path: root/source/fitz/memento.c

/* Copyright (C) 2001-2013 Artifex Software, Inc.
   All Rights Reserved.

   This software is provided AS-IS with no warranty, either express or
   implied.

   This software is distributed under license and may not be copied, modified
   or distributed except as expressly authorized under the terms of that
   license. Refer to licensing information at http://www.artifex.com
   or contact Artifex Software, Inc.,  7 Mt. Lassen Drive - Suite A-134,
   San Rafael, CA  94903, U.S.A., +1(415)492-9861, for further information.
*/

/* Inspired by Fortify by Simon P Bullen. */

/* Set the following if you're only looking for leaks, not memory overwrites
 * to speed the operation */
/* #define MEMENTO_LEAKONLY */

/* Don't keep blocks around if they'd mean losing more than a quarter of
 * the freelist. */
#define MEMENTO_FREELIST_MAX_SINGLE_BLOCK (MEMENTO_FREELIST_MAX/4)

#define COMPILING_MEMENTO_C

/* We have some GS specific tweaks; more for the GS build environment than
 * anything else. */
#undef MEMENTO_GS_HACKS

#ifdef MEMENTO_GS_HACKS
/* For GS we include malloc_.h. Anyone else would just include memento.h */
#include "malloc_.h"
#ifdef __MACH__
#include <string.h>
#else
#ifndef memset
void *memset(void *,int,size_t);
#endif
#endif
int atexit(void (*)(void));
#else
#include "mupdf/memento.h"
#include <stdio.h>
#include <stdlib.h>
#endif

#ifdef MEMENTO_ANDROID
#include <android/log.h>

static int
android_fprintf(FILE *file, const char *fmt, ...)
{
	va_list args;

	va_start(args, fmt);
	__android_log_vprint(ANDROID_LOG_ERROR,"memento", fmt, args);
	va_end(args);
}

#define fprintf android_fprintf
#define MEMENTO_STACKTRACE_METHOD 0
#endif

#ifdef _WIN32
#include <windows.h>

static int
windows_fprintf(FILE *file, const char *fmt, ...)
{
	va_list args;
	char text[4096];
	int ret;

	va_start(args, fmt);
	ret = vfprintf(file, fmt, args);
	va_end(args);

	va_start(args, fmt);
	vsnprintf(text, 4096, fmt, args);
	OutputDebugStringA(text);
	va_end(args);

	return ret;
}

#define fprintf windows_fprintf
#endif

#ifndef MEMENTO_STACKTRACE_METHOD
#ifdef __GNUC__
#define MEMENTO_STACKTRACE_METHOD 1
#endif
#endif

#if defined(__linux__)
#define MEMENTO_HAS_FORK
#elif defined(__APPLE__) && defined(__MACH__)
#define MEMENTO_HAS_FORK
#endif

/* Define the underlying allocators, just in case */
void *MEMENTO_UNDERLYING_MALLOC(size_t);
void MEMENTO_UNDERLYING_FREE(void *);
void *MEMENTO_UNDERLYING_REALLOC(void *,size_t);
void *MEMENTO_UNDERLYING_CALLOC(size_t,size_t);

/* And some other standard functions we use. We don't include the header
 * files, just in case they pull in unexpected others. */
int atoi(const char *);
char *getenv(const char *);

/* How far to search for pointers in each block when calculating nestings */
/* mupdf needs at least 34000ish (sizeof(fz_shade))/ */
#define MEMENTO_PTRSEARCH 65536

#ifndef MEMENTO_MAXPATTERN
#define MEMENTO_MAXPATTERN 0
#endif

#ifdef MEMENTO

#ifdef MEMENTO_GS_HACKS
#include "valgrind.h"
#else
#ifdef HAVE_VALGRIND
#include "valgrind/memcheck.h"
#else
#define VALGRIND_MAKE_MEM_NOACCESS(p,s)  do { } while (0==1)
#define VALGRIND_MAKE_MEM_UNDEFINED(p,s)  do { } while (0==1)
#define VALGRIND_MAKE_MEM_DEFINED(p,s)  do { } while (0==1)
#endif
#endif

enum {
    Memento_PreSize  = 16,
    Memento_PostSize = 16
};

enum {
    Memento_Flag_OldBlock = 1,
    Memento_Flag_HasParent = 2,
    Memento_Flag_BreakOnFree = 4,
    Memento_Flag_BreakOnRealloc = 8
};

/* When we list leaked blocks at the end of execution, we search for pointers
 * between blocks in order to be able to give a nice nested view.
 * Unfortunately, if you have are running your own allocator (such as
 * ghostscripts chunk allocator) you can often find that the header of the
 * block always contains pointers to next or previous blocks. This tends to
 * mean the nesting displayed is "uninteresting" at best :)
 *
 * As a hack to get around this, we have a define MEMENTO_SKIP_SEARCH that
 * indicates how many bytes to skip over at the start of the chunk.
 * This may cause us to miss true nestings, but such is life...
 */
#ifndef MEMENTO_SEARCH_SKIP
#ifdef MEMENTO_GS_HACKS
#define MEMENTO_SEARCH_SKIP (2*sizeof(void *))
#else
#define MEMENTO_SEARCH_SKIP 0
#endif
#endif

typedef struct Memento_BlkHeader Memento_BlkHeader;

struct Memento_BlkHeader
{
    size_t             rawsize;
    int                sequence;
    int                lastCheckedOK;
    int                flags;
    Memento_BlkHeader *next;
    Memento_BlkHeader *parent; /* Only used while printing out nested list */

    const char        *label;

    /* Entries for nesting display calculations */
    Memento_BlkHeader *child;
    Memento_BlkHeader *sibling;

    char               preblk[Memento_PreSize];
};

/* In future this could (should) be a smarter data structure, like, say,
 * splay trees. For now, we use a list.
 */
typedef struct Memento_Blocks
{
    Memento_BlkHeader  *head;
    Memento_BlkHeader **tail;
} Memento_Blocks;

