Python 模块安装失败，因为 gcc 命令缺少标志...gcc 命令具有

Question

我正在尝试从 C 代码构建一个（非常简单的）Python 扩展，但运行在编译过程中遇到了麻烦。

（郑重声明：我的 C 技能已经过时，我的代码可能很糟糕。）

按照指示 in the docs and on another site I found，我创建了一个 C 文件，公开了我需要内置到 Python 模块中的功能：

#include "strcrypto.h"
#include <stdlib.h>

#define CRYPTO_POOLNUMBER 15

int main() {
    return 0;
}

char* encryptString(char* string) {
    COMM* comm;
    char* encrypted_string = malloc(sizeof(char) * 4096);
    int res;

    comm = init_client(CRYPTO_PORT);

    if (comm == NULL) {
        return NULL;
    }

    res = StrEncrypt(comm, string, encrypted_string, CRYPTO_POOLNUMBER);

    end_client(comm);
    if (res != 1) {
        return NULL;
    }
    else {
        return encrypted_string;
    }
}

char* decrypt(char* string) {
    COMM* comm;
    char* decrypted_string = malloc(sizeof(char) * 4096);
    int res;

    comm = init_client(CRYPTO_PORT);

    if (comm == NULL) {
        return NULL;
    }

    res = StrDecrypt(comm, string, decrypted_string);

    end_client(comm);
    if (res != 1) {
        return NULL;
    }
    else {
        return decrypted_string;
    }
}

char* randomToken(char* string) {
    COMM* comm;
    char* token = malloc(sizeof(char) * 4096);
    int res;

    comm = init_client(CRYPTO_PORT);

    if (comm == NULL) {
        return NULL;
    }

    res = getPBToken(comm, string, token);

    end_client(comm);
    if (res != 1) {
        return NULL;
    }
    else {
        return token;
    }
}

char* fixedToken(char* string) {
    COMM* comm;
    char* token = malloc(sizeof(char) * 4096);
    int res;

    comm = init_client(CRYPTO_PORT);

    if (comm == NULL) {
        return NULL;
    }

    res = getFixedToken(comm, string, token);

    end_client(comm);
    if (res != 1) {
        return NULL;
    }
    else {
        return token;
    }
}

我还创建了包含 Python:

方法的 C 文件

#include <Python.h>

static PyObject* crypto_encrypt(PyObject* self, PyObject* args) {
    char* original_string;
    char* encrypted_string;
    PyObject* return_value;

    if (!PyArg_ParseTuple(args, "s", &original_string)) {
        return NULL;    // Could not parse string or no string was passed.
    }

    encrypted_string = encryptString(original_string);

    if (encrypted_string == NULL) {
        return NULL;
    }
    else {
        return_value = PyString_FromString(encrypted_string);
        free(encrypted_string);
        return return_value;
    }
}

static PyObject* crypto_decrypt(PyObject* self, PyObject* args) {
    char* original_string;
    char* decrypted_string;
    PyObject* return_value;

    if (!PyArg_ParseTuple(args, "s", &original_string)) {
        return NULL;    // Could not parse string or no string was passed.
    }

    decrypted_string = decryptString(original_string);

    if (decrypted_string == NULL) {
        return NULL;
    }
    else {
        return_value = PyString_FromString(decrypted_string);
        free(decrypted_string);
        return return_value;
    }
}

static PyObject* crypto_fixedToken(PyObject* self, PyObject* args) {
    char* original_string;
    char* token;
    PyObject* return_value;

    if (!PyArg_ParseTuple(args, "s", &original_string)) {
        return NULL;    // Could not parse string or no string was passed.
    }

    token = fixedToken(original_string);

    if (token == NULL) {
        return NULL;
    }
    else {
        return_value = PyString_FromString(token);
        free(token);
        return return_value;
    }
}

static PyObject* crypto_randomToken(PyObject* self, PyObject* args) {
    char* original_string;
    char* token;
    PyObject* return_value;

    if (!PyArg_ParseTuple(args, "s", &original_string)) {
        return NULL;    // Could not parse string or no string was passed.
    }

    token = randomToken(original_string);

    if (token == NULL) {
        return NULL;
    }
    else {
        return_value = PyString_FromString(token);
        free(token);
        return return_value;
    }
}

static PyMethodDef CryptoMethods[] = {
    { "encrypt", crypto_encrypt, METH_VARARGS, "Encrypt text using a Crypto server." },
    { "decrypt", crypto_decrypt, METH_VARARGS, "Decrypt text encrypted using a Crypto server." },
    { "getFixedToken", crypto_fixedToken, METH_VARARGS, "Return a fixed PKCS5 token from Crypto." },
    { "getRandomToken", crypto_randomToken, METH_VARARGS, "Return a random PKCS5 token from Crypto." },
    { NULL, NULL, 0, NULL }
};

PyMODINIT_FUNC initcrypto(void) {
    (void) Py_InitModule("crypto", CryptoMethods);
}

