在FreeBSD内核模块中读取文本文件的例子 [英] Examples for reading text files in FreeBSD kernel module

问题描述

任何人都可以给一些简单的例子（函数名称是好的）在一个FreeBSD内核模块中从一个给定的目录逐行读取文本文件（二进制文件确实是好的）？

真的很感谢你的帮助。

解决方案

etc / motd on load：

  //内核模块motd catter。 
 // Doug Luce [e-mail] 
 
 #include< sys / param.h> 
 #include< sys / vnode.h> 
 #include< sys / fcntl.h> 
 #include< sys / module.h> 
 #include< sys / kernel.h> 
 #include< sys / namei.h> 
 #include< sys / proc.h> 
 #include< sys / sbuf.h> 
 
 static int catfile（const char * filename）{
 struct sbuf * sb; 
 static char buf [128]; 
 struct nameidata nd; 
 off_t ofs; 
 ssize_t resid; 
 int错误，flags，len; 
 
 NDINIT（& nd，LOOKUP，FOLLOW，UIO_SYSSPACE，filename，curthread）; 
标志= FREAD; 
 error = vn_open（& nd，& flags，0，NULL）; 
 if（error）
 return（error）; 
 
 NDFREE（& nd，NDF_ONLY_PNBUF）; 
 
 ofs = 0; 
 len = sizeof（buf） -  1; 
 sb = sbuf_new_auto（）; 
 while（1）{
 error = vn_rdwr（UIO_READ，nd.ni_vp，buf，len，ofs，
 UIO_SYSSPACE，IO_NODELOCKED，curthread-> td_ucred，
 NOCRED，& ; resid，curthread）; 
 if（error）
 break; 
 if（resid == len）
 break; 
 buf [len  -  resid] = 0; 
 sbuf_printf（sb，％s，buf）; 
 ofs + = len  -  resid; 
} 
 
 VOP_UNLOCK（nd.ni_vp，0）; 
 vn_close（nd.ni_vp，FREAD，curthread-> td_ucred，curthread）; 
 uprintf（％s，sbuf_data（sb））; 
返回0; 
 
 $ b静态int EventHandler（struct module inModule，int inEvent，void * inArg）{
 switch（inEvent）{
 case MOD_LOAD：
 uprintf（MOTD module loading.\
）; 
 if（catfile（/ etc / motd）！= 0）
 uprintf（Error read MOTD.\\\
）; 
返回0; 
 case MOD_UNLOAD：
 uprintf（MOTD module unloading.\\\
）; 
返回0; 
默认值：
返回EOPNOTSUPP; 
 
 
 
 static moduledata_t moduleData = {
motd_kmod，
 EventHandler，
 NULL 
}; 
 
 DECLARE_MODULE（motd_kmod，moduleData，SI_SUB_DRIVERS，SI_ORDER_MIDDLE）; 
  

主要来自 https://svnweb.freebsd.org/base/release/10.1.0/ sys / kern / vfs_mountroot.c？revision = 274417& view = markup

没有很好的扫描/解析工具，原生的内核端，所以
通常很困难。

Could anyone give some simple examples (function names are good) for reading text files line by line (binary is OK if text is really hard) in a FreeBSD kernel module, from a given directory?

Really appreciate your kind help.

解决方案

Here's a sample kernel module that'll cat your /etc/motd on load:

// kernel module motd catter.
// Doug Luce [e-mail]

#include <sys/param.h>
#include <sys/vnode.h>
#include <sys/fcntl.h>
#include <sys/module.h>
#include <sys/kernel.h>
#include <sys/namei.h>
#include <sys/proc.h>
#include <sys/sbuf.h>

static int catfile(const char *filename) {
  struct sbuf *sb;
  static char buf[128];
  struct nameidata nd;
  off_t ofs;
  ssize_t resid;
  int error, flags, len;

  NDINIT(&nd, LOOKUP, FOLLOW, UIO_SYSSPACE, filename, curthread);
  flags = FREAD;
  error = vn_open(&nd, &flags, 0, NULL);
  if (error)
    return (error);

  NDFREE(&nd, NDF_ONLY_PNBUF);

  ofs = 0;
  len = sizeof(buf) - 1;
  sb = sbuf_new_auto();
  while (1) {
    error = vn_rdwr(UIO_READ, nd.ni_vp, buf, len, ofs,
                    UIO_SYSSPACE, IO_NODELOCKED, curthread->td_ucred,
                    NOCRED, &resid, curthread);
    if (error)
      break;
    if (resid == len)
      break;
    buf[len - resid] = 0;
    sbuf_printf(sb, "%s", buf);
    ofs += len - resid;
  }

  VOP_UNLOCK(nd.ni_vp, 0);
  vn_close(nd.ni_vp, FREAD, curthread->td_ucred, curthread);
  uprintf("%s", sbuf_data(sb));
  return 0;
}

static int EventHandler(struct module *inModule, int inEvent, void *inArg) {
  switch (inEvent) {
  case MOD_LOAD:
    uprintf("MOTD module loading.\n");
    if (catfile("/etc/motd") != 0)
      uprintf("Error reading MOTD.\n");
    return 0;
  case MOD_UNLOAD:
    uprintf("MOTD module unloading.\n");
    return 0;
  default:
    return EOPNOTSUPP;
  }
}

static moduledata_t  moduleData = {
  "motd_kmod",
  EventHandler,
  NULL
};

DECLARE_MODULE(motd_kmod, moduleData, SI_SUB_DRIVERS, SI_ORDER_MIDDLE);

This was cobbled together mostly from bits of https://svnweb.freebsd.org/base/release/10.1.0/sys/kern/vfs_mountroot.c?revision=274417&view=markup

There's no nice scanning/parsing facilities native kernel-side, so that's usually done the hard way.

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