qmail-local代码分析

2016-02-19 18:06 13 1 收藏

下面图老师小编要向大家介绍下qmail-local代码分析,看起来复杂实则是简单的,掌握好技巧就OK,喜欢就赶紧收藏起来吧!

【 tulaoshi.com - 编程语言 】


  我分析的代码没有“夜未眠”大哥的好,可能还有的不正确,就请各位多多指教,谢谢
  代码:
  #include sys/types.h
  #include sys/stat.h
  #include "readwrite.h"
  #include "sig.h"
  #include "env.h"
  #include "byte.h"
  #include "exit.h"
  #include "fork.h"
  #include "open.h"
  #include "wait.h"
  #include "lock.h"
  #include "seek.h"
  #include "substdio.h"
  #include "getln.h"
  #include "strerr.h"
  #include "subfd.h"
  #include "sgetopt.h"
  #include "alloc.h"
  #include "error.h"
  #include "stralloc.h"
  #include "fmt.h"
  #include "str.h"
  #include "now.h"
  #include "case.h"
  #include "quote.h"
  #include "qmail.h"
  #include "slurpclose.h"
  #include "myctime.h"
  #include "gfrom.h"
  #include "auto_patrn.h"
  
  void usage() { strerr_die1x(100,"qmail-local: usage: qmail-local [ -nN ] user homedir local dash ext domain sender aliasempty"); }
  
  void temp_nomem() { strerr_die1x(111,"Out of memory. (#4.3.0)"); }
  void temp_rewind() { strerr_die1x(111,"Unable to rewind message. (#4.3.0)"); }
  void temp_childcrashed() { strerr_die1x(111,"Aack, child crashed. (#4.3.0)"); }
  void temp_fork() { strerr_die3x(111,"Unable to fork: ",error_str(errno),". (#4.3.0)"); }
  void temp_read() { strerr_die3x(111,"Unable to read message: ",error_str(errno),". (#4.3.0)"); }
  void temp_slowlock()
  { strerr_die1x(111,"File has been locked for 30 seconds straight. (#4.3.0)"); }
  void temp_qmail(fn) char *fn;
  { strerr_die5x(111,"Unable to open ",fn,": ",error_str(errno),". (#4.3.0)"); }
  
  int flagdoit;
  int flag99;
  
  char *user;
  char *homedir;
  char *local;
  char *dash;
  char *ext;
  char *host;
  char *sender;
  char *aliasempty;
  
  stralloc safeext = {0};
  stralloc ufline = {0};
  stralloc rpline = {0};
  stralloc envrecip = {0};
  stralloc dtline = {0};
  stralloc qme = {0};
  stralloc ueo = {0};
  stralloc cmds = {0};
  stralloc messline = {0};
  stralloc foo = {0};
  
  char buf[1024];
  char outbuf[1024];
  
  /* child process */
  
  char fntmptph[80 + FMT_ULONG * 2];
  char fnnewtph[80 + FMT_ULONG * 2];
  void tryunlinktmp() { unlink(fntmptph); }/*删除fntmptph文件,或连接*/
  void sigalrm() { tryunlinktmp(); _exit(3); }
  
  void maildir_child(dir)
  char *dir;
  {
  unsigned long pid;
  unsigned long time;
  char host[64];
  char *s;
  int loop;
  strUCt stat st;
  int fd;
  substdio ss;
  substdio ssout;
  
  sig_alarmcatch(sigalrm);//捕捉时间信号。
  if (chdir(dir) == -1) { if (error_temp(errno)) _exit(1); _exit(2); }
  
