无法从 .gdbinit 获取文件

Question

我有一个包含 GDB 断点的文件 ~/.gdb_bps。我用save breakpoints .gdb_bps 生成了这个文件。我试图在 GDB 启动时通过将此行添加到 ~/.gdbinit 来获取此文件：

source .gdb_bps

当我启动 GDB 时出现错误：

No symbol table is loaded.  Use the "file" command.
Make breakpoint pending on future shared library load? (y or [n]) [answered N; input not from terminal]

但是 GDB 会话期间的采购按预期工作：

(gdb) source .gdb_bps
Breakpoint 1 at 0x401227: file test/varargs2_test.c, line 22.
Breakpoint 2 at 0x4012a3: file test/varargs2_test.c, line 27.
Breakpoint 3 at 0x40117b: file test/varargs2_test.c, line 9.
Breakpoint 4 at 0x401256: file test/varargs2_test.c, line 25.

我的问题是为什么source .gdb_bps 在~/.gdbinit 中使用时会出错？

Answer 1

~/.gdbinit 在处理命令行中的目标文件之前运行。

虽然需要进行一些设置，但将断点保存为 gdb 脚本（可以是 auto-loaded）可能是最简洁的方法。

首先，创建一个目录来保存脚本，并将适当的行添加到~/.gdbinit。

~/devel$ mkdir ~/gdbscripts
~/devel$ cat ~/.gdbinit
add-auto-load-safe-path /home/mp/gdbscripts
add-auto-load-scripts-directory /home/mp/gdbscripts
set debug auto-load on

我们将在一切正常后删除最后一行。

现在让我们看看 gdb 在哪里寻找它的脚本文件。

~/devel$ gdb -q sigw
Reading symbols from sigw...done.
auto-load: Attempted file "/home/mp/devel/sigw-gdb.gdb" does not exist.
auto-load: Expanded $-variables to "/usr/lib/debug:/usr/share/gdb/auto-load:/home/mp/gdbscripts".
auto-load: Searching 'set auto-load scripts-directory' path "$debugdir:$datadir/auto-load:/home/mp/gdbscripts".
auto-load: Attempted file "/usr/lib/debug/home/mp/devel/sigw-gdb.gdb" does not exist.
auto-load: Attempted file "/usr/share/gdb/auto-load/home/mp/devel/sigw-gdb.gdb" does not exist.
auto-load: Attempted file "/home/mp/gdbscripts/home/mp/devel/sigw-gdb.gdb" does not exist.
auto-load: Attempted file "/home/mp/devel/sigw-gdb.py" does not exist.
auto-load: Expanded $-variables to "/usr/lib/debug:/usr/share/gdb/auto-load:/home/mp/gdbscripts".
auto-load: Searching 'set auto-load scripts-directory' path "$debugdir:$datadir/auto-load:/home/mp/gdbscripts".
auto-load: Attempted file "/usr/lib/debug/home/mp/devel/sigw-gdb.py" does not exist.
auto-load: Attempted file "/usr/share/gdb/auto-load/home/mp/devel/sigw-gdb.py" does not exist.
auto-load: Attempted file "/home/mp/gdbscripts/home/mp/devel/sigw-gdb.py" does not exist.

那里有几个不错的候选者，其中一些只能由 root 写入，其中一些需要添加到安全路径中。让我们使用~/gdbscripts/$PWD/sigw-gdb.gdb。

(gdb) shell mkdir -p ~/gdbscripts/$PWD
(gdb) b main
Breakpoint 1 at 0x84f: file sigw.c, line 15.
(gdb) save breakpoints ~/gdbscripts/$PWD/sigw-gdb.gdb
Unable to open file '/home/mp/gdbscripts/$PWD/sigw-gdb.gdb' for saving (No such file or directory)

看起来save 命令扩展了~，但没有扩展环境变量。我们必须使用完整路径。

(gdb) save breakpoints ~/gdbscripts/home/mp/devel/sigw-gdb.gdb
Saved to file '/home/mp/gdbscripts/home/mp/devel/sigw-gdb.gdb'.

测试一下。

(gdb) quit
~/devel$ gdb -q sigw
Reading symbols from sigw...done.
...
auto-load: Matching file "/home/mp/gdbscripts/home/mp/devel/sigw-gdb.gdb" to pattern "/home/mp/gdbscripts"
auto-load: Matched - file "/home/mp/gdbscripts" to pattern "/home/mp/gdbscripts".
auto-load: File "/home/mp/gdbscripts/home/mp/devel/sigw-gdb.gdb" matches directory "/home/mp/gdbscripts".
Breakpoint 1 at 0x84f: file sigw.c, line 15.
...
(gdb) i b
Num     Type           Disp Enb Address            What
1       breakpoint     keep y   0x000000000000084f in main at sigw.c:15

Answer 2

可以在处理 .gdbinit 后加载断点。这可以通过-x option 来完成：

$ gdb -x .gdb_bps program
Reading symbols from test/varargs2_test...
Breakpoint 1 at 0x40117b: file test/varargs2_test.c, line 9.
Breakpoint 2 at 0x4011b2: file test/varargs2_test.c, line 12.
(gdb) 

为避免键入选项，请定义 bash 函数：

gdb() (
    [ -f .gdb_bps ] && xopt="-x .gdb_bps" || xopt=
    command gdb -q $@ $xopt
)

并像gdb program一样使用它