漲知識了，Linux的ld和ldd一起用，可以幫我們分析運行時載入庫檔案失敗的原因
- PHPz轉載
- 2024-02-20 08:36:031061瀏覽
通常，開發人員和維運人員在處理軟體執行時報錯誤找不到依賴函式庫的問題時，可以使用一些工具來追蹤啟動載入的過程，例如strace、gdb等。此外，還可以利用ld和ldd指令來協助分析依賴函式庫的情況，以便更快解決問題。這些工具可以幫助定位缺少的依賴庫，並指導使用者採取適當的措施來解決軟體運行時的問題。
這裡以分析 libmpi_usempif80.so 這個動態庫文件，依賴哪些其他動態庫，作為問題起因。
首先介紹 ld 指令如何幫我們分析mpi_usempif80 函式庫依賴其他哪些函式庫？ mpi_usempif80 函式庫被載入時，會從目前系統的哪些路徑下搜尋這些函式庫？
#ld -lmpi_usempif08 –verbose
GNU ld (GNU Binutils for Ubuntu) 2.38
Supported emulations:
elf_x86_64
elf32_x86_64
elf_i386
elf_iamcu
elf_l1om
elf_k1om
i386pep
i386pe
using internal linker script:
==================================================
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Copying and distribution of this script, with or without modification,
are permitted in any medium without royalty provided the copyright
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==================================================
ld: mode elf_x86_64
attempt to open /usr/local/lib/x86_64-linux-gnu/libmpi_usempif08.so failed
attempt to open /usr/local/lib/x86_64-linux-gnu/libmpi_usempif08.a failed
attempt to open /lib/x86_64-linux-gnu/libmpi_usempif08.so succeeded
/lib/x86_64-linux-gnu/libmpi_usempif08.so
libmpi_mpifh.so.40 needed by /lib/x86_64-linux-gnu/libmpi_usempif08.so
attempt to open /build/openmpi-RCkqwI/openmpi-4.1.2/debian/build-gfortran/ompi/mpi/fortran/mpif-h/.libs/libmpi_mpifh.so.40 failed
attempt to open /build/openmpi-RCkqwI/openmpi-4.1.2/debian/build-gfortran/ompi/.libs/libmpi_mpifh.so.40 failed
attempt to open /usr/lib/x86_64-linux-gnu/openmpi/lib/libmpi_mpifh.so.40 failed
attempt to open /usr/lib/x86_64-linux-gnu/libfakeroot/libmpi_mpifh.so.40 failed
attempt to open /usr/local/lib/libmpi_mpifh.so.40 failed
found libmpi_mpifh.so.40 at /usr/lib/x86_64-linux-gnu/libmpi_mpifh.so.40
libmpi.so.40 needed by /lib/x86_64-linux-gnu/libmpi_usempif08.so
attempt to open /build/openmpi-RCkqwI/openmpi-4.1.2/debian/build-gfortran/ompi/mpi/fortran/mpif-h/.libs/libmpi.so.40 failed
attempt to open /build/openmpi-RCkqwI/openmpi-4.1.2/debian/build-gfortran/ompi/.libs/libmpi.so.40 failed
attempt to open /usr/lib/x86_64-linux-gnu/openmpi/lib/libmpi.so.40 failed
attempt to open /usr/lib/x86_64-linux-gnu/libfakeroot/libmpi.so.40 failed
attempt to open /usr/local/lib/libmpi.so.40 failed
found libmpi.so.40 at /usr/lib/x86_64-linux-gnu/libmpi.so.40
libc.so.6 needed by /lib/x86_64-linux-gnu/libmpi_usempif08.so
attempt to open /build/openmpi-RCkqwI/openmpi-4.1.2/debian/build-gfortran/ompi/mpi/fortran/mpif-h/.libs/libc.so.6 failed
attempt to open /build/openmpi-RCkqwI/openmpi-4.1.2/debian/build-gfortran/ompi/.libs/libc.so.6 failed
attempt to open /usr/lib/x86_64-linux-gnu/openmpi/lib/libc.so.6 failed
attempt to open /usr/lib/x86_64-linux-gnu/libfakeroot/libc.so.6 failed
attempt to open /usr/local/lib/libc.so.6 failed