/* And our global structure */
static struct {
    int            inited;
    Memento_Blocks used;
    Memento_Blocks free;
    size_t         freeListSize;
    int            sequence;
    int            paranoia;
    int            paranoidAt;
    int            countdown;
    int            lastChecked;
    int            breakAt;
    int            failAt;
    int            failing;
    int            nextFailAt;
    int            squeezeAt;
    int            squeezing;
    int            segv;
    int            pattern;
    int            nextPattern;
    int            patternBit;
    size_t         maxMemory;
    size_t         alloc;
    size_t         peakAlloc;
    size_t         totalAlloc;
    size_t         numMallocs;
    size_t         numFrees;
    size_t         numReallocs;
} globals;

#define MEMENTO_EXTRASIZE (sizeof(Memento_BlkHeader) + Memento_PostSize)

/* Round up size S to the next multiple of N (where N is a power of 2) */
#define MEMENTO_ROUNDUP(S,N) ((S + N-1)&~(N-1))

#define MEMBLK_SIZE(s) MEMENTO_ROUNDUP(s + MEMENTO_EXTRASIZE, MEMENTO_MAXALIGN)

#define MEMBLK_FROMBLK(B)   (&((Memento_BlkHeader*)(void *)(B))[-1])
#define MEMBLK_TOBLK(B)     ((void*)(&((Memento_BlkHeader*)(void*)(B))[1]))
#define MEMBLK_POSTPTR(B) \
          (&((char *)(void *)(B))[(B)->rawsize + sizeof(Memento_BlkHeader)])

void Memento_breakpoint(void)
{
    /* A handy externally visible function for breakpointing */
#if 0 /* Enable this to force automatic breakpointing */
#ifdef DEBUG
#ifdef _MSC_VER
    __asm int 3;
#endif
#endif
#endif
}

static void Memento_addBlockHead(Memento_Blocks    *blks,
                                 Memento_BlkHeader *b,
                                 int                type)
{
    if (blks->tail == &blks->head) {
        /* Adding into an empty list, means the tail changes too */
        blks->tail = &b->next;
    }
    b->next    = blks->head;
    blks->head = b;
#ifndef MEMENTO_LEAKONLY
    memset(b->preblk, MEMENTO_PREFILL, Memento_PreSize);
    memset(MEMBLK_POSTPTR(b), MEMENTO_POSTFILL, Memento_PostSize);
#endif
    VALGRIND_MAKE_MEM_NOACCESS(MEMBLK_POSTPTR(b), Memento_PostSize);
    if (type == 0) { /* malloc */
        VALGRIND_MAKE_MEM_UNDEFINED(MEMBLK_TOBLK(b), b->rawsize);
    } else if (type == 1) { /* free */
        VALGRIND_MAKE_MEM_NOACCESS(MEMBLK_TOBLK(b), b->rawsize);
    }
    VALGRIND_MAKE_MEM_NOACCESS(b, sizeof(Memento_BlkHeader));
}

static void Memento_addBlockTail(Memento_Blocks    *blks,
                                 Memento_BlkHeader *b,
                                 int                type)
{
    VALGRIND_MAKE_MEM_DEFINED(blks->tail, sizeof(Memento_BlkHeader *));
    *blks->tail = b;
    blks->tail  = &b->next;
    b->next = NULL;
    VALGRIND_MAKE_MEM_NOACCESS(blks->tail, sizeof(Memento_BlkHeader *));
#ifndef MEMENTO_LEAKONLY
    memset(b->preblk, MEMENTO_PREFILL, Memento_PreSize);
    memset(MEMBLK_POSTPTR(b), MEMENTO_POSTFILL, Memento_PostSize);
#endif
    VALGRIND_MAKE_MEM_NOACCESS(MEMBLK_POSTPTR(b), Memento_PostSize);
    if (type == 0) { /* malloc */
        VALGRIND_MAKE_MEM_UNDEFINED(MEMBLK_TOBLK(b), b->rawsize);
    } else if (type == 1) { /* free */
        VALGRIND_MAKE_MEM_NOACCESS(MEMBLK_TOBLK(b), b->rawsize);
    }
    VALGRIND_MAKE_MEM_NOACCESS(b, sizeof(Memento_BlkHeader));
}

typedef struct BlkCheckData {
    int found;
    int preCorrupt;
    int postCorrupt;
    int freeCorrupt;
    int index;
} BlkCheckData;

static int Memento_Internal_checkAllocedBlock(Memento_BlkHeader *b, void *arg)
{
#ifndef MEMENTO_LEAKONLY
    int           i;
    char         *p;
    int           corrupt = 0;
    BlkCheckData *data = (BlkCheckData *)arg;

    p = b->preblk;
    i = Memento_PreSize;
    do {
        corrupt |= (*p++ ^ (char)MEMENTO_PREFILL);
    } while (--i);
    if (corrupt) {
        data->preCorrupt = 1;
    }
    p = MEMBLK_POSTPTR(b);
    i = Memento_PreSize;
    do {
        corrupt |= (*p++ ^ (char)MEMENTO_POSTFILL);
    } while (--i);
    if (corrupt) {
        data->postCorrupt = 1;
    }
    if ((data->freeCorrupt | data->preCorrupt | data->postCorrupt) == 0) {
        b->lastCheckedOK = globals.sequence;
    }
    data->found |= 1;
#endif
    return 0;
}

static int Memento_Internal_checkFreedBlock(Memento_BlkHeader *b, void *arg)
{
#ifndef MEMENTO_LEAKONLY
    int           i;
    char         *p;
    BlkCheckData *data = (BlkCheckData *)arg;

    p = MEMBLK_TOBLK(b);
    i = b->rawsize;
    /* Attempt to speed this up by checking an (aligned) int at a time */
    do {
        if (((size_t)p) & 1) {
            if (*p++ != (char)MEMENTO_FREEFILL)
                break;
            i--;
            if (i == 0)
                break;
        }
        if ((i >= 2) && (((size_t)p) & 2)) {
            if (*(short *)p != (short)(MEMENTO_FREEFILL | (MEMENTO_FREEFILL<<8)))
                goto mismatch;
            p += 2;
            i -= 2;
            if (i == 0)
                break;
        }
        i -= 4;
        while (i >= 0) {
            if (*(int *)p != (MEMENTO_FREEFILL |
                              (MEMENTO_FREEFILL<<8) |
                              (MEMENTO_FREEFILL<<16) |
                              (MEMENTO_FREEFILL<<24)))
                goto mismatch;
            p += 4;
            i -= 4;
        }
        i += 4;
        if ((i >= 2) && (((size_t)p) & 2)) {
            if (*(short *)p != (short)(MEMENTO_FREEFILL | (MEMENTO_FREEFILL<<8)))
                goto mismatch;
            p += 2;
            i -= 2;
        }
mismatch:
        while (i) {
            if (*p++ != (char)MEMENTO_FREEFILL)
                break;
            i--;
        }
    } while (0);
    if (i) {
        data->freeCorrupt = 1;
        data->index       = b->rawsize-i;
    }
    return Memento_Internal_checkAllocedBlock(b, arg);
#else
    return 0;
#endif
}

