nt-lite/code/kernel/ke_userenv.h

#pragma once
// ke_userenv.h - kernel view of the user-mode process/thread environment.
// This is this OS' ABI, not a Windows compatibility structure.

#include <stdint.h>
#include <stddef.h>

#define SYS_PEB_MAGIC   0x30424550u  /* "PEB0" */
#define SYS_TEB_MAGIC   0x30424554u  /* "TEB0" */
#define SYS_ENV_VERSION 1u
#define SYS_CWD_MAX     512u

typedef struct SYS_PEB {
    uint32_t Magic;
    uint32_t Version;
    uint32_t ProcessId;

    const char* ImagePath;
    size_t      ImagePathLength;

    const char* CommandLine;
    size_t      CommandLineLength;

    const char* CurrentDirectory;
    size_t      CurrentDirectoryLength;
} SYS_PEB;

typedef struct SYS_TEB {
    SYS_PEB*        Peb;
    void*           StackBase;
    void*           StackLimit;
    struct SYS_TEB* Self;
    uint32_t        ThreadId;
    uint32_t        Magic;
} SYS_TEB;