sys/shell: refactor readline function. #12099
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The test for the line cancellation (ctrl-c) functionality was unable to detect error because of the way pexpect matches output. While working on the long line shell bug, a regression was about to be introduced because of this. This commit fixes the test by directly reading from the child process and expects an exact response. To make the test more robust, the newline handling was changed in native, where an extra empty line was being sent with each character.
Add a command to retrieve buffer size and then force an extremely long line. This is failing right now because of a bug in the shell. The terminal was changed to socat, as pyterm messes up the I/O and makes testing impossible.
The numeric value for EOF is (-1). This caused the shell to return the same code when EOF was encountered and when the line lenght was exceeded. Additionally, if the line length is exceeded, the correct behaviour is to consume the remaining characters until the end of the line, to prevent the following line from containing (potentially dangerous) garbage.
There was some code added to "prevent putchar from being inlined", which supposedly enlarged the code size. It does not seem to have any effect: both before and after the change the size is the same: $ BOARD=samr21-xpro make -c tests/shell all ...... text data bss dec hex filename 10416 140 2612 13168 3370 /home/jcarrano/source/vanillaRIOT/tests/shell/bin/samr21-xpro/tests_shell.elf It makes sense: the compiler is not _that_ dumb.
ifdefs in the middle of code reduce readability and debugability and should be avoided.
This adds a persistent state to the shell that stores the echo configuration and the prompt character. Both can be changed by the user with special built in commmands - @eon: turn echo on. - @eon: turn echo off. - @ps x: make x the prompt character. "@ps" (without any char) disables the prompt. This is implemented in a way that does not consume any additional RAM- it only adds some bytes to the code. A couple of bytes are stolen from the user supplied buffer to store this new configurations. The default state us given by the same compile time defines as before so this change is backwards compatible.
handle_input_line can deal with empty lines, so "case 0:" is not needed.
This makes the code of `readline()` clearer and shorter. It also fixes a minor artifact of the long line handling. Previously it was not possible to recover from a long line. That is, if too many characters were sent, the line would be invalidated and pressing backspace would not fix it- the only option was to discard the line. It is now possible to bring the line back to size. Note that visual effects when deleting characters will still depend on the host's terminal. The new code is written in a way that all writes to memory are guarded by bounds check, so an assertion was removed.
It is not very correct that the readline fucntion prints the prompt.
Test erasing characters using backspace. The tests is not really testing a lot right now because the host is still line buffering.
jcarrano
added
Type: enhancement
jcarrano
added
the
State: waiting for other PR
This was referenced Aug 28, 2019
1 task
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Can be closed due to #13196 |
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Closing since #13196 is merged. |
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Contribution description
This makes the code of
readline()clearer and shorter. It also fixes a minor artifact of the long line handling.Previously it was not possible to recover from a long line. That is, if too many characters were sent, the line would be invalidated and pressing backspace would not fix it- the only option was to discard the line. It is now possible to bring the line back to size. Note that visual effects when deleting characters will still depend on the host's terminal.
The new code is written in a way that all writes to memory are guarded by bounds check, so an assertion was removed.
The main commit in this PR is b7294a6 .
Testing procedure
I added test vectors to
tests/shell. The tests is not really testing a lot right now because the host is still line buffering.Issues/PRs references
Depends on:
Related to: #12085 , #10994 . In a way I'm kind of rewriting the shell little by little.