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Subject[PATCH] Add lib/parser.c kernel-doc
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Date
When I converted befs's option parsing to use the new lib/parser.c
functions, I had to read the functions (and the patch converting ext3)
in order to understand exactly how to use them. They are not that
complicated, but since I'd already read and (hopefully) understood the
functions, I figured I'd add a bit of documentation for others.

I am not the author of the functions I am attempting to document here,
so any mistakes are just that: mistakes on my part.

# This is a BitKeeper generated patch for the following project:
# Project Name: Linux kernel tree
# This patch format is intended for GNU patch command version 2.5 or
higher.
# This patch includes the following deltas:
# ChangeSet 1.1352 -> 1.1353
# lib/parser.c 1.2 -> 1.3
# include/linux/parser.h 1.1 -> 1.2
#
# The following is the BitKeeper ChangeSet Log
# --------------------------------------------
# 03/11/16 will@thalience.(none) 1.1353
# Add documentation and comments to lib/parser.c and
include/linux/parser.h
# --------------------------------------------
#
diff -Nru a/include/linux/parser.h b/include/linux/parser.h
--- a/include/linux/parser.h Sun Nov 16 03:02:39 2003
+++ b/include/linux/parser.h Sun Nov 16 03:02:39 2003
@@ -1,3 +1,14 @@
+/*
+ * linux/include/linux/parser.h
+ *
+ * Header for lib/parser.c
+ * Intended use of these functions is parsing filesystem argument
lists,
+ * but could potentially be used anywhere else that simple option=arg
+ * parsing is required.
+ */
+
+
+// associates an integer enumerator with a pattern string.
struct match_token {
int token;
char *pattern;
@@ -5,17 +16,18 @@

typedef struct match_token match_table_t[];

+// Maximum number of arguments that match_token will find in a pattern
enum {MAX_OPT_ARGS = 3};

+// Describe the location within a string of a substring
typedef struct {
char *from;
char *to;
} substring_t;

int match_token(char *s, match_table_t table, substring_t args[]);
-
-int match_int(substring_t *, int *result);
-int match_octal(substring_t *, int *result);
-int match_hex(substring_t *, int *result);
-void match_strcpy(char *, substring_t *);
-char *match_strdup(substring_t *);
+int match_int(substring_t *s, int *result);
+int match_octal(substring_t *s, int *result);
+int match_hex(substring_t *s, int *result);
+void match_strcpy(char *to, substring_t *s);
+char *match_strdup(substring_t *s);
diff -Nru a/lib/parser.c b/lib/parser.c
--- a/lib/parser.c Sun Nov 16 03:02:39 2003
+++ b/lib/parser.c Sun Nov 16 03:02:39 2003
@@ -11,6 +11,17 @@
#include <linux/slab.h>
#include <linux/string.h>

+/**
+ * match_one: - Determines if a string matches a simple pattern
+ * @s: the string to examine for presense of the pattern
+ * @p: the string containing the pattern
+ * @args: array of %MAX_OPT_ARGS &substring_t elements. Used to return
match
+ * locations.
+ *
+ * Description: Determines if the pattern @p is present in string @s.
Can only
+ * match extremely simple token=arg style patterns. If the pattern is
found,
+ * the location(s) of the arguments will be returned in the @args
array.
+ */
static int match_one(char *s, char *p, substring_t args[])
{
char *meta;
@@ -74,6 +85,20 @@
}
}

+/**
+ * match_token: - Find a token (and optional args) in a string
+ * @s: the string to examine for token/argument pairs
+ * @table: match_table_t describing the set of allowed option tokens
and the
+ * arguments that may be associated with them. Must be terminated with
a
+ * &struct match_token who's pattern is set to the NULL pointer.
+ * @args: array of %MAX_OPT_ARGS &substring_t elements. Used to return
match
+ * locations.
+ *
+ * Description: Detects which if any of a set of token strings has been
passed
+ * to it. Tokens can include up to MAX_OPT_ARGS instances of basic
c-style
+ * format identifiers which will be taken into account when matching
the
+ * tokens, and who's locations will be returned in the @args array.
+ */
int match_token(char *s, match_table_t table, substring_t args[])
{
struct match_token *p;
@@ -84,6 +109,16 @@
return p->token;
}

+/**
+ * match_number: scan a number in the given base from a substring_t
+ * @s: substring to be scanned
+ * @result: resulting integer on success
+ * @base: base to use when converting string
+ *
+ * Description: Given a &substring_t and a base, attempts to parse the
substring
+ * as a number in that base. On success, sets @result to the integer
represented
+ * by the string and returns 0. Returns either -ENOMEM or -EINVAL on
failure.
+ */
static int match_number(substring_t *s, int *result, int base)
{
char *endp;
@@ -103,27 +138,71 @@
return ret;
}

+/**
+ * match_int: - scan a decimal representation of an integer from a
substring_t
+ * @s: substring_t to be scanned
+ * @result: resulting integer on success
+ *
+ * Description: Attempts to parse the &substring_t @s as a decimal
integer. On
+ * success, sets @result to the integer represented by the string and
returns 0.
+ * Returns either -ENOMEM or -EINVAL on failure.
+ */
int match_int(substring_t *s, int *result)
{
return match_number(s, result, 0);
}

+/**
+ * match_octal: - scan an octal representation of an integer from a
substring_t
+ * @s: substring_t to be scanned
+ * @result: resulting integer on success
+ *
+ * Description: Attempts to parse the &substring_t @s as an octal
integer. On
+ * success, sets @result to the integer represented by the string and
returns
+ * 0. Returns either -ENOMEM or -EINVAL on failure.
+ */
int match_octal(substring_t *s, int *result)
{
return match_number(s, result, 8);
}

+/**
+ * match_hex: - scan a hex representation of an integer from a
substring_t
+ * @s: substring_t to be scanned
+ * @result: resulting integer on success
+ *
+ * Description: Attempts to parse the &substring_t @s as a hexadecimal
integer.
+ * On success, sets @result to the integer represented by the string
and
+ * returns 0. Returns either -ENOMEM or -EINVAL on failure.
+ */
int match_hex(substring_t *s, int *result)
{
return match_number(s, result, 16);
}

+/**
+ * match_strcpy: - copies the characters from a substring_t to a
c-string
+ * @to: c-string to copy characters to.
+ * @s: &substring_t to copy
+ *
+ * Description: Copies the set of characters represented by the given
+ * &substring_t @s to the c-style string @to. Caller guarantees that
@to is
+ * large enough to hold the characters of @s.
+ */
void match_strcpy(char *to, substring_t *s)
{
memcpy(to, s->from, s->to - s->from);
to[s->to - s->from] = '\0';
}

+/**
+ * match_strdup: - allocate a new c-string with the contents of a
substring_t
+ * @s: &substring_t to copy
+ *
+ * Description: Allocates and returns a c-string filled with the
contents of
+ * the &substring_t @s. The caller is responsible for freeing the
returned
+ * string with kfree().
+ */
char *match_strdup(substring_t *s)
{
char *p = kmalloc(s->to - s->from + 1, GFP_KERNEL);

--
Will Dyson
"Back off man, I'm a scientist!" -Dr. Peter Venkman

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