安装

参考如下博文安装thttpd软件

thttpd配置文件：

root@fqs:/usr/local/bin# cat /usr/local/thttpd/
conf/ etc/ logs/ man/ sbin/ www/
root@fqs:/usr/local/bin# cat /usr/local/thttpd/conf/thttpd.conf

port=80
user=www
host=0.0.0.0
logfile=/usr/local/thttpd/logs/thttpd.log
pidfile=/usr/local/thttpd/logs/thttpd.pid
#throttles=/usr/local/thttpd/etc/throttle.conf
#urlpat=*.txt|*.mp3
#charset=utf-8
dir=/usr/local/thttpd/www
cgipat=/cgi-bin/*

cgilua采用luarocks安装。其依赖 wsapi运行。

cgilua.cgi launcher：

root@fqs:/usr/local/bin# cat cgilua.cgi
#!/bin/sh

exec '/usr/bin/lua5.1' -e 'package.path="/root/.luarocks/share/lua/5.1/?.lua;/root/.luarocks/share/lua/5.1/?/init.lua;/usr/local/share/lua/5.1/?.lua;/usr/local/share/lua/5.1/?/init.lua;"..package.path; package.cpath="/root/.luarocks/lib/lua/5.1/?.so;/usr/local/lib/lua/5.1/?.so;"..package.cpath' -e 'local k,l,_=pcall(require,"luarocks.loader") _=k and l.add_context("cgilua","5.1.4-2")' '/usr/local/lib/luarocks/rocks/cgilua/5.1.4-2/bin/cgilua.cgi' "$@"
root@fqs:/usr/local/bin#
root@fqs:/usr/local/bin#
root@fqs:/usr/local/bin# cat /usr/local/lib/luarocks/rocks/cgilua/5.1.4-2/bin/cgilua.cgi
#!/usr/bin/env lua

-- CGILua (SAPI) launcher, extracts script to launch
-- either from the command line (use #!cgilua in the script)
-- or from SCRIPT_FILENAME/PATH_TRANSLATED

pcall(require, "luarocks.require")

local common = require "wsapi.common"
local cgi = require "wsapi.cgi"

local sapi = require "wsapi.sapi"

local arg_filename = (...)

local function sapi_loader(wsapi_env)
common.normalize_paths(wsapi_env, arg_filename, "cgilua.cgi")
return sapi.run(wsapi_env)
end

cgi.run(sapi_loader)
root@fqs:/usr/local/bin#

流程分析

thttpd配置遇到 cgipat规则的请求，则启动cgi程序

cgipat规则为

cgipat=/cgi-bin/*

即， URL中含有 /cgi-bin/开头的文件名请求。

对应thttpd中的启动cgi子程序代码：

    /* Is it world-executable and in the CGI area? */
    if ( hc->hs->cgi_pattern != (char*) 0 &&
     ( hc->sb.st_mode & S_IXOTH ) &&
     match( hc->hs->cgi_pattern, hc->expnfilename ) )
    return cgi( hc );

启动cgi程序逻辑

cgi函数中，其实是fork了一个子进程

r = fork( );
if ( r < 0 )
    {

    syslog( LOG_ERR, "fork - %m" );
    httpd_send_err(
    hc, 500, err500title, "", err500form, hc->encodedurl );
    return -1;
    }
if ( r == 0 )
    {

    /* Child process. */
    sub_process = 1;
    httpd_unlisten( hc->hs );
    cgi_child( hc );
    }

cgi_child为子进程继续执行逻辑

1、准备环境变量：

/* Make the environment vector. */
envp = make_envp( hc );

/* Make the argument vector. */
argp = make_argp( hc );

环境变量中，包括若干 cgi参数：

static char**
make_envp( httpd_conn* hc )
    {

    static char* envp[50];
    int envn;
    char* cp;
    char buf[256];

    envn = 0;
    envp[envn++] = build_env( "PATH=%s", CGI_PATH );
#ifdef CGI_LD_LIBRARY_PATH
    envp[envn++] = build_env( "LD_LIBRARY_PATH=%s", CGI_LD_LIBRARY_PATH );
#endif /* CGI_LD_LIBRARY_PATH */
    envp[envn++] = build_env( "SERVER_SOFTWARE=%s", SERVER_SOFTWARE );
    if ( hc->hs->vhost && hc->hostname != (char*) 0 && hc->hostname[0] != '\0' )
    cp = hc->hostname;
    else if ( hc->hdrhost != (char*) 0 && hc->hdrhost[0] != '\0' )
    cp = hc->hdrhost;
    else if ( hc->reqhost != (char*) 0 && hc->reqhost[0] != '\0' )
    cp = hc->reqhost;
    else
    cp = hc->hs->server_hostname;
    if ( cp != (char*) 0 )
    envp[envn++] = build_env( "SERVER_NAME=%s", cp );
    envp[envn++] = "GATEWAY_INTERFACE=CGI/1.1";
    envp[envn++] = build_env("SERVER_PROTOCOL=%s", hc->protocol);
    (void) my_snprintf( buf, sizeof(buf), "%d", (int) hc->hs->port );
    envp[envn++] = build_env( "SERVER_PORT=%s", buf );
    envp[envn++] = build_env(
    "REQUEST_METHOD=%s", httpd_method_str( hc->method ) );
    if ( hc->pathinfo[0] != '\0' )
    {

    char* cp2;
    size_t l;
    envp[envn++] = build_env( "PATH_INFO=/%s", hc->pathinfo );
    l = strlen( hc->hs->cwd ) + strlen( hc->pathinfo ) + 1;
    cp2 = NEW( char, l );
    if ( cp2 != (char*) 0 )
        {

