Notes on acme.dump format (Plan 9 wiki)

The format of the files generated by Dump and read by Load in acme(1) is not formally documented, but this does a reasonable job of describing it.

HEADER

Dump files all start with three lines describing the global state of the Acme instance:

Working directory
Default font (like -f)
Alternate font (like -F)

The line following this describes the position for each column as a percentage offset from the left edge of the window, as a list of 11-character space-separated numbers. For example, the line

        0          30          85

describes a three-column window with columns starting at the left edge, 30% in, and 85% in.

OPTIONAL LINES

Two types of lines are newer additions. They are optional in current dump files, and not found in older ones. If these lines exist, they must come before row/window descriptors, described below.

w Tag

A line starting with "w" will treat the remainder of the line (after the first two characters, typically "w ") as the tag for the top-level window.

c colnum tag

A line starting with "c", followed by a space-padded 11-digit number, followed by a space, and then a tag. The number is the internal column ID, and the tag sets the tag for that column.

Note that these newer additions are not understood by Inferno's acme, and will cause exceptions if loaded.

ROW DESCRIPTORS

Subsequent lines define window ("rows" in acme's terminology). They come in sets of two or more lines each, depending on the type. The first two lines are common to all window types, with one exception.

FIRST LINE

A single character type specifier (see below), 5-6 11-character numeric fields, and an optional font name. Each field is space-separated. The numeric fields:

Column number, from above
Internal, unique window ID (t->file->dumpid)
Selection ("dot") start (w->body.q0)
Selection ("dot") end (w->body.q1)
Position in column, % from top (100.0*(w->r.min.y-c->r.min.y)/Dy(c->r))
F windows only: buffer size (w->body.file->b.nc)

The sixth numeric field is only allowed in F-type windows, where it is required.

SECOND LINE

Sometimes called the "ctl line", this is the first 5 fields from the window's ctl file (see acme(4) and wind.c:/^winctlprint), followed by a space, then the tag for that window. These first five fields are: Window ID; tag size in runes; body size in runes; 1 if the window is a directory, 0 otherwise, 1 if modified (dirty), 0 otherwise.

ROW TYPES

Internal file or directory window.

Regular file, dirty. Subsequent lines, if any, are the contents of the window, which must match the buffer length specified in the first line.

Zerox windows. Treated like f windows, with dumpid set.

Window for an external command. Fields for dot are always 0 on creation, and the second line ("ctl line") is ignored. "e" window definitions must be followed by two additional lines. The third line is working directory. If this is blank, it will be set to $home, or "./" if $home is not set. The fourth line is the command to run, via exec.c:/^run$.*$.