我正在尝试从C代码构建一个（非常简单的）Python扩展，并且在编译中遇到了麻烦。
（记录：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和another site I found，我创建了一个C文件，公开了我需要在Python模块中构建的功能：
#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;
}
}
我还创建了包装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，用于创建扩展名并在扩展名上调用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,])
图书馆＆＃34; strcrypto＆＃34;实际上是＆＃34; libstrcrypto.a＆＃34;并提供给我;这不是我写的东西。不幸的是，当我去安装文件时，这也是导致错误的原因：
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
我不知道该错误意味着什么，因为正如您所看到的，gcc调用确实在使用-fPIC。
有人可以指出我在这里做错了什么吗？提前谢谢。
答案 0 :(得分：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进行编译来完成的。
您的问题是您的libstrcrypto.a未使用-fPIC进行编译，因此无法在共享库中使用。你有几种选择：
libstrcrypto.a编译的-fPIC版本。libstrcrypto.a的共享库版本。