kernel/pipes: read & write support

1 files changed, 43 insertions, 0 deletions

diff --git a/src/kernel/pipe.c b/src/kernel/pipe.c
new file mode 100644
index 0000000..8afd359
--- /dev/null
+++ b/src/kernel/pipe.c
@@ -0,0 +1,43 @@
+#include <kernel/mem/virt.h>
+#include <kernel/panic.h>
+#include <kernel/pipe.h>
+#include <kernel/util.h>
+
+void pipe_joinqueue(struct handle *h, bool wants_write,
+		struct process *proc, void __user *pbuf, size_t pbuflen)
+{
+	struct process **slot = wants_write ? &h->pipe.reader : &h->pipe.writer;
+	if (*slot) {
+		assert((*slot)->state == PS_WAITS4PIPE);
+		panic_unimplemented();
+	}
+
+	process_transition(proc, PS_WAITS4PIPE);
+	*slot = proc;
+	proc->waits4pipe.pipe = h;
+	proc->waits4pipe.buf = pbuf;
+	proc->waits4pipe.len = pbuflen;
+}
+
+void pipe_trytransfer(struct handle *h) {
+	struct process *rdr = h->pipe.reader, *wtr = h->pipe.writer;
+	int len;
+	if (!(rdr && wtr)) return;
+	assert(rdr->state == PS_WAITS4PIPE);
+	assert(wtr->state == PS_WAITS4PIPE);
+	
+	len = min(rdr->waits4pipe.len, wtr->waits4pipe.len);
+
+	if (!virt_cpy(
+			rdr->pages, rdr->waits4pipe.buf,
+			wtr->pages, wtr->waits4pipe.buf, len))
+	{
+		panic_unimplemented();
+	}
+	process_transition(rdr, PS_RUNNING);
+	process_transition(wtr, PS_RUNNING);
+	h->pipe.reader = NULL;
+	h->pipe.writer = NULL;
+	regs_savereturn(&rdr->regs, len);
+	regs_savereturn(&wtr->regs, len);
+}