1 files changed, 96 insertions, 0 deletions

diff --git a/ext/erb/erb.c b/ext/erb/erb.c
new file mode 100644
index 0000000000..92cfbd0769
--- /dev/null
+++ b/ext/erb/erb.c
@@ -0,0 +1,96 @@
+#include "ruby.h"
+#include "ruby/encoding.h"
+
+static VALUE rb_cERB, rb_mEscape;
+
+#define HTML_ESCAPE_MAX_LEN 6
+
+static const struct {
+    uint8_t len;
+    char str[HTML_ESCAPE_MAX_LEN+1];
+} html_escape_table[UCHAR_MAX+1] = {
+#define HTML_ESCAPE(c, str) [c] = {rb_strlen_lit(str), str}
+    HTML_ESCAPE('\'', "'"),
+    HTML_ESCAPE('&', "&"),
+    HTML_ESCAPE('"', """),
+    HTML_ESCAPE('<', "&lt;"),
+    HTML_ESCAPE('>', "&gt;"),
+#undef HTML_ESCAPE
+};
+
+static inline void
+preserve_original_state(VALUE orig, VALUE dest)
+{
+    rb_enc_associate(dest, rb_enc_get(orig));
+}
+
+static inline long
+escaped_length(VALUE str)
+{
+    const long len = RSTRING_LEN(str);
+    if (len >= LONG_MAX / HTML_ESCAPE_MAX_LEN) {
+        ruby_malloc_size_overflow(len, HTML_ESCAPE_MAX_LEN);
+    }
+    return len * HTML_ESCAPE_MAX_LEN;
+}
+
+static VALUE
+optimized_escape_html(VALUE str)
+{
+    VALUE vbuf;
+    char *buf = ALLOCV_N(char, vbuf, escaped_length(str));
+    const char *cstr = RSTRING_PTR(str);
+    const char *end = cstr + RSTRING_LEN(str);
+
+    char *dest = buf;
+    while (cstr < end) {
+        const unsigned char c = *cstr++;
+        uint8_t len = html_escape_table[c].len;
+        if (len) {
+            memcpy(dest, html_escape_table[c].str, len);
+            dest += len;
+        }
+        else {
+            *dest++ = c;
+        }
+    }
+
+    VALUE escaped;
+    if (RSTRING_LEN(str) < (dest - buf)) {
+        escaped = rb_str_new(buf, dest - buf);
+        preserve_original_state(str, escaped);
+    }
+    else {
+        escaped = rb_str_dup(str);
+    }
+    ALLOCV_END(vbuf);
+    return escaped;
+}
+
+static VALUE
+cgiesc_escape_html(VALUE self, VALUE str)
+{
+    StringValue(str);
+
+    if (rb_enc_str_asciicompat_p(str)) {
+        return optimized_escape_html(str);
+    }
+    else {
+        return rb_call_super(1, &str);
+    }
+}
+
+static VALUE
+erb_escape_html(VALUE self, VALUE str)
+{
+    str = rb_funcall(str, rb_intern("to_s"), 0);
+    return cgiesc_escape_html(self, str);
+}
+
+void
+Init_erb(void)
+{
+    rb_cERB = rb_define_class("ERB", rb_cObject);
+    rb_mEscape = rb_define_module_under(rb_cERB, "Escape");
+    rb_define_method(rb_mEscape, "html_escape", erb_escape_html, 1);
+}