golang gdb-打印变量

小编典典

golang gdb-打印变量

我对gdb无法正确打印变量有疑问。通过以下方式构建简单程序：

chmurson-osx:helloworld chmurson$ go build -gcflags '-N' start.go

然后执行gdb：

chmurson-osx:helloworld chmurson$ gdb start -d $GOROOT
GNU gdb (GDB) 7.8
Copyright (C) 2014 Free Software Foundation, Inc.
License GPLv3+: GNU GPL version 3 or later <http://gnu.org/licenses/gpl.html>
This is free software: you are free to change and redistribute it.
There is NO WARRANTY, to the extent permitted by law.  Type "show copying"
and "show warranty" for details.
This GDB was configured as "x86_64-apple-darwin14.0.0".
Type "show configuration" for configuration details.
For bug reporting instructions, please see:
<http://www.gnu.org/software/gdb/bugs/>.
Find the GDB manual and other documentation resources online at:
<http://www.gnu.org/software/gdb/documentation/>.
For help, type "help".
Type "apropos word" to search for commands related to "word"...
Reading symbols from start...done.
warning: Missing auto-load scripts referenced in section .debug_gdb_scripts
of file /Users/chmurson/Dev/goprojects/misc/src/helloworld/start
Use `info auto-load python-scripts [REGEXP]' to list them.
(gdb) 
(gdb) source /usr/local/go/src/pkg/runtime/runtime-gdb.py
Loading Go Runtime support.

这是我下一步要做的：

(gdb) list
1   package main
2   
3   import "fmt"
4   
5   func main() {
6       x := "abc"
7       i := 3
8       fmt.Println(i)
9       fmt.Println(x)
10  }
(gdb) b 9
Breakpoint 1 at 0x2106: file /Users/chmurson/Dev/goprojects/misc/src/helloworld/start.go, line 9.
(gdb) run
Starting program: /Users/chmurson/Dev/goprojects/misc/src/helloworld/start 
3
[New Thread 0x1113 of process 14039]

Breakpoint 1, main.main () at /Users/chmurson/Dev/goprojects/misc/src/helloworld/start.go:9
9       fmt.Println(x)
(gdb) p x
Python Exception <type 'exceptions.OverflowError'> signed integer is greater than maximum: 
$1 = 
(gdb) p i
$2 = 8725692800
(gdb)

您可以看到在检查’p’变量时存在Python异常，而在显示’i’值时完全没有3。怎么了？

这是我去的版本

chmurson-osx:helloworld chmurson$ go version
go version go1.3.1 darwin/amd64

和gdb配置

(gdb) show configuration
This GDB was configured as follows:
   configure --host=x86_64-apple-darwin14.0.0 --target=x86_64-apple-darwin14.0.0
             --with-auto-load-dir=:${prefix}/share/auto-load
             --with-auto-load-safe-path=:${prefix}/share/auto-load
             --with-expat
             --with-gdb-datadir=/usr/local/share/gdb (relocatable)
             --with-jit-reader-dir=/usr/local/lib/gdb (relocatable)
             --without-libunwind-ia64
             --without-lzma
             --with-python=/System/Library/Frameworks/Python.framework/Versions/2.7
             --without-guile
             --with-separate-debug-dir=/usr/local/lib/debug (relocatable)
             --with-zlib
             --without-babeltrace

("Relocatable" means the directory can be moved with the GDB installation
tree, and GDB will still find it.)

阅读 390

2020-07-02

共1个答案

小编典典

添加到@AlexAtNet的答案中，Go 1.2.x之后的所有内容都中断了GDB支持，因此请使用go 1.2.x进行调试或使用gccgo（请记住，gcc
4.8.x支持go 1.1，gcc 4.9.x最高为1.2）。。

另一个选择是使用您自己的跟踪函数，虽然不是很漂亮，但它是go 1.3+的唯一真正的调试选项。

我个人使用这样的东西进行调试：

var traceLock sync.Mutex

func trace(a ...interface{}) {
    traceLock.Lock()
    pc, f, ln, ok := runtime.Caller(1)
    fn := ""
    if ok {
        fn = runtime.FuncForPC(pc).Name()
    }
    fmt.Printf("trace: %s %s:%d", fn, filepath.Base(f), ln)
    if len(a) > 0 {
        fmt.Println(append([]interface{}{": "}, a...)...)
    }
    traceLock.Unlock()
}

playground

2020-07-02