linux/arch/x86/lib/cmdline.c

// SPDX-License-Identifier: GPL-2.0-only
/*
 *
 * Misc librarized functions for cmdline poking.
 */
#include <linux/kernel.h>
#include <linux/string.h>
#include <linux/ctype.h>

#include <asm/setup.h>
#include <asm/cmdline.h>
#include <asm/bug.h>

static inline int myisspace(u8 c)
{ … }

/*
 * Find a boolean option (like quiet,noapic,nosmp....)
 *
 * @cmdline: the cmdline string
 * @max_cmdline_size: the maximum size of cmdline
 * @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)
{ … }

/*
 * Find a non-boolean option (i.e. option=argument). In accordance with
 * standard Linux practice, if this option is repeated, this returns the
 * last instance on the command line.
 *
 * @cmdline: the cmdline string
 * @max_cmdline_size: the maximum size of cmdline
 * @option: option string to look for
 * @buffer: memory buffer to return the option argument
 * @bufsize: size of the supplied memory buffer
 *
 * Returns the length of the argument (regardless of if it was
 * truncated to fit in the buffer), or -1 on not found.
 */
static int
__cmdline_find_option(const char *cmdline, int max_cmdline_size,
		      const char *option, char *buffer, int bufsize)
{ … }

int cmdline_find_option_bool(const char *cmdline, const char *option)
{ … }

int cmdline_find_option(const char *cmdline, const char *option, char *buffer,
			int bufsize)
{ … }