Aminet 49/Aminet 49 (2002)(GTI - Schatztruhe)[!][Jun 2002].iso/Aminet/util/boot/ShellUpdate.lha/NOTES/Shell_RelNotes

Text File | 2002-04-01 | 14.8 KB | 391 lines

Start log thor:

Shell V45.0:

Oh wow, this was a tough job. The Shell really looked like
some kind of BCPL left-over. It took several days just to
cleanup the code and turn it into something more readable.
BCPL was lurking thru the code all over. No more, folks,
no more...

The V40 shell was unable to perform the "implicit CD" command
properly if the directory name was quoted. It inserted an
unnecessary blank space behind the directory name.

The shell didn't support multiple backticks on the command line;
the backtick parser was simply broken: Fixed handling of
asterisk-backtick sequences. The backtick wasn't escaped properly.

The shell did not treat TABs as blank spaces. Fixed.

Removed the SetClock kludge. Whoever is still using a 1.3
SetClock nowadays cannot be helped anymore and deserves
to be crashed. (-;

Added a few missing Forbid/Permit locks around access of
the list of resident commands.

Removed an ugly hack to set the RC and Result2 variables;
this really uses now the proper system functions and doesn't
attempt to hack directly into the variable buffers.

Reworked the parser a lot; it partially tried to fiddle in
the internal buffers of file handles using structures that
have never been documented. The code now loads full lines
at once (no matter how big they are) and then parses within
its buffers. This removes all dependencies of implementation
details of the file handles.

Arguments to redirection did not expand backticks. Fixed.

Added a lot of proper error checking if it is low on memory.

The internal (and deceased "GlobalVector") is no longer
passed thru to all functions. Instead, I'm now using some
SAS magic to allocate my data segment myself on each
invocaton.

Decided not to disable echo-ing for non-interactive shells.
Otherwise, we could not debug scripts or the startup-sequence.
Sorry, Heinz, but I reconsidered and it's really better this
way.

Shell V45 re-introduces the handling of the "h" bit. Should it
find a command with "pure" and "h" bits set, it makes the
command resident automatically. Note that this is (again) the
V39 behaivour. Note that "h" is for "hold", not for "hidden".

The shell does no longer limit command lines to 512 characters.
Command lines can now be unlimited in size, provided the
command itself is smaller than the AmigaOs file name size
limit (107 characters). The Shell will now auto-expand all of
its internal buffers if required to do so. Furthermore, it
uses now memory pools for this kind of administration.

The shell offers now extended "script" support. In case a script
file - i.e. a file whose "s" and "e" bits are set - starts with
either the magic characters "#!" or ";!", the string behind this
magic cookie is understood as the path to a command parser that
shall execute this script.

Added support for "file browsing".

If the shell encounters now a file as first argument that has
its "e" bit cleared (!) and is parsed and recognized as a data-
type by the data types system, the shell runs a "viewer"
program whose path should be placed in the $VIEWER shell
variable.

Added support for "stderr" redirection. Therefore, the V45
shell introduces three new redirection symbols:

*>  filename    : redirects stderr to a file
*>> filename    : appends output to stderr to a file
*><         : redirects stderr to the same file that stdout
          goes into.

The shell will also assign the console to the stderr stream
should stderr be an interactive stream.

Added support for "script stdin". A "<<" will pull the next
symbol from the shell script and will push all following
lines up to a line starting with this symbol as input into
the command. Hence, "<<" is exactly the Un*xoid input redirection.

Added a new command line token, the "&" character,
the "implicit run". If found, the shell opens named consoles
with of a name generated thru utility/GetUniqueID(), and assigns
these to the stdin/stdout/stderr of the command, shouldn't
redirection be used anyhow. Then the command is detached from
the shell segment.

Added automatic stack size setup for shell commands. This is a
new feature that would hopefully limit the number of stack
underflows as it allows application developers to increase the
stack automatically without the need for stack swap code. The
shell scans now the first 1K of each segment of a loaded binary
for the magic cookie "$STACK:". The string behind this cookie
is expected to be a decimal number, terminated with a line feed
(and an ASCII NUL, i.e. '\0', as for all C strings).
This number is then interpreted as the stack size in bytes. The shell
will automatically increase the stack size *for this command only*.
If the pre-defined stack size is larger than the program-implicit,
nothing will happen.

