This is going to be used in the 9PFS code, but could be retrofitted to
other file systems as well in future.
Signed-off-by: Ahmad Fatoum <a.fat...@barebox.org>
---
include/linux/parser.h | 42 +++++
lib/Makefile | 1 +
lib/parser.c | 363 +++++++++++++++++++++++++++++++++++++++++
3 files changed, 406 insertions(+)
create mode 100644 include/linux/parser.h
create mode 100644 lib/parser.c
diff --git a/include/linux/parser.h b/include/linux/parser.h
new file mode 100644
index 000000000000..3c3185ddbad6
--- /dev/null
+++ b/include/linux/parser.h
@@ -0,0 +1,42 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * 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.
+ */
+#ifndef _LINUX_PARSER_H
+#define _LINUX_PARSER_H
+
+#include <linux/types.h>
+
+/* associates an integer enumerator with a pattern string. */
+struct match_token {
+ int token;
+ const char *pattern;
+};
+
+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 *, const match_table_t table, substring_t args[]);
+int match_int(substring_t *, int *result);
+int match_uint(substring_t *s, unsigned int *result);
+int match_u64(substring_t *, u64 *result);
+int match_octal(substring_t *, int *result);
+int match_hex(substring_t *, int *result);
+bool match_wildcard(const char *pattern, const char *str);
+size_t match_strlcpy(char *, const substring_t *, size_t);
+char *match_strdup(const substring_t *);
+
+#endif /* _LINUX_PARSER_H */
diff --git a/lib/Makefile b/lib/Makefile
index a1ca2803a095..468383508f17 100644
--- a/lib/Makefile
+++ b/lib/Makefile
@@ -32,6 +32,7 @@ obj-y += recursive_action.o
obj-y += make_directory.o
obj-y += arith.o
obj-$(CONFIG_IDR) += idr.o
+obj-y += parser.o
obj-y += iov_iter.o
obj-y += math/
obj-y += uuid.o
diff --git a/lib/parser.c b/lib/parser.c
new file mode 100644
index 000000000000..83c49352667c
--- /dev/null
+++ b/lib/parser.c
@@ -0,0 +1,363 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * lib/parser.c - simple parser for mount, etc. options.
+ */
+
+#include <linux/ctype.h>
+#include <linux/types.h>
+#include <linux/export.h>
+#include <linux/kstrtox.h>
+#include <linux/parser.h>
+#include <linux/slab.h>
+#include <linux/string.h>
+
+/*
+ * max size needed by different bases to express U64
+ * HEX: "0xFFFFFFFFFFFFFFFF" --> 18
+ * DEC: "18446744073709551615" --> 20
+ * OCT: "01777777777777777777777" --> 23
+ * pick the max one to define NUMBER_BUF_LEN
+ */
+#define NUMBER_BUF_LEN 24
+
+/**
+ * match_one - Determines if a string matches a simple pattern
+ * @s: the string to examine for presence 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, const char *p, substring_t args[])
+{
+ const char *meta;
+ int argc = 0;
+
+ if (!p)
+ return 1;
+
+ while(1) {
+ int len = -1;
+ meta = strchr(p, '%');
+ if (!meta)
+ return strcmp(p, s) == 0;
+
+ if (strncmp(p, s, meta-p))
+ return 0;
+
+ s += meta - p;
+ p = meta + 1;
+
+ if (isdigit(*p))
+ len = simple_strtoul(p, (char **) &p, 10);
+ else if (*p == '%') {
+ if (*s++ != '%')
+ return 0;
+ p++;
+ continue;
+ }
+
+ if (argc >= MAX_OPT_ARGS)
+ return 0;
+
+ args[argc].from = s;
+ switch (*p++) {
+ case 's': {
+ size_t str_len = strlen(s);
+
+ if (str_len == 0)
+ return 0;
+ if (len == -1 || len > str_len)
+ len = str_len;
+ args[argc].to = s + len;
+ break;
+ }
+ case 'd':
+ simple_strtol(s, &args[argc].to, 0);
+ goto num;
+ case 'u':
+ simple_strtoul(s, &args[argc].to, 0);
+ goto num;
+ case 'o':
+ simple_strtoul(s, &args[argc].to, 8);
+ goto num;
+ case 'x':
+ simple_strtoul(s, &args[argc].to, 16);
+ num:
+ if (args[argc].to == args[argc].from)
+ return 0;
+ break;
+ default:
+ return 0;
+ }
+ s = args[argc].to;
+ argc++;
+ }
+}
+
+/**
+ * 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 whose 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 whose locations will be returned in the @args array.
+ */
+int match_token(char *s, const match_table_t table, substring_t args[])
+{
+ const struct match_token *p;
+
+ for (p = table; !match_one(s, p->pattern, args) ; p++)
+ ;
+
+ return p->token;
+}
+EXPORT_SYMBOL(match_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.
+ *
+ * Return: On success, sets @result to the integer represented by the
+ * string and returns 0. Returns -EINVAL or -ERANGE on failure.
+ */
+static int match_number(substring_t *s, int *result, int base)
+{
+ char *endp;
+ char buf[NUMBER_BUF_LEN];
+ int ret;
+ long val;
+
+ if (match_strlcpy(buf, s, NUMBER_BUF_LEN) >= NUMBER_BUF_LEN)
+ return -ERANGE;
+ ret = 0;
+ val = simple_strtol(buf, &endp, base);
+ if (endp == buf)
+ ret = -EINVAL;
+ else if (val < (long)INT_MIN || val > (long)INT_MAX)
+ ret = -ERANGE;
+ else
+ *result = (int) val;
+ return ret;
+}
+
+/**
+ * match_u64int - scan a number in the given base from a substring_t
+ * @s: substring to be scanned
+ * @result: resulting u64 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.