最后，我创建了一个 setup.py 文件来创建扩展并在扩展上调用 setup()：

from distutils.core import setup, Extension

ext = Extension("crypto",
    ["cryptomodule.c", "crypto.c"],
    libraries = ["strcrypto",],
    library_dirs = ["/usr/local/lib",]
)

setup(name = "crypto", ext_modules = [ext,])

库 "strcrypto" 实际上是 "libstrcrypto.a" 并且是提供给我的；这不是我写的。不幸的是，这也是我安装文件时出现错误的原因：

running install
running build
running build_ext
building 'crypto' extension
x86_64-linux-gnu-gcc -pthread -fno-strict-aliasing -DNDEBUG -g -fwrapv -O2 -Wall -Wstrict-prototypes -fPIC -I/usr/include/python2.7 -c cryptomodule.c -o build/temp.linux-x86_64-2.7/cryptomodule.o
cryptomodule.c: In function ‘crypto_encrypt’:
cryptomodule.c:15:5: warning: implicit declaration of function ‘encryptString’ [-Wimplicit-function-declaration]
     encrypted_string = encryptString(original_string);
     ^
cryptomodule.c:15:22: warning: assignment makes pointer from integer without a cast [enabled by default]
     encrypted_string = encryptString(original_string);
                      ^
cryptomodule.c: In function ‘crypto_decrypt’:
cryptomodule.c:36:5: warning: implicit declaration of function ‘decryptString’ [-Wimplicit-function-declaration]
     decrypted_string = decryptString(original_string);
     ^
cryptomodule.c:36:22: warning: assignment makes pointer from integer without a cast [enabled by default]
     decrypted_string = decryptString(original_string);
                      ^
cryptomodule.c: In function ‘crypto_fixedToken’:
cryptomodule.c:57:5: warning: implicit declaration of function ‘fixedToken’ [-Wimplicit-function-declaration]
     token = fixedToken(original_string);
     ^
cryptomodule.c:57:11: warning: assignment makes pointer from integer without a cast [enabled by default]
     token = fixedToken(original_string);
           ^
cryptomodule.c: In function ‘crypto_randomToken’:
cryptomodule.c:78:5: warning: implicit declaration of function ‘randomToken’ [-Wimplicit-function-declaration]
     token = randomToken(original_string);
     ^
cryptomodule.c:78:11: warning: assignment makes pointer from integer without a cast [enabled by default]
     token = randomToken(original_string);
           ^
x86_64-linux-gnu-gcc -pthread -fno-strict-aliasing -DNDEBUG -g -fwrapv -O2 -Wall -Wstrict-prototypes -fPIC -I/usr/include/python2.7 -c crypto.c -o build/temp.linux-x86_64-2.7/crypto.o
crypto.c:6:5: warning: function declaration isn’t a prototype [-Wstrict-prototypes]
 int main() {
     ^
x86_64-linux-gnu-gcc -pthread -shared -Wl,-O1 -Wl,-Bsymbolic-functions -Wl,-Bsymbolic-functions -Wl,-z,relro -fno-strict-aliasing -DNDEBUG -g -fwrapv -O2 -Wall -Wstrict-prototypes -D_FORTIFY_SOURCE=2 -g -fstack-protector --param=ssp-buffer-size=4 -Wformat -Werror=format-security build/temp.linux-x86_64-2.7/cryptomodule.o build/temp.linux-x86_64-2.7/crypto.o -L/usr/local/lib -lstrcrypto -o build/lib.linux-x86_64-2.7/crypto.so
/usr/bin/ld: /usr/local/lib/libstrcrypto.a(strcrypto.o): relocation R_X86_64_32 against `.rodata.str1.1' can not be used when making a shared object; recompile with -fPIC
/usr/local/lib/libstrcrypto.a: error adding symbols: Bad value
collect2: error: ld returned 1 exit status
error: command 'x86_64-linux-gnu-gcc' failed with exit status 1

我不知道那个错误是什么意思，因为如您所见，gcc 调用确实使用了 -fPIC。

有人可以指出我在这里做错了什么吗？提前致谢。

Answer 1

您正在构建的 Python 扩展是一个共享库。共享库中的代码

必须编译为 position independent。这是通过使用 -fPIC 编译完成的。

你的问题是你的 libstrcrypto.a 不是用 -fPIC 编译的，因此不能在共享库中使用。您有多种选择：

请求使用 -fPIC.

libstrcrypto.a

请求 libstrcrypto.a 的共享库版本。
Link 您的扩展静态生成一个新的 Python 可执行文件，其中包含您的内置扩展。
将扩展拆分为与库链接的可执行文件和以某种方式与可执行文件通信的 python 扩展。

Python 模块安装失败，因为 gcc 命令缺少标志...gcc 命令具有

Python module installation fails because the gcc command is missing a flag...that the gcc command has

python

c

gcc

python-extensions