AGENDA:

Rewrite the parser for shell-variables. This looks currently messy
and not very well thought-about. Especially the handling of
asterisks is broken here.

Rewrite the parser for backticks. This happend already to some
degree, but it is not yet perfect.



Shell 45.1:

The shell did not handle script files correctly that did not end
on a line feed. Fixed.
The shell bootstrap code was partially broken and could not run
the "Initial CLI" correctly. The BCPL startup mechanism was
rewritten completely (to the better).
Incorporated all traditionally resident commands into the Shell-Seg
making this a self-contained shell with a resident segment that
is rom-able and can bootstrap the system.
Rewrote the shell command line parser to some degree. This implies
various changes on how the command line gets interpreted. Good
news is that backticks can now also be used to specify the command
itself, alias [] works within backticks, and backticks cooperate
nicely with aliases in general. Furthermore, the new parser
allows multiple, recursive, but non-looping alias expansion,
and aliases containing backticks that are expanded correctly.

Fixed *>< redirection hits. Fixed generation of result codes, the
shell forgot to forward command result codes properly. Fixed
stderr redirection: stderr defaults to stdout, it now defaults
to the shell output stream; hence, an explicit *>< is required
for the old behaivour.

Fixed escaping for implicit commands CD,EXECUTE, and others:
They no longer escape " and * if found in an unquoted string.
Note that this is the proper behaivour, even though this is
more a "feature" of ReadItem() than anything else.

Fixed the "CD" command: It did not allocate the anchor path
from memory resulting in a possibly mis-aligned "FileInfoBlock"
and damaged memory. Yikes!

Fixed the "resident" command: First of all, it also placed
"AnchorPath"s on the stack, which is no good. Second, it did
the printf for the resident command list within a loop while
Forbid(), making the forbid for the list lock pretty much
useless.

Reworked set,setenv,alias,unset,unsetenv,unalias: All of
these six commands are handled by the same segment, but the
division into various subcommands happened in a rather
unorthogonal way by second-guessing from the command name.
It is now organized in several segments calling the same
main routine with parameters. "set" became reorganized
a lot as well: "setenv" without parameters is no longer
redirected to "list", making this independent of whether
external commands are available. "set" reformats now ESC
and CSI sequences on the screen consistently by using the
BCPL escape character "*". Other non-printables are (as it
always has been the case) replaced by the smear-character
0x7f (DEL).

Reworked get, getenv for the same reason: One segment, two
commands.

Reworked "run", but not quite as much as I would like to.
This still rolls its own faked input file handle. Even
worse, it gets the command line from the undocumented
internal buffer of its stdin stream. There's currently no
better way of doing it.

Added a new option "HEAD" to "path". This will add new paths to
the start of the command search path and will hence search
them first.

Reworked "newshell". It no longer tries to place critical
DOS structures on the stack, and will therefore long-word align
them correctly all the time. The window open path of NewShell
has been changed to CON://130/AmigaShell/CLOSE/SHELL to signal
shell usage for console handlers, e.g. ViNCEd.

AGENDA:

The shell argument parsing is still somewhat wierd. Backticks
are not recognized as "quotes" and don't group commands
on parsing - this happens only on expanding them. This is
mainly the matter of ReadItem() which should be replaced
by a custom routine. Further, single quotes are not handled
at all. I wonder whether I should touch this or leave it as
"compatibility feature".



Shell 45.2:

Fixed several missing error reports, for example for out-of-memory
situations and unability to open redirection files.

Changes the style of stderr redirection: Stderr defaults now to
stdout, unless redirected otherwise. This is a compatibility
cludge for <>NIL: type redirection.

Redirection with <> checks now explicitly whether the target file
is interactive or NIL: It will fail in all other cases.

Redirection into "*" with the run-back operator "&" will now go
into the console owner established for the command output rather
than the current console.

Added PushCD, PopCD and SwapCD commands as build-ins.

Re-established the "oldredirect" variable. If set to "on", the
shell will check for redirection operators only immediately
behind the command name and nowhere else. This is a pre-V36
compatibility feature that was dropped in V40 due to limited
ROM space.

Added SAVE keyword to UNSETENV to make the changes permanent.

Fixed wrong templates for unalias, unset and unsetenv.

Reworked ASK a lot; this command allows now numeric and string
input, and places the result either on stdout or into a user
specified local variable.


