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Date:   Thu,  5 Sep 2019 15:44:30 -0400
From:   "J. Bruce Fields" <bfields@...hat.com>
To:     Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
Cc:     linux-kernel@...r.kernel.org, Kees Cook <keescook@...omium.org>,
        "J. Bruce Fields" <bfields@...hat.com>
Subject: [PATCH 6/9] Eliminate unused ESCAPE_NULL, ESCAPE_SPACE flags

From: "J. Bruce Fields" <bfields@...hat.com>

I can see how some finer-grained flags could be useful, but for now I'm
trying to simplify, so let's just remove these unused ones.

Note the trickiest part is actually the tests, and I still need to check
them.

Signed-off-by: J. Bruce Fields <bfields@...hat.com>
---
 fs/proc/array.c                |  2 +-
 include/linux/string_helpers.h |  6 ++--
 lib/string_helpers.c           | 54 +++----------------------------
 lib/test-string_helpers.c      | 58 ++++------------------------------
 4 files changed, 14 insertions(+), 106 deletions(-)

diff --git a/fs/proc/array.c b/fs/proc/array.c
index 46dcb6f0eccf..982c95d09176 100644
--- a/fs/proc/array.c
+++ b/fs/proc/array.c
@@ -111,7 +111,7 @@ void proc_task_name(struct seq_file *m, struct task_struct *p, bool escape)
 	size = seq_get_buf(m, &buf);
 	if (escape) {
 		ret = string_escape_str(tcomm, buf, size,
-					ESCAPE_SPACE | ESCAPE_SPECIAL, "\n\\");
+					ESCAPE_SPECIAL, "\n\\");
 		if (ret >= size)
 			ret = -1;
 	} else {
diff --git a/include/linux/string_helpers.h b/include/linux/string_helpers.h
index 8a299a29b767..7bf0d137373d 100644
--- a/include/linux/string_helpers.h
+++ b/include/linux/string_helpers.h
@@ -41,15 +41,13 @@ static inline int string_unescape_any_inplace(char *buf)
 	return string_unescape_any(buf, buf, 0);
 }
 
-#define ESCAPE_SPACE		0x01
 #define ESCAPE_SPECIAL		0x02
-#define ESCAPE_NULL		0x04
 #define ESCAPE_OCTAL		0x08
-#define ESCAPE_ANY		\
-	(ESCAPE_SPACE | ESCAPE_OCTAL | ESCAPE_SPECIAL | ESCAPE_NULL)
+#define ESCAPE_ANY		(ESCAPE_OCTAL | ESCAPE_SPECIAL)
 #define ESCAPE_NP		0x10
 #define ESCAPE_ANY_NP		(ESCAPE_ANY | ESCAPE_NP)
 #define ESCAPE_HEX		0x20
+#define ESCAPE_FLAG_MASK	0x3a
 
 int string_escape_mem(const char *src, size_t isz, char *dst, size_t osz,
 		unsigned int flags, const char *only);
diff --git a/lib/string_helpers.c b/lib/string_helpers.c
index 963050c0283e..ac72159d3980 100644
--- a/lib/string_helpers.c
+++ b/lib/string_helpers.c
@@ -310,7 +310,7 @@ static bool escape_passthrough(unsigned char c, char **dst, char *end)
 	return true;
 }
 
-static bool escape_space(unsigned char c, char **dst, char *end)
+static bool escape_special(unsigned char c, char **dst, char *end)
 {
 	char *out = *dst;
 	unsigned char to;
@@ -331,27 +331,6 @@ static bool escape_space(unsigned char c, char **dst, char *end)
 	case '\f':
 		to = 'f';
 		break;
-	default:
-		return false;
-	}
-
-	if (out < end)
-		*out = '\\';
-	++out;
-	if (out < end)
-		*out = to;
-	++out;
-
-	*dst = out;
-	return true;
-}
-
-static bool escape_special(unsigned char c, char **dst, char *end)
-{
-	char *out = *dst;
-	unsigned char to;
-
-	switch (c) {
 	case '\\':
 		to = '\\';
 		break;
@@ -361,6 +340,9 @@ static bool escape_special(unsigned char c, char **dst, char *end)
 	case '\e':
 		to = 'e';
 		break;
+	case '\0':
+		to = '0';
+		break;
 	default:
 		return false;
 	}
@@ -376,24 +358,6 @@ static bool escape_special(unsigned char c, char **dst, char *end)
 	return true;
 }
 