static void Memento_removeBlock(Memento_Blocks    *blks,
                                Memento_BlkHeader *b)
{
    Memento_BlkHeader *head = blks->head;
    Memento_BlkHeader *prev = NULL;
    while ((head) && (head != b)) {
        VALGRIND_MAKE_MEM_DEFINED(head, sizeof(*head));
        prev = head;
        head = head->next;
        VALGRIND_MAKE_MEM_NOACCESS(prev, sizeof(*prev));
    }
    if (head == NULL) {
        /* FAIL! Will have been reported to user earlier, so just exit. */
        return;
    }
    VALGRIND_MAKE_MEM_DEFINED(blks->tail, sizeof(*blks->tail));
    if (*blks->tail == head) {
        /* Removing the tail of the list */
        if (prev == NULL) {
            /* Which is also the head */
            blks->tail = &blks->head;
        } else {
            /* Which isn't the head */
            blks->tail = &prev->next;
        }
    }
    if (prev == NULL) {
        /* Removing from the head of the list */
        VALGRIND_MAKE_MEM_DEFINED(head, sizeof(*head));
        blks->head = head->next;
        VALGRIND_MAKE_MEM_NOACCESS(head, sizeof(*head));
    } else {
        /* Removing from not-the-head */
        VALGRIND_MAKE_MEM_DEFINED(head, sizeof(*head));
        VALGRIND_MAKE_MEM_DEFINED(prev, sizeof(*prev));
        prev->next = head->next;
        VALGRIND_MAKE_MEM_NOACCESS(head, sizeof(*head));
        VALGRIND_MAKE_MEM_NOACCESS(prev, sizeof(*prev));
    }
}

static int Memento_Internal_makeSpace(size_t space)
{
    /* If too big, it can never go on the freelist */
    if (space > MEMENTO_FREELIST_MAX_SINGLE_BLOCK)
        return 0;
    /* Pretend we added it on. */
    globals.freeListSize += space;
    /* Ditch blocks until it fits within our limit */
    while (globals.freeListSize > MEMENTO_FREELIST_MAX) {
        Memento_BlkHeader *head = globals.free.head;
        VALGRIND_MAKE_MEM_DEFINED(head, sizeof(*head));
        globals.free.head = head->next;
        globals.freeListSize -= MEMBLK_SIZE(head->rawsize);
        MEMENTO_UNDERLYING_FREE(head);
    }
    /* Make sure we haven't just completely emptied the free list */
    /* (This should never happen, but belt and braces... */
    if (globals.free.head == NULL)
        globals.free.tail = &globals.free.head;
    return 1;
}

static int Memento_appBlocks(Memento_Blocks *blks,
                             int             (*app)(Memento_BlkHeader *,
                                                    void *),
                             void           *arg)
{
    Memento_BlkHeader *head = blks->head;
    Memento_BlkHeader *next;
    int                result;
    while (head) {
        VALGRIND_MAKE_MEM_DEFINED(head, sizeof(Memento_BlkHeader));
        VALGRIND_MAKE_MEM_DEFINED(MEMBLK_TOBLK(head),
                                  head->rawsize + Memento_PostSize);
        result = app(head, arg);
        next = head->next;
        VALGRIND_MAKE_MEM_NOACCESS(MEMBLK_POSTPTR(head), Memento_PostSize);
        VALGRIND_MAKE_MEM_NOACCESS(head, sizeof(Memento_BlkHeader));
        if (result)
            return result;
        head = next;
    }
    return 0;
}

static int Memento_appBlock(Memento_Blocks    *blks,
                            int                (*app)(Memento_BlkHeader *,
                                                      void *),
                            void              *arg,
                            Memento_BlkHeader *b)
{
    Memento_BlkHeader *head = blks->head;
    Memento_BlkHeader *next;
    int                result;
    while (head && head != b) {
        VALGRIND_MAKE_MEM_DEFINED(head, sizeof(Memento_BlkHeader));
        next = head->next;
        VALGRIND_MAKE_MEM_NOACCESS(MEMBLK_POSTPTR(head), Memento_PostSize);
        head = next;
    }
    if (head == b) {
        VALGRIND_MAKE_MEM_DEFINED(head, sizeof(Memento_BlkHeader));
        VALGRIND_MAKE_MEM_DEFINED(MEMBLK_TOBLK(head),
                                  head->rawsize + Memento_PostSize);
        result = app(head, arg);
        VALGRIND_MAKE_MEM_NOACCESS(MEMBLK_POSTPTR(head), Memento_PostSize);
        VALGRIND_MAKE_MEM_NOACCESS(head, sizeof(Memento_BlkHeader));
        return result;
    }
    return 0;
}

static void showBlock(Memento_BlkHeader *b, int space)
{
    fprintf(stderr, "0x%p:(size=%d,num=%d)",
            MEMBLK_TOBLK(b), (int)b->rawsize, b->sequence);
    if (b->label)
        fprintf(stderr, "%c(%s)", space, b->label);
}

static void blockDisplay(Memento_BlkHeader *b, int n)
{
    n++;
    while (n > 40)
    {
            fprintf(stderr, "*");
            n -= 40;
    }
    while(n > 0)
    {
        int i = n;
        if (i > 32)
            i = 32;
        n -= i;
        fprintf(stderr, "%s", &"                                "[32-i]);
    }
    showBlock(b, '\t');
    fprintf(stderr, "\n");
}

static int Memento_listBlock(Memento_BlkHeader *b,
                             void              *arg)
{
    int *counts = (int *)arg;
    blockDisplay(b, 0);
    counts[0]++;
    counts[1]+= b->rawsize;
    return 0;
}

static void doNestedDisplay(Memento_BlkHeader *b,
                            int depth)
{
    /* Try and avoid recursion if we can help it */
    do {
        blockDisplay(b, depth);
        if (b->sibling) {
            if (b->child)
                doNestedDisplay(b->child, depth+1);
            b = b->sibling;
        } else {
            b = b->child;
            depth++;
        }
    } while (b);
}

static int ptrcmp(const void *a_, const void *b_)
{
    const char **a = (const char **)a_;
    const char **b = (const char **)b_;
    return (int)(*a-*b);
}

static
int Memento_listBlocksNested(void)
{
    int count, size, i;
    Memento_BlkHeader *b;
    void **blocks, *minptr, *maxptr;
    long mask;

