在PHP 7.4中使用FFI加载库时出现问题 [英] Problem loading a library with FFI in PHP 7.4
问题描述
我无法在PHP和新的FFI中使用第三方.so库. 当我运行这段代码时:
I'm having trouble using a third party .so library in PHP with the new FFI. When I run this little piece of code:
<?php
$ffi = FFI::cdef('typedef int (*NFE_Nome)(const char* sNome, int* esTamanho);', 'libacbrnfe64.so');
PHP向我输出此错误:
PHP outputs me this error:
double free or corruption (out)
Aborted (core dumped)
这是库本身，我的PHP配置或其他问题吗?这让我感到困惑，因为我通常可以将此同一个库与此C ++代码一起使用:
Is this a problem with the library itself, my PHP configuration or something else? It's confusing to me, because I can use normally this same library with this C++ code:
#include <iostream>
#include <dlfcn.h>
typedef int (*NFE_Nome)(const char* sNome, int* esTamanho);
#define BUFFER_LEN 256
int main() {
void *lib = dlopen("libacbrnfe64.so", RTLD_LAZY);
auto libMethod = (NFE_Nome) dlsym(lib, "NFE_Nome");
const std::string bufferNome(BUFFER_LEN, ' ');
int bufferNomeLength = BUFFER_LEN;
libMethod(bufferNome.c_str(), &bufferNomeLength);
std::cout << bufferNome << std::endl;
return 0;
}
我知道PHP代码不会执行NFE_Nome函数，但是在尝试调用函数本身之前遇到了错误.
I'm aware that the PHP code doesn't execute the NFE_Nome function, but I'm getting the error before trying to call the function itself.
推荐答案
-编辑-
此问题是两个不同程序中的两个错误导致的.
This problem is result of two bugs in two different programs.
-
链接共享对象时，fpc-3.0.0(或更高版本)将其添加到依赖项中(作为第一个依赖项):
/lib64/ld-linux-x86-64.so.2
ld-linux-x86-64.so.2导出一个calloc变体，该变体不会(始终)清除返回的内存(详细信息如下)
ld-linux-x86-64.so.2 exports a calloc variant, that doesn't (always) clears the memory it returns (details below)
建议的解决方法OP是在单独的过程中链接(使用fpc的-E(或-Cn)选项)，但是在运行./ppas.sh修复link.res文件之前.为此，我修改了这个awk脚本，但确实感到有些笨拙:
The workaround OP suggested is linking in a separate pass (using -E (or -Cn) option of fpc), but before running ./ppas.sh fixing link.res file. For that, I hacked this awk-script, but I do feel it a bit clumsy:
#!/usr/bin/awk -f
$0=="INPUT(" { state=1; next; }
$0=="/lib64/ld-linux-x86-64.so.2" { state=2; next; }
$0==")" && state>0 { state=0;next; }
state==1 { print "INPUT("; state=0; }
{ print $0; }
-原始答案-
听起来像是链接问题:您可能已经将/lib64/ld-linux-x86-64.so.2添加到了相关的共享库中，这既不是必需的，也不是有用的.
Sounds like a linking problem: you might have added /lib64/ld-linux-x86-64.so.2 into the dependent shared libraries, which is neither required or useful.
实际上，它产生了一个calloc版本，该版本返回未归零的内存.此处描述了详细信息: https://www.linuxquestions.org /questions/programming-9/debugging-dlopen-4175668676/和此处:
Actually, it resulted a calloc version that returns non-zeroed memory. The details are described here: https://www.linuxquestions.org/questions/programming-9/debugging-dlopen-4175668676/ and here: Why does calling calloc in gdb not appear to zero out the memory?
建议的解决方案:根据示例更改链接:
Suggested solution: change the linkage according to the example:
- gcc -shared -o demodule.so demodule.o /lib64/ld-linux-x86-64.so.2 -lglib-2.0
+ gcc -shared -o demodule.so demodule.o -lglib-2.0
可以使用readelf -d检查差异.错误:
The difference can be checked with readelf -d. Wrong:
Dynamic section at offset 0x828 contains 26 entries:
Tag Type Name/Value
0x0000000000000001 (NEEDED) Shared library: [ld-linux-x86-64.so.2]
0x0000000000000001 (NEEDED) Shared library: [libglib-2.0.so.0]
0x0000000000000001 (NEEDED) Shared library: [libc.so.6]
右输出:
Dynamic section at offset 0x7f8 contains 25 entries:
Tag Type Name/Value
0x0000000000000001 (NEEDED) Shared library: [libglib-2.0.so.0]
0x0000000000000001 (NEEDED) Shared library: [libc.so.6]
此外，使用命令ldd demodule.so，包含/lib64/ld-linux-x86-64.so.2的行应为最后一行.
Also, with command ldd demodule.so the line containing /lib64/ld-linux-x86-64.so.2 should be the last one.
关于此问题在sourceware.org上进行的讨论: https://sourceware.org/bugzilla/show_bug.cgi?id=25486
discussion on sourceware.org regarding this problem: https://sourceware.org/bugzilla/show_bug.cgi?id=25486
在Freepascal方面: https://bugs.freepascal.org/view .php?id = 36706
on Freepascal side: https://bugs.freepascal.org/view.php?id=36706
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