Add a couple of useful git_buf utilities

* `git_buf_rfind` (with tests and tests for `git_buf_rfind_next`)
* `git_buf_puts_escaped` and `git_buf_puts_escaped_regex` (with tests)
  to copy strings into a buffer while injecting an escape sequence
  (e.g. '\') in front of particular characters.

1 files changed, 34 insertions, 0 deletions

diff --git a/src/buffer.c b/src/buffer.c
index 04aaec3df..d16b17160 100644
--- a/src/buffer.c
+++ b/src/buffer.c
@@ -141,6 +141,40 @@ int git_buf_puts(git_buf *buf, const char *string)
 	return git_buf_put(buf, string, strlen(string));
 }
 
+int git_buf_puts_escaped(
+	git_buf *buf, const char *string, const char *esc_chars, const char *esc_with)
+{
+	const char *scan = string;
+	size_t total = 0, esc_with_len = strlen(esc_with);
+
+	while (*scan) {
+		size_t count = strcspn(scan, esc_chars);
+		total += count + 1 + esc_with_len;
+		scan += count + 1;
+	}
+
+	ENSURE_SIZE(buf, buf->size + total + 1);
+
+	for (scan = string; *scan; ) {
+		size_t count = strcspn(scan, esc_chars);
+
+		memmove(buf->ptr + buf->size, scan, count);
+		scan += count;
+		buf->size += count;
+
+		if (*scan) {
+			memmove(buf->ptr + buf->size, esc_with, esc_with_len);
+			buf->size += esc_with_len;
+
+			memmove(buf->ptr + buf->size, scan, 1);
+			scan += 1;
+			buf->size += 1;
+		}
+	}
+
+	return 0;
+}
+
 int git_buf_vprintf(git_buf *buf, const char *format, va_list ap)
 {
 	int len;