2 * This file is part of the Linux kernel, and is made available under
3 * the terms of the GNU General Public License version 2.
5 * Misc librarized functions for cmdline poking.
7 #include <linux/kernel.h>
8 #include <linux/string.h>
9 #include <linux/ctype.h>
10 #include <asm/setup.h>
12 static inline int myisspace(u8 c)
14 return c <= ' '; /* Close enough approximation */
18 * Find a boolean option (like quiet,noapic,nosmp....)
20 * @cmdline: the cmdline string
21 * @option: option string to look for
23 * Returns the position of that @option (starts counting with 1)
24 * or 0 on not found. @option will only be found if it is found
25 * as an entire word in @cmdline. For instance, if @option="car"
26 * then a cmdline which contains "cart" will not match.
28 int cmdline_find_option_bool(const char *cmdline, const char *option)
31 int pos = 0, wstart = 0;
32 const char *opptr = NULL;
34 st_wordstart = 0, /* Start of word/after whitespace */
35 st_wordcmp, /* Comparing this word */
36 st_wordskip, /* Miscompare, skip */
37 } state = st_wordstart;
40 return -1; /* No command line */
46 * This 'pos' check ensures we do not overrun
47 * a non-NULL-terminated 'cmdline'
49 while (pos < COMMAND_LINE_SIZE) {
50 c = *(char *)cmdline++;
57 else if (myisspace(c))
68 * We matched all the way to the end of the
69 * option we were looking for. If the
70 * command-line has a space _or_ ends, then
73 if (!c || myisspace(c))
76 * We hit the end of the option, but _not_
77 * the end of a word on the cmdline. Not
82 * Hit the NULL terminator on the end of
86 } else if (c == *opptr++) {
88 * We are currently matching, so continue
89 * to the next character on the cmdline.
99 else if (myisspace(c))
100 state = st_wordstart;
105 return 0; /* Buffer overrun */