xcode – 如何使用lldb“memory find”命令？

Find a value in the memory of the process being debugged.

Syntax: memory find <cmd-options> <address> <value> [<value> [...]]

Command Options Usage:
  memory find <address> <value> [<value> [...]]
  memory find [-e <expr>] [-s <name>] [-c <count>] [-o <offset>] <address> <value> [<value> [...]]

       -c <count> ( --count <count> )
            How many times to perform the search.

       -e <expr> ( --expression <expr> )
            Evaluate an expression to obtain a byte pattern.

       -o <offset> ( --dump-offset <offset> )
            When dumping memory for a match,an offset from the match location
            to start dumping from.

       -s <name> ( --string <name> )
            Use text to find a byte pattern.

     This command takes options and free-form arguments.  If your arguments
     resemble option specifiers (i.e.,they start with a - or --),you must use
     ' -- ' between the end of the command options and the beginning of the
     arguments.

我怀疑实现与帮助信息不匹配,因为我使用的任何语法我似乎得到各种神秘的错误消息之一,例如：

error: two addresses needed for memory find

要么

error: do not know how to deal with larger than 8 byte result types. pass a string instead

要么

error: please pass either a block of text,or an expression to evaluate.

我用Google搜索了一些用法示例,并且没有提出任何问题.如果有人有一个有效的例子,我将不胜感激.特别是我想从指针标识的块的开头搜索给定的字节数,以找到特定(字节)值的第一次出现(在这种情况下为255).

我在OS X上使用Xcode 7.0.1,而lldb版本是lldb-340.4.70.

UPDATE

我发现可以使-s选项起作用,例如像这样：

(lldb) me fi -s "f" -- ptr ptr+8192*256
Your data was found at location: 0x11033e20c
0x11033e20c: 66 bb 58 07 d0 b7 32 7d ff 7f 00 00 66 5b e7 82  f.X...2}....f[..

可能只是-e选项(这是我在这个例子中需要的)被破坏,例如：

(lldb) me fi -e 255 -- ptr ptr+8191*256
error: expression evaluation failed. pass a string instead?

不幸的是,试图哄骗-s选项接受转义的十六进制或十进制值似乎也不起作用：

(lldb) me fi -s "xff" -- ptr ptr+8191*256
Your data was not found within the range.

(lldb) me fi -s "255" -- ptr ptr+8191*256
Your data was not found within the range.