attempt to open /usr/lib/x86_64-linux-gnu/fortran/gfortran/libc.so.6 failed
attempt to open /usr/lib/x86_64-linux-gnu/openmpi/lib/libc.so.6 failed
attempt to open /usr/local/lib/x86_64-linux-gnu/libc.so.6 failed
attempt to open /usr/local/lib/x86_64-linux-gnu/libc.so.6 failed
attempt to open /usr/lib/x86_64-linux-gnu64/libc.so.6 failed
attempt to open /usr/local/lib64/libc.so.6 failed
attempt to open /lib64/libc.so.6 failed
attempt to open /usr/lib64/libc.so.6 failed
attempt to open /usr/local/lib/libc.so.6 failed
attempt to open /lib/libc.so.6 failed
attempt to open /usr/lib/libc.so.6 failed
attempt to open /usr/x86_64-linux-gnu/lib64/libc.so.6 failed
attempt to open /usr/x86_64-linux-gnu/lib/libc.so.6 failed
attempt to open /build/openmpi-RCkqwI/openmpi-4.1.2/debian/build-gfortran/ompi/mpi/fortran/mpif-h/.libs/libc.so.6 failed
attempt to open /build/openmpi-RCkqwI/openmpi-4.1.2/debian/build-gfortran/ompi/.libs/libc.so.6 failed
attempt to open /usr/lib/x86_64-linux-gnu/openmpi/lib/libc.so.6 failed
attempt to open /usr/lib/x86_64-linux-gnu/libfakeroot/libc.so.6 failed
attempt to open /usr/local/lib/libc.so.6 failed
found libc.so.6 at /usr/lib/x86_64-linux-gnu/libc.so.6
libopen-pal.so.40 needed by /usr/lib/x86_64-linux-gnu/libmpi_mpifh.so.40
attempt to open /build/openmpi-RCkqwI/openmpi-4.1.2/debian/build-gfortran/ompi/.libs/libopen-pal.so.40 failed
attempt to open /build/openmpi-RCkqwI/openmpi-4.1.2/debian/build-gfortran/opal/.libs/libopen-pal.so.40 failed
attempt to open /usr/lib/x86_64-linux-gnu/openmpi/lib/libopen-pal.so.40 failed
attempt to open /usr/lib/x86_64-linux-gnu/libfakeroot/libopen-pal.so.40 failed
attempt to open /usr/local/lib/libopen-pal.so.40 failed
found libopen-pal.so.40 at /usr/lib/x86_64-linux-gnu/libopen-pal.so.40
libopen-rte.so.40 needed by /usr/lib/x86_64-linux-gnu/libmpi.so.40
attempt to open /usr/lib/x86_64-linux-gnu/openmpi/lib/libopen-rte.so.40 failed
attempt to open /usr/lib/x86_64-linux-gnu/libfakeroot/libopen-rte.so.40 failed
attempt to open /usr/local/lib/libopen-rte.so.40 failed
found libopen-rte.so.40 at /usr/lib/x86_64-linux-gnu/libopen-rte.so.40
libm.so.6 needed by /usr/lib/x86_64-linux-gnu/libmpi.so.40
attempt to open /usr/lib/x86_64-linux-gnu/openmpi/lib/libm.so.6 failed
attempt to open /usr/lib/x86_64-linux-gnu/libfakeroot/libm.so.6 failed
attempt to open /usr/local/lib/libm.so.6 failed
found libm.so.6 at /usr/lib/x86_64-linux-gnu/libm.so.6
libhwloc.so.15 needed by /usr/lib/x86_64-linux-gnu/libmpi.so.40
attempt to open /usr/lib/x86_64-linux-gnu/openmpi/lib/libhwloc.so.15 failed
attempt to open /usr/lib/x86_64-linux-gnu/libfakeroot/libhwloc.so.15 failed
attempt to open /usr/local/lib/libhwloc.so.15 failed
found libhwloc.so.15 at /usr/lib/x86_64-linux-gnu/libhwloc.so.15
ld-linux-x86-64.so.2 needed by /usr/lib/x86_64-linux-gnu/libc.so.6
