Fixed a bug that failed when hooking functions in .symtab in Android 5.x.

Author: caikelun

README.md

@@ -1,7 +1,7 @@
 # android-inline-hook
 
 ![](https://img.shields.io/badge/license-MIT-brightgreen.svg?style=flat)
-![](https://img.shields.io/badge/release-1.0.2-red.svg?style=flat)
+![](https://img.shields.io/badge/release-1.0.3-red.svg?style=flat)
 ![](https://img.shields.io/badge/Android-4.1%20--%2012-blue.svg?style=flat)
 ![](https://img.shields.io/badge/arch-armeabi--v7a%20%7C%20arm64--v8a-blue.svg?style=flat)
 
@@ -55,7 +55,7 @@ android {
 }
 
 dependencies {
-    implementation 'com.bytedance.android:shadowhook:1.0.2'
+    implementation 'com.bytedance.android:shadowhook:1.0.3'
 }
 ```
 

README.zh-CN.md

@@ -1,7 +1,7 @@
 # android-inline-hook
 
 ![](https://img.shields.io/badge/license-MIT-brightgreen.svg?style=flat)
-![](https://img.shields.io/badge/release-1.0.2-red.svg?style=flat)
+![](https://img.shields.io/badge/release-1.0.3-red.svg?style=flat)
 ![](https://img.shields.io/badge/Android-4.1%20--%2012-blue.svg?style=flat)
 ![](https://img.shields.io/badge/arch-armeabi--v7a%20%7C%20arm64--v8a-blue.svg?style=flat)
 
@@ -55,7 +55,7 @@ android {
 }
 
 dependencies {
-    implementation 'com.bytedance.android:shadowhook:1.0.2'
+    implementation 'com.bytedance.android:shadowhook:1.0.3'
 }
 ```
 

build.gradle

@@ -23,11 +23,11 @@ ext {
     abiFilters = "armeabi-v7a,arm64-v8a"
     useASAN = false
     dependencyOnLocalLibrary = true
-    shadowhookVersion = "1.0.2"
+    shadowhookVersion = "1.0.3"
 
     POM_GROUP_ID = "com.bytedance.android"
     POM_ARTIFACT_ID = "shadowhook"
-    POM_VERSION_NAME = "1.0.2"
+    POM_VERSION_NAME = "1.0.3"
 
     POM_NAME = "shadowhook"
     POM_DESCRIPTION = "shadowhook is an inline hook library for Android apps."

shadowhook/src/main/cpp/third_party/xdl/xdl.c

@@ -46,6 +46,12 @@
 #include "xdl_lzma.h"
 #include "xdl_util.h"
 
+#ifndef __LP64__
+#define XDL_LIB_PATH "/system/lib"
+#else
+#define XDL_LIB_PATH "/system/lib64"
+#endif
+
 #define XDL_DYNSYM_IS_EXPORT_SYM(shndx) (SHN_UNDEF != (shndx))
 #define XDL_SYMTAB_IS_EXPORT_SYM(shndx) \
   (SHN_UNDEF != (shndx) && !((shndx) >= SHN_LORESERVE && (shndx) <= SHN_HIRESERVE))
@@ -282,6 +288,8 @@ static int xdl_symtab_load_from_debugdata(xdl_t *self, int file_fd, size_t file_
 
 // load from disk and memory
 static int xdl_symtab_load(xdl_t *self) {
+  if ('[' == self->pathname[0]) return -1;
+
   int r = -1;
   ElfW(Shdr) *shdrs = NULL;
   char *shstrtab = NULL;
@@ -298,7 +306,21 @@ static int xdl_symtab_load(xdl_t *self) {
   self->base = self->load_bias + vaddr_min;
 
   // open file
-  int file_fd = open(self->pathname, O_RDONLY | O_CLOEXEC);
+  int flags = O_RDONLY | O_CLOEXEC;
+  int file_fd;
+  if ('/' == self->pathname[0]) {
+    file_fd = open(self->pathname, flags);
+  } else {
+    char full_pathname[1024];
+    // try the fast method
+    snprintf(full_pathname, sizeof(full_pathname), "%s/%s", XDL_LIB_PATH, self->pathname);
+    file_fd = open(full_pathname, flags);
+    if (file_fd < 0) {
+      // try the slow method
+      if (0 != xdl_iterate_get_full_pathname(self->base, full_pathname, sizeof(full_pathname))) return -1;
+      file_fd = open(full_pathname, flags);
+    }
+  }
   if (file_fd < 0) return -1;
   struct stat st;
   if (0 != fstat(file_fd, &st)) goto end;

shadowhook/src/main/cpp/third_party/xdl/xdl.h

@@ -22,7 +22,7 @@
 // Created by caikelun on 2020-10-04.
 
