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谁能告诉我在构建使用已安装到非标准位置的 ImageMagick 库的 go 程序时我做错了什么。

我想我看到的是程序构建了，但是一个告诉程序在非标准位置查找动态库的标志没有设置在某处，因此程序无法找到该库。

重现步骤如下：

将 ImageMagick 配置为安装到非标准目录并构建它：

# ./configure --prefix="/temp/imagemagick-temp" --without-magick-plus-plus --without-perl --disable-openmp --with-gvc=no
# make install

将 pkgconfig 目录添加到 PKG_CONFIG_PATH 以便 pkg-config 可以找到它。

# export PKG_CONFIG_PATH=/temp/imagemagick-temp/lib/pkgconfig

检查 pkg-config 是否满意并且可以找到它：

# pkg-config --cflags --libs MagickWand MagickCore
-DMAGICKCORE_HDRI_ENABLE=0 -DMAGICKCORE_QUANTUM_DEPTH=16 -I/temp/imagemagick-temp/include/ImageMagick-6  -L/temp/imagemagick-temp/lib -lMagickWand-6.Q16 -lMagickCore-6.Q16

构建程序并捕获所有输出：

# go build -v -x debug.go > debug_build.txt 2>&1

尝试运行它：

# ./debug
./debug: error while loading shared libraries: libMagickWand-6.Q16.so.2: cannot open shared object file: No such file or directory

我还通过 strace 运行程序来捕获所有系统调用，捕获如下。它表明程序没有在正确的位置寻找库文件。

当程序位于该自定义位置时，我需要做什么才能使程序能够找到该库？

如果我手动设置 CGO_CFLAGS 和 CGO_LDFLAGS，然后使用 'no_pkgconfig' 选项集进行构建，我会得到相同的结果。

# export CGO_CFLAGS="-DMAGICKCORE_HDRI_ENABLE=0 -DMAGICKCORE_QUANTUM_DEPTH=16 -I/temp/imagemagick-temp/include/ImageMagick-6"
# export CGO_LDFLAGS="-L/temp/imagemagick-temp/lib -lMagickWand-6.Q16 -lMagickCore-6.Q16"
# go build -tags no_pkgconfig debug.go
# ./debug
./debug: error while loading shared libraries: libMagickWand-6.Q16.so.2: cannot open shared object file: No such file or directory

万一这很重要，我在 Centos6.4 上使用“go version go1.6.2 linux/amd64”

debug.go 源文件

package main

/*
#cgo !no_pkgconfig pkg-config: MagickWand MagickCore
#include <wand/MagickWand.h>
*/
import "C"
import "fmt"

type KernelInfoType int

const (
    KERNEL_UNDEFINED     KernelInfoType = C.UndefinedKernel
)

