1 files changed, 261 insertions, 0 deletions
diff --git a/src/libgit2/diff_xdiff.c b/src/libgit2/diff_xdiff.c
new file mode 100644
index 000000000..5f56c5209
--- /dev/null
+++ b/src/libgit2/diff_xdiff.c
@@ -0,0 +1,261 @@
+/*
+ * Copyright (C) the libgit2 contributors. All rights reserved.
+ *
+ * This file is part of libgit2, distributed under the GNU GPL v2 with
+ * a Linking Exception. For full terms see the included COPYING file.
+ */
+
+#include "diff_xdiff.h"
+
+#include "git2/errors.h"
+#include "diff.h"
+#include "diff_driver.h"
+#include "patch_generate.h"
+#include "utf8.h"
+
+static int git_xdiff_scan_int(const char **str, int *value)
+{
+	const char *scan = *str;
+	int v = 0, digits = 0;
+	/* find next digit */
+	for (scan = *str; *scan && !git__isdigit(*scan); scan++);
+	/* parse next number */
+	for (; git__isdigit(*scan); scan++, digits++)
+		v = (v * 10) + (*scan - '0');
+	*str = scan;
+	*value = v;
+	return (digits > 0) ? 0 : -1;
+}
+
+static int git_xdiff_parse_hunk(git_diff_hunk *hunk, const char *header)
+{
+	/* expect something of the form "@@ -%d[,%d] +%d[,%d] @@" */
+	if (*header != '@')
+		goto fail;
+	if (git_xdiff_scan_int(&header, &hunk->old_start) < 0)
+		goto fail;
+	if (*header == ',') {
+		if (git_xdiff_scan_int(&header, &hunk->old_lines) < 0)
+			goto fail;
+	} else
+		hunk->old_lines = 1;
+	if (git_xdiff_scan_int(&header, &hunk->new_start) < 0)
+		goto fail;
+	if (*header == ',') {
+		if (git_xdiff_scan_int(&header, &hunk->new_lines) < 0)
+			goto fail;
+	} else
+		hunk->new_lines = 1;
+	if (hunk->old_start < 0 || hunk->new_start < 0)
+		goto fail;
+
+	return 0;
+
+fail:
+	git_error_set(GIT_ERROR_INVALID, "malformed hunk header from xdiff");
+	return -1;
+}
+
+typedef struct {
+	git_xdiff_output *xo;
+	git_patch_generated *patch;
+	git_diff_hunk hunk;
+	int old_lineno, new_lineno;
+	mmfile_t xd_old_data, xd_new_data;
+} git_xdiff_info;
+
+static int diff_update_lines(
+	git_xdiff_info *info,
+	git_diff_line *line,
+	const char *content,
+	size_t content_len)
+{
+	const char *scan = content, *scan_end = content + content_len;
+
+	for (line->num_lines = 0; scan < scan_end; ++scan)
+		if (*scan == '\n')
+			++line->num_lines;
+
+	line->content     = content;
+	line->content_len = content_len;
+
+	/* expect " "/"-"/"+", then data */
+	switch (line->origin) {
+	case GIT_DIFF_LINE_ADDITION:
+	case GIT_DIFF_LINE_DEL_EOFNL:
+		line->old_lineno = -1;
+		line->new_lineno = info->new_lineno;
+		info->new_lineno += (int)line->num_lines;
+		break;
+	case GIT_DIFF_LINE_DELETION:
+	case GIT_DIFF_LINE_ADD_EOFNL:
+		line->old_lineno = info->old_lineno;
+		line->new_lineno = -1;
+		info->old_lineno += (int)line->num_lines;
+		break;
+	case GIT_DIFF_LINE_CONTEXT:
+	case GIT_DIFF_LINE_CONTEXT_EOFNL:
+		line->old_lineno = info->old_lineno;
+		line->new_lineno = info->new_lineno;
+		info->old_lineno += (int)line->num_lines;
+		info->new_lineno += (int)line->num_lines;
+		break;
+	default:
+		git_error_set(GIT_ERROR_INVALID, "unknown diff line origin %02x",
+			(unsigned int)line->origin);
+		return -1;
+	}
+
+	return 0;
+}
+
+static int git_xdiff_cb(void *priv, mmbuffer_t *bufs, int len)
+{
+	git_xdiff_info *info = priv;
+	git_patch_generated *patch = info->patch;
+	const git_diff_delta *delta = patch->base.delta;
+	git_patch_generated_output *output = &info->xo->output;
+	git_diff_line line;
+	size_t buffer_len;
+
+	if (len == 1) {
+		output->error = git_xdiff_parse_hunk(&info->hunk, bufs[0].ptr);
+		if (output->error < 0)
+			return output->error;
+
+		info->hunk.header_len = bufs[0].size;
+		if (info->hunk.header_len >= sizeof(info->hunk.header))
+			info->hunk.header_len = sizeof(info->hunk.header) - 1;
+
+		/* Sanitize the hunk header in case there is invalid Unicode */
+		buffer_len = git_utf8_valid_buf_length(bufs[0].ptr, info->hunk.header_len);
+		/* Sanitizing the hunk header may delete the newline, so add it back again if there is room */
+		if (buffer_len < info->hunk.header_len) {
+			bufs[0].ptr[buffer_len] = '\n';
+			buffer_len += 1;
+			info->hunk.header_len = buffer_len;
+		}
+
+		memcpy(info->hunk.header, bufs[0].ptr, info->hunk.header_len);
+		info->hunk.header[info->hunk.header_len] = '\0';
+
+		if (output->hunk_cb != NULL &&
+			(output->error = output->hunk_cb(
+				delta, &info->hunk, output->payload)))
+			return output->error;
+
+		info->old_lineno = info->hunk.old_start;
+		info->new_lineno = info->hunk.new_start;
+	}
+
+	if (len == 2 || len == 3) {
+		/* expect " "/"-"/"+", then data */
+		line.origin =
+			(*bufs[0].ptr == '+') ? GIT_DIFF_LINE_ADDITION :
+			(*bufs[0].ptr == '-') ? GIT_DIFF_LINE_DELETION :
+			GIT_DIFF_LINE_CONTEXT;
+
+		if (line.origin == GIT_DIFF_LINE_ADDITION)
+			line.content_offset = bufs[1].ptr - info->xd_new_data.ptr;
+		else if (line.origin == GIT_DIFF_LINE_DELETION)
+			line.content_offset = bufs[1].ptr - info->xd_old_data.ptr;
+		else
+			line.content_offset = -1;
+
+		output->error = diff_update_lines(
+			info, &line, bufs[1].ptr, bufs[1].size);
+
+		if (!output->error && output->data_cb != NULL)
+			output->error = output->data_cb(
+				delta, &info->hunk, &line, output->payload);
+	}
+
+	if (len == 3 && !output->error) {
+		/* If we have a '+' and a third buf, then we have added a line
+		 * without a newline and the old code had one, so DEL_EOFNL.