attempt to open /usr/lib/x86_64-linux-gnu/libfakeroot/ld-linux-x86-64.so.2 failed
attempt to open /usr/local/lib/ld-linux-x86-64.so.2 failed
found ld-linux-x86-64.so.2 at /usr/lib/x86_64-linux-gnu/ld-linux-x86-64.so.2
libevent_core-2.1.so.7 needed by /usr/lib/x86_64-linux-gnu/libopen-pal.so.40
attempt to open /usr/lib/x86_64-linux-gnu/libfakeroot/libevent_core-2.1.so.7 failed
attempt to open /usr/local/lib/libevent_core-2.1.so.7 failed
found libevent_core-2.1.so.7 at /usr/lib/x86_64-linux-gnu/libevent_core-2.1.so.7
libevent_pthreads-2.1.so.7 needed by /usr/lib/x86_64-linux-gnu/libopen-pal.so.40
attempt to open /usr/lib/x86_64-linux-gnu/libfakeroot/libevent_pthreads-2.1.so.7 failed
attempt to open /usr/local/lib/libevent_pthreads-2.1.so.7 failed
found libevent_pthreads-2.1.so.7 at /usr/lib/x86_64-linux-gnu/libevent_pthreads-2.1.so.7
libz.so.1 needed by /usr/lib/x86_64-linux-gnu/libopen-rte.so.40
attempt to open /usr/lib/x86_64-linux-gnu/openmpi/lib/libz.so.1 failed
attempt to open /usr/lib/x86_64-linux-gnu/libfakeroot/libz.so.1 failed
attempt to open /usr/local/lib/libz.so.1 failed
found libz.so.1 at /usr/lib/x86_64-linux-gnu/libz.so.1
libudev.so.1 needed by /usr/lib/x86_64-linux-gnu/libhwloc.so.15
attempt to open /usr/lib/x86_64-linux-gnu/libfakeroot/libudev.so.1 failed
attempt to open /usr/local/lib/libudev.so.1 failed
found libudev.so.1 at /usr/lib/x86_64-linux-gnu/libudev.so.1
ld -lmpi_usempif08 --verbose | grep found
found libmpi_mpifh.so.40 at /usr/lib/x86_64-linux-gnu/libmpi_mpifh.so.40
found libmpi.so.40 at /usr/lib/x86_64-linux-gnu/libmpi.so.40
ld: warning: cannot find entry symbol _start; not setting start address
found libc.so.6 at /usr/lib/x86_64-linux-gnu/libc.so.6
found libopen-pal.so.40 at /usr/lib/x86_64-linux-gnu/libopen-pal.so.40
found libopen-rte.so.40 at /usr/lib/x86_64-linux-gnu/libopen-rte.so.40
found libm.so.6 at /usr/lib/x86_64-linux-gnu/libm.so.6
found libhwloc.so.15 at /usr/lib/x86_64-linux-gnu/libhwloc.so.15
found ld-linux-x86-64.so.2 at /usr/lib/x86_64-linux-gnu/ld-linux-x86-64.so.2
found libevent_core-2.1.so.7 at /usr/lib/x86_64-linux-gnu/libevent_core-2.1.so.7
found libevent_pthreads-2.1.so.7 at /usr/lib/x86_64-linux-gnu/libevent_pthreads-2.1.so.7
found libz.so.1 at /usr/lib/x86_64-linux-gnu/libz.so.1
found libudev.so.1 at /usr/lib/x86_64-linux-gnu/libudev.so.1
上面這段訊息很長，有很多有價值的訊息，如果你只想看關鍵部分，那麼我保留其中的關鍵內容，來一個精華版的輸出訊息：
#ld -lmpi_usempif08 –verbose
GNU ld (GNU Binutils for Ubuntu) 2.38
Supported emulations:
elf_x86_64
……
using internal linker script:
notice and this notice are preserved.*/
OUTPUT_FORMAT("elf64-x86-64", "elf64-x86-64",
"elf64-x86-64")
OUTPUT_ARCH(i386:x86-64)
ENTRY(_start)# 运行时可执行文件从代码段的 _start 位置开始运行。
