objc-auto-dump.m

/*
 * Copyright (c) 2008 Apple Inc.  All Rights Reserved.
 * 
 * @APPLE_LICENSE_HEADER_START@
 * 
 * This file contains Original Code and/or Modifications of Original Code
 * as defined in and that are subject to the Apple Public Source License
 * Version 2.0 (the 'License'). You may not use this file except in
 * compliance with the License. Please obtain a copy of the License at
 * http://www.opensource.apple.com/apsl/ and read it before using this
 * file.
 * 
 * The Original Code and all software distributed under the License are
 * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
 * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
 * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
 * Please see the License for the specific language governing rights and
 * limitations under the License.
 * 
 * @APPLE_LICENSE_HEADER_END@
 */

#import <auto_zone.h>
#import <objc/objc.h>
#import <objc/runtime.h>
#import "objc-auto-dump.h"
#import "objc-private.h"
#import <strings.h>

/*
 * Utilities
 */

static char myType() {
    char type = 0;
    if (sizeof(void *) == 8) type |= SixtyFour;
#if __LITTLE_ENDIAN__
    type |= Little;
#endif
    return type;
}

/*
 *  Sigh, a mutable set.
 */
 
typedef struct {
    long *items;
    long count;
    long capacity;
} pointer_set_t;

static pointer_set_t *new_pointer_set() {
    pointer_set_t *result = malloc_zone_malloc(_objc_internal_zone(), sizeof(pointer_set_t));
    result->items = calloc(64, sizeof(long));
    result->count = 0;
    result->capacity = 63;  // last valid ptr, also mask
    return result;
}

static void pointer_set_grow(pointer_set_t *set);

static void pointer_set_add(pointer_set_t *set, long ptr) {
    long hash = ptr & set->capacity;
    while (1) {
        if (!set->items[hash]) {
            set->items[hash] = ptr;
            ++set->count;
            if (set->count*3 > set->capacity*2)
                pointer_set_grow(set);
            return;
        }
        if (set->items[hash] == ptr) return;
        hash = (hash + 1) & set->capacity;
    }
}

static void pointer_set_grow(pointer_set_t *set) {
    long oldCapacity = set->capacity;
    long *oldItems = set->items;
    long i;
    set->count = 0;
    set->capacity = 2*(oldCapacity+1)-1;
    set->items = malloc_zone_calloc(_objc_internal_zone(), 2*(oldCapacity+1), sizeof(long));
    for (i = 0; i < oldCapacity; ++i)
        if (oldItems[i]) pointer_set_add(set, oldItems[i]);
    free(oldItems);
}

static void pointer_set_iterate(pointer_set_t *set, void (^block)(long item)) {
    long i;
    for (i = 0; i < set->capacity; ++i)
        if (set->items[i]) block(set->items[i]);
}

static void pointer_set_dispose(pointer_set_t *set) {
    free(set->items);
    free(set);
}

/*
   Quickly dump heap to a named file in a pretty raw format.
 */
__private_extern__ BOOL _objc_dumpHeap(auto_zone_t *zone, const char *filename) {
    // just write interesting info to disk
    int fd = secure_open(filename, O_WRONLY|O_CREAT, geteuid());
    if (fd < 0) return NO;
    FILE *fp = fdopen(fd, "w");
    if (fp == NULL) {
        return NO;
    }
    
    fwrite(HEADER, strlen(HEADER), 1, fp);
    char type = myType();
    fwrite(&type, 1, 1, fp);
    
    // for each thread...
    
    // do registers first
    void (^dump_registers)(const void *, unsigned long) = ^(const void *base, unsigned long byte_size) {
        char type = REGISTER;
        fwrite(&type, 1, 1, fp);
        //fwrite(REGISTER, strlen(REGISTER), 1, fp);
        fwrite(&byte_size, sizeof(byte_size), 1, fp);
        fwrite(base, byte_size, 1, fp);
    };
    
    // then stacks
    void (^dump_stack)(const void *, unsigned long) = ^(const void *base, unsigned long byte_size) {
        char type = THREAD;
        fwrite(&type, 1, 1, fp);
        //fwrite(THREAD, strlen(THREAD), 1, fp);
        fwrite(&byte_size, sizeof(byte_size), 1, fp);
        fwrite(base, byte_size, 1, fp);
    };
    
    // then locals
    void (^dump_local)(const void *, unsigned long, unsigned int, unsigned long) =
        ^(const void *address, unsigned long size, unsigned int layout, unsigned long refcount) {
            // just write the value - rely on it showing up again as a node later
            char type = LOCAL;
            fwrite(&type, 1, 1, fp);
            fwrite(&address, sizeof(address), 1, fp);
    };
    
    
    
    // roots
    void (^dump_root)(const void **) = ^(const void **address) {
        char type = ROOT;
        fwrite(&type, 1, 1, fp);
        // write the address so that we can catch misregistered globals
        fwrite(&address, sizeof(address), 1, fp);
        // write content, even (?) if zero
        fwrite(address, sizeof(*address), 1, fp);
    };
    
    // the nodes
    pointer_set_t *classes = new_pointer_set();
    void (^dump_node)(const void *, unsigned long, unsigned int, unsigned long) =
        ^(const void *address, unsigned long size, unsigned int layout, unsigned long refcount) {
            char type = NODE;
            fwrite(&type, 1, 1, fp);
            fwrite(&address, sizeof(address), 1, fp);
            fwrite(&size, sizeof(size), 1, fp);
            fwrite(&layout, sizeof(layout), 1, fp);
            fwrite(&refcount, sizeof(refcount), 1, fp);
            if ((layout & AUTO_UNSCANNED) != AUTO_UNSCANNED) {
                // now the nodes unfiltered content
                fwrite(address, size, 1, fp);
            }
            if ((layout & AUTO_OBJECT) == AUTO_OBJECT) {
                long theClass = *(long *)address;
                if (theClass) pointer_set_add(classes, theClass);
            }
    };
    
    // weak
    void (^dump_weak)(const void **, const void *) = ^(const void **address, const void *item) {
        char type = WEAK;
        fwrite(&type, 1, 1, fp);
        fwrite(&address, sizeof(address), 1, fp);
        fwrite(&item, sizeof(item), 1, fp);
    };

    auto_zone_dump(zone, dump_stack, dump_registers, dump_local, dump_root, dump_node, dump_weak);
    
    pointer_set_iterate(classes, ^(long class) {
        char type = CLASS;
        fwrite(&type, 1, 1, fp);
        fwrite(&class, sizeof(class), 1, fp);   // write address so that we can map it from node isa's
        // classname (for grins)
        const char *className = class_getName((Class)class);
        unsigned int length = (int)strlen(className);
        fwrite(&length, sizeof(length), 1, fp);      // n
        fwrite(className, length, 1, fp);          // n bytes
        // strong layout
        const char *layout = class_getIvarLayout((Class)class);
        length = layout ? (int)strlen(layout)+1 : 0; // format is <skipnibble><count nibble> ending with <0><0>
        fwrite(&length, sizeof(length), 1, fp);      // n
        fwrite(layout, length, 1, fp);            // n bytes
        // weak layout
        layout = class_getWeakIvarLayout((Class)class);
        length = layout ? (int)strlen(layout)+1 : 0; // format is <skipnibble><count nibble> ending with <0><0>
        fwrite(&length, sizeof(length), 1, fp);      // n
        fwrite(layout, length, 1, fp);             // n bytes
    });

    {
        // end
        char type = END;
        fwrite(&type, 1, 1, fp);
        fclose(fp);
        pointer_set_dispose(classes);
    }
    return YES;
}