str: allow escaping with prefix and suffix

Allow `git_str_puts_escaped` to take an escaping prefix and an escaping
suffix; this allows for more options, including the ability to better
support escaping executed paths.

src/util/str.c

@@ -1065,10 +1065,13 @@ int git_str_puts_escaped(
 	git_str *buf,
 	const char *string,
 	const char *esc_chars,
-	const char *esc_with)
+	const char *esc_prefix,
+	const char *esc_suffix)
 {
 	const char *scan;
-	size_t total = 0, esc_len = strlen(esc_with), count, alloclen;
+	size_t total = 0, count, alloclen;
+	size_t esc_prefix_len = esc_prefix ? strlen(esc_prefix) : 0;
+	size_t esc_suffix_len = esc_suffix ? strlen(esc_suffix) : 0;
 
 	if (!string)
 		return 0;
@@ -1080,7 +1083,7 @@ int git_str_puts_escaped(
 		scan += count;
 		/* count run of escaped characters */
 		count = strspn(scan, esc_chars);
-		total += count * (esc_len + 1);
+		total += count * (esc_prefix_len + esc_suffix_len + 1);
 		scan += count;
 	}
 
@@ -1096,13 +1099,22 @@ int git_str_puts_escaped(
 		buf->size += count;
 
 		for (count = strspn(scan, esc_chars); count > 0; --count) {
-			/* copy escape sequence */
-			memmove(buf->ptr + buf->size, esc_with, esc_len);
-			buf->size += esc_len;
+			/* copy escape prefix sequence */
+			if (esc_prefix) {
+				memmove(buf->ptr + buf->size, esc_prefix, esc_prefix_len);
+				buf->size += esc_prefix_len;
+			}
+
 			/* copy character to be escaped */
 			buf->ptr[buf->size] = *scan;
 			buf->size++;
 			scan++;
+
+			/* copy escape suffix sequence */
+			if (esc_suffix) {
+				memmove(buf->ptr + buf->size, esc_suffix, esc_suffix_len);
+				buf->size += esc_suffix_len;
+			}
 		}
 	}
 

src/util/str.h

@@ -268,21 +268,23 @@ int git_str_splice(
  * @param str String buffer to append data to
  * @param string String to escape and append
  * @param esc_chars Characters to be escaped
- * @param esc_with String to insert in from of each found character
+ * @param esc_prefix String to insert as prefix of each found character
+ * @param esc_suffix String to insert as suffix of each found character
  * @return 0 on success, <0 on failure (probably allocation problem)
  */
 extern int git_str_puts_escaped(
 	git_str *str,
 	const char *string,
 	const char *esc_chars,
-	const char *esc_with);
+	const char *esc_prefix,
+	const char *esc_suffix);
 
 /**
  * Append string escaping characters that are regex special
  */
 GIT_INLINE(int) git_str_puts_escape_regex(git_str *str, const char *string)
 {
-	return git_str_puts_escaped(str, string, "^.[]$()|*+?{}\\", "\\");
+	return git_str_puts_escaped(str, string, "^.[]$()|*+?{}\\", "\\", NULL);
 }
 
 /**

tests/util/gitstr.c

@@ -691,17 +691,33 @@ void test_gitstr__puts_escaped(void)
 	git_str a = GIT_STR_INIT;
 
 	git_str_clear(&a);
-	cl_git_pass(git_str_puts_escaped(&a, "this is a test", "", ""));
+	cl_git_pass(git_str_puts_escaped(&a, "this is a test", "", "", ""));
 	cl_assert_equal_s("this is a test", a.ptr);
 
 	git_str_clear(&a);
-	cl_git_pass(git_str_puts_escaped(&a, "this is a test", "t", "\\"));
+	cl_git_pass(git_str_puts_escaped(&a, "this is a test", "", NULL, NULL));
+	cl_assert_equal_s("this is a test", a.ptr);
+
+	git_str_clear(&a);
+	cl_git_pass(git_str_puts_escaped(&a, "this is a test", "t", "\\", ""));
 	cl_assert_equal_s("\\this is a \\tes\\t", a.ptr);
 
 	git_str_clear(&a);
-	cl_git_pass(git_str_puts_escaped(&a, "this is a test", "i ", "__"));
+	cl_git_pass(git_str_puts_escaped(&a, "this is a test", "t", "\\", NULL));
+	cl_assert_equal_s("\\this is a \\tes\\t", a.ptr);
+
+	git_str_clear(&a);
+	cl_git_pass(git_str_puts_escaped(&a, "this is a test", "i ", "__", NULL));
 	cl_assert_equal_s("th__is__ __is__ a__ test", a.ptr);
 
+	git_str_clear(&a);
+	cl_git_pass(git_str_puts_escaped(&a, "this is a test", "i ", "__", "!!"));
+	cl_assert_equal_s("th__i!!s__ !!__i!!s__ !!a__ !!test", a.ptr);
+
+	git_str_clear(&a);
+	cl_git_pass(git_str_puts_escaped(&a, "this' is' an' escape! ", "'!", "'\\", "'"));
+	cl_assert_equal_s("this'\\'' is'\\'' an'\\'' escape'\\!' ", a.ptr);
+
 	git_str_clear(&a);
 	cl_git_pass(git_str_puts_escape_regex(&a, "^match\\s*[A-Z]+.*"));
 	cl_assert_equal_s("\\^match\\\\s\\*\\[A-Z\\]\\+\\.\\*", a.ptr);