Add git_buf_put_base64 to buffer API

1 files changed, 40 insertions, 0 deletions

diff --git a/src/buffer.c b/src/buffer.c
index 61cfaf9e2..ee2dd2804 100644
--- a/src/buffer.c
+++ b/src/buffer.c
@@ -186,6 +186,46 @@ int git_buf_puts_escaped(
 	return 0;
 }
 
+static const char b64str[64] =
+	"ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";
+
+int git_buf_put_base64(git_buf *buf, const char *data, size_t len)
+{
+	size_t extra = len % 3;
+	uint8_t *write, a, b, c;
+	const uint8_t *read = (const uint8_t *)data;
+
+	ENSURE_SIZE(buf, buf->size + ((len * 4 + 3) / 3) + 1);
+	write = (uint8_t *)&buf->ptr[buf->size];
+
+	/* convert each run of 3 bytes into 4 output bytes */
+	for (len -= extra; len > 0; len -= 3) {
+		a = *read++;
+		b = *read++;
+		c = *read++;
+
+		*write++ = b64str[a >> 2];
+		*write++ = b64str[(a & 0x03) << 4 | b >> 4];
+		*write++ = b64str[(b & 0x0f) << 2 | c >> 6];
+		*write++ = b64str[c & 0x3f];
+	}
+
+	if (extra > 0) {
+		a = *read++;
+		b = (extra > 1) ? *read++ : 0;
+
+		*write++ = b64str[a >> 2];
+		*write++ = b64str[(a & 0x03) << 4 | b >> 4];
+		*write++ = (extra > 1) ? b64str[(b & 0x0f) << 2] : '=';
+		*write++ = '=';
+	}
+
+	buf->size = ((char *)write) - buf->ptr;
+	buf->ptr[buf->size] = '\0';
+
+	return 0;
+}
+
 int git_buf_vprintf(git_buf *buf, const char *format, va_list ap)
 {
 	int len;