Shell 45.3:

The "&" symbol was broken in several ways: First of all, it
unlocked home and current directory twice instead of once,
causing possible memory trashes. Further, it did not set
CLI->cli_Module correctly which is required for some run-back
and stay-resident programs. Thrid, it did not check the very
same CLI variable to release the program again, hence might
have even unloaded segments that are not meant to be unloaded.
Fourth, it did not work well with "Execute" due to the rather
clumpsy way the original BCPL shell introduced the execute
logic. The "&" handling was more or less rewritten for the
45.3. The new logic introduced another kludge in the shell
startup logic (oh no!) but makes it possible to run programs
in background *without* destroying stdin, hence unlike run.
Therefore "run" is more or less obsolete now.

The shell command line parser was turned upside down. Nothing
of the old parser is left. The net effect is that the general
logic of argument parsing has been improved much. The shell
now knows on variable expansion and backtick expansion whether
it inserts arguments into quotes, and if so, escapes properly.

Fixed handling of aliases in some ways, especially fixed a
bug of the 45.2 where the shell forgot to insert a space.

Removed handling of ( and ) in pipes. They aren't used
by any pipe command I know of and are therefore just here to
make the syntax even more cludgy.

Fixed handling of interpreter setup by means of #! or #;.
The line behind the magic symbols is now parsed thru ReadItem
and hence requires proper quoting, so beware!

Fixed handling of implicit commands on arguments starting
with quotes. The old shell could not run these commands
properly due to unadequate re-escaping of the command argument.
This is now all handled (hopefully correctly) by one common
routine that is also used for variable and backtick sub-
stitution.


Version 45.4:

The 45.3 release caused problems with existing scripts because
quoted variables within quotes where escaped by * such that
double quotes resulted. While this is correct in principle,
it broke already existing scripts. For this reason, a special
rule is now applied: Variables within quotes get their first
pair of surrounding quotes removed. You can avoid this by
setting the variable "keepdoublequotes" to "on":

set keepdoublequotes on

Pre 45.3 releases generated a wrong error for script files
that are read-protected. Fixed.



Version 45.5:

Fixed the parser state machine such that variables of wierd
names like ">t" are possible. The parser used to be quite
inconsistent how to handle them.

SwapCD has an optional LEVEL argument that defines which
level of the directory stack to swap with.

The stack extension logic scans now the first 4K for the
stack cookie.

Setenv SAVE clears now the "e" bit on the saved variables.

The asterisk in front of $, [ and ` is now handled
correctly again. * escapes the following character, **
escapes the star from escaping, *** is a double star with
escaped following control character.

Added the possibility to check for the existance of a
variable by the $?varname method. $?a will expand to
1 if a is defined, 0 otherwise. $??a will expand to
1 only if a is found as a global variable.

Fixed handling of quotes in variables and backticks
outside of quotes. Behaivour of the shell depends here now
again on the "keepdoublequotes" variable. If "on", the
quotes are escaped and the full string is put into quotes,
otherwise the string is left alone. If already in quotes,
"keepdoublequotes" = "on" escapes quotes within the
variable body, otherwise the outermost quote gets removed.

Fixed the escaping of the rear backtick of a backtick
sequence.

StdErr redirection to NIL: by *>NIL: will now clear the
console task for the command to be run.

Command interpreters specified by the #! or ;! token may
now get additional arguments specified on this line. The
script file name is inserted between the command and these
arguments.

Fixed the multiple redirection issue. Fixed handling
of alias and redirection. As a side condition, the output
of the "set" and "setenv" commands can now be redirected just
fine.


Version 45.6:

Various minor code cleanup concerning the command buffers;
they are now all static to the functions they belong to.

Fixed recognition of $VIEWER which had to be a local variable
to be functional.

Removed beta warning message on startup.

The shell scans now all hunks of a loaded binary for the
stack size. Furthermore, several enhanced safety checks have
been added for this feature.

Added a german documentation, proof-read and spell-checked
the english documentation.


Version 45.7:

The run-back operator & did not move the shell segment in
the seg-array and hence might have crashed some BCPL commands.

The stack size search routine got improved quite a lot and is
now much faster than before - by a factor of four to five.

The "setenv" command clears now the "e" bit of the variables
it saves.

Added a Shell.guide (Thanks Martin for the help).


Version 45.8:

Fixed handling of backticks within comments. They are now
properly ignored.

Fixed handling of equal-signs within arguments. They are
now considered similar to blank spaces and consider
following double-quotes as function, not as literal.