        (void) my_snprintf( cp2, l, "%s%s", hc->hs->cwd, hc->pathinfo );
        envp[envn++] = build_env( "PATH_TRANSLATED=%s", cp2 );
        }
    }
    envp[envn++] = build_env(
    "SCRIPT_NAME=/%s", strcmp( hc->origfilename, "." ) == 0 ?
    "" : hc->origfilename );
    if ( hc->query[0] != '\0')
    envp[envn++] = build_env( "QUERY_STRING=%s", hc->query );
    envp[envn++] = build_env(
    "REMOTE_ADDR=%s", httpd_ntoa( &hc->client_addr ) );
    if ( hc->referrer[0] != '\0' )
    {

    envp[envn++] = build_env( "HTTP_REFERER=%s", hc->referrer );
    envp[envn++] = build_env( "HTTP_REFERRER=%s", hc->referrer );
    }
    if ( hc->useragent[0] != '\0' )
    envp[envn++] = build_env( "HTTP_USER_AGENT=%s", hc->useragent );
    if ( hc->accept[0] != '\0' )
    envp[envn++] = build_env( "HTTP_ACCEPT=%s", hc->accept );
    if ( hc->accepte[0] != '\0' )
    envp[envn++] = build_env( "HTTP_ACCEPT_ENCODING=%s", hc->accepte );
    if ( hc->acceptl[0] != '\0' )
    envp[envn++] = build_env( "HTTP_ACCEPT_LANGUAGE=%s", hc->acceptl );
    if ( hc->cookie[0] != '\0' )
    envp[envn++] = build_env( "HTTP_COOKIE=%s", hc->cookie );
    if ( hc->contenttype[0] != '\0' )
    envp[envn++] = build_env( "CONTENT_TYPE=%s", hc->contenttype );
    if ( hc->hdrhost[0] != '\0' )
    envp[envn++] = build_env( "HTTP_HOST=%s", hc->hdrhost );
    if ( hc->contentlength != -1 )
    {

    (void) my_snprintf(
        buf, sizeof(buf), "%lu", (unsigned long) hc->contentlength );
    envp[envn++] = build_env( "CONTENT_LENGTH=%s", buf );
    }
    if ( hc->remoteuser[0] != '\0' )
    envp[envn++] = build_env( "REMOTE_USER=%s", hc->remoteuser );
    if ( hc->authorization[0] != '\0' )
    envp[envn++] = build_env( "AUTH_TYPE=%s", "Basic" );
    /* We only support Basic auth at the moment. */
    if ( getenv( "TZ" ) != (char*) 0 )
    envp[envn++] = build_env( "TZ=%s", getenv( "TZ" ) );
    envp[envn++] = build_env( "CGI_PATTERN=%s", hc->hs->cgi_pattern );

    envp[envn] = (char*) 0;
    return envp;
    }

2、将连接fd设置为cgi程序的标准输入：

/* Otherwise, the request socket is stdin. */
if ( hc->conn_fd != STDIN_FILENO )
(void) dup2( hc->conn_fd, STDIN_FILENO );

3、将连接fd设置为cgi程序的标准输出和错误：

/* Otherwise, the request socket is stdout/stderr. */
if ( hc->conn_fd != STDOUT_FILENO )
(void) dup2( hc->conn_fd, STDOUT_FILENO );
if ( hc->conn_fd != STDERR_FILENO )
(void) dup2( hc->conn_fd, STDERR_FILENO );

4、启动cgi的业务进程，替代当前的 fork映像

/* Run the program. */
(void) execve( binary, argp, envp );

注意环境变量已经被注入到启动进程中，即在业务进程中，可以访问到 cgi参数。

包括当前脚本名称： SCRIPT_NAME

execv功能

The exec() family of functions replaces the current process image with a new process image. The functions described in this manual page are front-ends for execve(2). (See the
manual page for execve(2) for further details about the replacement of the current process image.)

execve() executes the program pointed to by filename. filename must be either a binary executable, or a script starting with a line of the form "#! interpreter [arg]". In the latter case, the interpreter must be a valid pathname for an executable which is not itself a script, which will be invoked as interpreter [arg] filename.

