Pass parameters to the process by the environment variable

#include "stdafx.h"
#include <windows.h>

//枚举所有环境变量
void EnumEnvironment()
{
    char *l_EnvStr;
    l_EnvStr = GetEnvironmentStrings();
    if (l_EnvStr)
    {
        LPTSTR l_str = l_EnvStr;

        int count = 0;
        while (true)
        {
           if (*l_str == 0) break;
           while (*l_str != 0) l_str++;
           l_str++;
           count++;
        }

        printf("count:%d\n",count);

        for (int i = 0; i < count; i++)
        {
          printf("%s\n", l_EnvStr);
          while(*l_EnvStr != '\0')
             l_EnvStr++;
          l_EnvStr++;
        }
        
        FreeEnvironmentStrings(l_EnvStr);
    }
}

//读取环境变量值
BOOL ReadUID()
{
    char uid[1024]={0};

    if (GetEnvironmentVariableA("param_uid",uid,sizeof(uid)))
    {
        printf("uid:%s\n",uid);
        return TRUE;
    }else{
        printf("获取参数失败\n");
    }

    return FALSE;
}

typedef struct tagEnvInfo
{
    LPSTR lpStr;
    DWORD dwSize;
    DWORD dwCount;
}EnvInfo;

//获取所有环境变量缓冲区信息
LPSTR GetEnvironmentStringsEx(EnvInfo * pEnvInfo)
{
    if (pEnvInfo)
    {
        pEnvInfo->lpStr=NULL;
        pEnvInfo->dwSize=0;
        pEnvInfo->dwCount=0;
    }

    LPSTR lpEnvStr=GetEnvironmentStrings();
    if (lpEnvStr)
    {
        pEnvInfo->lpStr=lpEnvStr;

        LPSTR p = lpEnvStr;

        while (true)
        {
            if (*p == 0) break;
            while (*p != 0)
            {
                p++;
                if (pEnvInfo) pEnvInfo->dwSize++;
            }

            p++;
            
            if (pEnvInfo)
            {
                pEnvInfo->dwSize++;
                pEnvInfo->dwCount++;
            }
        }

        return lpEnvStr;
    }

    return NULL;
}

//在当前环境变量后增加一个自定义的环境变量,返回环境变量字符串
LPSTR NewEnvironment(const char *name, const char *value)
{
    LPSTR lpEnvironment=NULL;

    EnvInfo env;
    LPSTR lpEnvStr=GetEnvironmentStringsEx(&env);
    if (lpEnvStr)
    {
        DWORD dwAllocSize=env.dwSize+strlen(name)+strlen(value)+3;//1个等号,2个空结束符号

        lpEnvironment=(LPSTR)GlobalAlloc(0, dwAllocSize);
        if (lpEnvironment)
        {
            memset(lpEnvironment,0,dwAllocSize);
            memcpy(lpEnvironment,lpEnvStr,env.dwSize);
            sprintf(lpEnvironment+env.dwSize,"%s=%s",name,value);
        }

        FreeEnvironmentStrings(lpEnvStr);
    }

    return lpEnvironment;
}

int main(int argc, char* argv[])
{
    if (ReadUID()) return 0;

    LPSTR lpEnvironment=NewEnvironment("param_uid","yangxiaowei");

    STARTUPINFO si;
    PROCESS_INFORMATION pi;
    memset( &si, 0, sizeof(si) );
    memset( &pi, 0, sizeof(pi) );

    si.cb = sizeof(si);
    si.dwFlags = STARTF_USESHOWWINDOW;
    si.wShowWindow=SW_SHOWNORMAL;

    char szBuff[1024]={0};
    GetModuleFileName(::GetModuleHandle(NULL), szBuff, sizeof(szBuff));

    if (CreateProcess(
            NULL,             // No module name (use command line).
            szBuff,           // Command line.
            NULL,             // Process handle not inheritable.
            NULL,             // Thread handle not inheritable.
            FALSE,            // Set handle inheritance to FALSE.
            NULL,             // No creation flags.
            lpEnvironment,    // Use parent's environment block.
            NULL,             // Use parent's starting directory.
            &si,              // Pointer to STARTUPINFO structure.
            &pi ))            // Pointer to PROCESS_INFORMATION structure.
    {

        printf("启动成功\n");
    }else{
        printf("启动失败\n");
    }

    if (lpEnvironment) GlobalFree(lpEnvironment);

    Sleep(600000);

    return 0;
}