-static bool escape_null(unsigned char c, char **dst, char *end)
-{
-	char *out = *dst;
-
-	if (c)
-		return false;
-
-	if (out < end)
-		*out = '\\';
-	++out;
-	if (out < end)
-		*out = '0';
-	++out;
-
-	*dst = out;
-	return true;
-}
-
 static bool escape_octal(unsigned char c, char **dst, char *end)
 {
 	char *out = *dst;
@@ -465,17 +429,15 @@ static bool escape_hex(unsigned char c, char **dst, char *end)
  * destination buffer will not be NULL-terminated, thus caller have to append
  * it if needs.   The supported flags are::
  *
- *	%ESCAPE_SPACE: (special white space, not space itself)
+ *	%ESCAPE_SPECIAL:
  *		'\f' - form feed
  *		'\n' - new line
  *		'\r' - carriage return
  *		'\t' - horizontal tab
  *		'\v' - vertical tab
- *	%ESCAPE_SPECIAL:
  *		'\\' - backslash
  *		'\a' - alert (BEL)
  *		'\e' - escape
- *	%ESCAPE_NULL:
  *		'\0' - null
  *	%ESCAPE_OCTAL:
  *		'\NNN' - byte with octal value NNN (3 digits)
@@ -519,15 +481,9 @@ int string_escape_mem(const char *src, size_t isz, char *dst, size_t osz,
 		    (is_dict && !strchr(only, c))) {
 			/* do nothing */
 		} else {
-			if (flags & ESCAPE_SPACE && escape_space(c, &p, end))
-				continue;
-
 			if (flags & ESCAPE_SPECIAL && escape_special(c, &p, end))
 				continue;
 
-			if (flags & ESCAPE_NULL && escape_null(c, &p, end))
-				continue;
-
 			/* ESCAPE_OCTAL and ESCAPE_HEX always go last */
 			if (flags & ESCAPE_OCTAL && escape_octal(c, &p, end))
 				continue;
diff --git a/lib/test-string_helpers.c b/lib/test-string_helpers.c
index 25b5cbfb7615..0da3c195a327 100644
--- a/lib/test-string_helpers.c
+++ b/lib/test-string_helpers.c
@@ -124,20 +124,6 @@ struct test_string_2 {
 
