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author | H. Peter Anvin <hpa@zytor.com> | 2007-07-11 19:18:44 (GMT) |
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committer | Linus Torvalds <torvalds@woody.linux-foundation.org> | 2007-07-12 17:55:55 (GMT) |
commit | e44c22f65f96217692e1a915032fbe7d22236751 (patch) | |
tree | 976498a1a75a88c999f604a6988b7a2ab5e5518f /arch/i386 | |
parent | 49df18fa3f95a5c988b64e4e20e15372282e96ea (diff) | |
download | linux-fsl-qoriq-e44c22f65f96217692e1a915032fbe7d22236751.tar.xz |
Command-line parsing code for the new x86 setup code
Simple command-line parser which allows us to access the kernel command
line from the setup code.
Signed-off-by: H. Peter Anvin <hpa@zytor.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'arch/i386')
-rw-r--r-- | arch/i386/boot/cmdline.c | 97 |
1 files changed, 97 insertions, 0 deletions
diff --git a/arch/i386/boot/cmdline.c b/arch/i386/boot/cmdline.c new file mode 100644 index 0000000..34bb778 --- /dev/null +++ b/arch/i386/boot/cmdline.c @@ -0,0 +1,97 @@ +/* -*- 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. + * + * ----------------------------------------------------------------------- */ + +/* + * arch/i386/boot/cmdline.c + * + * 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(const char *option, char *buffer, int bufsize) +{ + u32 cmdline_ptr = boot_params.hdr.cmd_line_ptr; + 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 || cmdline_ptr >= 0x100000) + return -1; /* No command line, or inaccessible */ + + 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; +} |