2 files changed, 33 insertions, 0 deletions
diff --git a/core/runtime.c b/core/runtime.c
index 4a857c7..19ff215 100644
--- a/core/runtime.c
+++ b/core/runtime.c
@@ -201,6 +201,35 @@ unsigned char *pure_runtime_ingress(PureTicket ticket, size_t *size) {
     return (unsigned char *)w->resource.body.data;
 }
 
+PureResult pure_runtime_grow(PureTicket ticket, size_t size) {
+    PureWork *w = lookup(ticket, true);
+    PureRuntime *r = ticket.runtime;
+    if (!w || r->running || w->state != RECEIVING || w->input != PURE_INPUT_WRITE || w->parent.runtime)
+        return PURE_INVALID;
+    size_t had = w->resource.body.size;
+    if (size <= had) return PURE_OK;
+    if (size - had > r->budget - r->retained) {
+        METRIC(++r->budget_rejections);
+        return PURE_BUDGET;
+    }
+    if (!r->host.allocate) return PURE_ALLOCATION;
+    PureResource grown = {0};
+    r->running = true;
+    bool ok = r->host.allocate(r->host.context, size, &grown);
+    r->running = false;
+    if (!ok || !grown.body.data || grown.body.size != size || !grown.release) {
+        dispose(r, &grown);
+        return PURE_ALLOCATION;
+    }
+    if (had) memcpy((unsigned char *)grown.body.data, w->resource.body.data, had);
+    dispose(r, &w->resource);
+    w->resource = grown;
+    w->charged += size - had;
+    r->retained += size - had;
+    METRIC(if (r->retained > r->peak_retained) r->peak_retained = r->retained);
+    return PURE_OK;
+}
+
 bool pure_runtime_step(PureRuntime *r) {
     if (!r || r->running || r->ready_head == NONE) return false;
 #ifdef PURE_ASYNC_EFFECTS
diff --git a/core/runtime.h b/core/runtime.h
index 70f5d08..fd19525 100644
--- a/core/runtime.h
+++ b/core/runtime.h
@@ -110,6 +110,10 @@ bool pure_runtime_bind(PureRuntime *, PureWork *, size_t capacity);
 PureResult pure_runtime_accept(PureRuntime *, PureInput, const char *key,
                                int64_t expected, size_t input_size, PureTicket *out);
 unsigned char *pure_runtime_ingress(PureTicket, size_t *size);
+/* A WRITE input still being filled grows to size with its bytes kept (the
+ * ingress moves: take it again), charged to the budget as its admission was;
+ * BUDGET or ALLOCATION leave it as it was. */
+PureResult pure_runtime_grow(PureTicket, size_t size);
 bool pure_runtime_ready(PureTicket);
 bool pure_runtime_step(PureRuntime *); /* execute at most one ready job */
 bool pure_runtime_result(PureTicket, PureOutcome *out);