Implementing a Simplified vmmap Tool on iOS for Memory Analysis

The vmmap tool is a macOS development utility bundled with Xcode that displays a process's memory layout, loaded dynamic libraries, permissions, and usage, similar to Linux's /proc/pid/maps file.

Because iOS is not open source and cannot run Xcode tools directly, the author ported (re‑implemented) a simplified vmmap for iOS to help reverse engineers inspect memory structures and loaded modules on jail‑broken devices.

The iOS implementation follows the macOS output format and consists of several functional steps:

1. Definition of a vmmap information structure.

2. Acquisition of the task object using get_task_for_pid to obtain a process handle (mach_port_name_t or vm_map_t).

3. Retrieval of region information by iterating with vm_region to collect each memory block.

4. Extraction of dyld information via the exported symbol __all_image_info , which points to a dyld_all_image_infos structure containing loaded dynamic library data.

5. Extraction of individual image information from the dyld_all_image_infos structure, yielding an array of dyld_image_info entries.

6. Parsing each dyld_image_info entry and converting it into a vmmap_region_info record, storing the results in a map.

7. Formatting of protection flags for readability.

8. Printing the assembled vmmap information in a table similar to the Linux maps output.

9. A simple main function ties all steps together to produce the final report.

The author concludes that this lightweight vmmap implementation, while basic, is sufficient for typical process module analysis on iOS, deepens understanding of iOS memory structures, and provides a useful foundation for future reverse‑engineering work.