stor_man.c

harvest是一个下载html网页得机器人

static char rcsid[] = "$Id: stor_man.c,v 2.3 2000/01/21 17:37:33 sxw Exp $";
/*
 *   stor_man.c -- Stores and retreives Summary Objects in the Broker.
 *   This storage manager is based on the UNIX file system.
 *
 *  DEBUG: section  74, level 1		Broker storage manager routines
 *  AUTHOR: Harvest derived
 *
 *  Harvest Indexer http://www.tardis.ed.ac.uk/harvest/
 *  ---------------------------------------------------
 *
 *  The Harvest Indexer is a continued development of code developed by
 *  the Harvest Project. Development is carried out by numerous individuals
 *  in the Internet community, and is not officially connected with the
 *  original Harvest Project or its funding sources.
 *
 *  Please mail [e-mail] if you are interested in participating
 *  in the development effort.
 *
 *  This program 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 this program; if not, write to the Free Software
 *  Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
 */
/*  ----------------------------------------------------------------------
 *  Copyright (c) 1994, 1995.  All rights reserved.
 *
 *    The Harvest software was developed by the Internet Research Task
 *    Force Research Group on Resource Discovery (IRTF-RD):
 *
 *          Mic Bowman of Transarc Corporation.
 *          Peter Danzig of the University of Southern California.
 *          Darren R. Hardy of the University of Colorado at Boulder.
 *          Udi Manber of the University of Arizona.
 *          Michael F. Schwartz of the University of Colorado at Boulder.
 *          Duane Wessels of the University of Colorado at Boulder.
 *
 *    This copyright notice applies to software in the Harvest
 *    ``src/'' directory only.  Users should consult the individual
 *    copyright notices in the ``components/'' subdirectories for
 *    copyright information about other software bundled with the
 *    Harvest source code distribution.
 *
 *  TERMS OF USE
 *
 *    The Harvest software may be used and re-distributed without
 *    charge, provided that the software origin and research team are
 *    cited in any use of the system.  Most commonly this is
 *    accomplished by including a link to the Harvest Home Page
 *    (http://harvest.cs.colorado.edu/) from the query page of any
 *    Broker you deploy, as well as in the query result pages.  These
 *    links are generated automatically by the standard Broker
 *    software distribution.
 *
 *    The Harvest software is provided ``as is'', without express or
 *    implied warranty, and with no support nor obligation to assist
 *    in its use, correction, modification or enhancement.  We assume
 *    no liability with respect to the infringement of copyrights,
 *    trade secrets, or any patents, and are not responsible for
 *    consequential damages.  Proper use of the Harvest software is
 *    entirely the responsibility of the user.
 *
 *  DERIVATIVE WORKS
 *
 *    Users may make derivative works from the Harvest software, subject
 *    to the following constraints:
 *
 *      - You must include the above copyright notice and these
 *        accompanying paragraphs in all forms of derivative works,
 *        and any documentation and other materials related to such
 *        distribution and use acknowledge that the software was
 *        developed at the above institutions.
 *
 *      - You must notify IRTF-RD regarding your distribution of
 *        the derivative work.
 *
 *      - You must clearly notify users that your are distributing
 *        a modified version and not the original Harvest software.
 *
 *      - Any derivative product is also subject to these copyright
 *        and use restrictions.
 *
 *    Note that the Harvest software is NOT in the public domain.  We
 *    retain copyright, as specified above.
 *
 *  HISTORY OF FREE SOFTWARE STATUS
 *
 *    Originally we required sites to license the software in cases
 *    where they were going to build commercial products/services
 *    around Harvest.  In June 1995 we changed this policy.  We now
 *    allow people to use the core Harvest software (the code found in
 *    the Harvest ``src/'' directory) for free.  We made this change
 *    in the interest of encouraging the widest possible deployment of
 *    the technology.  The Harvest software is really a reference
 *    implementation of a set of protocols and formats, some of which
 *    we intend to standardize.  We encourage commercial
 *    re-implementations of code complying to this set of standards.
 *
 */
#include <stdlib.h>

#include "broker.h"
#include "log.h"


/* Global variables */
extern char *DIRpath;
extern char *brk_obj_url;

/* Local functions */
char *SM_Get_Obj_Filename();	/* exported to other modules */
static fd_t new_fd_value();

/* #define MAX_DIR 100 */
#define MAX_DIR 256

/*
 *  SM_Init - Initialize the Storage Manager.
 */
int SM_Init()
{
	int i;
	char buf[BUFSIZ];