 //
-// xDL version: 1.1.2
+// xDL version: 1.1.3
 //
 // xDL is an enhanced implementation of the Android DL series functions.
 // For more information, documentation, and the latest version please check:

shadowhook/src/main/cpp/third_party/xdl/xdl_iterate.c

@@ -81,15 +81,9 @@ static int xdl_iterate_open_or_rewind_maps(FILE **maps) {
   return 0;
 }
 
-static uintptr_t xdl_iterate_get_pathname_from_maps(struct dl_phdr_info *info, char *buf, size_t buf_len,
-                                                    FILE **maps) {
-  // get base address
-  uintptr_t min_vaddr = xdl_iterate_get_min_vaddr(info);
-  if (UINTPTR_MAX == min_vaddr) return 0;  // failed
-  uintptr_t base = (uintptr_t)(info->dlpi_addr + min_vaddr);
-
+static int xdl_iterate_get_pathname_from_maps(uintptr_t base, char *buf, size_t buf_len, FILE **maps) {
   // open or rewind maps-file
-  if (0 != xdl_iterate_open_or_rewind_maps(maps)) return 0;  // failed
+  if (0 != xdl_iterate_open_or_rewind_maps(maps)) return -1;  // failed
 
   char line[1024];
   while (fgets(line, sizeof(line), *maps)) {
@@ -106,10 +100,10 @@ static uintptr_t xdl_iterate_get_pathname_from_maps(struct dl_phdr_info *info, c
 
     // found it
     strlcpy(buf, pathname, buf_len);
-    return (uintptr_t)buf;  // OK
+    return 0;  // OK
   }
 
-  return 0;  // failed
+  return -1;  // failed
 }
 
 static int xdl_iterate_by_linker_cb(struct dl_phdr_info *info, size_t size, void *arg) {
@@ -142,11 +136,15 @@ static int xdl_iterate_by_linker_cb(struct dl_phdr_info *info, size_t size, void
 
   // fix dlpi_name (from /proc/self/maps)
   if ('/' != info->dlpi_name[0] && '[' != info->dlpi_name[0] && (0 != (flags & XDL_FULL_PATHNAME))) {
-    char buf[512];
-    uintptr_t pathname = xdl_iterate_get_pathname_from_maps(info, buf, sizeof(buf), maps);
-    if (0 == pathname) return 0;  // ignore this ELF
+    // get base address
+    uintptr_t min_vaddr = xdl_iterate_get_min_vaddr(info);
+    if (UINTPTR_MAX == min_vaddr) return 0;  // ignore this ELF
+    uintptr_t base = (uintptr_t)(info->dlpi_addr + min_vaddr);
+
+    char buf[1024];
+    if (0 != xdl_iterate_get_pathname_from_maps(base, buf, sizeof(buf), maps)) return 0;  // ignore this ELF
 
-    info->dlpi_name = (const char *)pathname;
+    info->dlpi_name = (const char *)buf;
   }
 
   // callback
@@ -245,3 +243,10 @@ int xdl_iterate_phdr_impl(xdl_iterate_phdr_cb_t cb, void *cb_arg, int flags) {
   // iterate by dl_iterate_phdr()
   return xdl_iterate_by_linker(cb, cb_arg, flags);
 }
+
+int xdl_iterate_get_full_pathname(uintptr_t base, char *buf, size_t buf_len) {
+  FILE *maps = NULL;
+  int r = xdl_iterate_get_pathname_from_maps(base, buf, buf_len, &maps);
+  if (NULL != maps) fclose(maps);
+  return r;
+}

shadowhook/src/main/cpp/third_party/xdl/xdl_iterate.h

@@ -34,6 +34,8 @@ extern "C" {
 typedef int (*xdl_iterate_phdr_cb_t)(struct dl_phdr_info *info, size_t size, void *arg);
 int xdl_iterate_phdr_impl(xdl_iterate_phdr_cb_t cb, void *cb_arg, int flags);
 
+int xdl_iterate_get_full_pathname(uintptr_t base, char *buf, size_t buf_len);
+
 #ifdef __cplusplus
 }
 #endif