    /* Count the blocks */
    count = 0;
    size = 0;
    for (b = globals.used.head; b; b = b->next) {
        size += b->rawsize;
        count++;
    }

    /* Make our block list */
    blocks = MEMENTO_UNDERLYING_MALLOC(sizeof(void *) * count);
    if (blocks == NULL)
        return 1;

    /* Populate our block list */
    b = globals.used.head;
    minptr = maxptr = MEMBLK_TOBLK(b);
    mask = (long)minptr;
    for (i = 0; b; b = b->next, i++) {
        void *p = MEMBLK_TOBLK(b);
        mask &= (long)p;
        if (p < minptr)
            minptr = p;
        if (p > maxptr)
            maxptr = p;
        blocks[i] = p;
        b->flags &= ~Memento_Flag_HasParent;
        b->child   = NULL;
        b->sibling = NULL;
        b->parent  = NULL;
    }
    qsort(blocks, count, sizeof(void *), ptrcmp);

    /* Now, calculate tree */
    for (b = globals.used.head; b; b = b->next) {
        char *p = MEMBLK_TOBLK(b);
        int end = (b->rawsize < MEMENTO_PTRSEARCH ? b->rawsize : MEMENTO_PTRSEARCH);
        for (i = MEMENTO_SEARCH_SKIP; i < end; i += sizeof(void *)) {
            void *q = *(void **)(&p[i]);
            void **r;

            /* Do trivial checks on pointer */
            if ((mask & (int)q) != mask || q < minptr || q > maxptr)
                continue;

            /* Search for pointer */
            r = bsearch(&q, blocks, count, sizeof(void *), ptrcmp);
            if (r) {
                /* Found child */
                Memento_BlkHeader *child = MEMBLK_FROMBLK(*r);
                Memento_BlkHeader *parent;

                /* We're assuming tree structure, not graph - ignore second
                 * and subsequent pointers. */
                if (child->parent != NULL)
                    continue;
                if (child->flags & Memento_Flag_HasParent)
                    continue;

                /* We're also assuming acyclicness here. If this is one of
                 * our parents, ignore it. */
                parent = b->parent;
                while (parent != NULL && parent != child)
                    parent = parent->parent;
                if (parent == child)
                    continue;

                child->sibling = b->child;
                b->child = child;
                child->parent = b;
                child->flags |= Memento_Flag_HasParent;
            }
        }
    }

    /* Now display with nesting */
    for (b = globals.used.head; b; b = b->next) {
        if ((b->flags & Memento_Flag_HasParent) == 0)
            doNestedDisplay(b, 0);
    }
    fprintf(stderr, " Total number of blocks = %d\n", count);
    fprintf(stderr, " Total size of blocks = %d\n", size);

    MEMENTO_UNDERLYING_FREE(blocks);
    return 0;
}

void Memento_listBlocks(void)
{
    fprintf(stderr, "Allocated blocks:\n");
    if (Memento_listBlocksNested())
    {
        int counts[2];
        counts[0] = 0;
        counts[1] = 0;
        Memento_appBlocks(&globals.used, Memento_listBlock, &counts[0]);
        fprintf(stderr, " Total number of blocks = %d\n", counts[0]);
        fprintf(stderr, " Total size of blocks = %d\n", counts[1]);
    }
}

static int Memento_listNewBlock(Memento_BlkHeader *b,
                                void              *arg)
{
    if (b->flags & Memento_Flag_OldBlock)
        return 0;
    b->flags |= Memento_Flag_OldBlock;
    return Memento_listBlock(b, arg);
}

void Memento_listNewBlocks(void) {
    int counts[2];
    counts[0] = 0;
    counts[1] = 0;
    fprintf(stderr, "Blocks allocated and still extant since last list:\n");
    Memento_appBlocks(&globals.used, Memento_listNewBlock, &counts[0]);
    fprintf(stderr, "  Total number of blocks = %d\n", counts[0]);
    fprintf(stderr, "  Total size of blocks = %d\n", counts[1]);
}

static void Memento_endStats(void)
{
    fprintf(stderr, "Total memory malloced = %u bytes\n", (unsigned int)globals.totalAlloc);
    fprintf(stderr, "Peak memory malloced = %u bytes\n", (unsigned int)globals.peakAlloc);
    fprintf(stderr, "%u mallocs, %u frees, %u reallocs\n", (unsigned int)globals.numMallocs,
            (unsigned int)globals.numFrees, (unsigned int)globals.numReallocs);
    fprintf(stderr, "Average allocation size %u bytes\n", (unsigned int)
            (globals.numMallocs != 0 ? globals.totalAlloc/globals.numMallocs: 0));
}

void Memento_stats(void)
{
    fprintf(stderr, "Current memory malloced = %u bytes\n", (unsigned int)globals.alloc);
    Memento_endStats();
}

static void Memento_fin(void)
{
    Memento_checkAllMemory();
    Memento_endStats();
    if (globals.used.head != NULL) {
        Memento_listBlocks();
        Memento_breakpoint();
    }
    if (globals.segv) {
        fprintf(stderr, "Memory dumped on SEGV while squeezing @ %d\n", globals.failAt);
    } else if (globals.squeezing) {
        if (globals.pattern == 0)
            fprintf(stderr, "Memory squeezing @ %d complete\n", globals.squeezeAt);
        else
            fprintf(stderr, "Memory squeezing @ %d (%d) complete\n", globals.squeezeAt, globals.pattern);
    }
    if (globals.failing)
    {
        fprintf(stderr, "MEMENTO_FAILAT=%d\n", globals.failAt);
        fprintf(stderr, "MEMENTO_PATTERN=%d\n", globals.pattern);
    }
    if (globals.nextFailAt != 0)
    {
        fprintf(stderr, "MEMENTO_NEXTFAILAT=%d\n", globals.nextFailAt);
        fprintf(stderr, "MEMENTO_NEXTPATTERN=%d\n", globals.nextPattern);
    }
}