   pid = getpid();//获取当前的进程号。
  host[0] = 0;
  gethostname(host,sizeof(host));
  for (loop = 0;;++loop)
   {
   time = now();
   s = fntmptph;
   s += fmt_str(s,"tmp/");/*将"tmp/"拷到s中*/
   s += fmt_ulong(s,time); *s++ = '.';/*将时间转化为字符串*/
   s += fmt_ulong(s,pid); *s++ = '.';
   s += fmt_strn(s,host,sizeof(host)); *s++ = 0;
   if (stat(fntmptph,&st) == -1) if (errno == error_noent) break;
   /* really should never get to this point */
   if (loop == 2) _exit(1);
   sleep(2);
   }
  str_copy(fnnewtph,fntmptph);
  byte_copy(fnnewtph,3,"new");
  //时间为24小时
  alarm(86400);
  fd = open_excl(fntmptph);
  if (fd == -1) _exit(1);
  ///////////////////////////////////////////////////
  substdio_fdbuf(&ss,read,0,buf,sizeof(buf));
  substdio_fdbuf(&ssout,write,fd,outbuf,sizeof(outbuf));
  //dtline:邮件头Delivered-To部分
  //rpline:邮件头返回路径
  //无需"From "头部
  if (substdio_put(&ssout,rpline.s,rpline.len) == -1) goto fail;
  if (substdio_put(&ssout,dtline.s,dtline.len) == -1) goto fail;
  //将邮件写到文件fd中
  switch(substdio_copy(&ssout,&ss))
   {
   case -2: tryunlinktmp(); _exit(4);
   case -3: goto fail;
   }
  
  if (substdio_flush(&ssout) == -1) goto fail;
  //将fd所指文件数据由系统缓冲区写回磁盘正确返回0,错误返回-1
  if (fsync(fd) == -1) goto fail;
  if (close(fd) == -1) goto fail; /* NFS dorks */
  
  if (link(fntmptph,fnnewtph) == -1) goto fail;
   /* if it was error_exist, almost certainly successful; i hate NFS */
  tryunlinktmp(); _exit(0);
  
  fail: tryunlinktmp(); _exit(1);
  }
  
  /* end child process */
  //maildir 格式邮箱的邮件投递,不要锁定
  void maildir(fn)
  char *fn;
  {
  int child;
  int wstat;
  //#define seek_begin(fd) (seek_set((fd),(seek_pos) 0))
  //指向文件0的开头
  if (seek_begin(0) == -1) temp_rewind();
  
  switch(child = fork())
   {
   case -1:
   temp_fork();
   case 0:
   maildir_child(fn);/////////////////////////////////////
   _exit(111);
   }
  //返回子进程fd的结束状态值于wstat中
  wait_pid(&wstat,child);
  //#define wait_crashed(w) ((w) & 127)
  if (wait_crashed(wstat))
   temp_childcrashed();
  //#define wait_exitcode(w) ((w) 8)
  switch(wait_exitcode(wstat))
   {
   case 0: break;
   case 2: strerr_die1x(111,"Unable to chdir to maildir. (#4.2.1)");
   case 3: strerr_die1x(111,"Timeout on maildir delivery. (#4.3.0)");
   case 4: strerr_die1x(111,"Unable to read message. (#4.3.0)");
   default: strerr_die1x(111,"Temporary error on maildir delivery. (#4.3.0)");
   }
  }
  //mbox 格式邮箱的邮件投递,必须锁定
  void mailfile(fn)
  
   char *fn;
  {
  int fd;
  substdio ss;
  substdio ssout;
  int match;
  seek_pos pos;
  int flaglocked;
  //到文件0开头
  if (seek_begin(0) == -1) temp_rewind();
  //打开文件fn
  fd = open_append(fn);
  if (fd == -1)
   strerr_die5x(111,"Unable to open ",fn,": ",error_str(errno),". (#4.2.1)");
  //时间信号,30秒
  sig_alarmcatch(temp_slowlock);
  alarm(30);
  //锁定
  flaglocked = (lock_ex(fd) != -1);
  alarm(0);
  sig_alarmdefault();
  //结尾
  seek_end(fd);
  //pos实际指向文件尾(文件大小)
  pos = seek_cur(fd);
  
