Importing bash history is still prone to hanging

[sersorrel]

• fish 3.2.1
• Ubuntu 18.04, amd64
• kitty 0.19.3

When I run fish, it hangs at 100% CPU, and doesn't respond to SIGINT. If I move ~/.bash_history elsewhere, it starts up fine.

This seems similar to e.g. #7407 and #7497, but both of those issues appear fixed in fish 3.2.1.

My bash history is ~2.6MB, just under 95k lines long (though a little under 10k of those are HISTTIMEFORMAT comments).

I believe the problematic command (or, one of the problematic commands) is this one:

jq <<"EOF"
[{"background":null,"color":"#00000000","full_text":"","markup":"pango","separator":false,"separator_block_width":0},{"background":"#00000000","color":"#3c3836","full_text":"  141.57 GiB ","separator":false,"separator_block_width":0},{"background":"#00000000","color":"#00000000","full_text":"","markup":"pango","separator":false,"separator_block_width":0},{"background":"#00000000","color":"#3C3836FF","full_text":" ","markup":"pango","name":"e49dcba19c99470ca906c84bd7e2d26c","separator":false,"separator_block_width":0},{"background":"#00000000","color":"#00000000","full_text":"","markup":"pango","separator":false,"separator_block_width":0},{"background":"#00000000","color":"#3c3836","full_text":"   ","markup":"pango","name":"628b16c2ef8947d2aaab8e976c3eb135","separator":false,"separator_block_width":0},{"background":"#00000000","color":"#00000000","full_text":"","markup":"pango","separator":false,"separator_block_width":0},{"background":"#00000000","color":"#3C3836FF","full_text":"  5.3/15.5 (34%) ","markup":"pango","name":"memory","separator":false,"separator_block_width":0},{"background":"#00000000","color":"#00000000","full_text":"","markup":"pango","separator":false,"separator_block_width":0},{"background":"#00000000","color":"#3c3836","full_text":" compositor is already running ","markup":"pango","name":"e4033a10be4a4b05abd714430d0d7441","separator":false,"separator_block_width":0},{"background":"#00000000","color":"#00000000","full_text":"","markup":"pango","separator":false,"separator_block_width":0},{"background":"#00000000","color":"#FBF1C7FF","full_text":"   ","separator":false,"separator_block_width":0},{"background":"#00000000","color":"#00000000","full_text":"","markup":"pango","separator":false,"separator_block_width":0},{"background":"#00000000","color":"#3c3836","full_text":"  43° ","markup":"pango","name":"832500be70604dc485e351d1e552cec6","separator":false,"separator_block_width":0},{"background":"#00000000","color":"#00000000","full_text":"","markup":"pango","separator":false,"separator_block_width":0},{"background":"#00000000","color":"#3C3836FF","full_text":"  4d 3h ","separator":false,"separator_block_width":0},{"background":"#00000000","color":"#00000000","full_text":"","markup":"pango","separator":false,"separator_block_width":0},{"background":"#00000000","color":"#3c3836","full_text":"  n/a ","markup":"pango","name":"b3d7736948aa4c22a9392ec46715f160","separator":false,"separator_block_width":0},{"background":"#00000000","color":"#00000000","full_text":"","markup":"pango","separator":false,"separator_block_width":0},{"background":"#00000000","color":"#3C3836FF","full_text":" Monday 2019-07-15 10:51 pm ","markup":"pango","name":"7ac94d496c354d7d82734fb7bd9d6e3d","separator":false,"separator_block_width":0}]
EOF

The problem seems to be specific to the JSON – a history file containing a heredoc of 4kb of aaaaaaaa causes no issues.

[faho]

The issue here is that there is no way for fish to tell that's a multi-line construct.

The first line fails parsing, but since fish doesn't have heredocs the second line is looked at separately, and that then possibly causes some combinatoric explosion.

The solution is to tighten the checks for history import further.