apr_pools.c

Apache V2.0.15 Alpha For Linuxhttpd-2_0_15-alpha.tar.Z

/* ====================================================================
 * The Apache Software License, Version 1.1
 *
 * Copyright (c) 2000-2001 The Apache Software Foundation.  All rights
 * reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 *
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in
 *    the documentation and/or other materials provided with the
 *    distribution.
 *
 * 3. The end-user documentation included with the redistribution,
 *    if any, must include the following acknowledgment:
 *       "This product includes software developed by the
 *        Apache Software Foundation (http://www.apache.org/)."
 *    Alternately, this acknowledgment may appear in the software itself,
 *    if and wherever such third-party acknowledgments normally appear.
 *
 * 4. The names "Apache" and "Apache Software Foundation" must
 *    not be used to endorse or promote products derived from this
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 *
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 *
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 * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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 * ====================================================================
 *
 * This software consists of voluntary contributions made by many
 * individuals on behalf of the Apache Software Foundation.  For more
 * information on the Apache Software Foundation, please see
 * <http://www.apache.org/>.
 */

/*
 * Resource allocation code... the code here is responsible for making
 * sure that nothing leaks.
 *
 * rst --- 4/95 --- 6/95
 */

#include "apr.h"
#include "apr_private.h"

#include "apr_portable.h" /* for get_os_proc */
#include "apr_strings.h"
#include "apr_general.h"
#include "apr_pools.h"
#include "apr_lib.h"
#include "apr_lock.h"
#include "apr_hash.h"

#if APR_HAVE_STDIO_H
#include <stdio.h>
#endif
#ifdef HAVE_SYS_STAT_H
#include <sys/stat.h>
#endif
#if APR_HAVE_SYS_SIGNAL_H
#include <sys/signal.h>
#endif
#if APR_HAVE_SIGNAL_H
#include <signal.h>
#endif
#if APR_HAVE_SYS_WAIT_H
#include <sys/wait.h>
#endif
#if APR_HAVE_SYS_TYPES_H
#include <sys/types.h>
#endif
#if APR_HAVE_UNISTD_H
#include <unistd.h>
#endif
#if APR_HAVE_FCNTL_H
#include <fcntl.h>
#endif

#if APR_HAVE_STRING_H
#include <string.h>
#endif
#if APR_HAVE_STDLIB_H
#include <stdlib.h>
#endif
#ifdef HAVE_MALLOC_H
#include <malloc.h>
#endif

/* Details of the debugging options can now be found in the developer
 * section of the documentaion. */

/* magic numbers --- min free bytes to consider a free apr_pool_t block useable,
 * and the min amount to allocate if we have to go to malloc() */

#ifndef BLOCK_MINFREE
#define BLOCK_MINFREE 4096
#endif
#ifndef BLOCK_MINALLOC
#define BLOCK_MINALLOC 8192
#endif
 
#ifdef APR_POOL_DEBUG
/* first do some option checking... */
#ifdef ALLOC_USE_MALLOC
#error "sorry, no support for ALLOC_USE_MALLOC and APR_POOL_DEBUG at the same time"
#endif /* ALLOC_USE_MALLOC */

#ifdef MULTITHREAD
# error "sorry, no support for MULTITHREAD and APR_POOL_DEBUG at the same time"
#endif /* MULTITHREAD */

#endif /* APR_POOL_DEBUG */

#ifdef ALLOC_USE_MALLOC
#undef BLOCK_MINFREE
#undef BLOCK_MINALLOC
#define BLOCK_MINFREE	0
#define BLOCK_MINALLOC	0
#endif /* ALLOC_USE_MALLOC */

#define APR_SLACK_LOW    1
#define APR_SLACK_HIGH   2


/*****************************************************************
 *
 * Managing free storage blocks...
 */

union align {
    /*
     * Types which are likely to have the longest RELEVANT alignment
     * restrictions...
     */

    char *cp;
    void (*f) (void);
    long l;
    FILE *fp;
    double d;
};

#define CLICK_SZ (sizeof(union align))

union block_hdr {
    union align a;