  substdio_fdbuf(&ss,read,0,buf,sizeof(buf));
  substdio_fdbuf(&ssout,write,fd,outbuf,sizeof(outbuf));
  //dtline:邮件头Delivered-To部分
  //rpline:邮件头返回路径
  //ufline:mbox 是标准的UNIX邮箱格式, 多个邮件存放在一个独立文件内, 每个邮件由一个"From" 的行开始.
  //这一行看起来像一个标题字段, 不过那不是标题, 那仅仅是传送代理添加的, 便于邮件读出器可以找到每个邮件开始部分的一个标记.
  if (substdio_put(&ssout,ufline.s,ufline.len)) goto writeerrs;
  if (substdio_put(&ssout,rpline.s,rpline.len)) goto writeerrs;
  if (substdio_put(&ssout,dtline.s,dtline.len)) goto writeerrs;
  for (;;)
   {//读一行
   if (getln(&ss,&messline,&match,'') != 0)
  {
   strerr_warn3("Unable to read message: ",error_str(errno),". (#4.3.0)",0);
   if (flaglocked) seek_trunc(fd,pos); close(fd);
   _exit(111);
  }
   if (!match && !messline.len) break;
   if (gfrom(messline.s,messline.len))
   if (substdio_bput(&ssout,"",1)) goto writeerrs;
   if (substdio_bput(&ssout,messline.s,messline.len)) goto writeerrs;
   if (!match)
  {
   if (substdio_bputs(&ssout,"")) goto writeerrs;
   break;
  }
   }
  if (substdio_bputs(&ssout,"")) goto writeerrs;
  if (substdio_flush(&ssout)) goto writeerrs;
  //由缓冲区写回磁盘
  if (fsync(fd) == -1) goto writeerrs;
  close(fd);
  return;
  
  writeerrs:
  strerr_warn5("Unable to write ",fn,": ",error_str(errno),". (#4.3.0)",0);
  if (flaglocked) seek_trunc(fd,pos);
  close(fd);
  _exit(111);
  }
  
  void mailprogram(prog)
  char *prog;
  {
  int child;
  char *(args[4]);
  int wstat;
  
  if (seek_begin(0) == -1) temp_rewind();
  
  switch(child = fork())
   {
   case -1:
   temp_fork();
   case 0:
   args[0] = "/bin/sh"; args[1] = "-c"; args[2] = prog; args[3] = 0;
   sig_pipedefault();
   execv(*args,args);
   strerr_die3x(111,"Unable to run /bin/sh: ",error_str(errno),". (#4.3.0)");
   }
  
  wait_pid(&wstat,child);
  if (wait_crashed(wstat))
   temp_childcrashed();
  switch(wait_exitcode(wstat))
   {
   case 100:
   case 64: case 65: case 70: case 76: case 77: case 78: case 112: _exit(100);
  
   case 0: break;
   case 99: flag99 = 1; break;
   default: _exit(111);
   }
  }
  
  unsigned long mailforward_qp = 0;
  //转发邮件,地址在recips中
  void mailforward(recips)
  char **recips;
  {//struct qmail {
  // int flagerr;
  // unsigned long pid;
  // int fdm;
  // int fde;
  // substdio ss;
  // char buf[1024];
  // } ;
  struct qmail QQt;
  char *qqx;
  substdio ss;
  int match;
  
  if (seek_begin(0) == -1) temp_rewind();
  substdio_fdbuf(&ss,read,0,buf,sizeof(buf));
  
  if (qmail_open(&qqt) == -1) temp_fork();
  mailforward_qp = qmail_qp(&qqt);
  qmail_put(&qqt,dtline.s,dtline.len);
  do
   {
   if (getln(&ss,&messline,&match,'') != 0) { qmail_fail(&qqt); break; }
   qmail_put(&qqt,messline.s,messline.len);
   }
  while (match);
  qmail_from(&qqt,ueo.s);
  while (*recips) qmail_to(&qqt,*recips++);
  qqx = qmail_close(&qqt);
  if (!*qqx) return;
  strerr_die3x(*qqx == 'D' ? 100 : 111,"Unable to forward message: ",qqx + 1,".");
  }
  
