mod_acquire - Zope-like acquisition for Apache

[Richard Jones <ri...@annexia.org>]

Attached below is a highly experimental module which I hacked together
in an hour or so to add "acquisition" (a la Zope) to Apache.

It's mainly for comment.  Is it the correct approach?  Are there other
Apache modules already available which can add acquisition?

Rich.

-- 
Richard Jones. http://www.annexia.org/ http://freshmeat.net/users/rwmj
Merjis Ltd. http://www.merjis.com/ - improving website return on investment
http://www.winwinsales.co.uk/ - CRM improvement consultancy

----------------------------------------------------------------------
/* ====================================================================
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 * Copyright (c) 2004 Merjis Ltd.  All rights reserved.
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/*
 * mod_acquire: Implement Zope-like acquisition for Apache.
 *
 * By Richard W.M. Jones <ri...@annexia.org>.
 * Copyright (C) 2004 Merjis Ltd.  http://www.merjis.com/
 */

#include "httpd.h"
#include "http_config.h"
#include "http_request.h"
#include "http_core.h"
#include "http_protocol.h"
#include "http_main.h"
#include "http_log.h"
#include "util_script.h"

typedef struct {
  int acquisition;		/* Set if enabled for this directory. */
} acquire_dir_config;

module acquire_module;

static void *
create_acquire_dir_config (pool *p, char *dummy)
{
  acquire_dir_config *new =
    (acquire_dir_config *) ap_palloc(p, sizeof (acquire_dir_config));

  new->acquisition = 0;
  return new;
}

static void *
merge_acquire_dir_configs (pool *p, void *basev, void *addv)
{
  acquire_dir_config *base = (acquire_dir_config *) basev;
  acquire_dir_config *add = (acquire_dir_config *) addv;
  acquire_dir_config *new =
    (acquire_dir_config *) ap_palloc (p, sizeof (acquire_dir_config));

  new->acquisition = add->acquisition || base->acquisition;
  return new;
}

static const char *
acquire (cmd_parms *cmd, acquire_dir_config *m, int enabled)
{
  m->acquisition = enabled;
  return NULL;
}

static const command_rec acquire_cmds[] =
{
  {"Acquire", acquire, NULL, ACCESS_CONF | RSRC_CONF, FLAG,
   "enable acquisition in this scope"},
  {NULL}
};

static char *
rindex_from (char *str, char *from, char c)
{
  while (str <= from)
    {
      if (*from == c) return from;
      from--;
    }
  return 0;
}

static int
no_file (request_rec *r)
{
  return
    r->uri[strlen (r->uri) - 1] != '/' &&
    (r->finfo.st_mode == 0 || (r->path_info && *r->path_info));
}

static char *
uri_above (request_rec *r)
{
  char *pi, *pj, *new_uri;
  int i, j;

  pi = rindex (r->uri, '/');
  if (pi == 0 || pi == r->uri) return 0;
  i = pi - r->uri;

  pj = rindex_from (r->uri, pi-1, '/');
  if (pj == 0) return 0;
  j = pj - r->uri;

  new_uri = ap_pstrdup (r->pool, r->uri);
  memmove (new_uri + j, new_uri + i, strlen (new_uri + i) + 1);
  return new_uri;
}

static int
acquire_fixups (request_rec *r)
{
  acquire_dir_config *conf = (acquire_dir_config *)
    ap_get_module_config (r->per_dir_config, &acquire_module);

  if (! conf->acquisition) return DECLINED;

  /* If the file exists, the core default_handler or another handler
   * will serve it.
   */
  if (! no_file (r)) return DECLINED;

  /* Otherwise, it's a missing file, so a candidate for acquisition. */
  r->handler = "acquire-handler";
  return OK;
}

static int
acquire_handler (request_rec *r)
{
  char *new_uri;

  /* This is a candidate for acquisition (file not found) so do it. */
  new_uri = uri_above (r);
  if (!new_uri) return DECLINED;

  /* XXX ap_escape_uri? */
  /* XXX ap_internal_redirect_handler? */
  ap_internal_redirect (new_uri, r);
  return OK;
}

static const handler_rec acquire_handlers[] =
{
    {"acquire-handler", acquire_handler},
    {NULL}
};

module acquire_module =
{
    STANDARD_MODULE_STUFF,
    NULL,			/* initializer */
    create_acquire_dir_config,	/* dir config creater */
    merge_acquire_dir_configs,	/* dir merger --- default is to override */
    NULL,			/* server config */
    NULL,			/* merge server config */
    acquire_cmds,		/* command table */
    acquire_handlers,		/* handlers */
    NULL,			/* filename translation */
    NULL,			/* check_user_id */
    NULL,			/* check auth */
    NULL,			/* check access */
    NULL,			/* type_checker */
    acquire_fixups,		/* fixups */
    NULL,			/* logger */
    NULL,			/* header parser */
    NULL,			/* child_init */
    NULL,			/* child_exit */
    NULL			/* post read-request */
};