static void Memento_inited(void)
{
    /* A good place for a breakpoint */
}

static void Memento_init(void)
{
    char *env;
    memset(&globals, 0, sizeof(globals));
    globals.inited    = 1;
    globals.used.head = NULL;
    globals.used.tail = &globals.used.head;
    globals.free.head = NULL;
    globals.free.tail = &globals.free.head;
    globals.sequence  = 0;
    globals.countdown = 1024;

    env = getenv("MEMENTO_FAILAT");
    globals.failAt = (env ? atoi(env) : 0);

    env = getenv("MEMENTO_PARANOIA");
    globals.paranoia = (env ? atoi(env) : 0);
    if (globals.paranoia == 0)
        globals.paranoia = 1024;

    env = getenv("MEMENTO_PARANOIDAT");
    globals.paranoidAt = (env ? atoi(env) : 0);

    env = getenv("MEMENTO_SQUEEZEAT");
    globals.squeezeAt = (env ? atoi(env) : 0);

    env = getenv("MEMENTO_PATTERN");
    globals.pattern = (env ? atoi(env) : 0);

    env = getenv("MEMENTO_MAXMEMORY");
    globals.maxMemory = (env ? atoi(env) : 0);

    atexit(Memento_fin);

    Memento_inited();
}

#ifdef MEMENTO_HAS_FORK
#include <unistd.h>
#include <sys/wait.h>
#ifdef MEMENTO_STACKTRACE_METHOD
#if MEMENTO_STACKTRACE_METHOD == 1
#include <signal.h>
#endif
#endif

/* FIXME: Find some portable way of getting this */
/* MacOSX has 10240, Ubuntu seems to have 256 */
#define OPEN_MAX 10240

/* stashed_map[j] = i means that filedescriptor i-1 was duplicated to j */
int stashed_map[OPEN_MAX];

#ifdef MEMENTO_STACKTRACE_METHOD
#if MEMENTO_STACKTRACE_METHOD == 1
extern size_t backtrace(void **, int);
extern void backtrace_symbols_fd(void **, size_t, int);
#endif
#endif

static void Memento_signal(void)
{
    fprintf(stderr, "SEGV after Memory squeezing @ %d\n", globals.squeezeAt);

#ifdef MEMENTO_STACKTRACE_METHOD
#if MEMENTO_STACKTRACE_METHOD == 1
    {
      void *array[100];
      size_t size;

      size = backtrace(array, 100);
      fprintf(stderr, "------------------------------------------------------------------------\n");
      fprintf(stderr, "Backtrace:\n");
      backtrace_symbols_fd(array, size, 2);
      fprintf(stderr, "------------------------------------------------------------------------\n");
    }
#endif
#endif

    exit(1);
}

static int squeeze(void)
{
    pid_t pid;
    int i, status;

    if (globals.patternBit < 0)
        return 1;
    if (globals.squeezing && globals.patternBit >= MEMENTO_MAXPATTERN)
        return 1;

    if (globals.patternBit == 0)
        globals.squeezeAt = globals.sequence;

    if (!globals.squeezing) {
        fprintf(stderr, "Memory squeezing @ %d\n", globals.squeezeAt);
    } else
        fprintf(stderr, "Memory squeezing @ %d (%x,%x)\n", globals.squeezeAt, globals.pattern, globals.patternBit);

    /* When we fork below, the child is going to snaffle all our file pointers
     * and potentially corrupt them. Let's make copies of all of them before
     * we fork, so we can restore them when we restart. */
    for (i = 0; i < OPEN_MAX; i++) {
        if (stashed_map[i] == 0) {
            int j = dup(i);
            stashed_map[j] = i+1;
        }
    }

    pid = fork();
    if (pid == 0) {
        /* Child */
        signal(SIGSEGV, Memento_signal);
        /* In the child, we always fail the next allocation. */
        if (globals.patternBit == 0) {
            globals.patternBit = 1;
        } else
            globals.patternBit <<= 1;
        globals.squeezing = 1;
        return 1;
    }

    /* In the parent if we hit another allocation, pass it (and record the
     * fact we passed it in the pattern. */
    globals.pattern |= globals.patternBit;
    globals.patternBit <<= 1;

    /* Wait for pid to finish */
    waitpid(pid, &status, 0);

    if (status != 0) {
        fprintf(stderr, "Child status=%d\n", status);
    }

    /* Put the files back */
    for (i = 0; i < OPEN_MAX; i++) {
        if (stashed_map[i] != 0) {
            dup2(i, stashed_map[i]-1);
            close(i);
            stashed_map[i] = 0;
        }
    }

    return 0;
}
#else
#include <signal.h>

static void Memento_signal(void)
{
    globals.segv = 1;
    /* If we just return from this function the SEGV will be unhandled, and
     * we'll launch into whatever JIT debugging system the OS provides. At
     * least fprintf(stderr, something useful first. If MEMENTO_NOJIT is set, then
     * just exit to avoid the JIT (and get the usual atexit handling). */
    if (getenv("MEMENTO_NOJIT"))
        exit(1);
    else
        Memento_fin();
}

int squeeze(void)
{
    fprintf(stderr, "Memento memory squeezing disabled as no fork!\n");
    return 0;
}
#endif

static void Memento_startFailing(void)
{
    if (!globals.failing) {
        fprintf(stderr, "Starting to fail...\n");
        fflush(stderr);
        globals.failing = 1;
        globals.failAt = globals.sequence;
        globals.nextFailAt = globals.sequence+1;
        globals.pattern = 0;
        globals.patternBit = 0;
        signal(SIGSEGV, Memento_signal);
        signal(SIGABRT, Memento_signal);
        Memento_breakpoint();
    }
}

static void Memento_event(void)
{
    globals.sequence++;
    if ((globals.sequence >= globals.paranoidAt) && (globals.paranoidAt != 0)) {
        globals.paranoia = 1;
        globals.countdown = 1;
    }
    if (--globals.countdown == 0) {
        Memento_checkAllMemory();
        globals.countdown = globals.paranoia;
    }

    if (globals.sequence == globals.breakAt) {
        fprintf(stderr, "Breaking at event %d\n", globals.breakAt);
        Memento_breakpoint();
    }
}

int Memento_breakAt(int event)
{
    globals.breakAt = event;
    return event;
}

void *Memento_label(void *ptr, const char *label)
{
    Memento_BlkHeader *block;

    if (ptr == NULL)
        return NULL;
    block = MEMBLK_FROMBLK(ptr);
    block->label = label;
    return ptr;
}

int Memento_failThisEvent(void)
{
    int failThisOne;

    if (!globals.inited)
        Memento_init();

