Add basic diff view

Finally, xdiff is used to show per-file diffs via commit view.

Signed-off-by: Lars Hjemli <hjemli@gmail.com>

ui-diff.c

@@ -0,0 +1,131 @@
+/* ui-diff.c: show diff between two blobs
+ *
+ * Copyright (C) 2006 Lars Hjemli
+ *
+ * Licensed under GNU General Public License v2
+ *   (see COPYING for full license text)
+ */
+
+#include "cgit.h"
+#include "xdiff.h"
+
+char *diff_buffer;
+int diff_buffer_size;
+
+
+/*
+ * print a single line returned from xdiff
+ */
+static void print_line(char *line, int len)
+{
+	char *class = "ctx";
+	char c = line[len-1];
+
+	if (line[0] == '+')
+		class = "add";
+	else if (line[0] == '-')
+		class = "del";
+	else if (line[0] == '@')
+		class = "hunk";
+
+	htmlf("<div class='%s'>", class);
+	line[len-1] = '\0';
+	html_txt(line);
+	html("</div>");
+	line[len-1] = c;
+}
+
+/*
+ * Receive diff-buffers from xdiff and concatenate them as
+ * needed across multiple callbacks.
+ *
+ * This is basically a copy of xdiff-interface.c/xdiff_outf(),
+ * ripped from git and modified to use globals instead of
+ * a special callback-struct.
+ */
+int diff_cb(void *priv_, mmbuffer_t *mb, int nbuf)
+{
+	int i;
+
+	for (i = 0; i < nbuf; i++) {
+		if (mb[i].ptr[mb[i].size-1] != '\n') {
+			/* Incomplete line */
+			diff_buffer = xrealloc(diff_buffer,
+					       diff_buffer_size + mb[i].size);
+			memcpy(diff_buffer + diff_buffer_size,
+			       mb[i].ptr, mb[i].size);
+			diff_buffer_size += mb[i].size;
+			continue;
+		}
+
+		/* we have a complete line */
+		if (!diff_buffer) {
+			print_line(mb[i].ptr, mb[i].size);
+			continue;
+		}
+		diff_buffer = xrealloc(diff_buffer,
+				       diff_buffer_size + mb[i].size);
+		memcpy(diff_buffer + diff_buffer_size, mb[i].ptr, mb[i].size);
+		print_line(diff_buffer, diff_buffer_size + mb[i].size);
+		free(diff_buffer);
+		diff_buffer = NULL;
+		diff_buffer_size = 0;
+	}
+	if (diff_buffer) {
+		print_line(diff_buffer, diff_buffer_size);
+		free(diff_buffer);
+		diff_buffer = NULL;
+		diff_buffer_size = 0;
+	}
+	return 0;
+}
+
+static int load_mmfile(mmfile_t *file, const unsigned char *sha1)
+{
+	char type[20];
+
+	if (is_null_sha1(sha1)) {
+		file->ptr = (char *)"";
+		file->size = 0;
+	} else {
+		file->ptr = read_sha1_file(sha1, type, &file->size);
+	}
+	return 1;
+}
+
+static void run_diff(const unsigned char *sha1, const unsigned char *sha2)
+{
+	mmfile_t file1, file2;
+	xpparam_t diff_params;
+	xdemitconf_t emit_params;
+	xdemitcb_t emit_cb;
+
+	if (!load_mmfile(&file1, sha1) || !load_mmfile(&file2, sha2)) {
+		cgit_print_error("Unable to load files for diff");
+		return;
+	}
+
+	diff_params.flags = XDF_NEED_MINIMAL;
+
+	emit_params.ctxlen = 3;
+	emit_params.flags = XDL_EMIT_FUNCNAMES;
+
+	emit_cb.outf = diff_cb;
+
+	xdl_diff(&file1, &file2, &diff_params, &emit_params, &emit_cb);
+}
+
+
+
+void cgit_print_diff(const char *old_hex, const char *new_hex)
+{
+	unsigned char sha1[20], sha2[20];
+
+	get_sha1(old_hex, sha1);
+	get_sha1(new_hex, sha2);
+
+	html("<h2>diff</h2>\n");
+	html("<table class='diff'><tr><td>");
+	run_diff(sha1, sha2);
+	html("</td></tr></table>");
+}