From 73295e7acc1e5ec3ee8814fd4ccc45f7cee63392 Mon Sep 17 00:00:00 2001 From: user Date: Fri, 17 Jul 2026 01:04:16 +0200 Subject: kernel+sh: real anonymous pipes (concurrent, streaming, SIGPIPE) Replace the shell's temp-file pipe hack with proper in-kernel FIFOs. Kernel (src/pipe.asm, new): - A small pool of bounded ring buffers (PIPE_MAX=2, 64 B each) with writers/readers refcounts. Pipe fds are $F0+idx*2 (read) / +1 (write); $FF stays "console". - SYS_PIPE allocates one (writers=readers=1) and returns the read fd (write = read+1). getb/putb/close dispatch pipe fds here; sys_exit drops the refcounts held as PROC_STDIN/PROC_STDOUT. - Blocking with SchedYield, which is the flow control: read blocks while empty with a writer (EOF once writers hit 0), write blocks while full with a reader, and if the last reader is gone the writer is killed (SIGPIPE -> exit 141). Cooperative-scheduler friendly. Shell (c/sh.c): - run_pipeline(): split on '|', make a pipe between adjacent stages, and fork ALL stages concurrently (no wait between), wiring stdin/stdout; then wait for all. Per-stage >/< still honored; orphaned pipe ends are closed on a lookup miss so EOF/EPIPE propagate. - Drop the __pipe temp file and its 2 KB / serialized limits. libc: pipe(). New c/ptest.c exercises the FIFO (write, read back, EOF). Now works (old version couldn't): multi-stage a|b|c; streaming beyond 2 KB (count 120 | wc = 3372 bytes through a 64 B buffer); early-exit SIGPIPE (count 200 | true kills count instead of hanging/overflowing a file). --- c/ptest.c | 19 +++++++++++++++++++ 1 file changed, 19 insertions(+) create mode 100644 c/ptest.c (limited to 'c/ptest.c') diff --git a/c/ptest.c b/c/ptest.c new file mode 100644 index 0000000..88b7d30 --- /dev/null +++ b/c/ptest.c @@ -0,0 +1,19 @@ +#include "gbos.h" +/* ptest: exercise the kernel pipe in one process - write some bytes, read them + back, then close the write end and confirm the reader sees EOF. */ +void main(void) { + unsigned char pr = pipe(); + unsigned char pw = pr + 1; + int c; + if (pr == NOFD) { puts("pipe: none free"); nl(); return; } + fputc(pw, 'H'); fputc(pw, 'i'); fputc(pw, '!'); + c = fgetc(pr); putc(c); + c = fgetc(pr); putc(c); + c = fgetc(pr); putc(c); + nl(); + close(pw); /* last writer gone */ + c = fgetc(pr); + if (c < 0) puts("EOF"); else { puts("got "); putc(c); } + nl(); + close(pr); +} -- cgit v1.3.1-sl0p