	Log("Storage Manager: Initializing...\n");
	sprintf(buf, "%s/objects", DIRpath);
	if ((mkdir(buf, 0775) < 0) && errno != EEXIST) {
		log_errno(buf);
		return ERROR;
	}
	for (i = 0; i < MAX_DIR; i++) {
		sprintf(buf, "%s/objects/%d", DIRpath, i);
		if (mkdir(buf, 0775) < 0) {
			if (errno != EEXIST) {
				log_errno(buf);
				return ERROR;
			}
		}
	}
	return SUCCESS;
}

/*
 *  SM_Create_Obj - Creates a new object in the Storage Manager.
 *  Assigns a new FD and returns it.
 */
fd_t SM_Create_Obj()
{
	int i;
	fd_t new_fd;

	/* Try at most 100 times to create the object */
	for (i = 0; i < 100; i++) {
		new_fd = new_fd_value();
		if (SM_Exist_Obj(new_fd) == FALSE) {
			return(new_fd); /* non-existant, so use it. */
		}
	}

	/* this is very rare */
	errorlog("SM_Create_Obj: Unable to generate unique FD.\n");
	return ERROR;
}

/*
 *  SM_Read_Obj - Reads the object from the storage manager.  Returns
 *  a FILE * so that the caller can read the data.  Returns NULL on error.
 */
FILE *SM_Read_Obj(FD)
fd_t FD;
{
	static FILE *fp;
	char *fn;
	int fd;

	fp = NULL;
	fn = SM_Get_Obj_Filename(FD);
	fd = open(fn, O_RDONLY);
	if (fd < 0) {
		Log("Storage Manager: Cannot read object: %d\n", FD);
		log_errno(fn);
	} else {
		fp = fdopen(fd, "r");
	}
	xfree(fn);
	return(fp);
}

/*
 *  SM_Write_Obj - Creates the object in the storage manager, and
 *  returns a FILE * so that the caller can write the data to the
 *  storage manger.  Returns NULL on error.
 */
FILE *SM_Write_Obj(FD)
fd_t FD;
{
	static FILE *fp;
	char *fn;
	int fd;

	fp = NULL;
	fn = SM_Get_Obj_Filename(FD);
	fd = open(fn, O_RDWR | O_CREAT | O_TRUNC, 0664);
	if (fd < 0) {
		Log("Storage Manager: Cannot read object: %d\n", FD);
		log_errno(fn);
	} else {
		fp = fdopen(fd, "w+");
	}
	xfree(fn);
	return(fp);
}

/*
 *  SM_Destroy_Obj - Deletes an object from the storage manager.
 */
int SM_Destroy_Obj(FD)
fd_t FD;
{
	char *fn;

	fn = SM_Get_Obj_Filename(FD);
	if (unlink(fn) < 0) {
		errorlog("Storage Manager: Cannot delete object: %d\n", FD);
		log_errno(fn);
		xfree(fn);
		return ERROR;
	}
	xfree(fn);
	return SUCCESS;
}

/*
 *  SM_Exist_Obj - See if the FD object exists in the storage manager?
 */
int SM_Exist_Obj(FD)
fd_t FD;
{
	char *fn;
	int r;

	fn = SM_Get_Obj_Filename(FD);
	r = access(fn, R_OK);
	xfree(fn);
	return((r == 0) ? TRUE : FALSE);
}

/*
 *  new_fd_value - Grab another FD value.
 */
static fd_t new_fd_value()
{
#if defined(HAVE_LRAND48)
	extern long lrand48();
	return ((fd_t) lrand48());
#elif defined(HAVE_RANDOM)
#ifndef random
	extern long random();
#endif
	return ((fd_t) random());
#else
	extern int rand();
	return ((fd_t) rand());
#endif
}

/*
 *  SM_Get_Obj_Filename() - Returns the filename for the given object.
 *  Only valid for the UNIX file system storage manager.
 */
char *SM_Get_Obj_Filename(fd)
fd_t fd;
{
      	static char *fn;

      	fn = (char *) xmalloc(MAX_FN_SIZE);
	fn[0] = '\0';
      	sprintf(fn, "%s/objects/%d/OBJ%d", DIRpath, fd % MAX_DIR, fd);

      	return (fn);
}

/*
 *  SM_Get_Obj_URL - Returns the URL to read the object.
 */
char *SM_Get_Obj_URL(fd)
fd_t fd;
{
      	static char *fn;

      	fn = (char *) xmalloc(MAX_FN_SIZE);
	fn[0] = '\0';
      	sprintf(fn, "%s/%d/OBJ%d", brk_obj_url, fd % MAX_DIR, fd);

      	return (fn);
}