Move crlf conversion into buf_textautocrlf-fixes

This adds crlf/lf conversion functions into buf_text with more
efficient implementations that bypass the high level buffer
functions.  They attempt to minimize the number of reallocations
done and they directly write the buffer data as needed if they
know that there is enough memory allocated to memcpy data.

Tests are added for these new functions.  The crlf.c code is
updated to use the new functions.

Removed the include of buf_text.h from filter.h and just include
it more narrowly in the places that need it.

1 files changed, 77 insertions, 0 deletions

diff --git a/src/buf_text.c b/src/buf_text.c
index 3a8f442b4..443454b5f 100644
--- a/src/buf_text.c
+++ b/src/buf_text.c
@@ -60,6 +60,83 @@ void git_buf_text_unescape(git_buf *buf)
 	buf->size = git__unescape(buf->ptr);
 }
 
+int git_buf_text_crlf_to_lf(git_buf *tgt, const git_buf *src)
+{
+	const char *scan = src->ptr;
+	const char *scan_end = src->ptr + src->size;
+	const char *next = memchr(scan, '\r', src->size);
+	char *out;
+
+	assert(tgt != src);
+
+	if (!next)
+		return GIT_ENOTFOUND;
+
+	/* reduce reallocs while in the loop */
+	if (git_buf_grow(tgt, src->size) < 0)
+		return -1;
+	out = tgt->ptr;
+	tgt->size = 0;
+
+	/* Find the next \r and copy whole chunk up to there to tgt */
+	for (; next; scan = next + 1, next = memchr(scan, '\r', scan_end - scan)) {
+		if (next > scan) {
+			size_t copylen = next - scan;
+			memcpy(out, scan, copylen);
+			out += copylen;
+		}
+
+		/* Do not drop \r unless it is followed by \n */
+		if (next[1] != '\n')
+			*out++ = '\r';
+	}
+
+	/* Copy remaining input into dest */
+	memcpy(out, scan, scan_end - scan + 1); /* +1 for NUL byte */
+	out += (scan_end - scan);
+	tgt->size = out - tgt->ptr;
+
+	return 0;
+}
+
+int git_buf_text_lf_to_crlf(git_buf *tgt, const git_buf *src)
+{
+	const char *start = src->ptr;
+	const char *end = start + src->size;
+	const char *scan = start;
+	const char *next = memchr(scan, '\n', src->size);
+
+	assert(tgt != src);
+
+	if (!next)
+		return GIT_ENOTFOUND;
+
+	/* attempt to reduce reallocs while in the loop */
+	if (git_buf_grow(tgt, src->size + (src->size >> 4) + 1) < 0)
+		return -1;
+	tgt->size = 0;
+
+	for (; next; scan = next + 1, next = memchr(scan, '\n', end - scan)) {
+		size_t copylen = next - scan;
+		/* don't convert existing \r\n to \r\r\n */
+		size_t extralen = (next > start && next[-1] == '\r') ? 1 : 2;
+		size_t needsize = tgt->size + copylen + extralen + 1;
+
+		if (tgt->asize < needsize && git_buf_grow(tgt, needsize) < 0)
+			return -1;
+
+		if (next > scan) {
+			memcpy(tgt->ptr + tgt->size, scan, copylen);
+			tgt->size += copylen;
+		}
+		if (extralen == 2)
+			tgt->ptr[tgt->size++] = '\r';
+		tgt->ptr[tgt->size++] = '\n';
+	}
+
+	return git_buf_put(tgt, scan, end - scan);
+}
+
 int git_buf_text_common_prefix(git_buf *buf, const git_strarray *strings)
 {
 	size_t i;