hacking the spans

[visor] / libvisor / src / visor.c

diff --git a/libvisor/src/visor.c b/libvisor/src/visor.c
index b4ef116..cefc924 100644 (file)
--- a/libvisor/src/visor.c
+++ b/libvisor/src/visor.c
@@ -179,12 +179,30 @@ 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->spans + vb->num_spans - sp - 1;
+
+       memmove(tail + 1, sp + 1, num_move);
+       vb->num_spans += tail - sp;
+
+}
+
+static int add_span(struct vi_buffer *vb, vi_addr at, int src, vi_addr start, unsigned long size)
 {
        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 +210,16 @@ 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->start = start;
        sp->size = size;
+       vb->num_spans++;
        return 0;
 }
 
@@ -229,7 +254,7 @@ int vi_buf_read(struct vi_buffer *vb, const char *path)
 
        vi_buf_reset(vb);
 
-       if(!(fp = vi_open(path))) {
+       if(!(fp = vi_open(path, VI_RDONLY | VI_CREAT))) {
                return -1;
        }
        plen = strlen(path);
@@ -253,7 +278,7 @@ int vi_buf_read(struct vi_buffer *vb, const char *path)
                        vb->file_mapped = 1;
                }
 
-               if(add_span(vb, SPAN_ORIG, 0, fsz) == -1) {
+               if(add_span(vb, 0, SPAN_ORIG, 0, fsz) == -1) {
                        vi_error(vi, "failed to allocate span\n");
                        vi_buf_reset(vb);
                        return -1;
@@ -262,3 +287,79 @@ 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)
+{
+       int i, wbuf_count;
+       struct visor *vi = vb->vi;
+       vi_file *fp;
+       static char wbuf[512];
+
+       if(!path) path = vb->path;
+       if(!path) {
+               vi_error(vi, "failed to write buffer, unknown path\n");
+               return -1;
+       }
+
+       if(!(fp = vi_open(path, VI_WRONLY | VI_CREAT))) {
+               vi_error(vi, "failed to open %s for writing\n", path);
+               return -1;
+       }
+
+       wbuf_count = 0;
+       for(i=0; i<vb->num_spans; i++) {
+               struct vi_span *sp = vb->spans + i;
+               const char *sptxt = vi_buf_span_text(vb, sp);
+               int n, count = 0;
+               while(count < sp->size) {
+                       n = sp->size - count;
+                       if(n > sizeof wbuf - wbuf_count) {
+                               n = sizeof wbuf - wbuf_count;
+                       }
+                       memcpy(wbuf + wbuf_count, sptxt + count, n);
+                       count += n;
+                       wbuf_count += n;
+               }
+
+               if(wbuf_count >= sizeof wbuf) {
+                       vi_write(fp, wbuf, wbuf_count);
+               }
+       }
+
+       if(wbuf_count > 0) {
+               vi_write(fp, wbuf, wbuf_count);
+       }
+       vi_close(fp);
+       return 0;
+}
+
+long vi_buf_size(struct vi_buffer *vb)
+{
+       int i;
+       long sz = 0;
+
+       for(i=0; i<vb->num_spans; i++) {
+               sz += vb->spans[i].size;
+       }
+       return sz;
+}
+
+struct vi_span *vi_buf_find_span(struct vi_buffer *vb, vi_addr at)
+{
+       int i;
+       long sz = 0;
+
+       for(i=0; i<vb->num_spans; i++) {
+               sz += vb->spans[i].size;
+               if(sz > at) {
+                       return vb->spans + i;
+               }
+       }
+       return 0;
+}
+
+const char *vi_buf_span_text(struct vi_buffer *vb, struct vi_span *sp)
+{
+       const char *buf = sp->src == SPAN_ORIG ? vb->orig : vb->add;
+       return buf + sp->start;
+}