  void bouncexf()
  {
  int match;
  substdio ss;
  //#define seek_begin(fd) (seek_set((fd),(seek_pos) 0))
  //typedef unsigned long seek_pos
  //将文件0的指针移到开始位置。
  if (seek_begin(0) == -1) temp_rewind();
  //给ss附值,ss-x=buf,s-fd = 0;s-op = read;s-p = 0(字节数);s-n = sizeof(buf)(还有的空间)
  substdio_fdbuf(&ss,read,0,buf,sizeof(buf));
  for (;;)
   {
   if (getln(&ss,&messline,&match,'') != 0) temp_read();
   if (!match) break;
  //判定文件是否结束
   if (messline.len = 1)
   break;
   if (messline.len == dtline.len)
   if (!str_diffn(messline.s,dtline.s,dtline.len))
   strerr_die1x(100,"This message is looping: it already has my Delivered-To line. (#5.4.6)");
   }
  }
  
  void checkhome()
  {
  struct stat st;
  
  if (stat(".",&st) == -1)
   strerr_die3x(111,"Unable to stat home Directory: ",error_str(errno),". (#4.3.0)");
  if (st.st_mode & auto_patrn)
   strerr_die1x(111,"Uh-oh: home directory is writable. (#4.7.0)");
  if (st.st_mode & 01000)
   if (flagdoit)
   strerr_die1x(111,"Home directory is sticky: user is editing his .qmail file. (#4.2.1)");
   else
   strerr_warn1("Warning: home directory is sticky.",0);
  }
  //得到文件".qmail"+dash+safeext+dashowner的权限,正确返回0,错误为-1
  int qmeox(dashowner)
  char *dashowner;
  {
  struct stat st;
  
  if (!stralloc_copys(&qme,".qmail")) temp_nomem();
  if (!stralloc_cats(&qme,dash)) temp_nomem();
  
   if (!stralloc_cat(&qme,&safeext)) temp_nomem();
  if (!stralloc_cats(&qme,dashowner)) temp_nomem();
  if (!stralloc_0(&qme)) temp_nomem();
  if (stat(qme.s,&st) == -1)
   {
   if (error_temp(errno)) temp_qmail(qme.s);
   return -1;
   }
  return 0;
  }
  //qme文件存在且是一般文件返回1,否则为0
  int qmeexists(fd,cutable)
  int *fd;
  int *cutable;
  {
   struct stat st;
  
   if (!stralloc_0(&qme)) temp_nomem();
  
   *fd = open_read(qme.s);
   if (*fd == -1) {
  if (error_temp(errno)) temp_qmail(qme.s);
  if (errno == error_perm) temp_qmail(qme.s);
  if (errno == error_acces) temp_qmail(qme.s);
  return 0;
   }
  
   if (fstat(*fd,&st) == -1) temp_qmail(qme.s);
  //S_IFREG表示一般文件
   if ((st.st_mode & S_IFMT) == S_IFREG) {
  if (st.st_mode & auto_patrn)
   strerr_die1x(111,"Uh-oh: .qmail file is writable. (#4.7.0)");
  *cutable = !!(st.st_mode & 0100);//看文件的owner权限是否为可执行的。是*cutable = 1,不是*cutable = 0
  return 1;
   }
   close(*fd);
   return 0;
  }
  
  /* "" "": "" */
  /* "-/" "": "-/" "-/default" */
  /* "-/" "a": "-/a" "-/default" */
  /* "-/" "a-": "-/a-" "-/a-default" "-/default" */
  /* "-/" "a-b": "-/a-b" "-/a-default" "-/default" */
  /* "-/" "a-b-": "-/a-b-" "-/a-b-default" "-/a-default" "-/default" */
  /* "-/" "a-b-c": "-/a-b-c" "-/a-b-default" "-/a-default" "-/default" */
  //打开文件&qme,如是一般文件再看是否为default,假如是,"DEFAULT"+*(ext+i)结合加入
  void qmesearch(fd,cutable)
  int *fd;
  int *cutable;
  {
   int i;
  
