seq_file: introduce seq_escape_mem()

Introduce seq_escape_mem() to allow users to pass additional parameters to
string_escape_mem().

Link: https://lkml.kernel.org/r/20210504180819.73127-12-andriy.shevchenko@linux.intel.comSuggested-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Cc: Chuck Lever <chuck.lever@oracle.com>
Cc: "J. Bruce Fields" <bfields@fieldses.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

fs/seq_file.c

@@ -355,6 +355,31 @@ int seq_release(struct inode *inode, struct file *file)
 }
 EXPORT_SYMBOL(seq_release);
 
+/**
+ * seq_escape_mem - print data into buffer, escaping some characters
+ * @m: target buffer
+ * @src: source buffer
+ * @len: size of source buffer
+ * @flags: flags to pass to string_escape_mem()
+ * @esc: set of characters that need escaping
+ *
+ * Puts data into buffer, replacing each occurrence of character from
+ * given class (defined by @flags and @esc) with printable escaped sequence.
+ *
+ * Use seq_has_overflowed() to check for errors.
+ */
+void seq_escape_mem(struct seq_file *m, const char *src, size_t len,
+		    unsigned int flags, const char *esc)
+{
+	char *buf;
+	size_t size = seq_get_buf(m, &buf);
+	int ret;
+
+	ret = string_escape_mem(src, len, buf, size, flags, esc);
+	seq_commit(m, ret < size ? ret : -1);
+}
+EXPORT_SYMBOL(seq_escape_mem);
+
 /**
  *	seq_escape -	print string into buffer, escaping some characters
  *	@m:	target buffer

include/linux/seq_file.h

@@ -126,6 +126,8 @@ void seq_put_decimal_ll(struct seq_file *m, const char *delimiter, long long num
 void seq_put_hex_ll(struct seq_file *m, const char *delimiter,
 		    unsigned long long v, unsigned int width);
 
+void seq_escape_mem(struct seq_file *m, const char *src, size_t len,
+		    unsigned int flags, const char *esc);
 void seq_escape(struct seq_file *m, const char *s, const char *esc);
 void seq_escape_mem_ascii(struct seq_file *m, const char *src, size_t isz);