func main() {
    fmt.Println("Hello world")
}

这是构建的输出：

WORK=/tmp/go-build568335569
command-line-arguments
mkdir -p $WORK/command-line-arguments/_obj/
mkdir -p $WORK/command-line-arguments/_obj/exe/
cd /home/github/golang/goworkspace/src/debug
pkg-config --cflags MagickWand MagickCore
pkg-config --libs MagickWand MagickCore
CGO_LDFLAGS="-g" "-O2" "-L/temp/imagemagick-temp/lib" "-lMagickWand-6.Q16" "-lMagickCore-6.Q16" /home/github/golang/go/pkg/tool/linux_amd64/cgo -objdir $WORK/command-line-arguments/_obj/ -importpath command-line-arguments -- -DMAGICKCORE_HDRI_ENABLE=0 -DMAGICKCORE_QUANTUM_DEPTH=16 -I/temp/imagemagick-temp/include/ImageMagick-6 -I $WORK/command-line-arguments/_obj/ debug.go
gcc -I . -fPIC -m64 -pthread -fmessage-length=0 -DMAGICKCORE_HDRI_ENABLE=0 -DMAGICKCORE_QUANTUM_DEPTH=16 -I/temp/imagemagick-temp/include/ImageMagick-6 -I $WORK/command-line-arguments/_obj/ -g -O2 -o $WORK/command-line-arguments/_obj/_cgo_main.o -c $WORK/command-line-arguments/_obj/_cgo_main.c
gcc -I . -fPIC -m64 -pthread -fmessage-length=0 -DMAGICKCORE_HDRI_ENABLE=0 -DMAGICKCORE_QUANTUM_DEPTH=16 -I/temp/imagemagick-temp/include/ImageMagick-6 -I $WORK/command-line-arguments/_obj/ -g -O2 -o $WORK/command-line-arguments/_obj/_cgo_export.o -c $WORK/command-line-arguments/_obj/_cgo_export.c
gcc -I . -fPIC -m64 -pthread -fmessage-length=0 -DMAGICKCORE_HDRI_ENABLE=0 -DMAGICKCORE_QUANTUM_DEPTH=16 -I/temp/imagemagick-temp/include/ImageMagick-6 -I $WORK/command-line-arguments/_obj/ -g -O2 -o $WORK/command-line-arguments/_obj/debug.cgo2.o -c $WORK/command-line-arguments/_obj/debug.cgo2.c
gcc -I . -fPIC -m64 -pthread -fmessage-length=0 -o $WORK/command-line-arguments/_obj/_cgo_.o $WORK/command-line-arguments/_obj/_cgo_main.o $WORK/command-line-arguments/_obj/_cgo_export.o $WORK/command-line-arguments/_obj/debug.cgo2.o -g -O2 -L/temp/imagemagick-temp/lib -lMagickWand-6.Q16 -lMagickCore-6.Q16
/home/github/golang/go/pkg/tool/linux_amd64/cgo -objdir $WORK/command-line-arguments/_obj/ -dynpackage main -dynimport $WORK/command-line-arguments/_obj/_cgo_.o -dynout $WORK/command-line-arguments/_obj/_cgo_import.go
cd $WORK
gcc -I . -fPIC -m64 -pthread -fmessage-length=0 -no-pie -c trivial.c
cd /home/github/golang/goworkspace/src/debug
gcc -I . -fPIC -m64 -pthread -fmessage-length=0 -o $WORK/command-line-arguments/_obj/_all.o $WORK/command-line-arguments/_obj/_cgo_export.o $WORK/command-line-arguments/_obj/debug.cgo2.o -g -O2 -L/temp/imagemagick-temp/lib -Wl,-r -nostdlib -Wl,--build-id=none
/home/github/golang/go/pkg/tool/linux_amd64/compile -o $WORK/command-line-arguments.a -trimpath $WORK -p main -buildid f97632daf57e18f83c78ba78cc2d1ac8f96a4d1f -D _/home/github/golang/goworkspace/src/debug -I $WORK -pack $WORK/command-line-arguments/_obj/_cgo_gotypes.go $WORK/command-line-arguments/_obj/debug.cgo1.go $WORK/command-line-arguments/_obj/_cgo_import.go
pack r $WORK/command-line-arguments.a $WORK/command-line-arguments/_obj/_all.o # internal
cd .
/home/github/golang/go/pkg/tool/linux_amd64/link -o $WORK/command-line-arguments/_obj/exe/a.out -L $WORK -extld=gcc -buildmode=exe -buildid=f97632daf57e18f83c78ba78cc2d1ac8f96a4d1f $WORK/command-line-arguments.a
cp $WORK/command-line-arguments/_obj/exe/a.out debug