   if (!stralloc_copys(&qme,".qmail")) temp_nomem();
   if (!stralloc_cats(&qme,dash)) temp_nomem();
   if (!stralloc_cat(&qme,&safeext)) temp_nomem();
   if (qmeexists(fd,cutable)) {
  if (safeext.len = 7) {
   i = safeext.len - 7;
   if (!byte_diff("default",7,safeext.s + i))
   if (i = str_len(ext)) /* paranoia */
   if (!env_put2("DEFAULT",ext + i)) temp_nomem();
  }
  return;
   }
  
   for (i = safeext.len;i = 0;--i)
  if (!i (safeext.s[i - 1] == '-')) {
   if (!stralloc_copys(&qme,".qmail")) temp_nomem();
   if (!stralloc_cats(&qme,dash)) temp_nomem();
   if (!stralloc_catb(&qme,safeext.s,i)) temp_nomem();
   if (!stralloc_cats(&qme,"default")) temp_nomem();
   if (qmeexists(fd,cutable)) {
   if (i = str_len(ext)) /* paranoia */
   if (!env_put2("DEFAULT",ext + i)) temp_nomem();
  return;
   }
  }
  
   *fd = -1;
  }
  
  unsigned long count_file = 0;
  unsigned long count_forward = 0;
  unsigned long count_program = 0;
  char count_buf[FMT_ULONG];
  
  void count_print()
  
   {
  substdio_puts(subfdoutsmall,"did ");
  substdio_put(subfdoutsmall,count_buf,fmt_ulong(count_buf,count_file));
  substdio_puts(subfdoutsmall,"+");
  substdio_put(subfdoutsmall,count_buf,fmt_ulong(count_buf,count_forward));
  substdio_puts(subfdoutsmall,"+");
  substdio_put(subfdoutsmall,count_buf,fmt_ulong(count_buf,count_program));
  substdio_puts(subfdoutsmall,"");
  if (mailforward_qp)
   {
   substdio_puts(subfdoutsmall,"qp ");
   substdio_put(subfdoutsmall,count_buf,fmt_ulong(count_buf,mailforward_qp));
   substdio_puts(subfdoutsmall,"");
   }
  substdio_flush(subfdoutsmall);
  }
  
  void sayit(type,cmd,len)
  char *type;
  char *cmd;
  int len;
  {
  substdio_puts(subfdoutsmall,type);
  substdio_put(subfdoutsmall,cmd,len);
  substdio_putsflush(subfdoutsmall,"");
  }
  
  void main(argc,argv)
  int argc;
  char **argv;
  {
  int opt;
  int i;
  int j;
  int k;
  int fd;
  int numforward;
  char **recips;
  datetime_sec starttime;
  int flagforwardonly;
  char *x;
  
  umask(077);//将系统umask值设为077&0777的值。open函数的真正权限为mode&-umask
  sig_pipeignore();//忽略信号
  //将environ空间扩大(加10个字符串位置)错误返回0
  if (!env_init()) temp_nomem();
  //-n Instead of reading and delivering the message, print a description of
  // the delivery instructions. (man page)
  //-N 是默认值
  flagdoit = 1;
  while ((opt = getopt(argc,argv,"nN")) != opteof)
   switch(opt)
  {
   case 'n': flagdoit = 0; break;
   case 'N': flagdoit = 1; break;
   default:
   usage();
  }
  argc -= optind;
  argv += optind;
  //将参数拷到相应的变量中。
  if (!(user = *argv++)) usage();
  if (!(homedir = *argv++)) usage();
  if (!(local = *argv++)) usage();
  if (!(dash = *argv++)) usage();
  if (!(ext = *argv++)) usage();
  if (!(host = *argv++)) usage();
  if (!(sender = *argv++)) usage();
  if (!(aliasempty = *argv++)) usage();
  if (*argv) usage();
  //目录是以'/'开头的
  if (homedir[0] != '/') usage();
  if (chdir(homedir) == -1)
   strerr_die5x(111,"Unable to switch to ",homedir,": ",error_str(errno),". (#4.3.0)");
  checkhome();
  //将"HOST"和host结合为"HOST="+host,加到environ后面。下同
  if (!env_put2("HOST",host)) temp_nomem();//接收地址的域名部分
  if (!env_put2("HOME",homedir)) temp_nomem();//用户的主目录
  if (!env_put2("USER",user)) temp_nomem();//当前的用户
  if (!env_put2("LOCAL",local)) temp_nomem();//接收地址的local部分
  //将本地的地址扩展。如local为"dingwenbin",host为pact518.hit.edu.cn,则envrecip为"dingwenbin@pact518.hit.edu.cn"
  if (!stralloc_copys(&envrecip,local)) temp_nomem();
  if (!stralloc_cats(&envrecip,"@")) temp_nomem();
  
