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// Copyright 2015-2022 The Mumble Developers. All rights reserved.
// Use of this source code is governed by a BSD-style license
// that can be found in the LICENSE file at the root of the
// Mumble source tree or at <https://www.mumble.info/LICENSE>.
// This file is included by overlay.c for
// Unix/X11/GLX-specific overlay initialization.
#include <inttypes.h>
#if defined(__linux__)
// ELF32_ST_TYPE and ELF64_ST_TYPE are the same.
# define ELF_ST_TYPE ELF32_ST_TYPE
typedef ElfW(Dyn) Elf_Dyn;
typedef ElfW(Sym) Elf_Sym;
#endif
static void initializeLibrary();
#define RESOLVE(x) \
if (!o##x) \
o##x = (__typeof__(&x)) odlsym(RTLD_NEXT, #x)
static void resolveOpenGL() {
RESOLVE(glXSwapBuffers);
if (!oglXSwapBuffers) {
void *lib = dlopen("libGL.so.1", RTLD_GLOBAL | RTLD_NOLOAD);
if (!lib)
return;
RESOLVE(glXSwapBuffers);
if (!oglXSwapBuffers) {
dlclose(lib);
}
}
RESOLVE(glXGetProcAddressARB);
RESOLVE(glXGetProcAddress);
}
__attribute__((visibility("default"))) void glXSwapBuffers(Display *dpy, GLXDrawable draw) {
if (!oglXSwapBuffers) {
resolveOpenGL();
}
GLXContext ctx = glXGetCurrentContext();
Context *c = contexts;
while (c) {
if ((c->dpy == dpy) && (c->draw == draw))
break;
c = c->next;
}
if (!c) {
ods("Current context is: %p", ctx);
c = (Context *) malloc(sizeof(Context));
if (!c) {
ods("malloc failure");
return;
}
memset(c, 0, sizeof(Context));
c->next = contexts;
c->dpy = dpy;
c->draw = draw;
c->bMesa = false;
c->bValid = false;
int major, minor;
if (glXQueryVersion(dpy, &major, &minor)) {
ods("GLX version %d.%d", major, minor);
c->bValid = true;
}
const char *version = (const char *) glGetString(GL_VERSION);
if (version) {
ods("GL version string: %s", version);
if (strstr(version, "Mesa") != NULL) {
c->bMesa = true;
}
}
contexts = c;
newContext(c);
}
if (c->bValid) {
int width, height;
if (c->bMesa) {
GLint viewport[4];
glGetIntegerv(GL_VIEWPORT, viewport);
width = viewport[2];
height = viewport[3];
} else {
glXQueryDrawable(dpy, draw, GLX_WIDTH, (GLuint *) &width);
glXQueryDrawable(dpy, draw, GLX_HEIGHT, (GLuint *) &height);
}
drawContext(c, width, height);
}
oglXSwapBuffers(dpy, draw);
}
#define FGRAB(x) \
if (strcmp((const char *) (func), #x) == 0) \
return (__GLXextFuncPtr)(x);
__attribute__((visibility("default"))) void (*glXGetProcAddress(const GLubyte *func))(void) {
FGRAB(glXSwapBuffers);
FGRAB(glXGetProcAddressARB);
FGRAB(glXGetProcAddress);
if (!oglXGetProcAddressARB && !oglXGetProcAddress) {
resolveOpenGL();
}
if (oglXGetProcAddress)
return oglXGetProcAddress(func);
else if (oglXGetProcAddressARB)
return oglXGetProcAddressARB(func);
else
return (__GLXextFuncPtr)(odlsym(RTLD_NEXT, (const char *) (func)));
}
__attribute__((visibility("default"))) __GLXextFuncPtr glXGetProcAddressARB(const GLubyte *func) {
return (void (*)(void)) glXGetProcAddress(func);
}
#define OGRAB(name) \
if (handle == RTLD_DEFAULT) \
handle = RTLD_NEXT; \
symbol = odlsym(handle, #name); \
if (symbol) { \
o##name = (__typeof__(&name)) symbol; \
symbol = (void *) name; \
}
__attribute__((visibility("default"))) void *dlsym(void *handle, const char *name) {
if (!odlsym) {
initializeLibrary();
}
void *symbol;
ods("Request for symbol; name: %s, handle: %p, odlsym: %p", name, handle, odlsym);
if (strcmp(name, "glXSwapBuffers") == 0) {
OGRAB(glXSwapBuffers);
