From: Matthias Kruk <m@m10k.eu>
Date: Wed, 27 Nov 2019 06:27:21 +0000 (+0900)
Subject: Implement message handling in stdio process
X-Git-Url: https://git.corax.cc/?a=commitdiff_plain;h=23e6695fbf8276087b15effd4d474ef298a86cd2;p=corax

Implement message handling in stdio process
---

diff --git a/include/corax/ipc.h b/include/corax/ipc.h
index 2c941a5..4cc3291 100644
--- a/include/corax/ipc.h
+++ b/include/corax/ipc.h
@@ -1,19 +1,41 @@
 #ifndef __CORAX_IPC_H
 #define __CORAX_IPC_H
 
-struct cxmsg {
-	u32_t cm_src;
-	u32_t cm_dst;
-	u32_t cm_len;
+#define CX_MSG_RETVAL 0
+#define CX_MSG_READ   1
+#define CX_MSG_WRITE  2
+#define CX_MSG_FLUSH  3
+
+struct cxmsg_data_stdio {
+	int  sio_fd;
+	char sio_data[];
+};
 
-	u32_t cm_type;
+struct cxmsg_hdr {
+	u32_t cxh_src;
+	u32_t cxh_dst;
+	u32_t cxh_len;
+	u32_t cxh_type;
+};
+
+struct cxmsg {
+	struct cxmsg_hdr cm_hdr;
 
 	union {
+		int CM_retval;
+		struct cxmsg_data_stdio CM_stdio;
 		u8_t  CM_data[CONFIG_IPC_MSGSIZE];
 	} CM_dat;
 };
 
-#define cm_data CM_dat.CM_data
+#define cm_src    cm_hdr.cxh_src
+#define cm_dst    cm_hdr.cxh_dst
+#define cm_len    cm_hdr.cxh_len
+#define cm_type   cm_hdr.cxh_type
+
+#define cm_stdio  CM_dat.CM_stdio
+#define cm_retval CM_dat.CM_retval
+#define cm_data   CM_dat.CM_data
 
 #define PID_INIT  1
 #define PID_NET   10
diff --git a/kernel/core/stdio.c b/kernel/core/stdio.c
index 4af8b34..72c3c33 100644
--- a/kernel/core/stdio.c
+++ b/kernel/core/stdio.c
@@ -1,8 +1,34 @@
 #include <config.h>
 #include <crxstd.h>
 #include <corax/errno.h>
+#include <stddef.h>
 
-extern int wait(int*);
+#define STDIN  0
+#define STDOUT 1
+#define STDERR 2
+
+static int stdio_read(int fd, char *dst, size_t dsize)
+{
+	return(-ENOSYS);
+}
+
+static int stdio_write(int fd, const char *src, const size_t slen)
+{
+	return(-ENOSYS);
+}
+
+static int stdio_flush(int fd)
+{
+	if(fd < STDIN) {
+		return(-EINVAL);
+	}
+
+	if(fd > STDERR) {
+		return(-EBADF);
+	}
+
+	return(0);
+}
 
 void _stdio(void)
 {
@@ -13,11 +39,55 @@ void _stdio(void)
 		err = cxrecv(PID_ANY, &msg);
 		err = 0;
 
+		/*
+		 * The `cm_len' member includes the number of bytes consumed by the header
+		 * of the message, so we need to substract offsetof(struct cxmsg, cm_data)
+		 * to get the number of bytes that are supposed to be in the payload.
+		 */
+
+		if((msg.cm_len - offsetof(struct cxmsg, cm_stdio.sio_data)) > msg.cm_len) {
+			/* underflow - discard message */
+			continue;
+		}
+
+		msg.cm_len -= offsetof(struct cxmsg, cm_stdio.sio_data);
+
+		if(msg.cm_len > (sizeof(msg.cm_data) - offsetof(struct cxmsg, cm_stdio.sio_data))) {
+			/* message allegedly contains more data than possible - malicious input? */
+			continue;
+		}
+
+		/* msg.cm_len now contains the number of bytes in sio_data */
+
 		if(err > 0) {
-			/* FIXME: Handle message */
+			switch(msg.cm_type) {
+			case CX_MSG_READ:
+				err = stdio_read(msg.cm_stdio.sio_fd,
+								 msg.cm_stdio.sio_data,
+								 msg.cm_len);
+				break;
+
+			case CX_MSG_WRITE:
+				err = stdio_write(msg.cm_stdio.sio_fd,
+								  msg.cm_stdio.sio_data,
+								  msg.cm_len);
+				break;
+
+			case CX_MSG_FLUSH:
+				err = stdio_flush(msg.cm_stdio.sio_fd);
+				break;
+
+			default:
+				/* malformed input? */
+				err = -EINVAL;
+				break;
+			}
 
 			msg.cm_dst = msg.cm_src;
-			msg.cm_type = -ENOSYS;
+			msg.cm_type = CX_MSG_RETVAL;
+			msg.cm_retval = err;
+			msg.cm_len = sizeof(msg.cm_hdr) + sizeof(int);
+
 			cxsend(msg.cm_dst, &msg);
 		}
 	}