   if (!stralloc_cats(&envrecip,host)) temp_nomem();
  //将envrecip-s加'Z'拷到foo-s.
  if (!stralloc_copy(&foo,&envrecip)) temp_nomem();
  //#define stralloc_0(sa) stralloc_append(sa,"")
  //GEN_ALLOC_append(stralloc,char,s,len,a,i,n,x,30,stralloc_readyplus,stralloc_append)
  //struct stralloc{char *s;int len;int a;},len是s的长度,a是总共分配的空间。
  //stralloc_ready(x,n)作用是:x没有分配空间就分配n大小空间。已分配了且空间小于n就扩大空间
  //stralloc_readyplus(x,n)作用是:x没有分配空间就分配n大小空间。分配给x的空间小于x-len+n,就扩大空间
  if (!stralloc_0(&foo)) temp_nomem();
  //将"RECIPIENT"和foo.s结合为"RECIPIENT="+foo.s,加到environ后面。下同
  //信封上接收者的地址
  if (!env_put2("RECIPIENT",foo.s)) temp_nomem();
  //邮件头Delivered-To部分
  if (!stralloc_copys(&dtline,"Delivered-To: ")) temp_nomem();
  if (!stralloc_cat(&dtline,&envrecip)) temp_nomem();
  for (i = 0;i dtline.len;++i) if (dtline.s[i] == '') dtline.s[i] = '_';
  if (!stralloc_cats(&dtline,"")) temp_nomem();
  
  if (!stralloc_copy(&foo,&dtline)) temp_nomem();
  if (!stralloc_0(&foo)) temp_nomem();
  if (!env_put2("DTLINE",foo.s)) temp_nomem();
  
  if (flagdoit)
   bouncexf();
  //将"SENDER"和sender结合为"SENDER="+sender,加到environ后面。
  // 信封上发送者地址
  if (!env_put2("SENDER",sender)) temp_nomem();
  //将"RPLINE"和"Return-Path:"+"SENDER"+sender+""结合后加入environ
  if (!quote2(&foo,sender)) temp_nomem();
  if (!stralloc_copys(&rpline,"Return-Path: ")) temp_nomem();
  if (!stralloc_cat(&rpline,&foo)) temp_nomem();
  for (i = 0;i rpline.len;++i) if (rpline.s[i] == '') rpline.s[i] = '_';
  if (!stralloc_cats(&rpline,"")) temp_nomem();
  
  if (!stralloc_copy(&foo,&rpline)) temp_nomem();
  if (!stralloc_0(&foo)) temp_nomem();
  //邮件头返回路径
  if (!env_put2("RPLINE",foo.s)) temp_nomem();
  //将"From"+*sender拷到ufline中。*sender为空,则将"From"+"MAILER-DAEMON"拷进去
  if (!stralloc_copys(&ufline,"From ")) temp_nomem();
  if (*sender)
   {
   int len; int i; char ch;
  