    /* Actual header... */

    struct {
	char *endp;
	union block_hdr *next;
	char *first_avail;
#ifdef APR_POOL_DEBUG
	union block_hdr *global_next;
	apr_pool_t *owning_pool;
#endif /* APR_POOL_DEBUG */
    } h;
};

#define APR_ABORT(conditional, retcode, func, str) \
    if (conditional) { \
        if ((func) == NULL) { \
            return NULL; \
        } \
        else { \
            fprintf(stderr, "%s", str); \
            (*(func))(retcode); \
        } \
    }

/*
 * Static cells for managing our internal synchronisation.
 */
static union block_hdr *block_freelist = NULL;

#if APR_HAS_THREADS
static apr_lock_t *alloc_mutex;
static apr_lock_t *spawn_mutex;
#endif

#ifdef APR_POOL_DEBUG
static char *known_stack_point;
static int stack_direction;
static union block_hdr *global_block_list;
#define FREE_POOL	((apr_pool_t *)(-1))
#endif /* APR_POOL_DEBUG */

#ifdef ALLOC_STATS
static unsigned long long num_free_blocks_calls;
static unsigned long long num_blocks_freed;
static unsigned max_blocks_in_one_free;
static unsigned num_malloc_calls;
static unsigned num_malloc_bytes;
#endif /* ALLOC_STATS */

#ifdef ALLOC_DEBUG
#define FILL_BYTE	((char)(0xa5))
#define debug_fill(ptr,size)	((void)memset((ptr), FILL_BYTE, (size)))

static APR_INLINE void debug_verify_filled(const char *ptr, const char *endp,
					   const char *error_msg)
{
    for ( ; ptr < endp; ++ptr) {
	if (*ptr != FILL_BYTE) {
	    fputs(error_msg, stderr);
	    abort();
	    exit(1);
	}
    }
}

#else /* ALLOC_DEBUG */
#define debug_fill(a,b)
#define debug_verify_filled(a,b,c)
#endif /* ALLOC_DEBUG */

/*
 * Get a completely new block from the system pool. Note that we rely on
 * malloc() to provide aligned memory.
 */

static union block_hdr *malloc_block(int size, int (*apr_abort)(int retcode))
{
    union block_hdr *blok;

#ifdef ALLOC_DEBUG
    /* make some room at the end which we'll fill and expect to be
     * always filled
     */
    size += CLICK_SZ;
#endif /* ALLOC_DEBUG */

#ifdef ALLOC_STATS
    ++num_malloc_calls;
    num_malloc_bytes += size + sizeof(union block_hdr);
#endif /* ALLOC_STATS */

    blok = (union block_hdr *) malloc(size + sizeof(union block_hdr));
    APR_ABORT(blok == NULL, APR_ENOMEM, apr_abort,
              "Ouch!  malloc failed in malloc_block()\n");
    debug_fill(blok, size + sizeof(union block_hdr));

    blok->h.next = NULL;
    blok->h.first_avail = (char *) (blok + 1);
    blok->h.endp = size + blok->h.first_avail;

#ifdef ALLOC_DEBUG
    blok->h.endp -= CLICK_SZ;
#endif /* ALLOC_DEBUG */

#ifdef APR_POOL_DEBUG
    blok->h.global_next = global_block_list;
    global_block_list = blok;
    blok->h.owning_pool = NULL;
#endif /* APR_POOL_DEBUG */

    return blok;
}



#if defined(ALLOC_DEBUG) && !defined(ALLOC_USE_MALLOC)
static void chk_on_blk_list(union block_hdr *blok, union block_hdr *free_blk)
{
    debug_verify_filled(blok->h.endp, blok->h.endp + CLICK_SZ,
			"[chk_on_blk_list] Ouch!  Someone trounced the padding "
			"at the end of a block!\n");
    while (free_blk) {
	if (free_blk == blok) {
            fprintf(stderr, "Ouch!  Freeing free block\n");
	    abort();
	    exit(1);
	}
	free_blk = free_blk->h.next;
    }
}
#else /* defined(ALLOC_DEBUG) && !defined(ALLOC_USE_MALLOC) */
#define chk_on_blk_list(_x, _y)
#endif /* defined(ALLOC_DEBUG) && !defined(ALLOC_USE_MALLOC) */