如果待执行文件为脚本，则启动脚本脚本的解释器程序，并执行脚本。

脚本内容

Z:\cgilua-master\cgilua-master\examples\index.lp 样例中的此脚本

意思为启动程序 env，执行cgilua.cgi程序，来处理脚本文件

#!/usr/bin/env cgilua.cgi

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN"
   ">
<html xmlns=" xml:lang="en" lang="en">
<head>
    <title>Welcome to Kepler!</title>
    <link rel="stylesheet" href="css/doc.css" type="text/css"/>
    <meta http-equiv="Content-Type" content="text/html; charset=UTF-8"/>
</head>

<body>

env命令程序的作用，可以看出此处专门是用来启动命令的（cgilua.cgi），并没有设置环境变量

NAME
       env - run a program in a modified environment

SYNOPSIS
       env [OPTION]... [-] [NAME=VALUE]... [COMMAND [ARG]...]

DESCRIPTION
       Set each NAME to VALUE in the environment and run COMMAND.

       Mandatory arguments to long options are mandatory for short options too.

cgilua.cgi

cgilua.cgi 主要业务文件为 /usr/local/lib/luarocks/rocks/cgilua/5.1.4-2/bin/cgilua.cgi

依赖wsapi.cgi 和 wsapi.common 和 wsapi.cgi模块

root@fqs:/usr/local/bin# cat cgilua.cgi
#!/bin/sh

exec '/usr/bin/lua5.1' -e 'package.path="/root/.luarocks/share/lua/5.1/?.lua;/root/.luarocks/share/lua/5.1/?/init.lua;/usr/local/share/lua/5.1/?.lua;/usr/local/share/lua/5.1/?/init.lua;"..package.path; package.cpath="/root/.luarocks/lib/lua/5.1/?.so;/usr/local/lib/lua/5.1/?.so;"..package.cpath' -e 'local k,l,_=pcall(require,"luarocks.loader") _=k and l.add_context("cgilua","5.1.4-2")' '/usr/local/lib/luarocks/rocks/cgilua/5.1.4-2/bin/cgilua.cgi' "$@"
root@fqs:/usr/local/bin#
root@fqs:/usr/local/bin#
root@fqs:/usr/local/bin#
root@fqs:/usr/local/bin# cat /usr/local/lib/luarocks/rocks/cgilua/5.1.4-2/bin/cgilua.cgi
#!/usr/bin/env lua

-- CGILua (SAPI) launcher, extracts script to launch
-- either from the command line (use #!cgilua in the script)
-- or from SCRIPT_FILENAME/PATH_TRANSLATED

pcall(require, "luarocks.require")

local common = require "wsapi.common"
local cgi = require "wsapi.cgi"

local sapi = require "wsapi.sapi"

local arg_filename = (...)

local function sapi_loader(wsapi_env)
common.normalize_paths(wsapi_env, arg_filename, "cgilua.cgi")
return sapi.run(wsapi_env)
end

cgi.run(sapi_loader)
#

1、 wsapi.cgi模块为脚本入口，其提供了获取环境变量的通道，设置到 wsapi_env表中：

并将前文中说的， cgi程序将连接fd，接管后，作为标准输入和输出以及错误的代表。

local os = require"os"
local io = require"io"
local common = require"wsapi.common"

common.setmode()

local _M = {}

-- Runs an WSAPI application for this CGI request
function _M.run(app_run)
common.run(app_run, { input = io.stdin, output = io.stdout,
error = io.stderr, env = os.getenv })
end

return _M

2、 wsapi.sapi 脚本实现，启动cgilua执行的逻辑：

local response = require "wsapi.response"

local _M = {}

function _M.run(wsapi_env)
_G.CGILUA_APPS = _G.CGILUA_APPS or wsapi_env.DOCUMENT_ROOT .. "/cgilua"
_G.CGILUA_CONF = _G.CGILUA_CONF or wsapi_env.DOCUMENT_ROOT .. "/cgilua"
_G.CGILUA_TMP = _G.CGILUA_TMP or os.getenv("TMP") or os.getenv("TEMP") or "/tmp"
_G.CGILUA_ISDIRECT = true

local res = response.new()

_G.SAPI = {

    Info = {

      _COPYRIGHT = "Copyright (C) 2007 Kepler Project",
      _DESCRIPTION = "WSAPI SAPI implementation",
      _VERSION = "WSAPI SAPI 1.0",
      ispersistent = false,
    },
    Request = {

      servervariable = function (name) return wsapi_env[name] end,
      getpostdata = function (n) return wsapi_env.input:read(n) end
    },
    Response = {

      contenttype = function (header)
        res:content_type(header)
      end,
      errorlog = function (msg, errlevel)
        wsapi_env.error:write (msg)
      end,
      header = function (header, value)
        if res.headers[header] then
          if type(res.headers[header]) == "table" then
            table.insert(res.headers[header], value)
          else
            res.headers[header] = { res.headers[header], value }
          end
        else
          res.headers[header] = value
        end
      end,
      redirect = function (url)
        res.status = 302
        res.headers["Location"] = url
      end,
      write = function (...)
        res:write({...})
      end,
    },
}
local cgilua = require "cgilua"
cgilua.main()
return res:finish()
end

return _M