   len = str_len(sender);
   if (!stralloc_readyplus(&ufline,len)) temp_nomem();
   for (i = 0;i len;++i)
  {
   ch = sender[i];
   if ((ch == ' ') (ch == '') (ch == '')) ch = '-';
   ufline.s[ufline.len + i] = ch;
  }
   ufline.len += len;
   }
  else
   if (!stralloc_cats(&ufline,"MAILER-DAEMON")) temp_nomem();
  if (!stralloc_cats(&ufline," ")) temp_nomem();
  //在ufline后面加上现在时间。
  starttime = now();
  if (!stralloc_cats(&ufline,myctime(starttime))) temp_nomem();
  
  if (!stralloc_copy(&foo,&ufline)) temp_nomem();
  if (!stralloc_0(&foo)) temp_nomem();
  //UUCP风格的"From"行它包含消息所参与的UUCP大宗
  //路径形式的路由、最后一台接收消息的机器处理消息的时间和日期以及一
  //指明从哪台主机接收来的可选部分。由于每个处理过这个消息的系统都会生成这个字段,所
  
   //以它通常包括在信封数据下。
  if (!env_put2("UFLINE",foo.s)) temp_nomem();
  //到空行的作用是:假如ext为"aa-bb-cc-dd",则依次把"EXT=aa-bb-cc-dd","EXT2=bb-cc-dd","EXT3=cc-dd","EXT4=dd"加入
  //地址扩展
  x = ext;
  if (!env_put2("EXT",x)) temp_nomem();
  x += str_chr(x,'-'); if (*x) ++x;
  if (!env_put2("EXT2",x)) temp_nomem();
  x += str_chr(x,'-'); if (*x) ++x;
  if (!env_put2("EXT3",x)) temp_nomem();
  x += str_chr(x,'-'); if (*x) ++x;
  if (!env_put2("EXT4",x)) temp_nomem();
  
  if (!stralloc_copys(&safeext,ext)) temp_nomem();
  //将safeext中字符串转化为小写的
  case_lowerb(safeext.s,safeext.len);
  for (i = 0;i safeext.len;++i)
   if (safeext.s[i] == '.')
   safeext.s[i] = ':';
  //例如host为202.18.236.150,则"HOST2=202.18.236","HOST3=202.18","HOST4=202",加入其中
  //接收地址的域名部分
  i = str_len(host);
  i = byte_rchr(host,i,'.');
  if (!stralloc_copyb(&foo,host,i)) temp_nomem();
  if (!stralloc_0(&foo)) temp_nomem();
  if (!env_put2("HOST2",foo.s)) temp_nomem();
  i = byte_rchr(host,i,'.');
  if (!stralloc_copyb(&foo,host,i)) temp_nomem();
  if (!stralloc_0(&foo)) temp_nomem();
  if (!env_put2("HOST3",foo.s)) temp_nomem();
  i = byte_rchr(host,i,'.');
  if (!stralloc_copyb(&foo,host,i)) temp_nomem();
  if (!stralloc_0(&foo)) temp_nomem();
  if (!env_put2("HOST4",foo.s)) temp_nomem();
  
  flagforwardonly = 0;
  qmesearch(&fd,&flagforwardonly);
  if (fd == -1)/*文件没打开*/
   if (*dash)
   strerr_die1x(100,"Sorry, no mailbox here by that name. (#5.1.1)");
  
  if (!stralloc_copys(&ueo,sender)) temp_nomem();
  if (str_diff(sender,""))/*sender不空*/
   if (str_diff(sender,"#@[]"))/*sender和"#@[]"不同*/
   if (qmeox("-owner") == 0)
   {
   if (qmeox("-owner-default") == 0)
   {
   if (!stralloc_copys(&ueo,local)) temp_nomem();
   if (!stralloc_cats(&ueo,"-owner-@")) temp_nomem();
   if (!stralloc_cats(&ueo,host)) temp_nomem();
   if (!stralloc_cats(&ueo,"-@[]")) temp_nomem();
   }/*ueo为local+"-owner-@"+host+"-@[]"*/
   else
   {
   if (!stralloc_copys(&ueo,local)) temp_nomem();
   if (!stralloc_cats(&ueo,"-owner@")) temp_nomem();
   if (!stralloc_cats(&ueo,host)) temp_nomem();
   }/*ueo为local+"-owner@"+host*/
   }
  if (!stralloc_0(&ueo)) temp_nomem();
  //转发的发送人地址
  if (!env_put2("NEWSENDER",ueo.s)) temp_nomem();
  
