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libepoxy/test/dlwrap.c

320 lines
9.8 KiB

/* Copyright © 2013, Intel Corporation
*
* Permission is hereby granted, free of charge, to any person obtaining a copy
* of this software and associated documentation files (the "Software"), to deal
* in the Software without restriction, including without limitation the rights
* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
* copies of the Software, and to permit persons to whom the Software is
* furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included in
* all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
* THE SOFTWARE.
*/
/** @file dlwrap.c
*
* Implements a wrapper for dlopen() and dlsym() so that epoxy will
* end up finding symbols from the testcases named
* "override_EGL_eglWhatever()" or "override_GLES2_glWhatever()" or
* "override_GL_glWhatever()" when it tries to dlopen() and dlsym()
* the real GL or EGL functions in question.
*
* This lets us simulate some target systems in the test suite, or
* just stub out GL functions so we can be sure of what's being
* called.
*/
/* dladdr is a glibc extension */
#define _GNU_SOURCE
#include <dlfcn.h>
#include <stdbool.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <assert.h>
#include "dlwrap.h"
#define STRNCMP_LITERAL(var, literal) \
strncmp ((var), (literal), sizeof (literal) - 1)
#define ARRAY_SIZE(arr) (sizeof(arr) / sizeof(arr[0]))
void *libfips_handle;
typedef void *(*fips_dlopen_t)(const char *filename, int flag);
typedef void *(*fips_dlsym_t)(void *handle, const char *symbol);
void *override_EGL_eglGetProcAddress(const char *name);
void *override_GL_glXGetProcAddress(const char *name);
void *override_GL_glXGetProcAddressARB(const char *name);
void __dlclose(void *handle);
static struct libwrap {
const char *filename;
const char *symbol_prefix;
void *handle;
} wrapped_libs[] = {
{ "libGL.so", "GL", NULL },
{ "libEGL.so", "EGL", NULL },
{ "libGLESv2.so", "GLES2", NULL },
};
/* Match 'filename' against an internal list of libraries for which
* libfips has wrappers.
*
* Returns true and sets *index_ret if a match is found.
* Returns false if no match is found. */
static struct libwrap *
find_wrapped_library(const char *filename)
{
unsigned i;
if (!filename)
return NULL;
for (i = 0; i < ARRAY_SIZE(wrapped_libs); i++) {
if (strncmp(wrapped_libs[i].filename, filename,
strlen(wrapped_libs[i].filename)) == 0) {
return &wrapped_libs[i];
}
}
return NULL;
}
/* Many (most?) OpenGL programs dlopen libGL.so.1 rather than linking
* against it directly, which means they would not be seeing our
* wrapped GL symbols via LD_PRELOAD. So we catch the dlopen in a
* wrapper here and redirect it to our library.
*/
void *
dlopen(const char *filename, int flag)
{
void *ret;
struct libwrap *wrap;
/* Before deciding whether to redirect this dlopen to our own
* library, we call the real dlopen. This assures that any
* expected side-effects from loading the intended library are
* resolved. Below, we may still return a handle pointing to
* our own library, and not what is opened here. */
ret = dlwrap_real_dlopen(filename, flag);
/* If filename is not a wrapped library, just return real dlopen */
wrap = find_wrapped_library(filename);
if (!wrap)
return ret;
wrap->handle = ret;
/* We use wrapped_libs as our handles to libraries. */
return wrap;
}
/**
* Wraps dlclose to hide our faked handles from it.
*/
void
__dlclose(void *handle)
{
struct libwrap *wrap = handle;
if (wrap < wrapped_libs ||
wrap >= wrapped_libs + ARRAY_SIZE(wrapped_libs)) {
void (*real_dlclose)(void *handle) = dlwrap_real_dlsym(RTLD_NEXT, "__dlclose");
real_dlclose(handle);
}
}
void *
dlwrap_real_dlopen(const char *filename, int flag)
{
static fips_dlopen_t real_dlopen = NULL;
if (!real_dlopen) {
real_dlopen = (fips_dlopen_t) dlwrap_real_dlsym(RTLD_NEXT, "dlopen");
if (!real_dlopen) {
fprintf(stderr, "Error: Failed to find symbol for dlopen.\n");
exit(1);
}
}
return real_dlopen(filename, flag);
}
/**
* Return the dlsym() on the application's namespace for
* "override_<prefix>_<name>"
*/
static void *
wrapped_dlsym(const char *prefix, const char *name)
{
char *wrap_name;
void *symbol;
asprintf(&wrap_name, "override_%s_%s", prefix, name);
symbol = dlwrap_real_dlsym(RTLD_DEFAULT, wrap_name);
free(wrap_name);
return symbol;
}
/* Since we redirect dlopens of libGL.so and libEGL.so to libfips we
* need to ensure that dlysm succeeds for all functions that might be
* defined in the real, underlying libGL library. But we're far too
* lazy to implement wrappers for function that would simply
* pass-through, so instead we also wrap dlysm and arrange for it to
* pass things through with RTLD_next if libfips does not have the
* function desired. */
void *
dlsym(void *handle, const char *name)
{
struct libwrap *wrap = handle;
/* Make sure that handle is actually one of our wrapped libs. */
if (wrap < wrapped_libs ||
wrap >= wrapped_libs + ARRAY_SIZE(wrapped_libs)) {
wrap = NULL;
}
/* Failing that, anything specifically requested from the
* libfips library should be redirected to a real GL
* library. */
if (wrap) {
void *symbol = wrapped_dlsym(wrap->symbol_prefix, name);
if (symbol)
return symbol;
else
return dlwrap_real_dlsym(wrap->handle, name);
}
/* And anything else is some unrelated dlsym. Just pass it
* through. (This also covers the cases of lookups with
* special handles such as RTLD_DEFAULT or RTLD_NEXT.)
