From: H. Peter Anvin <[EMAIL PROTECTED]>
Simple command-line parser which allows us to access the kernel command
line from the setup code.
Signed-off-by: H. Peter Anvin <[EMAIL PROTECTED]>
---
arch/i386/boot/cmdline.c | 97 ++++++++++++++++++++++++++++++++++++++++++++++
1 files changed, 97 insertions(+), 0 deletions(-)
create mode 100644 arch/i386/boot/cmdline.c
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;
+}
--
1.5.2.2
-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to [EMAIL PROTECTED]
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/
