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
[code:1:c552cb0758]#include
#include
#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,%26amp;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(%26amp;ss,read,0,buf,sizeof(buf));
substdio_fdbuf(%26amp;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(%26amp;ssout,rpline.s,rpline.len) == -1) goto fail;
if (substdio_put(%26amp;ssout,dtline.s,dtline.len) == -1) goto fail;
//将邮件写到文件fd中
switch(substdio_copy(%26amp;ssout,%26amp;ss))
{
case -2: tryunlinktmp(); _exit(4);
case -3: goto fail;
}
if (substdio_flush(%26amp;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(%26amp;wstat,child);
//#define wait_crashed(w) ((w) %26amp; 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)");
}
}
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