    Memento_event();

    if ((globals.sequence >= globals.failAt) && (globals.failAt != 0))
        Memento_startFailing();
    if ((globals.sequence >= globals.squeezeAt) && (globals.squeezeAt != 0)) {
        return squeeze();
    }

    if (!globals.failing)
        return 0;
    failThisOne = ((globals.patternBit & globals.pattern) == 0);
    /* If we are failing, and we've reached the end of the pattern and we've
     * still got bits available in the pattern word, and we haven't already
     * set a nextPattern, then extend the pattern. */
    if (globals.failing &&
        ((~(globals.patternBit-1) & globals.pattern) == 0) &&
        (globals.patternBit != 0) &&
        globals.nextPattern == 0)
    {
        /* We'll fail this one, and set the 'next' one to pass it. */
        globals.nextFailAt = globals.failAt;
        globals.nextPattern = globals.pattern | globals.patternBit;
    }
    globals.patternBit = (globals.patternBit ? globals.patternBit << 1 : 1);

    return failThisOne;
}

void *Memento_malloc(size_t s)
{
    Memento_BlkHeader *memblk;
    size_t             smem = MEMBLK_SIZE(s);

    if (Memento_failThisEvent())
        return NULL;

    if (s == 0)
        return NULL;

    globals.numMallocs++;

    if (globals.maxMemory != 0 && globals.alloc + s > globals.maxMemory)
        return NULL;

    memblk = MEMENTO_UNDERLYING_MALLOC(smem);
    if (memblk == NULL)
        return NULL;

    globals.alloc      += s;
    globals.totalAlloc += s;
    if (globals.peakAlloc < globals.alloc)
        globals.peakAlloc = globals.alloc;
#ifndef MEMENTO_LEAKONLY
    memset(MEMBLK_TOBLK(memblk), MEMENTO_ALLOCFILL, s);
#endif
    memblk->rawsize       = s;
    memblk->sequence      = globals.sequence;
    memblk->lastCheckedOK = memblk->sequence;
    memblk->flags         = 0;
    memblk->label         = 0;
    memblk->child         = NULL;
    memblk->sibling       = NULL;
    Memento_addBlockHead(&globals.used, memblk, 0);
    return MEMBLK_TOBLK(memblk);
}

void *Memento_calloc(size_t n, size_t s)
{
    void *block = Memento_malloc(n*s);

    if (block)
        memset(block, 0, n*s);
    return block;
}

static int checkBlock(Memento_BlkHeader *memblk, const char *action)
{
#ifndef MEMENTO_LEAKONLY
    BlkCheckData data;

    memset(&data, 0, sizeof(data));
    Memento_appBlock(&globals.used, Memento_Internal_checkAllocedBlock,
                     &data, memblk);
    if (!data.found) {
        /* Failure! */
        fprintf(stderr, "Attempt to %s block ", action);
        showBlock(memblk, 32);
        Memento_breakpoint();
        return 1;
    } else if (data.preCorrupt || data.postCorrupt) {
        fprintf(stderr, "Block ");
        showBlock(memblk, ' ');
        fprintf(stderr, " found to be corrupted on %s!\n", action);
        if (data.preCorrupt) {
            fprintf(stderr, "Preguard corrupted\n");
        }
        if (data.postCorrupt) {
            fprintf(stderr, "Postguard corrupted\n");
        }
        fprintf(stderr, "Block last checked OK at allocation %d. Now %d.\n",
                memblk->lastCheckedOK, globals.sequence);
        Memento_breakpoint();
        return 1;
    }
#endif
    return 0;
}

void Memento_free(void *blk)
{
    Memento_BlkHeader *memblk;

    if (!globals.inited)
        Memento_init();

    Memento_event();

    if (blk == NULL)
        return;

    memblk = MEMBLK_FROMBLK(blk);
    VALGRIND_MAKE_MEM_DEFINED(memblk, sizeof(*memblk));
    if (checkBlock(memblk, "free"))
        return;

    if (memblk->flags & Memento_Flag_BreakOnFree)
        Memento_breakpoint();

    VALGRIND_MAKE_MEM_DEFINED(memblk, sizeof(*memblk));
    globals.alloc -= memblk->rawsize;
    globals.numFrees++;

    Memento_removeBlock(&globals.used, memblk);

    VALGRIND_MAKE_MEM_DEFINED(memblk, sizeof(*memblk));
    if (Memento_Internal_makeSpace(MEMBLK_SIZE(memblk->rawsize))) {
        VALGRIND_MAKE_MEM_DEFINED(memblk, sizeof(*memblk));
        VALGRIND_MAKE_MEM_DEFINED(MEMBLK_TOBLK(memblk),
                                  memblk->rawsize + Memento_PostSize);
#ifndef MEMENTO_LEAKONLY
        memset(MEMBLK_TOBLK(memblk), MEMENTO_FREEFILL, memblk->rawsize);
#endif
        Memento_addBlockTail(&globals.free, memblk, 1);
    } else {
        MEMENTO_UNDERLYING_FREE(memblk);
    }
}

void *Memento_realloc(void *blk, size_t newsize)
{
    Memento_BlkHeader *memblk, *newmemblk;
    size_t             newsizemem;
    int                flags;

    if (blk == NULL)
        return Memento_malloc(newsize);
    if (newsize == 0) {
        Memento_free(blk);
        return NULL;
    }

    if (Memento_failThisEvent())
        return NULL;

