Backtrace in Android

Backtrace in Android
96 Tsing2015
0.7 2016.02.28 23:03* 字数 33 阅读 2491评论 8喜欢 4
libscorkscrew.so在android 5.0之后已经没有了，之前追踪backtrace的方法已经：
转：https://www.jianshu.com/p/38dbcc392a67

#define MAX_DEPTH                       31
#define MAX_BACKTRACE_LINE_LENGTH   800
#define PATH "/system/lib/libcorkscrew.so"

typedef ssize_t (*unwindFn)(backtrace_frame_t*, size_t, size_t);
typedef void (*unwindSymbFn)(const backtrace_frame_t*, size_t, backtrace_symbol_t*);
typedef void (*unwindSymbFreeFn)(backtrace_symbol_t*, size_t);

static void *gHandle = NULL;

static int getCallStack(void){
    ssize_t i = 0;
    ssize_t result = 0;
    ssize_t count;
    backtrace_frame_t mStack[MAX_DEPTH];
    backtrace_symbol_t symbols[MAX_DEPTH];

    unwindFn unwind_backtrace = NULL;
    unwindSymbFn get_backtrace_symbols = NULL;
    unwindSymbFreeFn free_backtrace_symbols = NULL;

    // open the so.
    if(gHandle == NULL) gHandle = dlopen(PATH, RTLD_NOW);

    // get the interface for unwind and symbol analyse
    if(gHandle != NULL) unwind_backtrace = (unwindFn)dlsym(gHandle, "unwind_backtrace");
    if(gHandle != NULL) get_backtrace_symbols = (unwindSymbFn)dlsym(gHandle, "get_backtrace_symbols");
    if(gHandle != NULL) free_backtrace_symbols = (unwindSymbFreeFn)dlsym(gHandle, "free_backtrace_symbols");

    if(!gHandle ||!unwind_backtrace ||!get_backtrace_symbols || !free_backtrace_symbols  ){
        ALOGE("Error! cannot get unwind info: handle:%p %p %p %p",
            gHandle, unwind_backtrace, get_backtrace_symbols, free_backtrace_symbols );
        return result;
    }

    count= unwind_backtrace(mStack, 1, MAX_DEPTH);
    get_backtrace_symbols(mStack, count, symbols);

    for (i = 0; i < count; i++) {
        char line[MAX_BACKTRACE_LINE_LENGTH];

        const char* mapName = symbols[i].map_name ? symbols[i].map_name : "<unknown>";
        const char* symbolName =symbols[i].demangled_name ? symbols[i].demangled_name : symbols[i].symbol_name;
        size_t fieldWidth = (MAX_BACKTRACE_LINE_LENGTH - 80) / 2;
        
        if (symbolName) {
            uint32_t pc_offset = symbols[i].relative_pc - symbols[i].relative_symbol_addr;
            if (pc_offset) {
                snprintf(line, MAX_BACKTRACE_LINE_LENGTH, "#%02d  pc %08x  %.*s (%.*s+%u)",
                        i, symbols[i].relative_pc, fieldWidth, mapName,
                        fieldWidth, symbolName, pc_offset);
            } else {
                snprintf(line, MAX_BACKTRACE_LINE_LENGTH, "#%02d  pc %08x  %.*s (%.*s)",
                        i, symbols[i].relative_pc, fieldWidth, mapName,
                        fieldWidth, symbolName);
            }
        } else {
            snprintf(line, MAX_BACKTRACE_LINE_LENGTH, "#%02d  pc %08x  %.*s",
                    i, symbols[i].relative_pc, fieldWidth, mapName);
        }

        ALOGD("%s", line);
    }

    free_backtrace_symbols(symbols, count);

    return result;
}

上面这个用法其实会缺几个头文件，到源码里抠出来，可能会有错误，修改下，经测试可以用。

在android5.0之后的做法

#incude "backtrace/Backtrace.h"
int btdump()
{
    void * libbacktrace = dlopen("/system/lib/libbacktrace.so",RTLD_LOCAL);
    if(!libbacktrace)
    {
        return -1;
    }

    Backtrace* (*create)(int,int,void*);
    *(void**) &create = dlsym(libbacktrace,"_ZN9Backtrace6CreateEiiP12BacktraceMap");
    if(!create)
    {
        return -1;
    }
    Backtrace* t = create(-1,-1,NULL);
    if(!t)
    {
        return -1;
    }
    int ret = t->Unwind(0);
    if(!ret)
    {
        return -1;
    }
    int count = t->NumFrames();
    printf("Backtrace:n")
    for(i = 0; i < count; i++)
    {
        std::string line = t->FormatFrameData(i);
        print("t%s",line.c_str());
    }
    return 0;
}

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