} else if (strcmp(name, "glXGetProcAddress") == 0) {
OGRAB(glXGetProcAddress);
} else if (strcmp(name, "glXGetProcAddressARB") == 0) {
OGRAB(glXGetProcAddressARB);
} else if (strcmp(name, "dlsym") == 0) {
return (void *) dlsym;
} else if (odlsym) {
symbol = odlsym(handle, name);
} else {
return NULL;
}
return symbol;
}
static int find_odlsym() {
#if defined(__linux__)
void *dl = dlopen("libdl.so.2", RTLD_LAZY);
if (!dl) {
ods("Failed to open libdl.so.2!");
return -1;
}
struct link_map *lm = dl;
#elif defined(__FreeBSD__)
struct link_map *lm = NULL;
if (dlinfo(RTLD_SELF, RTLD_DI_LINKMAP, &lm) == -1) {
ods("Unable to acquire link_map: %s", dlerror());
return -1;
}
while (lm) {
if (strcmp(lm->l_name, "/libexec/ld-elf.so.1") == 0) {
break;
}
lm = lm->l_next;
}
if (!lm) {
ods("Failed to find ld-elf.so.1!");
return -1;
}
#endif
bool hashTableGNU = false;
uintptr_t hashTable = 0;
const char *strTable = NULL;
Elf_Sym *symTable = NULL;
#if defined(__GLIBC__)
const uintptr_t base = 0;
#else
const uintptr_t base = (uintptr_t) lm->l_addr;
#endif
for (const Elf_Dyn *dyn = lm->l_ld; dyn; ++dyn) {
switch (dyn->d_tag) {
case DT_GNU_HASH:
if (!hashTable) {
hashTable = base + dyn->d_un.d_ptr;
hashTableGNU = true;
}
break;
case DT_HASH:
if (!hashTable) {
hashTable = base + dyn->d_un.d_ptr;
}
break;
case DT_STRTAB:
strTable = (const char *) (base + dyn->d_un.d_ptr);
break;
case DT_SYMTAB:
symTable = (Elf_Sym *) (base + dyn->d_un.d_ptr);
break;
}
if (hashTable && strTable && symTable) {
break;
}
}
ods("hashTable: 0x%" PRIxPTR ", strTable: %p, symTable: %p", hashTable, strTable, symTable);
if (!hashTable || !strTable || !symTable) {
return -1;
}
if (!hashTableGNU) {
ods("Using DT_HASH");
// Hash table pseudo-struct:
// uint32_t nBucket;
// uint32_t nChain;
// uint32_t bucket[nBucket];
// uint32_t chain[nChain];
const uint32_t nChain = ((uint32_t *) hashTable)[1];
for (uint32_t i = 0; i < nChain; ++i) {
if (ELF_ST_TYPE(symTable[i].st_info) != STT_FUNC) {
continue;
}
if (strcmp(strTable + symTable[i].st_name, "dlsym") == 0) {
odlsym = (void *) lm->l_addr + symTable[i].st_value;
break;
}
}
} else {
ods("Using DT_GNU_HASH");
// Hash table pseudo-struct:
// uint32_t nBucket;
// uint32_t symOffset;
// uint32_t nBloom;
// uint32_t bloomShift;
// uintptr_t blooms[nBloom];
// uint32_t buckets[nBucket];
// uint32_t chain[];
uint32_t *hashStruct = (uint32_t *) hashTable;
const uint32_t nBucket = hashStruct[0];
const uint32_t symOffset = hashStruct[1];
const uint32_t nBloom = hashStruct[2];
const uintptr_t *bloom = (uintptr_t *) &hashStruct[4];
const uint32_t *buckets = (uint32_t *) &bloom[nBloom];
const uint32_t *chain = &buckets[nBucket];
for (uint32_t i = 0; i < nBucket; ++i) {
uint32_t symIndex = buckets[i];
if (symIndex < symOffset) {
continue;
}
do {
if (strcmp(strTable + symTable[symIndex].st_name, "dlsym") == 0) {
odlsym = (void *) lm->l_addr + symTable[symIndex].st_value;
}
} while (!odlsym && !(chain[symIndex++ - symOffset] & 1));
}
}
if (!odlsym) {
return -1;
}
ods("Original dlsym at %p", odlsym);
return 0;
}
__attribute__((constructor)) static void initializeLibrary() {
if (odlsym)
return;
if (getenv("MUMBLE_OVERLAY_DEBUG")) {
bDebug = true;
} else {
bDebug = false;
}
bCursorAvail = false;
ods("Mumble overlay library loaded");
if (find_odlsym() == -1) {
ods("Failed to find original address of dlsym().");
}
}
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