iphone - 如何在运行时确定二进制图像架构？

Question

崩溃日志包含“二进制图像”部分，其中包含有关架构（armv6/armv7）和所有加载模块的标识符的信息。如何在运行时确定这些信息？（至少，仅适用于应用程序可执行文件）
NSBundle 具有方法 executableArchitectures，但如何确定正在运行哪个架构？

Answer 1

是时候回答长篇大论了。应用程序中 dyld 图像的 mach 标头包含您要查找的信息。我添加了一个示例，我只测试过它可以工作，所以我不建议将它直接粘贴到生产代码中。它的作用是获取所有当前加载的 dyld 图像的所有 mach 标头，并打印与崩溃日志的二进制图像部分非常相似的输出。我调用的方法不是线程安全的。我缺少的一件事是二进制图像的结束地址，因为我没有费心查找如何找到它。

主程序

#import <UIKit/UIKit.h>

#include <string.h>
#import <mach-o/loader.h>
#import <mach-o/dyld.h>
#import <mach-o/arch.h>

void printImage(const struct mach_header *header)
{
    uint8_t *header_ptr = (uint8_t*)header;
    typedef struct load_command load_command;

    const NXArchInfo *info = NXGetArchInfoFromCpuType(header->cputype, header->cpusubtype);

    //Print the architecture ex. armv7
    printf("%s ", info->name);

    header_ptr += sizeof(struct mach_header);
    load_command *command = (load_command*)header_ptr;

    for(int i = 0; i < header->ncmds > 0; ++i)
    {
        if(command->cmd == LC_UUID)
        {
            struct uuid_command ucmd = *(struct uuid_command*)header_ptr;

            CFUUIDRef cuuid = CFUUIDCreateFromUUIDBytes(kCFAllocatorDefault, *((CFUUIDBytes*)ucmd.uuid));
            CFStringRef suuid = CFUUIDCreateString(kCFAllocatorDefault, cuuid);
            CFStringEncoding encoding = CFStringGetFastestEncoding(suuid);

            //Print UUID
            printf("<%s> ", CFStringGetCStringPtr(suuid, encoding));

            CFRelease(cuuid);
            CFRelease(suuid);

            break;
        }

        header_ptr += command->cmdsize;
        command = (load_command*)header_ptr;
    }
}

void printBinaryImages()
{
    printf("Binary Images:\n");
    //Get count of all currently loaded DYLD
    uint32_t count = _dyld_image_count();

    for(uint32_t i = 0; i < count; i++)
    {
        //Name of image (includes full path)
        const char *dyld = _dyld_get_image_name(i);

        //Get name of file
        int slength = strlen(dyld);

        int j;
        for(j = slength - 1; j>= 0; --j)
            if(dyld[j] == '/') break;

        //strndup only available in iOS 4.3
        char *name = strndup(dyld + ++j, slength - j);
        printf("%s ", name);
        free(name);

        const struct mach_header *header = _dyld_get_image_header(i);
        //print address range
        printf("0x%X - ??? ", (uint32_t)header);

        printImage(header);

        //print file path
        printf("%s\n",  dyld);
    }
    printf("\n");
}

int main(int argc, char *argv[])
{        
    NSAutoreleasePool *pool = [[NSAutoreleasePool alloc] init];
    printBinaryImages();
    [pool release];
    return retVal;
}

示例输出：

Binary Images:
TestBed 0x1000 - ??? i386 <E96D079C-E035-389D-AA12-71E968C76BFE> /Users/username/Library/Application Support/iPhone Simulator/4.3/Applications/6F64D9F8-9179-4E21-AE32-4D4604BE77E5/TestBed.app/TestBed
UIKit 0x8000 - ??? i386 <72030911-362F-3E47-BAF3-ACD2CB6F88C0> /Developer/Platforms/iPhoneSimulator.platform/Developer/SDKs/iPhoneSimulator4.3.sdk/System/Library/Frameworks/UIKit.framework/UIKit
Foundation 0x772000 - ??? i386 <EB718CBD-1D57-3D31-898D-7CFA9C172A46> /Developer/Platforms/iPhoneSimulator.platform/Developer/SDKs/iPhoneSimulator4.3.sdk/System/Library/Frameworks/Foundation.framework/Foundation
CoreGraphics 0xA10000 - ??? i386 <D168A716-71F2-337A-AE0B-9DCF51AE9181> /Developer/Platforms/iPhoneSimulator.platform/Developer/SDKs/iPhoneSimulator4.3.sdk/System/Library/Frameworks/CoreGraphics.framework/CoreGraphics
libSystem.dylib 0xCAA000 - ??? i386 <8DF0AFCD-FFA5-3049-88E2-7410F8398749> /Developer/Platforms/iPhoneSimulator.platform/Developer/SDKs/iPhoneSimulator4.3.sdk/usr/lib/libSystem.dylib
...

Answer 2

由于您正在构建应用程序，因此对于仅关于架构的快速回答，您可以检查一些预处理器定义以确定构建应用程序的当前架构。确保首先检查可用的最高版本的 arm，因为每个新版本都定义了所有旧版本。

#if __arm__
#import <arm/arch.h>

#ifdef __ARM_ARCH_6K__
//This is armv6
#endif //__ARM_ARCH_6K__
#endif //__arm__

Answer 3

我们可以使用 sysctl、sysctlbyname 系统调用来获取或设置系统信息。

示例代码：

#import <sys/sysctl.h>
#import <mach/machine.h>

int32_t value = 0;
size_t length = sizeof(value);
sysctlbyname("hw.cputype", &value, &length, NULL, 0);

if (value == CPU_TYPE_ARM64) {
    // arm64
}
else if (value == CPU_TYPE_ARM) {
    // armv7/armv7s
}
else if (value == CPU_TYPE_X86) {
    // simulator
}

我只是列出了 2016 年最常见的拱门。寻找“hw.cpusubtype”以获得更多细节，比如CPU_SUBTYPE_ARM_V6 CPU_SUBTYPE_ARM_V7 CPU_SUBTYPE_ARM_V7S