From b8be671580f22479d534e188aec9c81a01a3d5f8 Mon Sep 17 00:00:00 2001
From: Jari Vetoniemi <mailroxas@gmail.com>
Date: Sat, 10 Mar 2018 17:20:28 +0200
Subject: linker: Refactor glibc dlopen hacks

Allows us to return "valid" pointer when bionic program calls dlopen.
---
 src/linker/dlfcn.c  | 16 ++++++++--------
 src/linker/linker.c | 17 +++++++----------
 src/linker/linker.h |  3 ++-
 3 files changed, 17 insertions(+), 19 deletions(-)

(limited to 'src/linker')

diff --git a/src/linker/dlfcn.c b/src/linker/dlfcn.c
index 38fc215..22d212a 100644
--- a/src/linker/dlfcn.c
+++ b/src/linker/dlfcn.c
@@ -67,10 +67,11 @@ void *bionic_dlopen(const char *filename, int flag)
     verbose("%s (%d)", filename, flag);
     soinfo *ret;
     pthread_mutex_lock(&apkenv_dl_lock);
-    ret = apkenv_find_library(filename);
+    ret = apkenv_find_library(filename, false);
 
     if (unlikely(ret == NULL)) {
-        set_dlerror(DL_ERR_CANNOT_LOAD_LIBRARY);
+        if (!(ret = dlopen(filename, flag)))
+            set_dlerror(DL_ERR_CANNOT_LOAD_LIBRARY);
     } else {
         apkenv_call_constructors_recursive(ret);
         ret->refcount++;
@@ -102,12 +103,6 @@ void *bionic_dlsym(void *handle, const char *symbol)
 
     pthread_mutex_lock(&apkenv_dl_lock);
 
-#if 0
-    if(unlikely(handle == 0)) {
-        set_dlerror(DL_ERR_INVALID_LIBRARY_HANDLE);
-        goto err;
-    }
-#endif
     if(unlikely(symbol == 0)) {
         set_dlerror(DL_ERR_BAD_SYMBOL_NAME);
         goto err;
@@ -127,6 +122,11 @@ void *bionic_dlsym(void *handle, const char *symbol)
         }
     }
 
+    if(unlikely(handle == 0)) {
+        set_dlerror(DL_ERR_INVALID_LIBRARY_HANDLE);
+        goto err;
+    }
+
     if(handle == RTLD_DEFAULT) {
         sym = apkenv_lookup(symbol, &found, NULL);
     } else if(handle == RTLD_NEXT) {
diff --git a/src/linker/linker.c b/src/linker/linker.c
index e72b9aa..12a3521 100644
--- a/src/linker/linker.c
+++ b/src/linker/linker.c
@@ -1121,7 +1121,7 @@ get_wr_offset(int fd, const char *name, Elf32_Ehdr *ehdr)
 #endif
 
 static soinfo *
-apkenv_load_library(const char *name)
+apkenv_load_library(const char *name, const bool try_glibc)
 {
     char fullpath[512];
     int fd = apkenv_open_library(name, fullpath);
@@ -1133,14 +1133,11 @@ apkenv_load_library(const char *name)
     Elf32_Ehdr *hdr;
 
     if(fd == -1) {
-        if (dlopen(name, RTLD_NOW | RTLD_GLOBAL)) {
+        if (try_glibc && dlopen(name, RTLD_NOW | RTLD_GLOBAL)) {
             DEBUG("Loaded %s with glibc dlopen\n", name);
             return NULL;
         }
-#if !LINKER_DEBUG
-        if (!is_lib_optional(name))
-#endif
-            DL_ERR("Library '%s' not found", name);
+        DL_ERR("Bionic library '%s' not found", name);
         return NULL;
     }
 
@@ -1245,7 +1242,7 @@ apkenv_init_library(soinfo *si)
     return si;
 }
 
-soinfo *apkenv_find_library(const char *name)
+soinfo *apkenv_find_library(const char *name, const bool try_glibc)
 {
     soinfo *si;
     const char *bname;
@@ -1274,7 +1271,7 @@ soinfo *apkenv_find_library(const char *name)
     }
 
     TRACE("[ %5d '%s' has not been loaded yet.  Locating...]\n", apkenv_pid, name);
-    si = apkenv_load_library(name);
+    si = apkenv_load_library(name, try_glibc);
     if(si == NULL)
         return NULL;
     return apkenv_init_library(si);
@@ -2055,7 +2052,7 @@ static int apkenv_link_image(soinfo *si, unsigned wr_offset)
         int i;
         memset(apkenv_preloads, 0, sizeof(apkenv_preloads));
         for(i = 0; apkenv_ldpreload_names[i] != NULL; i++) {
-            soinfo *lsi = apkenv_find_library(apkenv_ldpreload_names[i]);
+            soinfo *lsi = apkenv_find_library(apkenv_ldpreload_names[i], true);
             if(lsi == 0) {
                 apkenv_strlcpy(apkenv_tmp_err_buf, apkenv_linker_get_error(), sizeof(apkenv_tmp_err_buf));
                 DL_ERR("%5d could not load needed library '%s' for '%s' (%s)",
@@ -2072,7 +2069,7 @@ static int apkenv_link_image(soinfo *si, unsigned wr_offset)
             DEBUG("%5d %s needs %s\n", apkenv_pid, si->name, si->strtab + d[1]);
             soinfo *lsi = NULL;
             // if (get_builtin_lib_handle(si->strtab + d[1]) == NULL)
-            lsi = apkenv_find_library(si->strtab + d[1]);
+            lsi = apkenv_find_library(si->strtab + d[1], true);
             if(lsi == 0) {
                 /**
                  * XXX Dirty Hack Alarm --thp XXX
diff --git a/src/linker/linker.h b/src/linker/linker.h
index 13d9bff..6b1924b 100644
--- a/src/linker/linker.h
+++ b/src/linker/linker.h
@@ -33,6 +33,7 @@
 #include <sys/types.h>
 #include <elf.h>
 #include <link.h>
+#include <stdbool.h>
 
 #undef PAGE_MASK
 #undef PAGE_SIZE
@@ -204,7 +205,7 @@ extern soinfo apkenv_libdl_info;
 #define DT_PREINIT_ARRAYSZ 33
 #endif
 
-soinfo *apkenv_find_library(const char *name);
+soinfo *apkenv_find_library(const char *name, const bool try_glibc);
 unsigned apkenv_unload_library(soinfo *si);
 Elf32_Sym *apkenv_lookup_in_library(soinfo *si, const char *name);
 Elf32_Sym *apkenv_lookup(const char *name, soinfo **found, soinfo *start);
-- 
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