From d81447526cde6fa98dfa792a65f71acb78ef1398 Mon Sep 17 00:00:00 2001
From: Peter Mikkelsen <peter@pmikkelsen.com>
Date: Fri, 2 Jul 2021 22:01:59 +0000
Subject: Start work on input/output streams

---
 streams.c | 204 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 204 insertions(+)
 create mode 100644 streams.c

(limited to 'streams.c')

diff --git a/streams.c b/streams.c
new file mode 100644
index 0000000..d089b23
--- /dev/null
+++ b/streams.c
@@ -0,0 +1,204 @@
+#include <u.h>
+#include <libc.h>
+
+#include "dat.h"
+#include "fns.h"
+
+typedef struct Stream Stream;
+
+struct Stream
+{
+	ulong fd;
+	int type;
+	int mode;
+	int nalias;
+	Rune **aliases;
+	Stream *next;
+};
+
+enum {
+	TextStream,
+	BinaryStream,
+};
+
+enum {
+	ReadStream,
+	WriteStream,
+	AppendStream
+};
+
+static Stream *streams;
+static Stream *currentinput;
+static Stream *currentoutput;
+
+Stream *openstreamfd(int, int, int);
+Stream *getstreambyfd(int);
+Stream *getstreambyalias(Rune *);
+Stream *getstream(Term *);
+
+void
+initstreams(void)
+{
+	currentinput = openstreamfd(0, TextStream, ReadStream);
+	currentoutput = openstreamfd(1, TextStream, WriteStream);
+}
+
+int
+openstream(Rune *sourcesink, Rune *mode, Term *options, Term **stream)
+{
+	USED(options);
+	int omode;
+	int smode;
+	if(runestrcmp(mode, L"read") == 0){
+		omode = OREAD;
+		smode = ReadStream;
+	}else if(runestrcmp(mode, L"write") == 0){
+		omode = OWRITE;
+		smode = WriteStream;
+	}else if(runestrcmp(mode, L"append") == 0){
+		omode = OWRITE; /* Is this correct? */
+		smode = AppendStream;
+	}else{
+		*stream = existenceerror(L"source_sink", mkatom(sourcesink));
+		return 1;
+	}
+
+	char *filename = smprint("%S", sourcesink);
+	int fd = open(filename, omode);
+	if(fd < 0){
+		*stream = permissionerror(L"open", L"source_sink", mkatom(sourcesink));
+		return 1;
+	}
+	Stream *s = openstreamfd(fd, TextStream, smode);
+	*stream = mknumber(NumberInt, s->fd, 0);
+	return 0;
+}
+
+void
+closestream(Term *t)
+{
+	Stream *s = getstream(t);
+	if(s == nil)
+		return;
+
+	Stream *tmp;
+	Stream *prev = nil;
+	for(tmp = streams; tmp != nil; tmp = tmp->next){
+		if(tmp == s){
+			if(prev == nil)
+				streams = tmp->next;
+			else
+				prev->next = tmp->next;
+			break;
+		}
+		if(prev == nil)
+			prev = tmp;
+	}
+}
+
+Term *
+currentinputstream(void)
+{
+	return mknumber(NumberInt, currentinput->fd, 0);
+}
+
+Term *
+currentoutputstream(void)
+{
+	return mknumber(NumberInt, currentoutput->fd, 0);
+}
+
+void
+setcurrentinputstream(Term *t)
+{
+	Stream *s = getstream(t);
+	if(s)
+		currentinput = s;
+}
+
+void
+setcurrentoutputstream(Term *t)
+{
+	Stream *s = getstream(t);
+	if(s)
+		currentoutput = s;
+}
+
+int
+isopenstream(Term *t)
+{
+	Stream *s = getstream(t);
+	if(s)
+		return 1;
+	else
+		return 0;
+}
+
+int
+isinputstream(Term *t)
+{
+	Stream *s = getstream(t);
+	if(s && s->mode == ReadStream)
+		return 1;
+	else
+		return 0;
+}
+
+int
+isoutputstream(Term *t)
+{
+	Stream *s = getstream(t);
+	if(s && (s->mode == WriteStream || s->mode == AppendStream))
+		return 1;
+	else
+		return 0;
+}
+
+Stream *
+openstreamfd(int fd, int type, int mode)
+{
+	Stream *s = malloc(sizeof(Stream));
+	s->fd = fd;
+	s->type = type;
+	s->mode = mode;
+	s->nalias = 0;
+	s->aliases = nil;
+	s->next = streams;
+	streams = s;
+	return s;
+}
+
+Stream *
+getstreambyfd(int fd)
+{
+	Stream *s;
+	for(s = streams; s != nil; s = s->next)
+		if(s->fd == fd)
+			return s;
+	return nil;
+}
+
+Stream *
+getstreambyalias(Rune *alias)
+{
+	Stream *s;
+	for(s = streams; s != nil; s = s->next){
+		int i;
+		for(i = 0; i < s->nalias; i++){
+			if(runestrcmp(alias, s->aliases[i]) == 0)
+				return s;
+		}
+	}
+	return nil;
+}
+
+Stream *
+getstream(Term *t)
+{
+	Stream *s = nil;
+	if(t->tag == NumberTerm && t->numbertype == NumberInt)
+		s = getstreambyfd(t->ival);
+	else if(t->tag == AtomTerm)
+		s = getstreambyalias(t->text);
+	return s;
+}
\ No newline at end of file
-- 
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