+ *
+ * Return: On success, sets @result to the integer represented by the
+ * string and returns 0. Returns -EINVAL or -ERANGE on failure.
+ */
+static int match_u64int(substring_t *s, u64 *result, int base)
+{
+ char buf[NUMBER_BUF_LEN];
+ int ret;
+ u64 val;
+
+ if (match_strlcpy(buf, s, NUMBER_BUF_LEN) >= NUMBER_BUF_LEN)
+ return -ERANGE;
+ ret = kstrtoull(buf, base, &val);
+ if (!ret)
+ *result = val;
+ 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.
+ *
+ * Return: On success, sets @result to the integer represented by the string
+ * and returns 0. Returns -EINVAL or -ERANGE on failure.
+ */
+int match_int(substring_t *s, int *result)
+{
+ return match_number(s, result, 0);
+}
+EXPORT_SYMBOL(match_int);
+
+/**
+ * match_uint - 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.
+ *
+ * Return: On success, sets @result to the integer represented by the string
+ * and returns 0. Returns -EINVAL or -ERANGE on failure.
+ */
+int match_uint(substring_t *s, unsigned int *result)
+{
+ char buf[NUMBER_BUF_LEN];
+
+ if (match_strlcpy(buf, s, NUMBER_BUF_LEN) >= NUMBER_BUF_LEN)
+ return -ERANGE;
+
+ return kstrtouint(buf, 10, result);
+}
+EXPORT_SYMBOL(match_uint);
+
+/**
+ * match_u64 - scan a decimal representation of a u64 from
+ * a substring_t
+ * @s: substring_t to be scanned
+ * @result: resulting unsigned long long on success
+ *
+ * Description: Attempts to parse the &substring_t @s as a long decimal
+ * integer.
+ *
+ * Return: On success, sets @result to the integer represented by the string
+ * and returns 0. Returns -EINVAL or -ERANGE on failure.
+ */
+int match_u64(substring_t *s, u64 *result)
+{
+ return match_u64int(s, result, 0);
+}
+EXPORT_SYMBOL(match_u64);
+
+/**
+ * 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.
+ *
+ * Return: On success, sets @result to the integer represented by the string
+ * and returns 0. Returns -EINVAL or -ERANGE on failure.
+ */
+int match_octal(substring_t *s, int *result)
+{
+ return match_number(s, result, 8);
+}
+EXPORT_SYMBOL(match_octal);
+
+/**
+ * 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.
+ *
+ * Return: On success, sets @result to the integer represented by the string
+ * and returns 0. Returns -EINVAL or -ERANGE on failure.
+ */
+int match_hex(substring_t *s, int *result)
+{
+ return match_number(s, result, 16);
+}
+EXPORT_SYMBOL(match_hex);
+
+/**
+ * match_wildcard - parse if a string matches given wildcard pattern
+ * @pattern: wildcard pattern
+ * @str: the string to be parsed
+ *
+ * Description: Parse the string @str to check if matches wildcard
+ * pattern @pattern. The pattern may contain two types of wildcards:
+ * '*' - matches zero or more characters
+ * '?' - matches one character
+ *
+ * Return: If the @str matches the @pattern, return true, else return false.
+ */
+bool match_wildcard(const char *pattern, const char *str)
+{
+ const char *s = str;
+ const char *p = pattern;
+ bool star = false;
+
+ while (*s) {
+ switch (*p) {
+ case '?':
+ s++;
+ p++;
+ break;
+ case '*':
+ star = true;
+ str = s;
+ if (!*++p)
+ return true;
+ pattern = p;
+ break;
+ default:
+ if (*s == *p) {
+ s++;
+ p++;
+ } else {
+ if (!star)
+ return false;
+ str++;
+ s = str;
+ p = pattern;
+ }
+ break;
+ }
+ }
+
+ if (*p == '*')
+ ++p;
+ return !*p;
+}
+EXPORT_SYMBOL(match_wildcard);
+
+/**
+ * match_strlcpy - Copy the characters from a substring_t to a sized buffer
+ * @dest: where to copy to
+ * @src: &substring_t to copy
+ * @size: size of destination buffer
+ *
+ * Description: Copy the characters in &substring_t @src to the
+ * c-style string @dest. Copy no more than @size - 1 characters, plus
+ * the terminating NUL.
+ *
+ * Return: length of @src.
+ */
+size_t match_strlcpy(char *dest, const substring_t *src, size_t size)
+{
+ size_t ret = src->to - src->from;
+
+ if (size) {
+ size_t len = ret >= size ? size - 1 : ret;
+ memcpy(dest, src->from, len);
+ dest[len] = '\0';
+ }
+ return ret;
+}
+EXPORT_SYMBOL(match_strlcpy);
+
+/**
+ * match_strdup - allocate a new string with the contents of a substring_t
+ * @s: &substring_t to copy
+ *
+ * Description: Allocates and returns a string filled with the contents of
+ * the &substring_t @s. The caller is responsible for freeing the returned
+ * string with kfree().
+ *
+ * Return: the address of the newly allocated NUL-terminated string or
+ * %NULL on error.
+ */
+char *match_strdup(const substring_t *s)
+{
+ return memdup_nul(s->from, s->to - s->from);
+}
+EXPORT_SYMBOL(match_strdup);
--
2.39.5
