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如何轻松打包分析核心转储所需的库（即 packcore）

发布于 2024-12-06 16:54:45 字数 195 浏览 0 评论 0原文

HPUX 上可用的 GDB 版本有一个名为“packcore”的命令，该命令创建一个包含核心转储、可执行文件和所有库的 tarball。当尝试在不同的机器上调试核心转储时，我发现这非常有用。

在 Linux 机器上的 GDB 标准版本中是否有类似的命令？

我正在寻找一个简单的命令，当生产机器上出现问题时，不一定是开发人员的人也可以运行该命令。

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相守太难 2024-12-13 16:54:45

核心文件包含生成它的命令。理想情况下，这将包括相应可执行文件的完整路径。例如：

$ file core.29529 
core.29529: ELF 64-bit LSB core file x86-64, version 1 (SYSV), SVR4-style, from '/bin/sleep 60'

在 ELF 二进制文件上运行 ldd 将显示它所依赖的库：

$ ldd /bin/sleep
linux-vdso.so.1 =>  (0x00007fff1d3ff000)
libc.so.6 => /lib64/libc.so.6 (0x0000003d3ce00000)
/lib64/ld-linux-x86-64.so.2 (0x0000003d3ca00000)

所以现在我知道了分析核心转储所需的可执行文件和库。

这里棘手的部分是从核心文件中提取可执行路径。似乎没有一个好的工具可以直接阅读此内容。数据以 prpsinfo 结构编码（来自 /usr/include/sys/procfs.h），您可以使用 readelf: 找到数据的位置大小

$ readelf -n core.29529
Notes at offset 0x00000468 with length 0x00000558:
  Owner         Data size       Description
  CORE          0x00000150      NT_PRSTATUS (prstatus structure)
  CORE          0x00000088      NT_PRPSINFO (prpsinfo structure)
  CORE          0x00000130      NT_AUXV (auxiliary vector)
  CORE          0x00000200      NT_FPREGSET (floating point registers)

。 ..因此，理论上可以编写一个代码片段来从该结构中提取命令行，并以一种使整个过程更容易自动化的方式打印出来。当然，您可以只解析 file 的输出：

$ file core.29529  | sed "s/.*from '\([^']*\)'/\1/"
/bin/sleep 60

这就是所有部分。这是将所有内容放在一起的起点：

#!/bin/sh

core=$1
exe=$(file $core  | sed "s/.*from '\([^']*\)'/\1/" | awk '{print $1}')

libs=$(
    ldd $exe |
    awk '
        /=> \// {print $3}
        ! /=>/ {print $1}
    '
    )

cat <<EOF | tar -cah -T- -f $1-all.tar.xz
$libs
$exe
EOF

对于我的示例，如果我将此脚本命名为 packcore 并通过 sleep 命令在核心文件上运行它，我会得到以下结果：

$ packcore core.29529
tar: Removing leading `/' from member names
$ tar -c -f core.29529-all.tar.xz
core.29529
lib64/libc.so.6
lib64/ld-linux-x86-64.so.2
bin/sleep

就目前而言，这个脚本非常脆弱；我仅根据此示例输出对 ldd 的输出做出了很多假设。

The core file includes the command from which it was generated. Ideally this will include the full path to the appropriate executable. For example:

$ file core.29529 
core.29529: ELF 64-bit LSB core file x86-64, version 1 (SYSV), SVR4-style, from '/bin/sleep 60'

Running ldd on an ELF binary will show what libraries it depends on:

$ ldd /bin/sleep
linux-vdso.so.1 =>  (0x00007fff1d3ff000)
libc.so.6 => /lib64/libc.so.6 (0x0000003d3ce00000)
/lib64/ld-linux-x86-64.so.2 (0x0000003d3ca00000)

So now I know the executable and the libraries needed to analyze the core dump.

The tricky part here is extracting the executable path from the core file. There doesn't appear to be a good tool for reading this directly. The data is encoded in a prpsinfo structure (from /usr/include/sys/procfs.h), and you can find the location size of the data using readelf:

$ readelf -n core.29529
Notes at offset 0x00000468 with length 0x00000558:
  Owner         Data size       Description
  CORE          0x00000150      NT_PRSTATUS (prstatus structure)
  CORE          0x00000088      NT_PRPSINFO (prpsinfo structure)
  CORE          0x00000130      NT_AUXV (auxiliary vector)
  CORE          0x00000200      NT_FPREGSET (floating point registers)

...so one could in theory write a code snippet to extract the command line from this structure and print it out in a way that would make this whole process easier to automate. You could, of course, just parse the output of file:

$ file core.29529  | sed "s/.*from '\([^']*\)'/\1/"
/bin/sleep 60

So that's all the parts. Here's a starting point for putting it all together:

#!/bin/sh

core=$1
exe=$(file $core  | sed "s/.*from '\([^']*\)'/\1/" | awk '{print $1}')

libs=$(
    ldd $exe |
    awk '
        /=> \// {print $3}
        ! /=>/ {print $1}
    '
    )

cat <<EOF | tar -cah -T- -f $1-all.tar.xz
$libs
$exe
EOF

For my example, if I name this script packcore and run it on the core file from the sleep command, I get this:

$ packcore core.29529
tar: Removing leading `/' from member names
$ tar -c -f core.29529-all.tar.xz
core.29529
lib64/libc.so.6
lib64/ld-linux-x86-64.so.2
bin/sleep

As it stands this script is pretty fragile; I've made lots of assumptions about the output from ldd based on only this sample output.