这是 strace 捕获的输出，表明程序没有在正确的位置查找。

execve("./debug", ["./debug"], [/* 28 vars */]) = 0
brk(0)                                  = 0xc44000
mmap(NULL, 4096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0x7facec440000
access("/etc/ld.so.preload", R_OK)      = -1 ENOENT (No such file or directory)
open("/etc/ld.so.cache", O_RDONLY)      = 3
fstat(3, {st_mode=S_IFREG|0644, st_size=30417, ...}) = 0
mmap(NULL, 30417, PROT_READ, MAP_PRIVATE, 3, 0) = 0x7facec438000
close(3)                                = 0
open("/lib64/tls/x86_64/libMagickWand-6.Q16.so.2", O_RDONLY) = -1 ENOENT (No such file or directory)
stat("/lib64/tls/x86_64", 0x7fff50c5d9e0) = -1 ENOENT (No such file or directory)
open("/lib64/tls/libMagickWand-6.Q16.so.2", O_RDONLY) = -1 ENOENT (No such file or directory)
stat("/lib64/tls", {st_mode=S_IFDIR|0555, st_size=4096, ...}) = 0
open("/lib64/x86_64/libMagickWand-6.Q16.so.2", O_RDONLY) = -1 ENOENT (No such file or directory)
stat("/lib64/x86_64", 0x7fff50c5d9e0)   = -1 ENOENT (No such file or directory)
open("/lib64/libMagickWand-6.Q16.so.2", O_RDONLY) = -1 ENOENT (No such file or directory)
stat("/lib64", {st_mode=S_IFDIR|0555, st_size=12288, ...}) = 0
open("/usr/lib64/tls/x86_64/libMagickWand-6.Q16.so.2", O_RDONLY) = -1 ENOENT (No such file or directory)
stat("/usr/lib64/tls/x86_64", 0x7fff50c5d9e0) = -1 ENOENT (No such file or directory)
open("/usr/lib64/tls/libMagickWand-6.Q16.so.2", O_RDONLY) = -1 ENOENT (No such file or directory)
stat("/usr/lib64/tls", {st_mode=S_IFDIR|0555, st_size=4096, ...}) = 0
open("/usr/lib64/x86_64/libMagickWand-6.Q16.so.2", O_RDONLY) = -1 ENOENT (No such file or directory)
stat("/usr/lib64/x86_64", 0x7fff50c5d9e0) = -1 ENOENT (No such file or directory)
open("/usr/lib64/libMagickWand-6.Q16.so.2", O_RDONLY) = -1 ENOENT (No such file or directory)
stat("/usr/lib64", {st_mode=S_IFDIR|0555, st_size=20480, ...}) = 0
writev(2, [{"./debug", 7}, {": ", 2}, {"error while loading shared libra"..., 36}, {": ", 2}, {"libMagickWand-6.Q16.so.2", 24}, {": ", 2}, {"cannot open shared object file", 30}, {": ", 2}, {"No such file or directory", 25}, {"\n", 1}], 10./debug: error while loading shared libraries: libMagickWand-6.Q16.so.2: cannot open shared object file: No such file or directory
) = 131
exit_group(127)                         = ?
+++ exited with 127 +++
4

1 回答 1

3

The iMagick library is set up to rely on pkg-config, by default, in order to make it compatible out of the box with standard ImageMagick installs from package managers. It allows you to use a build tag to tell it not to use pkg-config and to instead rely on your own provided env to locate the includes and libs.

This is actually defined in the project README:

Build tags

If you want to specify CGO_CFLAGS/CGO_LDFLAGS manually at build time, such as for building statically or without pkg-config, you can use the "no_pkgconfig" build tag:

go build -tags no_pkgconfig gopkg.in/gographics/imagick.v2/imagick

In my own project that used iMagick, I used the custom build tag with a custom ImageMagick location.

Update

Since you have updated your question, it is apparent now that your problem is not really a Go problem, but rather a standard linux problem of a binary needing to dynamically load a library at runtime (You can see details about how shared libraries work here)

Do the following and it should fix your runtime problem:

$ export LD_LIBRARY_PATH=/temp/imagemagick-temp/lib:$LD_LIBRARY_PATH

LD_LIBRARY_PATH contains a list of paths that should be searched by the linker when a program starts. You have actually succeeded in providing the right info when building the program, as you can confirm by doing the following:

$ ldd ./debug

In that previously mentioned link you can also read about how to provide an rpath when building your binary. This is a path that gets baked into the binary, to tell the linker to search in that location for dependencies. It would allow you to avoid setting the LD_LIBRARY_PATH to your custom ImageMagick location for that particular binary.

于 2016-07-12T20:12:04.553 回答