gdb结合valgrind一起使用

一、简介

        这篇文章使我学习gdb与valgrind一起使用的记录

二、gdb和valgrind结合使用

       这个是一个例子Use Valgrind, GDB, and vgdb to debug | Red Hat Developer 里面有个简单的示例，这个示例让我看到这个工具挺强大的。

下面使我代码的结构

makefile中，记得启用调试选项。

在一个终端输入：

 valgrind  -q --vgdb-error=0 ./main //成功运行后，会显示pid号

 在另一个终端输入：

gdb ./main

成功后

再输入target remote | vgdb --pid=***

现在，你就可以愉快的调试了。

在gdb端，运行，可以看到valgrind 的一些监视器的一些命令

 具体是：

general valgrind monitor commands:
  help [debug]            : monitor command help. With debug: + debugging commands
  v.wait [<ms>]           : sleep <ms> (default 0) then continue
  v.info all_errors       : show all errors found so far
  v.info last_error       : show last error found
  v.info location <addr>  : show information about location <addr>
  v.info n_errs_found [msg] : show the nr of errors found so far and the given msg
  v.info open_fds         : show open file descriptors (only if --track-fds=yes)
  v.kill                  : kill the Valgrind process
  v.set gdb_output        : set valgrind output to gdb
  v.set log_output        : set valgrind output to log
  v.set mixed_output      : set valgrind output to log, interactive output to gdb
  v.set merge-recursive-frames <num> : merge recursive calls in max <num> frames
  v.set vgdb-error <errornr> : debug me at error >= <errornr> 
 
memcheck monitor commands:
  xb <addr> [<len>]
        prints validity bits for <len> (or 1) bytes at <addr>
            bit values 0 = valid, 1 = invalid, __ = unaddressable byte
        Then prints the bytes values below the corresponding validity bits
        in a layout similar to the gdb command 'x /xb '
        Example: xb 0x8049c78 10
  get_vbits <addr> [<len>]
        Similar to xb, but only prints the validity bytes by group of 4.
  make_memory [noaccess|undefined
                     |defined|Definedifaddressable] <addr> [<len>]
        mark <len> (or 1) bytes at <addr> with the given accessibility
  check_memory [addressable|defined] <addr> [<len>]
        check that <len> (or 1) bytes at <addr> have the given accessibility
            and outputs a description of <addr>
  leak_check [full*|summary|xtleak]
                [kinds kind1,kind2,...|reachable|possibleleak*|definiteleak]
                [heuristics heur1,heur2,...]
                [increased*|changed|any]
                [unlimited*|limited <max_loss_records_output>]
            * = defaults
         xtleak produces an xtree full leak result in xtleak.kcg.%p.%n
       where kind is one of:
         definite indirect possible reachable all none
       where heur is one of:
         stdstring length64 newarray multipleinheritance all none*
       Examples: leak_check
                 leak_check summary any
                 leak_check full kinds indirect,possible
                 leak_check full reachable any limited 100
  block_list <loss_record_nr>|<loss_record_nr_from>..<loss_record_nr_to>
                [unlimited*|limited <max_blocks>]
                [heuristics heur1,heur2,...]
        after a leak search, shows the list of blocks of <loss_record_nr>
        (or of the range <loss_record_nr_from>..<loss_record_nr_to>).
        With heuristics, only shows the blocks found via heur1,heur2,...
            * = defaults
  who_points_at <addr> [<len>]
        shows places pointing inside <len> (default 1) bytes at <addr>
        (with len 1, only shows "start pointers" pointing exactly to <addr>,
         with len > 1, will also show "interior pointers")
  xtmemory [<filename>]
        dump xtree memory profile in <filename> (default xtmemory.kcg.%p.%n)
给我解释一下，仔细的解释

 使用方式，比如：

 monitor v.info last_error