/* Free a chain of blocks --- must be called with alarms blocked. */

static void free_blocks(union block_hdr *blok)
{
#ifdef ALLOC_USE_MALLOC
    union block_hdr *next;

    for ( ; blok; blok = next) {
	next = blok->h.next;
	free(blok);
    }
#else /* ALLOC_USE_MALLOC */

#ifdef ALLOC_STATS
    unsigned num_blocks;
#endif /* ALLOC_STATS */

    /*
     * First, put new blocks at the head of the free list ---
     * we'll eventually bash the 'next' pointer of the last block
     * in the chain to point to the free blocks we already had.
     */

    union block_hdr *old_free_list;

    if (blok == NULL) {
	return;			/* Sanity check --- freeing empty pool? */
    }

#if APR_HAS_THREADS
    if (alloc_mutex) {
        apr_lock_acquire(alloc_mutex);
    }
#endif
    old_free_list = block_freelist;
    block_freelist = blok;

    /*
     * Next, adjust first_avail pointers of each block --- have to do it
     * sooner or later, and it simplifies the search in new_block to do it
     * now.
     */

#ifdef ALLOC_STATS
    num_blocks = 1;
#endif /* ALLOC_STATS */

    while (blok->h.next != NULL) {

#ifdef ALLOC_STATS
	++num_blocks;
#endif /* ALLOC_STATS */

	chk_on_blk_list(blok, old_free_list);
	blok->h.first_avail = (char *) (blok + 1);
	debug_fill(blok->h.first_avail, blok->h.endp - blok->h.first_avail);
#ifdef APR_POOL_DEBUG 
	blok->h.owning_pool = FREE_POOL;
#endif /* APR_POOL_DEBUG */
	blok = blok->h.next;
    }

    chk_on_blk_list(blok, old_free_list);
    blok->h.first_avail = (char *) (blok + 1);
    debug_fill(blok->h.first_avail, blok->h.endp - blok->h.first_avail);
#ifdef APR_POOL_DEBUG
    blok->h.owning_pool = FREE_POOL;
#endif /* APR_POOL_DEBUG */

    /* Finally, reset next pointer to get the old free blocks back */

    blok->h.next = old_free_list;

#ifdef ALLOC_STATS
    if (num_blocks > max_blocks_in_one_free) {
	max_blocks_in_one_free = num_blocks;
    }
    ++num_free_blocks_calls;
    num_blocks_freed += num_blocks;
#endif /* ALLOC_STATS */

#if APR_HAS_THREADS
    if (alloc_mutex) {
        apr_lock_release(alloc_mutex);
    }
#endif /* APR_HAS_THREADS */
#endif /* ALLOC_USE_MALLOC */
}

/*
 * Get a new block, from our own free list if possible, from the system
 * if necessary.  Must be called with alarms blocked.
 */

static union block_hdr *new_block(int min_size, int (*apr_abort)(int retcode))
{
    union block_hdr **lastptr = &block_freelist;
    union block_hdr *blok = block_freelist;

    /* First, see if we have anything of the required size
     * on the free list...
     */

    while (blok != NULL) {
	if (min_size + BLOCK_MINFREE <= blok->h.endp - blok->h.first_avail) {
	    *lastptr = blok->h.next;
	    blok->h.next = NULL;
	    debug_verify_filled(blok->h.first_avail, blok->h.endp,
				"[new_block] Ouch!  Someone trounced a block "
				"on the free list!\n");
	    return blok;
	}
	else {
	    lastptr = &blok->h.next;
	    blok = blok->h.next;
	}
    }

    /* Nope. */

    min_size += BLOCK_MINFREE;
    blok = malloc_block((min_size > BLOCK_MINALLOC)
			? min_size : BLOCK_MINALLOC, apr_abort);
    return blok;
}


/* Accounting */

static apr_size_t bytes_in_block_list(union block_hdr *blok)
{
    apr_size_t size = 0;

    while (blok) {