mirror of https://gitee.com/openkylin/linux.git
111 lines
2.4 KiB
C
111 lines
2.4 KiB
C
/*
|
|
* This file is part of the Linux kernel, and is made available under
|
|
* the terms of the GNU General Public License version 2.
|
|
*
|
|
* Misc librarized functions for cmdline poking.
|
|
*/
|
|
#include <linux/kernel.h>
|
|
#include <linux/string.h>
|
|
#include <linux/ctype.h>
|
|
#include <asm/setup.h>
|
|
|
|
static inline int myisspace(u8 c)
|
|
{
|
|
return c <= ' '; /* Close enough approximation */
|
|
}
|
|
|
|
/**
|
|
* Find a boolean option (like quiet,noapic,nosmp....)
|
|
*
|
|
* @cmdline: the cmdline string
|
|
* @option: option string to look for
|
|
*
|
|
* Returns the position of that @option (starts counting with 1)
|
|
* or 0 on not found. @option will only be found if it is found
|
|
* as an entire word in @cmdline. For instance, if @option="car"
|
|
* then a cmdline which contains "cart" will not match.
|
|
*/
|
|
static int
|
|
__cmdline_find_option_bool(const char *cmdline, int max_cmdline_size,
|
|
const char *option)
|
|
{
|
|
char c;
|
|
int pos = 0, wstart = 0;
|
|
const char *opptr = NULL;
|
|
enum {
|
|
st_wordstart = 0, /* Start of word/after whitespace */
|
|
st_wordcmp, /* Comparing this word */
|
|
st_wordskip, /* Miscompare, skip */
|
|
} state = st_wordstart;
|
|
|
|
if (!cmdline)
|
|
return -1; /* No command line */
|
|
|
|
/*
|
|
* This 'pos' check ensures we do not overrun
|
|
* a non-NULL-terminated 'cmdline'
|
|
*/
|
|
while (pos < max_cmdline_size) {
|
|
c = *(char *)cmdline++;
|
|
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) {
|
|
/*
|
|
* We matched all the way to the end of the
|
|
* option we were looking for. If the
|
|
* command-line has a space _or_ ends, then
|
|
* we matched!
|
|
*/
|
|
if (!c || myisspace(c))
|
|
return wstart;
|
|
/*
|
|
* We hit the end of the option, but _not_
|
|
* the end of a word on the cmdline. Not
|
|
* a match.
|
|
*/
|
|
} else if (!c) {
|
|
/*
|
|
* Hit the NULL terminator on the end of
|
|
* cmdline.
|
|
*/
|
|
return 0;
|
|
} else if (c == *opptr++) {
|
|
/*
|
|
* We are currently matching, so continue
|
|
* to the next character on the cmdline.
|
|
*/
|
|
break;
|
|
}
|
|
state = st_wordskip;
|
|
/* fall through */
|
|
|
|
case st_wordskip:
|
|
if (!c)
|
|
return 0;
|
|
else if (myisspace(c))
|
|
state = st_wordstart;
|
|
break;
|
|
}
|
|
}
|
|
|
|
return 0; /* Buffer overrun */
|
|
}
|
|
|
|
int cmdline_find_option_bool(const char *cmdline, const char *option)
|
|
{
|
|
return __cmdline_find_option_bool(cmdline, COMMAND_LINE_SIZE, option);
|
|
}
|