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kernel/linux-imx6_3.14.28/arch/x86/boot/cmdline.c 3.22 KB
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  /* -*- linux-c -*- ------------------------------------------------------- *
   *
   *   Copyright (C) 1991, 1992 Linus Torvalds
   *   Copyright 2007 rPath, Inc. - All Rights Reserved
   *
   *   This file is part of the Linux kernel, and is made available under
   *   the terms of the GNU General Public License version 2.
   *
   * ----------------------------------------------------------------------- */
  
  /*
   * Simple command-line parser for early boot.
   */
  
  #include "boot.h"
  
  static inline int myisspace(u8 c)
  {
  	return c <= ' ';	/* Close enough approximation */
  }
  
  /*
   * Find a non-boolean option, that is, "option=argument".  In accordance
   * with standard Linux practice, if this option is repeated, this returns
   * the last instance on the command line.
   *
   * Returns the length of the argument (regardless of if it was
   * truncated to fit in the buffer), or -1 on not found.
   */
  int __cmdline_find_option(unsigned long cmdline_ptr, const char *option, char *buffer, int bufsize)
  {
  	addr_t cptr;
  	char c;
  	int len = -1;
  	const char *opptr = NULL;
  	char *bufptr = buffer;
  	enum {
  		st_wordstart,	/* Start of word/after whitespace */
  		st_wordcmp,	/* Comparing this word */
  		st_wordskip,	/* Miscompare, skip */
  		st_bufcpy	/* Copying this to buffer */
  	} state = st_wordstart;
  
  	if (!cmdline_ptr)
  		return -1;      /* No command line */
  
  	cptr = cmdline_ptr & 0xf;
  	set_fs(cmdline_ptr >> 4);
  
  	while (cptr < 0x10000 && (c = rdfs8(cptr++))) {
  		switch (state) {
  		case st_wordstart:
  			if (myisspace(c))
  				break;
  
  			/* else */
  			state = st_wordcmp;
  			opptr = option;
  			/* fall through */
  
  		case st_wordcmp:
  			if (c == '=' && !*opptr) {
  				len = 0;
  				bufptr = buffer;
  				state = st_bufcpy;
  			} else if (myisspace(c)) {
  				state = st_wordstart;
  			} else if (c != *opptr++) {
  				state = st_wordskip;
  			}
  			break;
  
  		case st_wordskip:
  			if (myisspace(c))
  				state = st_wordstart;
  			break;
  
  		case st_bufcpy:
  			if (myisspace(c)) {
  				state = st_wordstart;
  			} else {
  				if (len < bufsize-1)
  					*bufptr++ = c;
  				len++;
  			}
  			break;
  		}
  	}
  
  	if (bufsize)
  		*bufptr = '\0';
  
  	return len;
  }
  
  /*
   * Find a boolean option (like quiet,noapic,nosmp....)
   *
   * Returns the position of that option (starts counting with 1)
   * or 0 on not found
   */
  int __cmdline_find_option_bool(unsigned long cmdline_ptr, const char *option)
  {
  	addr_t cptr;
  	char c;
  	int pos = 0, wstart = 0;
  	const char *opptr = NULL;
  	enum {
  		st_wordstart,	/* Start of word/after whitespace */
  		st_wordcmp,	/* Comparing this word */
  		st_wordskip,	/* Miscompare, skip */
  	} state = st_wordstart;
  
  	if (!cmdline_ptr)
  		return -1;      /* No command line */
  
  	cptr = cmdline_ptr & 0xf;
  	set_fs(cmdline_ptr >> 4);
  
  	while (cptr < 0x10000) {
  		c = rdfs8(cptr++);
  		pos++;
  
  		switch (state) {
  		case st_wordstart:
  			if (!c)
  				return 0;
  			else if (myisspace(c))
  				break;
  
  			state = st_wordcmp;
  			opptr = option;
  			wstart = pos;
  			/* fall through */
  
  		case st_wordcmp:
  			if (!*opptr)
  				if (!c || myisspace(c))
  					return wstart;
  				else
  					state = st_wordskip;
  			else if (!c)
  				return 0;
  			else if (c != *opptr++)
  				state = st_wordskip;
  			break;
  
  		case st_wordskip:
  			if (!c)
  				return 0;
  			else if (myisspace(c))
  				state = st_wordstart;
  			break;
  		}
  	}
  
  	return 0;	/* Buffer overrun */
  }