name too long");
	memcpy(enbuf, en, n);
	enbuf[n]= 0;
	D( if (debugmode)
	     printf(";;     full = `%s'; tail = `%s'; value = `%s'\n",
		    enbuf, enbuf + pn, ev); )
	foundone(enbuf, enbuf + pn, ev, p);
      } D( else if (debugmode)
	     printf(";;     matched negated pattern\n"); )
      goto next_ev;
    next_pat:;
    }
  next_ev:;
  }
}