From 2e3cec9f53a10e7c71da4a0d999a00bddae2935c Mon Sep 17 00:00:00 2001
From: John Tsiombikas <nuclear@member.fsf.org>
Date: Mon, 18 Nov 2019 15:08:38 +0200
Subject: [PATCH] split and span mess

---
 libvisor/include/visor.h |    6 +++++-
 libvisor/src/vilibc.h    |    3 +++
 libvisor/src/visor.c     |   39 +++++++++++++++++++++++++++++++++++----
 3 files changed, 43 insertions(+), 5 deletions(-)

diff --git a/libvisor/include/visor.h b/libvisor/include/visor.h
index 55dcc48..73fb7dc 100644
--- a/libvisor/include/visor.h
+++ b/libvisor/include/visor.h
@@ -26,8 +26,9 @@ struct visor;
 struct vi_buffer;
 
 struct vi_span {
-	vi_addr beg;
+	vi_addr start;
 	unsigned long size;
+	int src;
 };
 
 enum vi_motdir {
@@ -135,6 +136,9 @@ int vi_buf_read(struct vi_buffer *vb, const char *path);
 int vi_buf_write(struct vi_buffer *vb, const char *path);
 long vi_buf_size(struct vi_buffer *vb);
 
+/* find the span which corresponds to the specified text position */
+struct vi_span *vi_buf_find_span(struct vi_buffer *vb, vi_addr at);
+
 void vi_buf_ins_begin(struct vi_buffer *vb, vi_motion mot);
 void vi_buf_insert(struct vi_buffer *vb, char *s);
 void vi_buf_ins_end(struct vi_buffer *vb);
diff --git a/libvisor/src/vilibc.h b/libvisor/src/vilibc.h
index 047fa18..f9e8d06 100644
--- a/libvisor/src/vilibc.h
+++ b/libvisor/src/vilibc.h
@@ -30,6 +30,7 @@ along with this program.  If not, see <https://www.gnu.org/licenses/>.
 #include <stdarg.h>
 #include <ctype.h>
 #include <limit.h>
+#include <assert.h>
 #else
 
 int atoi(const char *str);
@@ -71,6 +72,8 @@ int isspace(int c);
 int toupper(int c);
 int tolower(int c);
 
+#define assert(x)
+
 #endif	/* !HAVE_LIBC */
 
 struct visor;
diff --git a/libvisor/src/visor.c b/libvisor/src/visor.c
index b4ef116..08c88a7 100644
--- a/libvisor/src/visor.c
+++ b/libvisor/src/visor.c
@@ -179,12 +179,32 @@ struct vi_buffer *vi_prev_buf(struct visor *vi)
 	return vi->buflist ? vi->buflist->prev : 0;
 }
 
-static int add_span(struct vi_buffer *vb, int src, vi_addr start, unsigned long size)
+/* split_span splits the span sp. if size > 0 it moves the second part to sp+2,
+ * leaving an empty place at sp+1 for the new span. The start point of the
+ * second part is adjusted by size.
+ *
+ * It can't fail, because it's always called with the span array having at
+ * least two empty slots (see: add_span).
+ */
+void split_span(struct vi_buffer *vb, struct vi_span *sp, vi_addr at, unsigned long size)
 {
+	struct vi_span *tail = sp + (size ? 2 : 1);
+	int num_move = vb->num_spans - sp - 1;
+
+	memmove(tail + 1, sp + 1, num_move);
+	vb->num_span += tail - sp;
+
+	sp->size ... CONTINUE HERE.
+}
+
+static int add_span(struct vi_buffer *vb, vi_addr at, int src, vi_addr start, unsigned long size)
+{
+	int i;
 	struct visor *vi = vb->vi;
 	struct vi_span *sp;
 
-	if(vb->num_spans >= vb->max_spans) {
+	/* make sure we have space for at least two new spans (split + add) */
+	if(vb->num_spans + 1 >= vb->max_spans) {
 		int newmax = vb->max_spans > 0 ? (vb->max_spans << 1) : 16;
 		struct vi_span *tmp = vi_realloc(vb->spans, newmax * sizeof *tmp);
 		if(!tmp) return -1;
@@ -192,9 +212,16 @@ static int add_span(struct vi_buffer *vb, int src, vi_addr start, unsigned long
 		vb->max_spans = newmax;
 	}
 
-	sp = vb->spans + vb->num_spans++;
-	sp->beg = start;
+	if((sp = vi_buf_find_span(vb, at))) {
+		split_span(vb, sp++, at, size);
+	} else {
+		sp = vb->spans + vb->num_spans;
+	}
+
+	sp->src = src;
+	sp->addr = start;
 	sp->size = size;
+	vb->num_spans++;
 	return 0;
 }
 
@@ -262,3 +289,7 @@ int vi_buf_read(struct vi_buffer *vb, const char *path)
 	vb->orig_size = fsz;
 	return 0;
 }
+
+int vi_buf_write(struct vi_buffer *vb, const char *path)
+{
+}
-- 
1.7.10.4