sycall: conform to POSIX

arch/at91sam3x8e/syscall.S

@@ -39,8 +39,8 @@ syscall:
 	mov	r12,	r3		/* arg3 */
 	mov	r2,	r12
 
-	pop	{r3}
-	mov	r12,	r3
+	pop	{r4}
+	mov	r12,	r4
 
 	/* stack params begin at 12 bytes offset because we already pushed three registers */
 	ldr	r3,	[sp, #12]	/* arg4 */

include/ardix/syscall.h

@@ -27,8 +27,8 @@ extern const int (*sys_table[NSYSCALLS])(sysarg_t arg1, sysarg_t arg2, sysarg_t
 /* catchall handler that returns -ENOSYS */
 int sys_stub(void);
 
-int sys_read(int fd, void *buf, size_t len, size_t off);
-int sys_write(int fd, const void *buf, size_t len, size_t off);
+int sys_read(int fd, void *buf, size_t len);
+int sys_write(int fd, const void *buf, size_t len);
 
 /*
  * Copyright (c) 2020 Felix Kopp <sandtler@sandtler.club>

include/unistd.h

@@ -5,7 +5,7 @@
 
 #include <stdint.h>
 
-ssize_t pwrite(int fildes, const void *buf, size_t nbyte, off_t offset);
+ssize_t read(int fildes, void *buf, size_t nbyte);
 ssize_t write(int fildes, const void *buf, size_t nbyte);
 
 /*

kernel/fs/write.c

@@ -10,25 +10,25 @@
 #include <stddef.h>
 #include <toolchain.h>
 
-ssize_t sys_write(int fd, __user const void *buf, size_t len, size_t off)
+ssize_t sys_write(int fd, __user const void *buf, size_t len)
 {
 	ssize_t ret;
 	void *copy;
 
-	if (fd != 1) /* we only support stdout (serial console) right now ... */
-		return -ENOTSUP;
-	if (off != 0) /* ... and the serial console doesn't support seeking */
-		return -ESPIPE;
+	if (fd != 1) /* we only support stdout (serial console) right now */
+		return -EBADF;
 
 	copy = malloc(len);
 	if (copy == NULL)
 		return -ENOMEM;
-	ret = (ssize_t)copy_from_user(copy, buf, (size_t)len);
+	ret = (ssize_t)copy_from_user(copy, buf, len);
 
 	/* TODO: reschedule if blocking */
 	ret = serial_write(serial_default_interface, copy, (size_t)ret);
 
-	return ret;
+	free(copy);
+
+	return 0x42424242;
 }
 
 /*

lib/unistd.c

@@ -8,10 +8,9 @@
 #include <toolchain.h>
 #include <unistd.h>
 
-__shared ssize_t pwrite(int fildes, const void *buf, size_t nbyte, off_t offset)
+__shared ssize_t read(int fildes, void *buf, size_t nbyte)
 {
-	return syscall(SYSCALL_WRITE, (sysarg_t)fildes, (sysarg_t)buf, (sysarg_t)nbyte,
-		       (sysarg_t)offset, 0, 0);
+	return syscall(SYSCALL_READ, (sysarg_t)fildes, (sysarg_t)buf, (sysarg_t)nbyte, 0, 0, 0);
 }
 
 __shared ssize_t write(int fildes, const void *buf, size_t nbyte)