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