git_buf_quote: quote ugly characters

src/buffer.c

@@ -858,6 +858,72 @@ int git_buf_splice(
 	return 0;
 }
 
+/* Quote per http://marc.info/?l=git&m=112927316408690&w=2 */
+int git_buf_quote(git_buf *buf)
+{
+	const char whitespace[] = { 'a', 'b', 't', 'n', 'v', 'f', 'r' };
+	git_buf quoted = GIT_BUF_INIT;
+	size_t i = 0;
+	bool quote = false;
+	int error = 0;
+
+	/* walk to the first char that needs quoting */
+	if (buf->size && buf->ptr[0] == '!')
+		quote = true;
+
+	for (i = 0; !quote && i < buf->size; i++) {
+		if (buf->ptr[i] == '"' || buf->ptr[i] == '\\' ||
+			buf->ptr[i] < ' ' || buf->ptr[i] > '~') {
+			quote = true;
+			break;
+		}
+	}
+
+	if (!quote)
+		goto done;
+
+	git_buf_putc(&quoted, '"');
+	git_buf_put(&quoted, buf->ptr, i);
+
+	for (; i < buf->size; i++) {
+		/* whitespace - use the map above, which is ordered by ascii value */
+		if (buf->ptr[i] >= '\a' && buf->ptr[i] <= '\r') {
+			git_buf_putc(&quoted, '\\');
+			git_buf_putc(&quoted, whitespace[buf->ptr[i] - '\a']);
+		}
+
+		/* double quote and backslash must be escaped */
+		else if (buf->ptr[i] == '"' || buf->ptr[i] == '\\') {
+			git_buf_putc(&quoted, '\\');
+			git_buf_putc(&quoted, buf->ptr[i]);
+		}
+
+		/* escape anything unprintable as octal */
+		else if (buf->ptr[i] != ' ' &&
+				(buf->ptr[i] < '!' || buf->ptr[i] > '~')) {
+			git_buf_printf(&quoted, "\\%03o", buf->ptr[i]);
+		}
+
+		/* yay, printable! */
+		else {
+			git_buf_putc(&quoted, buf->ptr[i]);
+		}
+	}
+
+	git_buf_putc(&quoted, '"');
+
+	if (git_buf_oom(&quoted)) {
+		error = -1;
+		goto done;
+	}
+
+	git_buf_swap(&quoted, buf);
+
+done:
+	git_buf_free(&quoted);
+	return error;
+}
+
 /* Unquote per http://marc.info/?l=git&m=112927316408690&w=2 */
 int git_buf_unquote(git_buf *buf)
 {

src/buffer.h

@@ -173,9 +173,10 @@ void git_buf_rtrim(git_buf *buf);
 
 int git_buf_cmp(const git_buf *a, const git_buf *b);
 
-/* Unquote a buffer as specified in
+/* Quote and unquote a buffer as specified in
  * http://marc.info/?l=git&m=112927316408690&w=2
  */
+int git_buf_quote(git_buf *buf);
 int git_buf_unquote(git_buf *buf);
 
 /* Write data as base64 encoded in buffer */

tests/buf/quote.c

 #include "clar_libgit2.h"
 #include "buffer.h"
 
-static void expect_pass(const char *expected, const char *quoted)
+static void expect_quote_pass(const char *expected, const char *str)
+{
+	git_buf buf = GIT_BUF_INIT;
+
+	cl_git_pass(git_buf_puts(&buf, str));
+	cl_git_pass(git_buf_quote(&buf));
+
+	cl_assert_equal_s(expected, git_buf_cstr(&buf));
+	cl_assert_equal_i(strlen(expected), git_buf_len(&buf));
+
+	git_buf_free(&buf);
+}
+
+void test_buf_quote__quote_succeeds(void)
+{
+	expect_quote_pass("", "");
+	expect_quote_pass("foo", "foo");
+	expect_quote_pass("foo/bar/baz.c", "foo/bar/baz.c");
+	expect_quote_pass("foo bar", "foo bar");
+	expect_quote_pass("\"\\\"leading quote\"", "\"leading quote");
+	expect_quote_pass("\"slash\\\\y\"", "slash\\y");
+	expect_quote_pass("\"foo\\r\\nbar\"", "foo\r\nbar");
+	expect_quote_pass("\"foo\\177bar\"", "foo\177bar");
+	expect_quote_pass("\"foo\\001bar\"", "foo\001bar");
+}
+
+static void expect_unquote_pass(const char *expected, const char *quoted)
 {
 	git_buf buf = GIT_BUF_INIT;
 
