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From:   Lukas Czerner <lczerner@redhat.com>
To:     linux-ext4@vger.kernel.org
Cc:     dhowells@redhat.com, viro@zeniv.linux.org.uk
Subject: [PATCH v2 01/17] fs_parse: allow parameter value to be empty
Date:   Tue, 28 Apr 2020 18:45:20 +0200
Message-Id: <20200428164536.462-2-lczerner@redhat.com>
In-Reply-To: <20200428164536.462-1-lczerner@redhat.com>
References: <20200428164536.462-1-lczerner@redhat.com>
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Allow parameter value to be empty by spcifying fs_param_can_be_empty
flag.

Signed-off-by: Lukas Czerner <lczerner@redhat.com>
---
 fs/fs_parser.c            | 31 +++++++++++++++++++++++--------
 include/linux/fs_parser.h |  2 +-
 2 files changed, 24 insertions(+), 9 deletions(-)

diff --git a/fs/fs_parser.c b/fs/fs_parser.c
index ab53e42a874a..0d44801919f9 100644
--- a/fs/fs_parser.c
+++ b/fs/fs_parser.c
@@ -200,6 +200,8 @@ int fs_param_is_bool(struct p_log *log, const struct =
fs_parameter_spec *p,
 	int b;
 	if (param->type !=3D fs_value_is_string)
 		return fs_param_bad_value(log, param);
+	if (!*param->string && (p->flags & fs_param_can_be_empty))
+		return 0;
 	b =3D lookup_constant(bool_names, param->string, -1);
 	if (b =3D=3D -1)
 		return fs_param_bad_value(log, param);
@@ -212,8 +214,11 @@ int fs_param_is_u32(struct p_log *log, const struct =
fs_parameter_spec *p,
 		    struct fs_parameter *param, struct fs_parse_result *result)
 {
 	int base =3D (unsigned long)p->data;
-	if (param->type !=3D fs_value_is_string ||
-	    kstrtouint(param->string, base, &result->uint_32) < 0)
+	if (param->type !=3D fs_value_is_string)
+		return fs_param_bad_value(log, param);
+	if (!*param->string && (p->flags & fs_param_can_be_empty))
+		return 0;
+	if (kstrtouint(param->string, base, &result->uint_32) < 0)
 		return fs_param_bad_value(log, param);
 	return 0;
 }
@@ -222,8 +227,11 @@ EXPORT_SYMBOL(fs_param_is_u32);
 int fs_param_is_s32(struct p_log *log, const struct fs_parameter_spec *p=
,
 		    struct fs_parameter *param, struct fs_parse_result *result)
 {
-	if (param->type !=3D fs_value_is_string ||
-	    kstrtoint(param->string, 0, &result->int_32) < 0)
+	if (param->type !=3D fs_value_is_string)
+		return fs_param_bad_value(log, param);
+	if (!*param->string && (p->flags & fs_param_can_be_empty))
+		return 0;
+	if (kstrtoint(param->string, 0, &result->int_32) < 0)
 		return fs_param_bad_value(log, param);
 	return 0;
 }
@@ -232,8 +240,11 @@ EXPORT_SYMBOL(fs_param_is_s32);
 int fs_param_is_u64(struct p_log *log, const struct fs_parameter_spec *p=
,
 		    struct fs_parameter *param, struct fs_parse_result *result)
 {
-	if (param->type !=3D fs_value_is_string ||
-	    kstrtoull(param->string, 0, &result->uint_64) < 0)
+	if (param->type !=3D fs_value_is_string)
+		return fs_param_bad_value(log, param);
+	if (!*param->string && (p->flags & fs_param_can_be_empty))
+		return 0;
+	if (kstrtoull(param->string, 0, &result->uint_64) < 0)
 		return fs_param_bad_value(log, param);
 	return 0;
 }
@@ -245,6 +256,8 @@ int fs_param_is_enum(struct p_log *log, const struct =
fs_parameter_spec *p,
 	const struct constant_table *c;
 	if (param->type !=3D fs_value_is_string)
 		return fs_param_bad_value(log, param);
+	if (!*param->string && (p->flags & fs_param_can_be_empty))
+		return 0;
 	c =3D __lookup_constant(p->data, param->string);
 	if (!c)
 		return fs_param_bad_value(log, param);
@@ -256,7 +269,8 @@ EXPORT_SYMBOL(fs_param_is_enum);
 int fs_param_is_string(struct p_log *log, const struct fs_parameter_spec=
 *p,
 		       struct fs_parameter *param, struct fs_parse_result *result)
 {
-	if (param->type !=3D fs_value_is_string || !*param->string)
+	if (param->type !=3D fs_value_is_string ||
+	    (!*param->string && !(p->flags & fs_param_can_be_empty)))
 		return fs_param_bad_value(log, param);
 	return 0;
 }
@@ -276,7 +290,8 @@ int fs_param_is_fd(struct p_log *log, const struct fs=
_parameter_spec *p,
 {
 	switch (param->type) {
 	case fs_value_is_string:
-		if (kstrtouint(param->string, 0, &result->uint_32) < 0)
+		if ((!*param->string && !(p->flags & fs_param_can_be_empty)) ||
+		    kstrtouint(param->string, 0, &result->uint_32) < 0)
 			break;
 		if (result->uint_32 <=3D INT_MAX)
 			return 0;
diff --git a/include/linux/fs_parser.h b/include/linux/fs_parser.h
index 2eab6d5f6736..1cde756ef0fd 100644
--- a/include/linux/fs_parser.h
+++ b/include/linux/fs_parser.h
@@ -42,7 +42,7 @@ struct fs_parameter_spec {
 	u8			opt;	/* Option number (returned by fs_parse()) */
 	unsigned short		flags;
 #define fs_param_neg_with_no	0x0002	/* "noxxx" is negative param */
-#define fs_param_neg_with_empty	0x0004	/* "xxx=3D" is negative param */
+#define fs_param_can_be_empty	0x0004	/* "xxx=3D" is allowed */
 #define fs_param_deprecated	0x0008	/* The param is deprecated */
 	const void		*data;
 };
--=20
2.21.1