*/
return dlwrap_real_dlsym(handle, name);
}
void *
dlwrap_real_dlsym(void *handle, const char *name)
{
static fips_dlsym_t real_dlsym = NULL;
if (!real_dlsym) {
/* FIXME: This brute-force, hard-coded searching for a versioned
* symbol is really ugly. The only reason I'm doing this is because
* I need some way to lookup the "dlsym" function in libdl, but
* I can't use 'dlsym' to do it. So dlvsym works, but forces me
* to guess what the right version is.
*
* Potential fixes here:
*
* 1. Use libelf to actually inspect libdl.so and
* find the right version, (finding the right
* libdl.so can be made easier with
* dl_iterate_phdr).
*
* 2. Use libelf to find the offset of the 'dlsym'
* symbol within libdl.so, (and then add this to
* the base address at which libdl.so is loaded
* as reported by dl_iterate_phdr).
*
* In the meantime, I'll just keep augmenting this
* hard-coded version list as people report bugs. */
const char *version[] = {
"GLIBC_2.17",
"GLIBC_2.4",
"GLIBC_2.3",
"GLIBC_2.2.5",
"GLIBC_2.2",
"GLIBC_2.0"
};
int num_versions = sizeof(version) / sizeof(version[0]);
int i;
for (i = 0; i < num_versions; i++) {
real_dlsym = (fips_dlsym_t) dlvsym(RTLD_NEXT, "dlsym", version[i]);
if (real_dlsym)
break;
}
if (i == num_versions) {
fprintf(stderr, "Internal error: Failed to find real dlsym\n");
fprintf(stderr,
"This may be a simple matter of fips not knowing about the version of GLIBC that\n"
"your program is using. Current known versions are:\n\n\t");
for (i = 0; i < num_versions; i++)
fprintf(stderr, "%s ", version[i]);
fprintf(stderr,
"\n\nYou can inspect your version by first finding libdl.so.2:\n"
"\n"
"\tldd <your-program> | grep libdl.so\n"
"\n"
"And then inspecting the version attached to the dlsym symbol:\n"
"\n"
"\treadelf -s /path/to/libdl.so.2 | grep dlsym\n"
"\n"
"And finally, adding the version to dlwrap.c:dlwrap_real_dlsym.\n");
exit(1);
}
}
return real_dlsym(handle, name);
}
void *
override_GL_glXGetProcAddress(const char *name)
{
void *symbol;
symbol = wrapped_dlsym("GL", name);
if (symbol)
return symbol;
return DEFER_TO_GL("libGL.so.1", override_GL_glXGetProcAddress,
"glXGetProcAddress", (name));
}
void *
override_GL_glXGetProcAddressARB(const char *name)
{
void *symbol;
symbol = wrapped_dlsym("GL", name);
if (symbol)
return symbol;
return DEFER_TO_GL("libGL.so.1", override_GL_glXGetProcAddressARB,
"glXGetProcAddressARB", (name));
}
void *
override_EGL_eglGetProcAddress(const char *name)
{
void *symbol;
if (!STRNCMP_LITERAL(name, "gl")) {
symbol = wrapped_dlsym("GLES2", name);
if (symbol)
return symbol;
}
if (!STRNCMP_LITERAL(name, "egl")) {
symbol = wrapped_dlsym("EGL", name);
if (symbol)
return symbol;
}
return DEFER_TO_GL("libEGL.so.1", override_EGL_eglGetProcAddress,
"eglGetProcAddress", (name));
}