GDB script flow control for remote target

问题

I would like to do only flash the code on a remote gdb target if it has changed since last time gdb was run. I envisage something along the lines of the following in gdb script;

target extended-remote /dev/<device>
<Attach to Target>
file <Target Program>
if ![compare-sections -r]
    load
start

...however, I cannot see how to make a conditional on a command output.

Can anyone help? I think I probably missed something, but I've no idea what....

回答1:

The compare-sections command doesn't return a value that can be used in an if statement, but the following may do what you want.

First, define a convenience function named $cmdeval which will execute a gdb command and return its output as a string:

import gdb

class CmdEval(gdb.Function):
    """$cmdeval(str) - evaluate argument string as a gdb command
    and return the result as a string. Trailing newlines are removed.
    """

    def __init__(self):
        super(CmdEval, self).__init__("cmdeval")

    def invoke(self, gdbcmd):
        return gdb.execute(gdbcmd.string(), from_tty=False, to_string=True).rstrip('\n')

CmdEval()

You can put this in a file named cmdeval.py and type (gdb) source cmdeval.py to load it into gdb.

Next, since compare-sections outputs "MIS-MATCHED" for any section that has been changed, you can look for that string using the $_regex convenience function, which is included in more recent versions of gdb:

(gdb) if $_regex($cmdeval("compare-sections -r"),".*MIS-MATCHED.*")
 >echo need to load again\n
 >end

来源：https://stackoverflow.com/questions/43219115/gdb-script-flow-control-for-remote-target

标签

gdb

remote-debugging