    memblk     = MEMBLK_FROMBLK(blk);
    if (checkBlock(memblk, "realloc"))
        return NULL;

    if (memblk->flags & Memento_Flag_BreakOnRealloc)
        Memento_breakpoint();

    if (globals.maxMemory != 0 && globals.alloc - memblk->rawsize + newsize > globals.maxMemory)
        return NULL;

    newsizemem = MEMBLK_SIZE(newsize);
    Memento_removeBlock(&globals.used, memblk);
    flags = memblk->flags;
    newmemblk  = MEMENTO_UNDERLYING_REALLOC(memblk, newsizemem);
    if (newmemblk == NULL)
    {
        Memento_addBlockHead(&globals.used, memblk, 2);
        return NULL;
    }
    globals.numReallocs++;
    globals.totalAlloc += newsize;
    globals.alloc      -= newmemblk->rawsize;
    globals.alloc      += newsize;
    if (globals.peakAlloc < globals.alloc)
        globals.peakAlloc = globals.alloc;
    newmemblk->flags = flags;
    if (newmemblk->rawsize < newsize) {
        char *newbytes = ((char *)MEMBLK_TOBLK(newmemblk))+newmemblk->rawsize;
#ifndef MEMENTO_LEAKONLY
        memset(newbytes, MEMENTO_ALLOCFILL, newsize - newmemblk->rawsize);
#endif
        VALGRIND_MAKE_MEM_UNDEFINED(newbytes, newsize - newmemblk->rawsize);
    }
    newmemblk->rawsize = newsize;
#ifndef MEMENTO_LEAKONLY
    memset(newmemblk->preblk, MEMENTO_PREFILL, Memento_PreSize);
    memset(MEMBLK_POSTPTR(newmemblk), MEMENTO_POSTFILL, Memento_PostSize);
#endif
    Memento_addBlockHead(&globals.used, newmemblk, 2);
    return MEMBLK_TOBLK(newmemblk);
}

int Memento_checkBlock(void *blk)
{
    Memento_BlkHeader *memblk;

    if (blk == NULL)
        return 0;
    memblk = MEMBLK_FROMBLK(blk);
    return checkBlock(memblk, "check");
}

static int Memento_Internal_checkAllAlloced(Memento_BlkHeader *memblk, void *arg)
{
    BlkCheckData *data = (BlkCheckData *)arg;

    Memento_Internal_checkAllocedBlock(memblk, data);
    if (data->preCorrupt || data->postCorrupt) {
        if ((data->found & 2) == 0) {
            fprintf(stderr, "Allocated blocks:\n");
            data->found |= 2;
        }
        fprintf(stderr, "  Block ");
        showBlock(memblk, ' ');
        if (data->preCorrupt) {
            fprintf(stderr, " Preguard ");
        }
        if (data->postCorrupt) {
            fprintf(stderr, "%s Postguard ",
                    (data->preCorrupt ? "&" : ""));
        }
        fprintf(stderr, "corrupted.\n    "
                "Block last checked OK at allocation %d. Now %d.\n",
                memblk->lastCheckedOK, globals.sequence);
        data->preCorrupt  = 0;
        data->postCorrupt = 0;
        data->freeCorrupt = 0;
    }
    else
        memblk->lastCheckedOK = globals.sequence;
    return 0;
}

static int Memento_Internal_checkAllFreed(Memento_BlkHeader *memblk, void *arg)
{
    BlkCheckData *data = (BlkCheckData *)arg;

    Memento_Internal_checkFreedBlock(memblk, data);
    if (data->preCorrupt || data->postCorrupt || data->freeCorrupt) {
        if ((data->found & 4) == 0) {
            fprintf(stderr, "Freed blocks:\n");
            data->found |= 4;
        }
        fprintf(stderr, "  ");
        showBlock(memblk, ' ');
        if (data->freeCorrupt) {
            fprintf(stderr, " index %d (address 0x%p) onwards", data->index,
                    &((char *)MEMBLK_TOBLK(memblk))[data->index]);
            if (data->preCorrupt) {
                fprintf(stderr, "+ preguard");
            }
            if (data->postCorrupt) {
                fprintf(stderr, "+ postguard");
            }
        } else {
            if (data->preCorrupt) {
                fprintf(stderr, " preguard");
            }
            if (data->postCorrupt) {
                fprintf(stderr, "%s Postguard",
                        (data->preCorrupt ? "+" : ""));
            }
        }
        fprintf(stderr, " corrupted.\n"
                "    Block last checked OK at allocation %d. Now %d.\n",
                memblk->lastCheckedOK, globals.sequence);
        data->preCorrupt  = 0;
        data->postCorrupt = 0;
        data->freeCorrupt = 0;
    }
    else
        memblk->lastCheckedOK = globals.sequence;
    return 0;
}

int Memento_checkAllMemory(void)
{
#ifndef MEMENTO_LEAKONLY
    BlkCheckData data;

    memset(&data, 0, sizeof(data));
    Memento_appBlocks(&globals.used, Memento_Internal_checkAllAlloced, &data);
    Memento_appBlocks(&globals.free, Memento_Internal_checkAllFreed, &data);
    if (data.found & 6) {
        Memento_breakpoint();
        return 1;
    }
#endif
    return 0;
}

int Memento_setParanoia(int i)
{
    globals.paranoia = i;
    globals.countdown = globals.paranoia;
    return i;
}

int Memento_paranoidAt(int i)
{
    globals.paranoidAt = i;
    return i;
}

int Memento_getBlockNum(void *b)
{
    Memento_BlkHeader *memblk;
    if (b == NULL)
        return 0;
    memblk = MEMBLK_FROMBLK(b);
    return (memblk->sequence);
}

int Memento_check(void)
{
    int result;

    fprintf(stderr, "Checking memory\n");
    result = Memento_checkAllMemory();
    fprintf(stderr, "Memory checked!\n");
    return result;
}

typedef struct findBlkData {
    void              *addr;
    Memento_BlkHeader *blk;
    int                flags;
} findBlkData;

