playing with ramfs implemenatation

xrxs.c

@@ -22,20 +22,120 @@ char *ccat(char *dst, char c) { int len = slen(dst); dst[len] = c; dst[len + 1]
 
 /* clang-format on */
 
-int i = 0;
+static char Ebad[] = "something bad happened";
+static char Enomem[] = "no memory";
+
+typedef struct Ramfile Ramfile;
+struct Ramfile {
+  char* data;
+  int ndata;
+};
 
 void fsread(Req* r) {
-  char numReads[32];
-  i++;
-  sprintf(numReads, "Hello from 9p!\n%d reads\n", i);
-  readstr(r, numReads);
+  Ramfile* rf;
+  vlong offset;
+  long count;
+
+  rf = r->fid->file->aux;
+  offset = r->ifcall.offset;
+  count = r->ifcall.count;
+
+  /*print("read %ld %lld\n", *count, offset); */
+  if (offset >= rf->ndata) {
+    r->ofcall.count = 0;
+    respond(r, nil);
+    return;
+  }
+
+  if (offset + count >= rf->ndata)
+    count = rf->ndata - offset;
+
+  memmove(r->ofcall.data, rf->data + offset, count);
+  r->ofcall.count = count;
   respond(r, nil);
 }
 
+void fswrite(Req* r) {
+  void* v;
+  Ramfile* rf;
+  vlong offset;
+  long count;
+
+  rf = r->fid->file->aux;
+  offset = r->ifcall.offset;
+  count = r->ifcall.count;
+
+  if (offset + count >= rf->ndata) {
+    v = realloc(rf->data, offset + count);
+    if (v == nil) {
+      respond(r, Enomem);
+      return;
+    }
+    rf->data = v;
+    rf->ndata = offset + count;
+    r->fid->file->dir.length = rf->ndata;
+  }
+  memmove(rf->data + offset, r->ifcall.data, count);
+  r->ofcall.count = count;
+  respond(r, nil);
+}
+
+void fscreate(Req* r) {
+  Ramfile* rf;
+  File* f;
+
+  if (
+    f = createfile(
+      r->fid->file,
+      r->ifcall.name,
+      nil,
+      r->ifcall.perm,
+      nil)) {
+    rf = emalloc9p(sizeof *rf);
+    f->aux = rf;
+    r->fid->file = f;
+    r->ofcall.qid = f->dir.qid;
+    respond(r, nil);
+    return;
+  }
+  respond(r, Ebad);
+}
+
+void fsopen(Req* r) {
+  Ramfile* rf;
+
+  rf = r->fid->file->aux;
+
+  if (rf && (r->ifcall.mode & OTRUNC)) {
+    rf->ndata = 0;
+    r->fid->file->dir.length = 0;
+  }
+
+  respond(r, nil);
+}
+
+void fsdestroyfile(File* f) {
+  Ramfile* rf;
+
+  /*fprint(2, "clunk\n"); */
+  rf = f->aux;
+  if (rf) {
+    free(rf->data);
+    free(rf);
+  }
+}
+
 Srv fs = {
+  .open = fsopen,
   .read = fsread,
+  .write = fswrite,
+  .create = fscreate,
 };
 
+int threadmaybackground(void) {
+  return 1;
+}
+
 void threadmain(int argc, char* argv[]) {
   Tree* tree;
   char* mtpt = nil;
@@ -60,10 +160,8 @@ void threadmain(int argc, char* argv[]) {
 
   /* create a single file called 'hello'. reading it calls fsread() */
 
-  tree = alloctree(nil, nil, DMDIR | 0555, nil);
-  fs.tree = tree;
-  fs.foreground = 1;
-  createfile(tree->root, "hello", nil, 0555, nil);
+	fs.tree = alloctree(nil, nil, DMDIR|0777, fsdestroyfile);
+	fs.foreground = 1;
 
   if (argc >= 3) {
     if (mtpt != nil && access(mtpt, AEXIST) < 0 && access(mtpt, AEXIST) < 0)