 #define	TEST_STRING_2_DICT_0		NULL
 static const struct test_string_2 escape0[] __initconst = {{
-	.in = "\f\\ \n\r\t\v",
-	.s1 = {{
-		.out = "\\f\\ \\n\\r\\t\\v",
-		.flags = ESCAPE_SPACE,
-	},{
-		.out = "\\f\\134\\040\\n\\r\\t\\v",
-		.flags = ESCAPE_SPACE | ESCAPE_OCTAL,
-	},{
-		.out = "\\f\\x5c\\x20\\n\\r\\t\\v",
-		.flags = ESCAPE_SPACE | ESCAPE_HEX,
-	},{
-		/* terminator */
-	}},
-},{
 	.in = "\\h\\\"\a\e\\",
 	.s1 = {{
 		.out = "\\\\h\\\\\"\\a\\e\\\\",
@@ -154,48 +140,26 @@ static const struct test_string_2 escape0[] __initconst = {{
 },{
 	.in = "\eb \\C\007\"\x90\r]",
 	.s1 = {{
-		.out = "\eb \\C\007\"\x90\\r]",
-		.flags = ESCAPE_SPACE,
-	},{
-		.out = "\\eb \\\\C\\a\"\x90\r]",
-		.flags = ESCAPE_SPECIAL,
-	},{
 		.out = "\\eb \\\\C\\a\"\x90\\r]",
-		.flags = ESCAPE_SPACE | ESCAPE_SPECIAL,
+		.flags = ESCAPE_SPECIAL,
 	},{
 		.out = "\\033\\142\\040\\134\\103\\007\\042\\220\\015\\135",
 		.flags = ESCAPE_OCTAL,
-	},{
-		.out = "\\033\\142\\040\\134\\103\\007\\042\\220\\r\\135",
-		.flags = ESCAPE_SPACE | ESCAPE_OCTAL,
-	},{
-		.out = "\\e\\142\\040\\\\\\103\\a\\042\\220\\015\\135",
-		.flags = ESCAPE_SPECIAL | ESCAPE_OCTAL,
 	},{
 		.out = "\\e\\142\\040\\\\\\103\\a\\042\\220\\r\\135",
-		.flags = ESCAPE_SPACE | ESCAPE_SPECIAL | ESCAPE_OCTAL,
+		.flags = ESCAPE_SPECIAL | ESCAPE_OCTAL,
 	},{
 		.out = "\eb \\C\007\"\x90\r]",
 		.flags = ESCAPE_NP,
-	},{
-		.out = "\eb \\C\007\"\x90\\r]",
-		.flags = ESCAPE_SPACE | ESCAPE_NP,
-	},{
-		.out = "\\eb \\C\\a\"\x90\r]",
-		.flags = ESCAPE_SPECIAL | ESCAPE_NP,
 	},{
 		.out = "\\eb \\C\\a\"\x90\\r]",
-		.flags = ESCAPE_SPACE | ESCAPE_SPECIAL | ESCAPE_NP,
+		.flags = ESCAPE_SPECIAL | ESCAPE_NP,
 	},{
 		.out = "\\033b \\C\\007\"\\220\\015]",
 		.flags = ESCAPE_OCTAL | ESCAPE_NP,
-	},{
-		.out = "\\033b \\C\\007\"\\220\\r]",
-		.flags = ESCAPE_SPACE | ESCAPE_OCTAL | ESCAPE_NP,
 	},{
 		.out = "\\eb \\C\\a\"\\220\\r]",
-		.flags = ESCAPE_SPECIAL | ESCAPE_SPACE | ESCAPE_OCTAL |
-			 ESCAPE_NP,
+		.flags = ESCAPE_SPECIAL ESCAPE_OCTAL | ESCAPE_NP,
 	},{
 		.out = "\\x1bb \\C\\x07\"\\x90\\x0d]",
 		.flags = ESCAPE_NP | ESCAPE_HEX,
@@ -247,9 +211,6 @@ static __init const char *test_string_find_match(const struct test_string_2 *s2,
 	if (!flags)
 		return s2->in;
 
-	/* Test cases are NULL-aware */
-	flags &= ~ESCAPE_NULL;
-
 	/* ESCAPE_OCTAL has a higher priority */
 	if (flags & ESCAPE_OCTAL)
 		flags &= ~ESCAPE_HEX;
@@ -290,13 +251,6 @@ static __init void test_string_escape(const char *name,
 		const char *out;
 		int len;
 
-		/* NULL injection */
-		if (flags & ESCAPE_NULL) {
-			in[p++] = '\0';
-			out_test[q_test++] = '\\';
-			out_test[q_test++] = '0';
-		}
-
 		/* Don't try strings that have no output */
 		out = test_string_find_match(s2, flags);
 		if (!out)
@@ -401,11 +355,11 @@ static int __init test_string_helpers_init(void)
 			     get_random_int() % (UNESCAPE_ANY + 1), true);
 
 	/* Without dictionary */
-	for (i = 0; i < (ESCAPE_ANY_NP | ESCAPE_HEX) + 1; i++)
+	for (i = 0; i < ESCAPE_FLAG_MASK + 1; i++)
 		test_string_escape("escape 0", escape0, i, TEST_STRING_2_DICT_0);
 
 	/* With dictionary */
-	for (i = 0; i < (ESCAPE_ANY_NP | ESCAPE_HEX) + 1; i++)
+	for (i = 0; i < ESCAPE_FLAG_MASK + 1; i++)
 		test_string_escape("escape 1", escape1, i, TEST_STRING_2_DICT_1);
 
 	/* Test string_get_size() */
-- 
2.21.0

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