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lwhay

vxworks 加载共享库, 求帮助! [复制链接]

 
struct FindWellKnownSymbolCallbackInfo {
    char *name;
    UINT16 group;
};

static BOOL
findWellKnownSymbolCB(char *name,
                      int val,
                      SYM_TYPE type,
                      int arg,
                      UINT16 group)
{
    struct FindWellKnownSymbolCallbackInfo *info =
        (struct FindWellKnownSymbolCallbackInfo *) arg;

    if (!strcmp(name, info->name)) {
        info->group = group;
        return FALSE;
    }
    return TRUE;
}

/* Returns CVM_TRUE upon success, CVM_FALSE upon error */
static CVMBool
getWellKnownSymbolGroupId(UINT16* group)
{

    static CVMBool gotId = CVM_FALSE;
    static UINT16 id;

    if (gotId == CVM_FALSE) {
        struct FindWellKnownSymbolCallbackInfo info;
        SYMBOL* sym;
#ifdef CVM_DYNLINKSYM_PREPEND_UNDERSCORE
        info.name = "_CVMgcUnsafeExecuteJavaMethod";
#else
        info.name = "CVMgcUnsafeExecuteJavaMethod";
#endif
       
        sym = symEach(sysSymTbl, (FUNCPTR) &findWellKnownSymbolCB,
                      (int) &info);
        /* If sym is NULL, failed to find symbol -- should not happen. */
        if (sym == NULL) {
            return CVM_FALSE;
        }

        id = info.group;
        gotId = CVM_TRUE;
    }

    *group = id;
    return gotId;
}

struct CallbackInfo {
    char *name;
    UINT16 group;
    void *val;
};

static BOOL
findSymbolCB(char *name,
             int val,
             SYM_TYPE type,
             int arg,
             UINT16 group)
{
    struct CallbackInfo *info = (struct CallbackInfo *) arg;

    if ((!strcmp(name, info->name)) &&
        (info->group == group)) {
        /* Found the symbol we're looking for. Returning FALSE from
           this callback will cause symEach() to return the current
           symbol to its caller. */
        info->val = (void *) val;
        return FALSE;
    }
    return TRUE;
}


void *
CVMdynlinkSym(void *dsoHandle, const void *nameArg)
{
    VxWorksLibraryHandle* handle = (VxWorksLibraryHandle*)dsoHandle;
    const char* name = (const char*)nameArg;
    struct CallbackInfo info;
    SYMBOL* sym;
    void *value;

#ifdef CVM_DYNLINKSYM_PREPEND_UNDERSCORE
    /*
     * %comment: mam051
     * It might be nice if we could modify nameArg in place.
     */
    char *buf = malloc(strlen(nameArg) + 1 + 1);
    if (buf == NULL) {
        return NULL;
    }
    strcpy(buf, "_");
    strcat(buf, nameArg);
    name = buf;
#endif

    assert(handle != NULL);
   
    if (handle->isGlobal) {
        /* Look up a well-known CVM symbol and match its group
           ID. This protects us whether cvm.o is dynamically loaded,
           or statically linked into the kernel. */
        if (getWellKnownSymbolGroupId(&info.group) == CVM_FALSE) {
            value = NULL;
            goto done;
        }
    } else {
        MODULE_ID mid;
        MODULE_INFO mInfo;

        mid = handle->id;
        if (moduleInfoGet(mid, &mInfo) == ERROR) {
            value = NULL;
            goto done;
        }
        info.group = (UINT16) mInfo.group;
    }
    info.name = (char*)name;
    sym = symEach(sysSymTbl, (FUNCPTR) &findSymbolCB, (int) &info);
    if (sym == NULL) {
        value = NULL;
    } else {
        value = info.val;
    }

done:
#ifdef CVM_DYNLINKSYM_PREPEND_UNDERSCORE
    free(buf);
#endif
    return value;
}

void
CVMdynlinkClose(void *dsoHandle)
{
    VxWorksLibraryHandle* handle = (VxWorksLibraryHandle *)dsoHandle;
    if (handle->id != NULL) {
        unldByModuleId(handle->id, 0);
    }
    free(handle);
}

jw_1001

  主要是vxworks的这个函数, symEach(sysSymTbl, (FUNCPTR) &findWellKnownSymbolCB, (int) &info);

  不明白呀! 也找不到原代码. 谢谢!

sjhlhj

workbench的帮助里面有这个函数说明呀，调用findWellKnownSymbolCB这个callback函数
你这里好像是查询系统符号表，看有没有Info->name这个符号参数