dev/todo/install-bb-without-bb: Crazy good

1 files changed, 38 insertions, 60 deletions

diff --git a/dev/todo/install-bb-without-bb.mdwn b/dev/todo/install-bb-without-bb.mdwn
index 55ae48c..ca71b6b 100644
--- a/dev/todo/install-bb-without-bb.mdwn
+++ b/dev/todo/install-bb-without-bb.mdwn
@@ -2,11 +2,11 @@
 
 **or, Adventures in Regressions and Crazy Ideas**
 
-`opkg` and the Outsourced Inflation
-===================================
+Two Problems
+============
 
-The Problem
------------
+`opkg` and the Outsourced Inflation
+-----------------------------------
 
 opkg-lede now [relies][opkg-lede-dd4c78a] on an external `gzip` executable.
 When upgrading a package, it tries to execute `gzip` to unpack maintainer
@@ -17,26 +17,8 @@ package.  When the package being upgraded is `busybox`, which provides `gzip`,
 [opkg-lede-dd4c78a]: https://git.openwrt.org/?p=project/opkg-lede.git;a=commitdiff;h=dd4c78aa88efd3b9cf516030937c684814df7962
 [opkg_install_pkg]: https://git.openwrt.org/?p=project/opkg-lede.git;a=blob;f=libopkg/opkg_install.c;hb=d4ba162#l1520
 
-Possible Solutions
-------------------
-
-A wrapper script that calls `opkg-cl` (the actual binary executable) needs to
-save a copy of `/bin/busybox` which `opkg-cl` can execute as `gzip`.
-
-**Solution 1:**  `opkg-cl`'s [`gzip_exec()`][gzip_exec] is patched to execute
-the absolute path of the `busybox` copy as `gzip`.
-
-**Solution 2:**  The wrapper copies `/bin/busybox` to an empty directory and
-either names the copy `gzip` or generates links to it.  It then runs `opkg-cl`
-with the (temporary) directory in `PATH`.
-
-[gzip_exec]: https://git.openwrt.org/?p=project/opkg-lede.git;a=blob;f=libbb/gzip.c;hb=d4ba162#l70
-
 The Amazing Alternatives of `busybox`
-=====================================
-
-The Problem
------------
+-------------------------------------
 
 Instead of adding alternatives one at a time, [it would be nice][bb-ua] to
 manage all of `busybox`'s utility links using `update-alternatives`.
@@ -50,40 +32,36 @@ can't be configured when first unpacked by `prokit`.
 [bb.pi]: http://git.proteanos.com/pkg/busybox.git/tree/busybox.pkg/postinst
 [u-a]: https://git.openwrt.org/?p=project/opkg-lede.git;a=blob;f=utils/update-alternatives.in;hb=d4ba162
 
-A Non-Solution
---------------
-
-`busybox`'s `postinst` script doesn't (need to) execute any commands that aren't
-`ash` built-ins (`cat` is there but can be replaced with `read`), but it will
-need to have its interpreter line changed from `#!/bin/sh` to
-`#!/bin/busybox sh`.  `update-alternatives` will need to be modified
-(rewritten?) to execute `busybox` directly.
-
-However, there are at least two problems with this approach.
-
-When installing a system, `busybox` won't necessarily be the first package to be
-configured.  Other maintainer scripts may be executed before `busybox`'s
-`postinst` is able to create the utility links they need.
-
-Additionally, foreign-architecture system installations aren't configured at
-install time.  Instead, they need to be able to at least boot far enough to run
-`opkg install $(opkg list-installed | cut -d " " -f 1)`, which, again as above,
-may run other maintainer scripts before `busybox`'s `postinst`.
-
-Another possible solution is to add special-case code to `prokit` to create
-`busybox`'s links between unpacking and configuring, but that further opens the
-can of worms that is compatibility between versions of `prokit` and the
-distribution it installs.
-
-The End?
---------
-
-Perhaps this idea is too crazy?
-
-Crazier idea: could solution 2 of the first problem above actually solve this
-problem?  `busybox` would need to declare that it `Breaks` older versions of
-`opkg-lede`, to ensure a sufficiently new `opkg-lede` is installed to handle
-`busybox`'s alternatives madness.  Also, the `opkg` wrapper itself would have to
-be careful to execute utilities as `busybox $util` (including `#!/bin/busybox
-sh`) at least until setting up the temporary directory and setting and exporting
-`PATH`.
+One Solution
+============
+
+The next version of `src:opkg-lede` (likely 0+git20190131.d4ba162-7) already
+will have a [wrapper script called `opkg`][opkg] that executes `opkg-cl` (the
+actual binary executable).  The script can be extended to first save a copy of
+`/bin/busybox` to an empty temporary directory, generate utility links to it in
+the directory, and add the directory to `PATH`.  Until all of this setup is
+complete, the wrapper script must be careful to execute utilities as `busybox
+$util` (a full path to `busybox` won't be necessary, as the usual `/bin/busybox`
+will be available at that point).  This includes the interpreter line, which
+will need to be changed to `#!/bin/busybox sh`.  `ash` built-in utilities can be
+used as usual.
+
+The `busybox` package can't use `update-alternatives` to manage all of its
+utility links until an `opkg-lede` with this wrapper script functionality is
+uploaded.  This is because, even if `busybox`'s `postinst` script is modified to
+use the `busybox` executable directly, other packages' maintainer scripts may be
+executed first, while `busybox` is unpacked but not yet configured (and
+therefore utility links are not yet created).
+
+Once this new `opkg-lede` package is uploaded and `busybox` uses
+`update-alternatives` for everything, `busybox` would need to declare that it
+`Breaks` older versions of `opkg-lede`, to ensure that `opkg-lede` will preserve
+a copy of the `busybox` executable and its utility links.
+
+The `opkg` script of the `opkg-lede` package will need to read `busybox`'s list
+of alternatives links.  This is currently located at
+`/usr/share/busybox/alternatives`, though the file's format will change when
+`busybox` uses `update-alternatives` for everything.  A migration strategy for
+`opkg-lede` will need to be designed.
+
+[opkg]: http://git.proteanos.com/pkg/opkg-lede.git/tree/opkg