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Don't fail to run DT_INIT and DT_INIT_ARRAY constructors if a shared library has DT_PREINIT_ARRAY constructors.

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The GNU dynamic linker silently ignores a DT_PREINIT_ARRAY section
in a shared library. We had ineffectual code that tried to report
an error, which I tried to fix but got wrong --- my version still
wouldn't report the error to the caller, but would prevent us from
continuing to call constructors.

Bug: 8825226

(cherry picked from commit 8147d3c284932896ab6095232b355979b9eb33d3)

Change-Id: Iad8e7e3743d1a5e6bd1d44ef40b1ab3499cb64f2
This commit is contained in:
Elliott Hughes 2013-05-09 14:19:58 -07:00
parent 262b7384e4
commit 738370d938
1 changed files with 24 additions and 38 deletions
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62
linker/linker.cpp
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@ -801,14 +801,8 @@ static int soinfo_unload(soinfo* si) {
for (Elf32_Dyn* d = si->dynamic; d->d_tag != DT_NULL; ++d) {
if (d->d_tag == DT_NEEDED) {
const char* library_name = si->strtab + d->d_un.d_val;
soinfo* lsi = find_loaded_library(library_name);
if (lsi != NULL) {
TRACE("%s needs to unload %s", si->name, lsi->name);
soinfo_unload(lsi);
} else {
// TODO: should we return -1 in this case?
DL_ERR("\"%s\": could not unload dependent library", si->name);
}
TRACE("%s needs to unload %s", si->name, library_name);
soinfo_unload(find_loaded_library(library_name));
}
}
@ -1161,21 +1155,6 @@ static int mips_relocate_got(soinfo* si, soinfo* needed[]) {
}
#endif
/* Please read the "Initialization and Termination functions" functions.
* of the linker design note in bionic/linker/README.TXT to understand
* what the following code is doing.
*
* The important things to remember are:
*
* DT_PREINIT_ARRAY must be called first for executables, and should
* not appear in shared libraries.
*
* DT_INIT should be called before DT_INIT_ARRAY if both are present
*
* DT_FINI should be called after DT_FINI_ARRAY if both are present
*
* DT_FINI_ARRAY must be parsed in reverse order.
*/
void soinfo::CallArray(const char* array_name UNUSED, linker_function_t* functions, size_t count, bool reverse) {
if (functions == NULL) {
return;
@ -1210,6 +1189,8 @@ void soinfo::CallFunction(const char* function_name UNUSED, linker_function_t fu
}
void soinfo::CallPreInitConstructors() {
// DT_PREINIT_ARRAY functions are called before any other constructors for executables,
// but ignored in a shared library.
CallArray("DT_PREINIT_ARRAY", preinit_array, preinit_array_count, false);
}
@ -1230,31 +1211,36 @@ void soinfo::CallConstructors() {
// out above, the libc constructor will be called again (recursively!).
constructors_called = true;
if (!(flags & FLAG_EXE) && preinit_array) {
DL_ERR("shared library \"%s\" has a preinit_array table @ %p", name, preinit_array);
return;
if ((flags & FLAG_EXE) == 0 && preinit_array != NULL) {
// The GNU dynamic linker silently ignores these, but we warn the developer.
PRINT("\"%s\": ignoring %d-entry DT_PREINIT_ARRAY in shared library!",
name, preinit_array_count);
}
if (dynamic != NULL) {
for (Elf32_Dyn* d = dynamic; d->d_tag != DT_NULL; ++d) {
if (d->d_tag == DT_NEEDED) {
const char* library_name = strtab + d->d_un.d_val;
soinfo* lsi = find_loaded_library(library_name);
if (lsi == NULL) {
DL_ERR("\"%s\": could not initialize dependent library", name);
} else {
lsi->CallConstructors();
}
TRACE("\"%s\": calling constructors in DT_NEEDED \"%s\"", name, library_name);
find_loaded_library(library_name)->CallConstructors();
}
}
}
TRACE("\"%s\": calling constructors", name);
// DT_INIT should be called before DT_INIT_ARRAY if both are present.
CallFunction("DT_INIT", init_func);
CallArray("DT_INIT_ARRAY", init_array, init_array_count, false);
}
void soinfo::CallDestructors() {
TRACE("\"%s\": calling destructors", name);
// DT_FINI_ARRAY must be parsed in reverse order.
CallArray("DT_FINI_ARRAY", fini_array, fini_array_count, true);
// DT_FINI should be called after DT_FINI_ARRAY if both are present.
CallFunction("DT_FINI", fini_func);
}
@ -1353,7 +1339,7 @@ static bool soinfo_link_image(soinfo* si) {
&si->ARM_exidx, &si->ARM_exidx_count);
#endif
/* extract useful information from dynamic section */
// Extract useful information from dynamic section.
uint32_t needed_count = 0;
for (Elf32_Dyn* d = si->dynamic; d->d_tag != DT_NULL; ++d) {
DEBUG("d = %p, d[0](tag) = 0x%08x d[1](val) = 0x%08x", d, d->d_tag, d->d_un.d_val);
@ -1404,29 +1390,29 @@ static bool soinfo_link_image(soinfo* si) {
return false;
case DT_INIT:
si->init_func = reinterpret_cast<linker_function_t>(base + d->d_un.d_ptr);
DEBUG("%s constructors (init func) found at %p", si->name, si->init_func);
DEBUG("%s constructors (DT_INIT) found at %p", si->name, si->init_func);
break;
case DT_FINI:
si->fini_func = reinterpret_cast<linker_function_t>(base + d->d_un.d_ptr);
DEBUG("%s destructors (fini func) found at %p", si->name, si->fini_func);
DEBUG("%s destructors (DT_FINI) found at %p", si->name, si->fini_func);
break;
case DT_INIT_ARRAY:
si->init_array = reinterpret_cast<linker_function_t*>(base + d->d_un.d_ptr);
DEBUG("%s constructors (init_array) found at %p", si->name, si->init_array);
DEBUG("%s constructors (DT_INIT_ARRAY) found at %p", si->name, si->init_array);
break;
case DT_INIT_ARRAYSZ:
si->init_array_count = ((unsigned)d->d_un.d_val) / sizeof(Elf32_Addr);
break;
case DT_FINI_ARRAY:
si->fini_array = reinterpret_cast<linker_function_t*>(base + d->d_un.d_ptr);
DEBUG("%s destructors (fini_array) found at %p", si->name, si->fini_array);
DEBUG("%s destructors (DT_FINI_ARRAY) found at %p", si->name, si->fini_array);
break;
case DT_FINI_ARRAYSZ:
si->fini_array_count = ((unsigned)d->d_un.d_val) / sizeof(Elf32_Addr);
break;
case DT_PREINIT_ARRAY:
si->preinit_array = reinterpret_cast<linker_function_t*>(base + d->d_un.d_ptr);
DEBUG("%s constructors (preinit_array) found at %p", si->name, si->preinit_array);
DEBUG("%s constructors (DT_PREINIT_ARRAY) found at %p", si->name, si->preinit_array);
break;
case DT_PREINIT_ARRAYSZ:
si->preinit_array_count = ((unsigned)d->d_un.d_val) / sizeof(Elf32_Addr);