+		 * If we have a '-' and a third buf, then we have removed a line
+		 * with out a newline but added a blank line, so ADD_EOFNL.
+		 */
+		line.origin =
+			(*bufs[0].ptr == '+') ? GIT_DIFF_LINE_DEL_EOFNL :
+			(*bufs[0].ptr == '-') ? GIT_DIFF_LINE_ADD_EOFNL :
+			GIT_DIFF_LINE_CONTEXT_EOFNL;
+
+		line.content_offset = -1;
+
+		output->error = diff_update_lines(
+			info, &line, bufs[2].ptr, bufs[2].size);
+
+		if (!output->error && output->data_cb != NULL)
+			output->error = output->data_cb(
+				delta, &info->hunk, &line, output->payload);
+	}
+
+	return output->error;
+}
+
+static int git_xdiff(git_patch_generated_output *output, git_patch_generated *patch)
+{
+	git_xdiff_output *xo = (git_xdiff_output *)output;
+	git_xdiff_info info;
+	git_diff_find_context_payload findctxt;
+
+	memset(&info, 0, sizeof(info));
+	info.patch = patch;
+	info.xo    = xo;
+
+	xo->callback.priv = &info;
+
+	git_diff_find_context_init(
+		&xo->config.find_func, &findctxt, git_patch_generated_driver(patch));
+	xo->config.find_func_priv = &findctxt;
+
+	if (xo->config.find_func != NULL)
+		xo->config.flags |= XDL_EMIT_FUNCNAMES;
+	else
+		xo->config.flags &= ~XDL_EMIT_FUNCNAMES;
+
+	/* TODO: check ofile.opts_flags to see if driver-specific per-file
+	 * updates are needed to xo->params.flags
+	 */
+
+	if (git_patch_generated_old_data(&info.xd_old_data.ptr, &info.xd_old_data.size, patch) < 0 ||
+	    git_patch_generated_new_data(&info.xd_new_data.ptr, &info.xd_new_data.size, patch) < 0)
+		return -1;
+
+	xdl_diff(&info.xd_old_data, &info.xd_new_data,
+		&xo->params, &xo->config, &xo->callback);
+
+	git_diff_find_context_clear(&findctxt);
+
+	return xo->output.error;
+}
+
+void git_xdiff_init(git_xdiff_output *xo, const git_diff_options *opts)
+{
+	uint32_t flags = opts ? opts->flags : 0;
+
+	xo->output.diff_cb = git_xdiff;
+
+	xo->config.ctxlen = opts ? opts->context_lines : 3;
+	xo->config.interhunkctxlen = opts ? opts->interhunk_lines : 0;
+
+	if (flags & GIT_DIFF_IGNORE_WHITESPACE)
+		xo->params.flags |= XDF_WHITESPACE_FLAGS;
+	if (flags & GIT_DIFF_IGNORE_WHITESPACE_CHANGE)
+		xo->params.flags |= XDF_IGNORE_WHITESPACE_CHANGE;
+	if (flags & GIT_DIFF_IGNORE_WHITESPACE_EOL)
+		xo->params.flags |= XDF_IGNORE_WHITESPACE_AT_EOL;
+	if (flags & GIT_DIFF_INDENT_HEURISTIC)
+		xo->params.flags |= XDF_INDENT_HEURISTIC;
+
+	if (flags & GIT_DIFF_PATIENCE)
+		xo->params.flags |= XDF_PATIENCE_DIFF;
+	if (flags & GIT_DIFF_MINIMAL)
+		xo->params.flags |= XDF_NEED_MINIMAL;
+
+	if (flags & GIT_DIFF_IGNORE_BLANK_LINES)
+		xo->params.flags |= XDF_IGNORE_BLANK_LINES;
+
+	xo->callback.out_line = git_xdiff_cb;
+}