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allendowney
GitHub Repository: allendowney/cpython
 Path: blob/main/Python/dynload_shlib.c
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/* Support for dynamic loading of extension modules */

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#include "Python.h"

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#include "pycore_interp.h"    // _PyInterpreterState.dlopenflags

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#include "pycore_pystate.h"   // _PyInterpreterState_GET()

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#include "importdl.h"

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#include <sys/types.h>

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#include <sys/stat.h>

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#if defined(__NetBSD__)

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#include <sys/param.h>

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#if (NetBSD < 199712)

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#include <nlist.h>

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#include <link.h>

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#define dlerror() "error in dynamic linking"

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#endif

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#endif /* NetBSD */

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#ifdef HAVE_DLFCN_H

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#include <dlfcn.h>

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#endif

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#if (defined(__OpenBSD__) || defined(__NetBSD__)) && !defined(__ELF__)

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#define LEAD_UNDERSCORE "_"

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#else

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#define LEAD_UNDERSCORE ""

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#endif

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/* The .so extension module ABI tag, supplied by the Makefile via

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   Makefile.pre.in and configure.  This is used to discriminate between

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   incompatible .so files so that extensions for different Python builds can

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   live in the same directory.  E.g. foomodule.cpython-32.so

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*/

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const char *_PyImport_DynLoadFiletab[] = {

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#ifdef __CYGWIN__

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    ".dll",

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#else  /* !__CYGWIN__ */

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    "." SOABI ".so",

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#ifdef ALT_SOABI

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    "." ALT_SOABI ".so",

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#endif

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    ".abi" PYTHON_ABI_STRING ".so",

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    ".so",

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#endif  /* __CYGWIN__ */

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    NULL,

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};

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dl_funcptr

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_PyImport_FindSharedFuncptr(const char *prefix,

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                            const char *shortname,

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                            const char *pathname, FILE *fp)

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{

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    dl_funcptr p;

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    void *handle;

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    char funcname[258];

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    char pathbuf[260];

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    int dlopenflags=0;

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    if (strchr(pathname, '/') == NULL) {

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        /* Prefix bare filename with "./" */

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        PyOS_snprintf(pathbuf, sizeof(pathbuf), "./%-.255s", pathname);

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        pathname = pathbuf;

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    }

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    PyOS_snprintf(funcname, sizeof(funcname),

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                  LEAD_UNDERSCORE "%.20s_%.200s", prefix, shortname);

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    if (fp != NULL) {

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        struct _Py_stat_struct status;

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        if (_Py_fstat(fileno(fp), &status) == -1)

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            return NULL;

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    }

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    dlopenflags = _PyImport_GetDLOpenFlags(_PyInterpreterState_GET());

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    handle = dlopen(pathname, dlopenflags);

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    if (handle == NULL) {

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        PyObject *mod_name;

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        PyObject *path;

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        PyObject *error_ob;

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        const char *error = dlerror();

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        if (error == NULL)

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            error = "unknown dlopen() error";

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        error_ob = PyUnicode_DecodeLocale(error, "surrogateescape");

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        if (error_ob == NULL)

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            return NULL;

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        mod_name = PyUnicode_FromString(shortname);

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        if (mod_name == NULL) {

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            Py_DECREF(error_ob);

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            return NULL;

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        }

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        path = PyUnicode_DecodeFSDefault(pathname);

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        if (path == NULL) {

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            Py_DECREF(error_ob);

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            Py_DECREF(mod_name);

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            return NULL;

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        }

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        PyErr_SetImportError(error_ob, mod_name, path);

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        Py_DECREF(error_ob);

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        Py_DECREF(mod_name);

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        Py_DECREF(path);

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        return NULL;

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    }

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    p = (dl_funcptr) dlsym(handle, funcname);

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    return p;

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}

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