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原谅我要高飞 2024-12-13 16:54:45

下面是执行必要步骤的脚本（仅在 RHEL5 上测试，但也可能在其他地方工作）：

#!/bin/sh
#
# Take a core dump and create a tarball of all of the binaries and libraries
# that are needed to debug it.
#

include_core=1
keep_workdir=0

usage()
{
        argv0="$1"
        retval="$2"
        errmsg="$3"
        if [ ! -z "$errmsg" ] ; then
                echo "ERROR: $errmsg" 1>&2
        fi
        cat <<EOF
Usage: $argv0 [-k] [-x] <corefile>
        Parse a core dump and create a tarball with all binaries and libraries
        needed to be able to debug the core dump.
        Creates <corefile>.tgz

        -k - Keep temporary working directory
        -x - Exclude the core dump from the generated tarball
EOF
        exit $retval
}

while [ $# -gt 0 ] ; do
        case "$1" in
        -k)
                keep_workdir=1
                ;;
        -x)
                include_core=0
                ;;
        -h|--help)
                usage "$0" 0
                ;;
        -*)
                usage "$0" 1 "Unknown command line arguments: $*"
                ;;
        *)
                break
                ;;
        esac
        shift
done

COREFILE="$1"

if [ ! -e "$COREFILE" ] ; then
        usage "$0" 1 "core dump '$COREFILE' doesn't exist."
fi
case "$(file "$COREFILE")" in
        *"core file"*)
                break
                ;;
        *)
                usage "$0" 1 "per the 'file' command, core dump '$COREFILE' is not a core dump."
                ;;
esac

cmdname=$(file "$COREFILE" | sed -e"s/.*from '\(.*\)'/\1/")
echo "Command name from core file: $cmdname"
fullpath=$(which "$cmdname")
if [ ! -x "$fullpath" ] ; then
        usage "$0" 1 "unable to find command '$cmdname'"
fi
echo "Full path to executable: $fullpath"

mkdir "${COREFILE}.pack"
gdb --eval-command="quit" "${fullpath}" ${COREFILE}  2>&1 | \
  grep "Reading symbols" | \
  sed -e's/Reading symbols from //' -e's/\.\.\..*//' | \
  tar --files-from=- -cf - | (cd "${COREFILE}.pack" && tar xf -)
if [ $include_core -eq 1 ] ; then
        cp "${COREFILE}" "${COREFILE}.pack"
fi
tar czf "${COREFILE}.pack.tgz" "${COREFILE}.pack"

if [ $keep_workdir -eq 0 ] ; then
        rm -r "${COREFILE}.pack"
fi

echo "Done, created ${COREFILE}.path.tgz"

Here's a script that does the necessary steps (tested only on RHEL5, but might work elsewhere too):

#!/bin/sh
#
# Take a core dump and create a tarball of all of the binaries and libraries
# that are needed to debug it.
#

include_core=1
keep_workdir=0

usage()
{
        argv0="$1"
        retval="$2"
        errmsg="$3"
        if [ ! -z "$errmsg" ] ; then
                echo "ERROR: $errmsg" 1>&2
        fi
        cat <<EOF
Usage: $argv0 [-k] [-x] <corefile>
        Parse a core dump and create a tarball with all binaries and libraries
        needed to be able to debug the core dump.
        Creates <corefile>.tgz

        -k - Keep temporary working directory
        -x - Exclude the core dump from the generated tarball
EOF
        exit $retval
}

while [ $# -gt 0 ] ; do
        case "$1" in
        -k)
                keep_workdir=1
                ;;
        -x)
                include_core=0
                ;;
        -h|--help)
                usage "$0" 0
                ;;
        -*)
                usage "$0" 1 "Unknown command line arguments: $*"
                ;;
        *)
                break
                ;;
        esac
        shift
done

COREFILE="$1"

if [ ! -e "$COREFILE" ] ; then
        usage "$0" 1 "core dump '$COREFILE' doesn't exist."
fi
case "$(file "$COREFILE")" in
        *"core file"*)
                break
                ;;
        *)
                usage "$0" 1 "per the 'file' command, core dump '$COREFILE' is not a core dump."
                ;;
esac

cmdname=$(file "$COREFILE" | sed -e"s/.*from '\(.*\)'/\1/")
echo "Command name from core file: $cmdname"
fullpath=$(which "$cmdname")
if [ ! -x "$fullpath" ] ; then
        usage "$0" 1 "unable to find command '$cmdname'"
fi
echo "Full path to executable: $fullpath"

mkdir "${COREFILE}.pack"
gdb --eval-command="quit" "${fullpath}" ${COREFILE}  2>&1 | \
  grep "Reading symbols" | \
  sed -e's/Reading symbols from //' -e's/\.\.\..*//' | \
  tar --files-from=- -cf - | (cd "${COREFILE}.pack" && tar xf -)
if [ $include_core -eq 1 ] ; then
        cp "${COREFILE}" "${COREFILE}.pack"
fi
tar czf "${COREFILE}.pack.tgz" "${COREFILE}.pack"

if [ $keep_workdir -eq 0 ] ; then
        rm -r "${COREFILE}.pack"
fi

echo "Done, created ${COREFILE}.path.tgz"

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