# 运行时需从哪些目录找动态库文件
SEARCH_DIR("=/usr/local/lib/x86_64-linux-gnu"); SEARCH_DIR("=/lib/x86_64-linux-gnu"); SEARCH_DIR("=/usr/lib/x86_64-linux-gnu"); SEARCH_DIR("=/usr/lib/x86_64-linux-gnu64"); SEARCH_DIR("=/usr/local/lib64"); SEARCH_DIR("=/lib64"); SEARCH_DIR("=/usr/lib64"); SEARCH_DIR("=/usr/local/lib"); SEARCH_DIR("=/lib"); SEARCH_DIR("=/usr/lib"); SEARCH_DIR("=/usr/x86_64-linux-gnu/lib64"); SEARCH_DIR("=/usr/x86_64-linux-gnu/lib");
# 二进制文件有哪些的代码段、数据段
SECTIONS
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PROVIDE (__executable_start = SEGMENT_START("text-segment", 0x400000)); . = SEGMENT_START("text-segment", 0x400000) + SIZEOF_HEADERS;
.interp : { *(.interp) }
……
.rodata : { *(.rodata .rodata.* .gnu.linkonce.r.*) }
……
/* Thread Local Storage sections*/
# 线程本地存储区域
.tdata :
{
PROVIDE_HIDDEN (__tdata_start = .);
*(.tdata .tdata.* .gnu.linkonce.td.*)
}
.tbss: { *(.tbss .tbss.* .gnu.linkonce.tb.*) *(.tcommon) }
.preinit_array:
{
PROVIDE_HIDDEN (__preinit_array_start = .);
KEEP (*(.preinit_array))
PROVIDE_HIDDEN (__preinit_array_end = .);
}
# 数据区
.data :
{
*(.data .data.* .gnu.linkonce.d.*)
SORT(CONSTRUCTORS)
}
.data1: { *(.data1) }
_edata = .; PROVIDE (edata = .);
. = .;
__bss_start = .;
# BSS区
.bss:
{
……
}
……
}
# 下面是本文的重点关注部分
==================================================
# 文件1：逐个目录匹配是否找到被依赖的libmpi_usempif08.so 库文件
ld: mode elf_x86_64
attempt to open /usr/local/lib/x86_64-linux-gnu/libmpi_usempif08.so failed
attempt to open /usr/local/lib/x86_64-linux-gnu/libmpi_usempif08.a failed
attempt to open /lib/x86_64-linux-gnu/libmpi_usempif08.so succeeded
# 找到了 libmpi_usempif08.so 库文件
# 文件2：逐个目录匹配是否找到被依赖的 libmpi_mpifh.so 库文件
libmpi_mpifh.so.40 needed by /lib/x86_64-linux-gnu/libmpi_usempif08.so
attempt to open /build/openmpi-RCkqwI/openmpi-4.1.2/debian/build-gfortran/ompi/mpi/fortran/mpif-h/.libs/libmpi_mpifh.so.40 failed
attempt to open /build/openmpi-RCkqwI/openmpi-4.1.2/debian/build-gfortran/ompi/.libs/libmpi_mpifh.so.40 failed
attempt to open /usr/lib/x86_64-linux-gnu/openmpi/lib/libmpi_mpifh.so.40 failed
attempt to open /usr/lib/x86_64-linux-gnu/libfakeroot/libmpi_mpifh.so.40 failed
attempt to open /usr/local/lib/libmpi_mpifh.so.40 failed
found libmpi_mpifh.so.40 at /usr/lib/x86_64-linux-gnu/libmpi_mpifh.so.40
# 找到了 libmpi_mpifh.so 库文件
# 找 libmpi.so.40
libmpi.so.40 needed by /lib/x86_64-linux-gnu/libmpi_usempif08.so
……
found libmpi.so.40 at /usr/lib/x86_64-linux-gnu/libmpi.so.40
# 找 libc.so.6
libc.so.6 needed by /lib/x86_64-linux-gnu/libmpi_usempif08.so
……
found libc.so.6 at /usr/lib/x86_64-linux-gnu/libc.so.6
# 找 libopen-pal.so.40
libopen-pal.so.40 needed by /usr/lib/x86_64-linux-gnu/libmpi_mpifh.so.40
……
found libopen-pal.so.40 at /usr/lib/x86_64-linux-gnu/libopen-pal.so.40
# 找 libopen-rte.so.40
libopen-rte.so.40 needed by /usr/lib/x86_64-linux-gnu/libmpi.so.40
……
found libopen-rte.so.40 at /usr/lib/x86_64-linux-gnu/libopen-rte.so.40
