### Build and Install xHook Native Libraries

Source: https://github.com/iqiyi/xhook/blob/master/README.md

Builds and installs the native libraries for xHook. Ensure you have Android NDK r16b set up in your PATH.

```bash
./build_libs.sh
./install_libs.sh
```

--------------------------------

### Install xHook Demo App

Source: https://github.com/iqiyi/xhook/blob/master/README.md

Builds and installs the debug version of the xHook demo application. This is typically done after building the native libraries.

```bash
cd ./xhookwrapper/
./gradlew assembleDebug
adb install ./app/build/outputs/apk/debug/app-debug.apk
```

--------------------------------

### Register and Ignore Hooks for Tracking

Source: https://github.com/iqiyi/xhook/blob/master/README.md

Register hooks for mmap and munmap in system and vendor paths, while ignoring linker and linker64.

```c
//tracking (ignore linker and linker64)
xhook_register("^/system/.*$", "mmap",   my_mmap,   NULL);
xhook_register("^/vendor/.*$", "munmap", my_munmap, NULL);
xhook_ignore  (".*/linker$",   "mmap");
xhook_ignore  (".*/linker$",   "munmap");
xhook_ignore  (".*/linker64$", "mmap");
xhook_ignore  (".*/linker64$", "munmap");
```

--------------------------------

### xhook_enable_sigsegv_protection

Source: https://github.com/iqiyi/xhook/blob/master/README.md

Enables or disables segmentation fault protection (SFP).

```APIDOC
## xhook_enable_sigsegv_protection

### Description
Enables or disables segmentation fault protection (SFP).

### Function Signature
```c
void xhook_enable_sigsegv_protection(int flag);
```

### Parameters
- **flag** (int) - Pass `1` to enable SFP, `0` to disable. SFP is enabled by default.

### Notes
- SFP is recommended for release builds to prevent app crashes. Disable SFP for debug builds to catch coding mistakes.
- SFP uses `sigaction()`, `SIGSEGV`, `siglongjmp()`, and `sigsetjmp()` to prevent harmless crashes.
```

--------------------------------

### Apply Registered Hooks

Source: https://github.com/iqiyi/xhook/blob/master/README.md

Performs the actual PLT hooking operations based on registered information. Can be executed asynchronously by passing 1 to 'async'.

```c
int xhook_refresh(int async);
```

--------------------------------

### Register Hooks for Socket Lifecycle Inspection

Source: https://github.com/iqiyi/xhook/blob/master/README.md

Register hooks for socket-related functions to inspect their lifecycle.

```c
//inspect sockets lifecycle
xhook_register(".*\\.so$", "getaddrinfo", my_getaddrinfo, NULL);
xhook_register(".*\\.so$", "socket",      my_socket,      NULL);
xhook_register(".*\\.so$", "setsockopt"   my_setsockopt,  NULL);
xhook_register(".*\\.so$", "bind",        my_bind,        NULL);
xhook_register(".*\\.so$", "listen",      my_listen,      NULL);
xhook_register(".*\\.so$", "connect",     my_connect,     NULL);
xhook_register(".*\\.so$", "shutdown",    my_shutdown,    NULL);
xhook_register(".*\\.so$", "close",       my_close,       NULL);
```

--------------------------------

### Register Hook to Fix System Bugs

Source: https://github.com/iqiyi/xhook/blob/master/README.md

Register a hook to fix a specific system bug in a vendor library.

```c
//fix some system bug
xhook_register(".*some_vendor.*/libvictim\\.so$", "bad_func", my_nice_func, NULL);
```

--------------------------------

### xhook_enable_debug

Source: https://github.com/iqiyi/xhook/blob/master/README.md

Enables or disables debug information logging to logcat.

```APIDOC
## xhook_enable_debug

### Description
Enables or disables debug information logging to logcat.

### Function Signature
```c
void xhook_enable_debug(int flag);
```

### Parameters
- **flag** (int) - Pass `1` to enable debug info, `0` to disable. Debug info is disabled by default.

### Notes
- Debug info will be sent to logcat with the tag `xhook`.
```

--------------------------------

### Enable/Disable Segmentation Fault Protection (SFP)

Source: https://github.com/iqiyi/xhook/blob/master/README.md

Enables or disables the segmentation fault protection mechanism. SFP is enabled by default and recommended for release builds to prevent crashes. Disable for debug builds to catch coding errors.

```c
void xhook_enable_sigsegv_protection(int flag);
```

--------------------------------

### Register Hooks for Defense Against Injection Attacks

Source: https://github.com/iqiyi/xhook/blob/master/README.md

Register hooks to defend against injection attacks, such as always returning NULL for malloc or recording connect calls.

```c
//defense to some injection attacks
xhook_register(".*com\\.hacker.*\\.so$", "malloc",  my_malloc_always_return_NULL, NULL);
xhook_register(".*/libhacker\\.so$",     "connect", my_connect_with_recorder,     NULL);
```

--------------------------------

### Ignore All Hooks in a Specific Library

Source: https://github.com/iqiyi/xhook/blob/master/README.md

Ignore all hooks for the libwebviewchromium.so library.

```c
//ignore all hooks in libwebviewchromium.so
xhook_ignore(".*/libwebviewchromium.so$", NULL);
```

