cosmopolitan/third_party/python/Python/dynload_shlib.c
Justine Tunney 5e8c928f1a
Introduce dlopen() support
Every program built using Cosmopolitan is statically-linked. However
there are some cases, e.g. GUIs and video drivers, where linking the
host platform libraries is desirable. So what we do in such cases is
launch a stub executable using the host platform's libc, and longjmp
back into this executable. The stub executable passes back to us the
platform-specific dlopen() implementation, which we shall then wrap.

Here's the list of platforms that are supported so far:

- x86-64 Linux w/ Glibc
- x86-64 Linux w/ Musl Libc
- x86-64 FreeBSD
- x86-64 Windows
- aarch64 Linux w/ Glibc
- aarch64 MacOS

What this means is your Cosmo programs can call foreign functions on
your host operating system. However, it's important to note that any
foreign library you link won't have the ability to call functions in
your Cosmopolitan program. For example it's now technically possible
that Lua can load a module, however that almost certainly won't work
since the Lua module won't have access to Cosmo's Lua API.

Kudos to @jacereda for figuring out how to do this.
2023-11-03 06:37:18 -07:00

117 lines
4.1 KiB
C

/*-*- mode:c;indent-tabs-mode:nil;c-basic-offset:4;tab-width:8;coding:utf-8 -*-│
│vi: set net ft=c ts=4 sts=4 sw=4 fenc=utf-8 :vi│
╞══════════════════════════════════════════════════════════════════════════════╡
│ Python 3 │
│ https://docs.python.org/3/license.html │
╚─────────────────────────────────────────────────────────────────────────────*/
#include "libc/calls/weirdtypes.h"
#include "libc/dlopen/dlfcn.h"
#include "third_party/python/Include/fileutils.h"
#include "third_party/python/Include/modsupport.h"
#include "third_party/python/Include/pyerrors.h"
#include "third_party/python/Include/pystate.h"
#include "third_party/python/Python/importdl.h"
/* clang-format off */
#define SOABI "cpython36m-x86_64-cosmo"
#if (defined(__OpenBSD__) || defined(__NetBSD__)) && !defined(__ELF__)
#define LEAD_UNDERSCORE "_"
#else
#define LEAD_UNDERSCORE ""
#endif
/* The .so extension module ABI tag, supplied by the Makefile via
Makefile.pre.in and configure. This is used to discriminate between
incompatible .so files so that extensions for different Python builds can
live in the same directory. E.g. foomodule.cpython-32.so
*/
const char *_PyImport_DynLoadFiletab[] = {
#ifdef __CYGWIN__
".dll",
#else /* !__CYGWIN__ */
"." SOABI ".so",
".abi" PYTHON_ABI_STRING ".so",
".so",
#endif /* __CYGWIN__ */
NULL,
};
static struct {
dev_t dev;
ino_t ino;
void *handle;
} handles[128];
static int nhandles = 0;
dl_funcptr
_PyImport_FindSharedFuncptr(const char *prefix,
const char *shortname,
const char *pathname, FILE *fp)
{
dl_funcptr p;
void *handle;
char funcname[258];
char pathbuf[260];
int dlopenflags=0;
if (strchr(pathname, '/') == NULL) {
/* Prefix bare filename with "./" */
PyOS_snprintf(pathbuf, sizeof(pathbuf), "./%-.255s", pathname);
pathname = pathbuf;
}
PyOS_snprintf(funcname, sizeof(funcname),
LEAD_UNDERSCORE "%.20s_%.200s", prefix, shortname);
if (fp != NULL) {
int i;
struct _Py_stat_struct status;
if (_Py_fstat(fileno(fp), &status) == -1)
return NULL;
for (i = 0; i < nhandles; i++) {
if (status.st_dev == handles[i].dev &&
status.st_ino == handles[i].ino) {
p = (dl_funcptr) dlsym(handles[i].handle,
funcname);
return p;
}
}
if (nhandles < 128) {
handles[nhandles].dev = status.st_dev;
handles[nhandles].ino = status.st_ino;
}
}
dlopenflags = PyThreadState_GET()->interp->dlopenflags;
handle = dlopen(pathname, dlopenflags);
if (handle == NULL) {
PyObject *mod_name;
PyObject *path;
PyObject *error_ob;
const char *error = dlerror();
if (error == NULL)
error = "unknown dlopen() error";
error_ob = PyUnicode_FromString(error);
if (error_ob == NULL)
return NULL;
mod_name = PyUnicode_FromString(shortname);
if (mod_name == NULL) {
Py_DECREF(error_ob);
return NULL;
}
path = PyUnicode_FromString(pathname);
if (path == NULL) {
Py_DECREF(error_ob);
Py_DECREF(mod_name);
return NULL;
}
PyErr_SetImportError(error_ob, mod_name, path);
Py_DECREF(error_ob);
Py_DECREF(mod_name);
Py_DECREF(path);
return NULL;
}
if (fp != NULL && nhandles < 128)
handles[nhandles++].handle = handle;
p = (dl_funcptr) dlsym(handle, funcname);
return p;
}