# 找 libm.so.6
libm.so.6 needed by /usr/lib/x86_64-linux-gnu/libmpi.so.40
……
found libm.so.6 at /usr/lib/x86_64-linux-gnu/libm.so.6
libhwloc.so.15 needed by /usr/lib/x86_64-linux-gnu/libmpi.so.40
# 找 libhwloc.so.15
……略
# 找 libudev.so.1
libudev.so.1 needed by /usr/lib/x86_64-linux-gnu/libhwloc.so.15
attempt to open /usr/lib/x86_64-linux-gnu/libfakeroot/libudev.so.1 failed
attempt to open /usr/local/lib/libudev.so.1 failed
found libudev.so.1 at /usr/lib/x86_64-linux-gnu/libudev.so.1
進一步，我們可以用 grep 過濾只顯示 mpi_usempif08 實際找到的函式庫的資訊：
#ld -lmpi_usempif08 –verbose | grep found
found libmpi_mpifh.so.40 at /usr/lib/x86_64-linux-gnu/libmpi_mpifh.so.40 found libmpi.so.40 at /usr/lib/x86_64-linux-gnu/libmpi.so.40 ld: warning: cannot find entry symbol _start; not setting start address found libc.so.6 at /usr/lib/x86_64-linux-gnu/libc.so.6 found libopen-pal.so.40 at /usr/lib/x86_64-linux-gnu/libopen-pal.so.40 found libopen-rte.so.40 at /usr/lib/x86_64-linux-gnu/libopen-rte.so.40 found libm.so.6 at /usr/lib/x86_64-linux-gnu/libm.so.6 found libhwloc.so.15 at /usr/lib/x86_64-linux-gnu/libhwloc.so.15 found ld-linux-x86-64.so.2 at /usr/lib/x86_64-linux-gnu/ld-linux-x86-64.so.2 found libevent_core-2.1.so.7 at /usr/lib/x86_64-linux-gnu/libevent_core-2.1.so.7 found libevent_pthreads-2.1.so.7 at /usr/lib/x86_64-linux-gnu/libevent_pthreads-2.1.so.7 found libz.so.1 at /usr/lib/x86_64-linux-gnu/libz.so.1 found libudev.so.1 at /usr/lib/x86_64-linux-gnu/libudev.so.1
而ldd 與 ld是不同的。 ldd是分析linux的運行程式庫的依賴關係、ld是可執行檔連結器常用於C/C /Fortran等語言程式碼產生執行檔的連結階段。
我們看下 使用 ldd 對同一個動態函式庫所依賴的其他函式庫的分析：
#ldd/usr/lib/x86_64-linux-gnu/libmpi_usempif08.so.40.30.0
linux-vdso.so.1 (0x00007ffd2f3fd000) libmpi_mpifh.so.40 => /usr/lib/x86_64-linux-gnu/libmpi_mpifh.so.40 (0x00007f34366bf000) libmpi.so.40 => /usr/lib/x86_64-linux-gnu/libmpi.so.40 (0x00007f3436588000) libc.so.6 => /usr/lib/x86_64-linux-gnu/libc.so.6 (0x00007f3436200000) libopen-pal.so.40 => /usr/lib/x86_64-linux-gnu/libopen-pal.so.40 (0x00007f34364d5000) libopen-rte.so.40 => /usr/lib/x86_64-linux-gnu/libopen-rte.so.40 (0x00007f3436143000) libm.so.6 => /usr/lib/x86_64-linux-gnu/libm.so.6 (0x00007f343605c000) libhwloc.so.15 => /usr/lib/x86_64-linux-gnu/libhwloc.so.15 (0x00007f3436477000) /lib64/ld-linux-x86-64.so.2 (0x00007f343677c000) libevent_core-2.1.so.7 => /usr/lib/x86_64-linux-gnu/libevent_core-2.1.so.7 (0x00007f3436442000) libevent_pthreads-2.1.so.7 => /usr/lib/x86_64-linux-gnu/libevent_pthreads-2.1.so.7 (0x00007f343643d000) libz.so.1 => /usr/lib/x86_64-linux-gnu/libz.so.1 (0x00007f3436040000) libudev.so.1 => /usr/lib/x86_64-linux-gnu/libudev.so.1 (0x00007f3436016000)
這裡的順序與ld -lmpi_usempif08 –verbose | grep found 的結果是一致的。
以上是漲知識了，Linux的ld和ldd一起用，可以幫我們分析運行時載入庫檔案失敗的原因的詳細內容。更多資訊請關注PHP中文網其他相關文章！
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