@@ -14,7 +40,7 @@ static void expect_pass(const char *expected, const char *quoted)
 	git_buf_free(&buf);
 }
 
-static void expect_fail(const char *quoted)
+static void expect_unquote_fail(const char *quoted)
 {
 	git_buf buf = GIT_BUF_INIT;
 
@@ -26,32 +52,32 @@ static void expect_fail(const char *quoted)
 
 void test_buf_quote__unquote_succeeds(void)
 {
-	expect_pass("", "\"\"");
-	expect_pass(" ", "\" \"");
-	expect_pass("foo", "\"foo\"");
-	expect_pass("foo bar", "\"foo bar\"");
-	expect_pass("foo\"bar", "\"foo\\\"bar\"");
-	expect_pass("foo\\bar", "\"foo\\\\bar\"");
-	expect_pass("foo\tbar", "\"foo\\tbar\"");
-	expect_pass("\vfoo\tbar\n", "\"\\vfoo\\tbar\\n\"");
-	expect_pass("foo\nbar", "\"foo\\012bar\"");
-	expect_pass("foo\r\nbar", "\"foo\\015\\012bar\"");
-	expect_pass("foo\r\nbar", "\"\\146\\157\\157\\015\\012\\142\\141\\162\"");
-	expect_pass("newline: \n", "\"newline: \\012\"");
+	expect_unquote_pass("", "\"\"");
+	expect_unquote_pass(" ", "\" \"");
+	expect_unquote_pass("foo", "\"foo\"");
+	expect_unquote_pass("foo bar", "\"foo bar\"");
+	expect_unquote_pass("foo\"bar", "\"foo\\\"bar\"");
+	expect_unquote_pass("foo\\bar", "\"foo\\\\bar\"");
+	expect_unquote_pass("foo\tbar", "\"foo\\tbar\"");
+	expect_unquote_pass("\vfoo\tbar\n", "\"\\vfoo\\tbar\\n\"");
+	expect_unquote_pass("foo\nbar", "\"foo\\012bar\"");
+	expect_unquote_pass("foo\r\nbar", "\"foo\\015\\012bar\"");
+	expect_unquote_pass("foo\r\nbar", "\"\\146\\157\\157\\015\\012\\142\\141\\162\"");
+	expect_unquote_pass("newline: \n", "\"newline: \\012\"");
 }
 
 void test_buf_quote__unquote_fails(void)
 {
-	expect_fail("no quotes at all");
-	expect_fail("\"no trailing quote");
-	expect_fail("no leading quote\"");
-	expect_fail("\"invalid \\z escape char\"");
-	expect_fail("\"\\q invalid escape char\"");
-	expect_fail("\"invalid escape char \\p\"");
-	expect_fail("\"invalid \\1 escape char \"");
-	expect_fail("\"invalid \\14 escape char \"");
-	expect_fail("\"invalid \\411 escape char\"");
-	expect_fail("\"truncated escape char \\\"");
-	expect_fail("\"truncated escape char \\0\"");
-	expect_fail("\"truncated escape char \\01\"");
+	expect_unquote_fail("no quotes at all");
+	expect_unquote_fail("\"no trailing quote");
+	expect_unquote_fail("no leading quote\"");
+	expect_unquote_fail("\"invalid \\z escape char\"");
+	expect_unquote_fail("\"\\q invalid escape char\"");
+	expect_unquote_fail("\"invalid escape char \\p\"");
+	expect_unquote_fail("\"invalid \\1 escape char \"");
+	expect_unquote_fail("\"invalid \\14 escape char \"");
+	expect_unquote_fail("\"invalid \\411 escape char\"");
+	expect_unquote_fail("\"truncated escape char \\\"");
+	expect_unquote_fail("\"truncated escape char \\0\"");
+	expect_unquote_fail("\"truncated escape char \\01\"");
 }