static int Memento_containsAddr(Memento_BlkHeader *b,
                                void *arg)
{
    findBlkData *data = (findBlkData *)arg;
    char *blkend = &((char *)MEMBLK_TOBLK(b))[b->rawsize];
    if ((MEMBLK_TOBLK(b) <= data->addr) &&
        ((void *)blkend > data->addr)) {
        data->blk = b;
        data->flags = 1;
        return 1;
    }
    if (((void *)b <= data->addr) &&
        (MEMBLK_TOBLK(b) > data->addr)) {
        data->blk = b;
        data->flags = 2;
        return 1;
    }
    if (((void *)blkend <= data->addr) &&
        ((void *)(blkend + Memento_PostSize) > data->addr)) {
        data->blk = b;
        data->flags = 3;
        return 1;
    }
    return 0;
}

int Memento_find(void *a)
{
    findBlkData data;

    data.addr  = a;
    data.blk   = NULL;
    data.flags = 0;
    Memento_appBlocks(&globals.used, Memento_containsAddr, &data);
    if (data.blk != NULL) {
        fprintf(stderr, "Address 0x%p is in %sallocated block ",
                data.addr,
                (data.flags == 1 ? "" : (data.flags == 2 ?
                                         "preguard of " : "postguard of ")));
        showBlock(data.blk, ' ');
        fprintf(stderr, "\n");
        return data.blk->sequence;
    }
    data.blk   = NULL;
    data.flags = 0;
    Memento_appBlocks(&globals.free, Memento_containsAddr, &data);
    if (data.blk != NULL) {
        fprintf(stderr, "Address 0x%p is in %sfreed block ",
                data.addr,
                (data.flags == 1 ? "" : (data.flags == 2 ?
                                         "preguard of " : "postguard of ")));
        showBlock(data.blk, ' ');
        fprintf(stderr, "\n");
        return data.blk->sequence;
    }
    return 0;
}

void Memento_breakOnFree(void *a)
{
    findBlkData data;

    data.addr  = a;
    data.blk   = NULL;
    data.flags = 0;
    Memento_appBlocks(&globals.used, Memento_containsAddr, &data);
    if (data.blk != NULL) {
        fprintf(stderr, "Will stop when address 0x%p (in %sallocated block ",
                data.addr,
                (data.flags == 1 ? "" : (data.flags == 2 ?
                                         "preguard of " : "postguard of ")));
        showBlock(data.blk, ' ');
        fprintf(stderr, ") is freed\n");
        data.blk->flags |= Memento_Flag_BreakOnFree;
        return;
    }
    data.blk   = NULL;
    data.flags = 0;
    Memento_appBlocks(&globals.free, Memento_containsAddr, &data);
    if (data.blk != NULL) {
        fprintf(stderr, "Can't stop on free; address 0x%p is in %sfreed block ",
                data.addr,
                (data.flags == 1 ? "" : (data.flags == 2 ?
                                         "preguard of " : "postguard of ")));
        showBlock(data.blk, ' ');
        fprintf(stderr, "\n");
        return;
    }
    fprintf(stderr, "Can't stop on free; address 0x%p is not in a known block.\n", a);
}

void Memento_breakOnRealloc(void *a)
{
    findBlkData data;

    data.addr  = a;
    data.blk   = NULL;
    data.flags = 0;
    Memento_appBlocks(&globals.used, Memento_containsAddr, &data);
    if (data.blk != NULL) {
        fprintf(stderr, "Will stop when address 0x%p (in %sallocated block ",
                data.addr,
                (data.flags == 1 ? "" : (data.flags == 2 ?
                                         "preguard of " : "postguard of ")));
        showBlock(data.blk, ' ');
        fprintf(stderr, ") is freed (or realloced)\n");
        data.blk->flags |= Memento_Flag_BreakOnFree | Memento_Flag_BreakOnRealloc;
        return;
    }
    data.blk   = NULL;
    data.flags = 0;
    Memento_appBlocks(&globals.free, Memento_containsAddr, &data);
    if (data.blk != NULL) {
        fprintf(stderr, "Can't stop on free/realloc; address 0x%p is in %sfreed block ",
                data.addr,
                (data.flags == 1 ? "" : (data.flags == 2 ?
                                         "preguard of " : "postguard of ")));
        showBlock(data.blk, ' ');
        fprintf(stderr, "\n");
        return;
    }
    fprintf(stderr, "Can't stop on free/realloc; address 0x%p is not in a known block.\n", a);
}

int Memento_failAt(int i)
{
    globals.failAt = i;
    if ((globals.sequence > globals.failAt) &&
        (globals.failing != 0))
        Memento_startFailing();
    return i;
}

size_t Memento_setMax(size_t max)
{
    globals.maxMemory = max;
    return max;
}

#else

/* Just in case anyone has left some debugging code in... */
void (Memento_breakpoint)(void)
{
}

int (Memento_checkBlock)(void *b)
{
    return 0;
}

int (Memento_checkAllMemory)(void)
{
    return 0;
}

int (Memento_check)(void)
{
    return 0;
}

int (Memento_setParanoia)(int i)
{
    return 0;
}

int (Memento_paranoidAt)(int i)
{
    return 0;
}

int (Memento_breakAt)(int i)
{
    return 0;
}

int  (Memento_getBlockNum)(void *i)
{
    return 0;
}

int (Memento_find)(void *a)
{
    return 0;
}

int (Memento_failAt)(int i)
{
    return 0;
}

void (Memento_breakOnFree)(void *a)
{
}

void (Memento_breakOnRealloc)(void *a)
{
}

#undef Memento_malloc
#undef Memento_free
#undef Memento_realloc
#undef Memento_calloc

void *Memento_malloc(size_t size)
{
    return MEMENTO_UNDERLYING_MALLOC(size);
}

void Memento_free(void *b)
{
    MEMENTO_UNDERLYING_FREE(b);
}

void *Memento_realloc(void *b, size_t s)
{
    return MEMENTO_UNDERLYING_REALLOC(b, s);
}

void *Memento_calloc(size_t n, size_t s)
{
    return MEMENTO_UNDERLYING_CALLOC(n, s);
}

void (Memento_listBlocks)(void)
{
}

void (Memento_listNewBlocks)(void)
{
}

size_t (Memento_setMax)(size_t max)
{
    return 0;
}

void (Memento_stats)(void)
{
}

void *(Memento_label)(void *ptr, const char *label)
{
    return ptr;
}

#endif