  if (!stralloc_ready(&cmds,0)) temp_nomem();
  cmds.len = 0;
  if (fd != -1)
   if (slurpclose(fd,&cmds,256) == -1) temp_nomem();
  
  if (!cmds.len)/*假如fd文件中没有内容*/
   {
   if (!stralloc_copys(&cmds,aliasempty)) temp_nomem();
   flagforwardonly = 0;
   }
  if (!cmds.len (cmds.s[cmds.len - 1] != ''))
   if (!stralloc_cats(&cmds,"")) temp_nomem();
  
  
  numforward = 0;/*检查有几行的第一个字符不是'#','.','/',''*/
  i = 0;/*i为每行的开始位置*/
  for (j = 0;j cmds.len;++j)
   if (cmds.s[j] == '')
  {
   switch(cmds.s[i]) { case '#': case '.': case '/': case '': break;
   default: ++numforward; }
   i = j + 1;
  }
  
  recips = (char **) alloc((numforward + 1) * sizeof(char *));
  if (!recips) temp_nomem();
  numforward = 0;
  
  flag99 = 0;
  
  i = 0;
  for (j = 0;j cmds.len;++j)
   if (cmds.s[j] == '')
  {
   cmds.s[j] = 0;
   k = j;
   while ((k i) && (cmds.s[k - 1] == ' ') (cmds.s[k - 1] == ''))
   cmds.s[--k] = 0;
  //字符 传送类型 值
  // # 无 (注释)忽略
  // 程序由shell 执行的命令
  // / 或者 . mbox邮箱格式 (假如路径最后一个字符不是一个斜杠)mbox 的路径名 (包括斜杠"/"或者 点".")
  // / 或者 . maildir邮箱格式 (假如路径最后一个字符是一个反斜杠) maildir 的路径名 (包括斜杠"/"或者 点".")
  // & 转发转发邮件的地址
  // 字母或者数字 转发转发邮件的地址 (包括第一个字符)
  
   switch(cmds.s[i])
   {
   case 0: /* k == i */
  if (i) break;
   strerr_die1x(111,"Uh-oh: first line of .qmail file is blank. (#4.2.1)");
   case '#':
   break;
   case '.':
   case '/':
  ++count_file;
  if (flagforwardonly) strerr_die1x(111,"Uh-oh: .qmail has file delivery but has x bit set. (#4.7.0)");
  if (cmds.s[k - 1] == '/')
   if (flagdoit) maildir(cmds.s + i);///////////////////////////////////////////
   else sayit("maildir ",cmds.s + i,k - i);
  else
   if (flagdoit) mailfile(cmds.s + i);
   else sayit("mbox ",cmds.s + i,k - i);
   break;
   case '':
  ++count_program;
  if (flagforwardonly) strerr_die1x(111,"Uh-oh: .qmail has prog delivery but has x bit set. (#4.7.0)");
   if (flagdoit) mailprogram(cmds.s + i + 1);
   else sayit("program ",cmds.s + i + 1,k - i - 1);
   break;
   case '+':
  if (str_equal(cmds.s + i + 1,"list"))
   flagforwardonly = 1;
  break;
   case '&':
   ++i;
   default:
  ++count_forward;
   if (flagdoit) recips[numforward++] = cmds.s + i;
   else sayit("forward ",cmds.s + i,k - i);
   break;
   }
   i = j + 1;
   if (flag99) break;
  }
  //转发的地址数不为0就转发
  if (numforward) if (flagdoit)
  
  {
   recips[numforward] = 0;
   mailforward(recips);
   }
  
  count_print();
  _exit(0);
  }

来源:http://www.tulaoshi.com/n/20160219/1616814.html

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