Feat: added buffered io from plan9

As we no longer have the FILE type, we need to buffer our reading and
writing so that we don't have to make so many syscalls. The API is nice
so that we can buffer other readers. We will update it so that it eats
io·Readers/io·Writers.

1 files changed, 102 insertions, 0 deletions

diff --git a/src/base/bufio/init.c b/src/base/bufio/init.c
new file mode 100644
index 0000000..7e6dcee
--- /dev/null
+++ b/src/base/bufio/init.c
@@ -0,0 +1,102 @@
+#include "internal.h"
+
+#define MAXHEADERS 20
+static io·Header *tracked[MAXHEADERS];
+static int doexit;
+
+static void
+untrackall(void *arg)
+{
+    int i;
+    io·Header *it;
+
+    for(i=0; i < MAXHEADERS; i++){
+        it = tracked[i];
+        if(it){
+            tracked[i] = nil;
+            bio·flush(it);
+        }
+    }
+}
+
+static void
+untrack(io·Header *io)
+{
+    int i;
+
+    for(i=0; i<arrlen(tracked); i++){
+        if(tracked[i] == io)
+            tracked[i] = nil;
+    }
+}
+
+static void
+track(io·Header *io)
+{
+    int i;
+
+    untrack(io);
+    for(i=0; i<arrlen(tracked); i++){
+        if(!tracked[i]){
+            tracked[i] = io;
+            break;
+        }
+    }
+
+    if(!doexit){
+        doexit = 1;
+        rt·atexit(untrackall, nil);
+    }
+}
+
+int
+bio·initcap(io·Header *io, int fd, int mode, int cap, uchar *buf)
+{
+    buf += io·BufUngets;
+    cap += io·BufUngets;
+
+    switch(mode & ~(sys·OCloseExec|sys·OTrunc)){
+    default:
+        fmt·fprint(2, "initcap: unknown mode %d\n" , mode);
+        return io·BufErr;
+    case sys·ORead:
+        io->state = io·BufRdr;
+        io->olen  = 0;
+        break;
+    case sys·OWrite:
+        track(io);
+        io->state = io·BufWtr;
+        io->olen  = -cap;
+        break;
+    }
+
+    io->b   = buf;
+    io->e   = buf+cap;
+    io->g   = io->e;
+    io->fd  = fd;
+    io->cap = cap;
+    io->pos = io->runesz = io->flag = io->ilen = io->line = 0;
+    return 0;
+}
+
+int
+bio·init(io·Buffer *io, int fd, int mode)
+{
+    return bio·initcap(header(io), fd, mode, io·BufLen + io·BufUngets, io->b);
+}
+
+int
+bio·close(io·Header *io)
+{
+    int err;
+
+    untrack(io);
+
+    err = bio·flush(io);
+    if(io->flag == io·BufMagic){
+        io->flag = 0;
+        if((err=sys·close(io->fd)))
+            return err;
+    }
+    return 0;
+}