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-rw-r--r--src/ninep/pane.zig19
1 files changed, 10 insertions, 9 deletions
diff --git a/src/ninep/pane.zig b/src/ninep/pane.zig
index f87e43a6..714a2566 100644
--- a/src/ninep/pane.zig
+++ b/src/ninep/pane.zig
@@ -29,14 +29,15 @@ const Node = tree.Node;
/// Filesystem state a pane carries beside its editor state.
pub const State = struct {
/// The range `data` and `xdata` read and write through. acme clears it
- /// when the first client opens `addr` (editors/acme/xfid.c:105), which
- /// suits a client that holds the fid open and leaves a shell reading back
- /// `0 0` from the address it just wrote. Here it is the pane's own
- /// register, cleared by truncating the file, so that `cp addr dot` and
+ /// when the first client opens `addr` (editors/acme/xfid.c:105-108),
+ /// which suits a client that holds the fid open; a shell cannot, and
+ /// would evaluate every `echo /re/ > addr` from #0 and never advance.
+ /// Here it is the pane's own register, cleared by neither an open nor
+ /// a truncation: `0` or `,` starts over, and `cp addr dot` and
/// `cat addr` answer what was written.
addr: Range = .{},
/// The last address written to `addr` failed, so there is none: `data`
- /// and `xdata` refuse until one is written or `addr` is truncated,
+ /// and `xdata` refuse until a good one is written,
/// rather than act at the address before it, which acme would do.
addr_failed: bool = false,
limit: ?Range = null,
@@ -634,10 +635,10 @@ pub fn truncate(p: *Pardes, pane: *Pane, file: PaneFile) tree.Status {
pane.tag.vsel.active = false;
pane.tag.nsel = 0;
},
- .addr => {
- pf.addr = .{};
- pf.addr_failed = false;
- },
+ // A shell's `>` truncates before it writes: the address written
+ // is evaluated from where the last one left off, as with `>>`.
+ // `0` (or `,`) is how to start over. See State.addr.
+ .addr => {},
.limit => pf.limit = null,
.dot => if (fileOf(pane) != null) setDot(pane, .{}),
else => {},