--------------------------------

### xhook_register

Source: https://github.com/iqiyi/xhook/blob/master/README.md

Registers a hook for a specific symbol in ELF files matching a given pathname regular expression. The original function pointer is saved.

```APIDOC
## xhook_register

### Description
Registers a hook for a specific symbol in ELF files matching a given pathname regular expression. The original function pointer is saved.

### Function Signature
```c
int xhook_register(const char  *pathname_regex_str,  
                   const char  *symbol,  
                   void        *new_func,  
                   void       **old_func);
```

### Parameters
- **pathname_regex_str** (const char *) - Regular expression string to match ELF file paths.
- **symbol** (const char *) - The symbol name to hook.
- **new_func** (void *) - Pointer to the new function to replace the original.
- **old_func** (void **) - Pointer to a variable where the original function pointer will be stored.

### Return Value
Returns zero if successful, non-zero otherwise.

### Notes
- The regular expression for `pathname_regex_str` only supports POSIX BRE.
- The `new_func` must have the same function declaration as the original one.
```

--------------------------------

### xhook_refresh

Source: https://github.com/iqiyi/xhook/blob/master/README.md

Performs the actual hook operations based on registered hook information.

```APIDOC
## xhook_refresh

### Description
Performs the actual hook operations based on registered hook information.

### Function Signature
```c
int xhook_refresh(int async);
```

### Parameters
- **async** (int) - Pass `1` for asynchronous hook, `0` for synchronous hook.

### Return Value
Returns zero if successful, non-zero otherwise.

### Notes
- This function updates a global cache of ELF loading info from `/proc/self/maps` to determine which newly loaded ELFs need hooking.
```

--------------------------------

### xhook_clear

Source: https://github.com/iqiyi/xhook/blob/master/README.md

Clears all cache owned by xhook and resets global flags.

```APIDOC
## xhook_clear

### Description
Clears all cache owned by xhook and resets all global flags to their default values.

### Function Signature
```c
void xhook_clear();
```

### Notes
- This function can be called after confirming all desired PLT entries have been hooked to save memory.
```

--------------------------------

### Register Hooks for Memory Leak Detection

Source: https://github.com/iqiyi/xhook/blob/master/README.md

Register hooks for malloc, calloc, realloc, and free functions to detect memory leaks in .so files.

```c
//detect memory leaks
xhook_register(".*\\.so$", "malloc",  my_malloc,  NULL);
xhook_register(".*\\.so$", "calloc",  my_calloc,  NULL);
xhook_register(".*\\.so$", "realloc", my_realloc, NULL);
xhook_register(".*\\.so$", "free",    my_free,    NULL);
```

--------------------------------

### Refresh Hooks

Source: https://github.com/iqiyi/xhook/blob/master/README.md

Refresh all registered hooks. The argument '1' indicates an immediate refresh.

```c
//hook now!
xhook_refresh(1);
```

--------------------------------

### Register a PLT Hook

Source: https://github.com/iqiyi/xhook/blob/master/README.md

Registers a hook for a specific symbol within ELF files matching a pathname regex. The original function pointer is saved in old_func. Requires the new_func to have the same signature as the original.

```c
int xhook_register(const char  *pathname_regex_str,  
                   const char  *symbol,  
                   void        *new_func,  
                   void       **old_func);
```

--------------------------------

### Register Hooks for Android Log Filtering

Source: https://github.com/iqiyi/xhook/blob/master/README.md

Register hooks for Android logging functions to filter and save logs to a local file.

```c
//filter off and save some android log to local file
xhook_register(".*\\.so$", "__android_log_write",  my_log_write,  NULL);
xhook_register(".*\\.so$", "__android_log_print",  my_log_print,  NULL);
xhook_register(".*\\.so$", "__android_log_vprint", my_log_vprint, NULL);
xhook_register(".*\\.so$", "__android_log_assert", my_log_assert, NULL);
```

--------------------------------

### xhook_ignore

Source: https://github.com/iqiyi/xhook/blob/master/README.md

Ignores previously registered hook information based on pathname and symbol.

```APIDOC
## xhook_ignore

### Description
Ignores previously registered hook information based on pathname and symbol.

### Function Signature
```c
int xhook_ignore(const char *pathname_regex_str,  
                 const char *symbol);
```

### Parameters
- **pathname_regex_str** (const char *) - Regular expression string to match ELF file paths.
- **symbol** (const char *) - The symbol name to ignore. If NULL, all symbols from matching ELFs are ignored.

### Return Value
Returns zero if successful, non-zero otherwise.

### Notes
- The regular expression for `pathname_regex_str` only supports POSIX BRE.
```

--------------------------------

### Enable/Disable Debug Logging

Source: https://github.com/iqiyi/xhook/blob/master/README.md

Enables or disables debug information output to logcat with the tag 'xhook'. Debugging is disabled by default.

```c
void xhook_enable_debug(int flag);
```

--------------------------------

### Clear xHook Cache

Source: https://github.com/iqiyi/xhook/blob/master/README.md

Clears all internal caches and resets global flags. This can be called after confirming all desired hooks have been applied to free up memory.

```c
void xhook_clear();
```

--------------------------------

### Ignore a Registered Hook

Source: https://github.com/iqiyi/xhook/blob/master/README.md

Ignores previously registered hook information based on a pathname regex and symbol. If the symbol is NULL, all symbols from matching ELFs are ignored.

```c
int xhook_ignore(const char *pathname_regex_str,  
                 const char *symbol);
```

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