Mark Millard wrote: > > > On 2020-Jul-10, at 11:05, Yuri Pankov <yuripv at yuripv.dev> wrote: > >> Steve Wills wrote: >>> On 11/28/19 4:08 PM, Mark Millard via svn-src-head wrote: >>>>> Author: daichi >>>>> Date: Fri Sep 20 17:37:23 2019 >>>>> New Revision: 352558 >>>>> URL: >>>>> https://svnweb.freebsd.org/changeset/base/352558 >>>>> >>>>> >>>>> Log: >>>>> top(1): support multibyte characters in command names (ARGV array) >>>>> depending on locale. >>>>> - add setlocale() >>>>> - remove printable() function >>>>> - add VIS_OCTAL and VIS_SAFE to the flag of strvisx() to display >>>>> non-printable characters that do not use C-style backslash sequences >>>>> in three digit octal sequence, or remove it >>>>> This change allows multibyte characters to be displayed according to >>>>> locale. If it is recognized as a non-display character according to the >>>>> locale, it is displayed in three digit octal sequence. >>>>> >>>> >>>> Initially picking on tab characters as an example of what is >>>> probably a somewhat broader issue . . . >>>> >>>> Ever since this change, characters like tabs that do not fit >>>> in the next character cell when output, but for which they >>>> are !isprintable(...), now mess up the top display. Again >>>> using tab as an example: line wrapping from the text having >>>> been shifted over by more than one character cell. top does >>>> not track the line wrapping result in how it decides what >>>> to output for the following display updates. >>>> >>> Apologies for the way late reply here, but I just now bothered tracking this down. This commit seems to be the cause of some corruption I'm seeing in long running top(1) as well. As Mark mentions, if I use "hh" it clears up. Should I open a bugzilla bug? I can share screenshots of the corruption, such as: >>> https://i.imgur.com/Xqlwf9h.png >>> https://i.imgur.com/Jv0d5NU.png >> >> Does removing VIS_SAFE fixes the issue for you? >> >> As for original Mark's report (which I missed), removing isprintable() doesn't look wrong as vis(3) should take of its functionality (and in multibyte-aware way). > > vis (as used) and the old isprintable logic are not > equivalent when multi-byte is not needed/involved. > Otherwise I'd not have had anything to ever report. > If vis can do what is needed, more work needed to > be done when the change was made in order to avoid > msesed up displays in single-byte contexts. > >> Also, is there an easy way to reproduce this? > > The following sort of command (the empty space inside quoted > text are tab characters): > > # tr '0\n 1\n 2\n 3\n 4\n 5\n 6\n 7\n 8\n' '\t0 \t1 \t2 \t3 \t4 \t5 \t6 \t7 \t8' < /dev/zero > /dev/null > > causes my 200 character wide window running top to show: > > 32920 root 100 0 12764Ki 2420Ki CPU3 3 2:22 99.87% tr 0\\n 1\\n 2\\n 3\\n 4\\n 5\\n 6\\n 7\\n 8\\n \\t0 \\t1 \\t2 \\t3 \\t4 \\t5 \\t6 \\t733 \\t8 20 7172 5448Ki CPU23 23 0:00 0.04% top -HiSCazopid > > But that does not show where the lines wrap at the edges of the window, > so breaking it up explicitly after the first "\" in \\7: > > 32920 root 100 0 12764Ki 2420Ki CPU3 3 2:22 99.87% tr 0\\n 1\\n 2\\n 3\\n 4\\n 5\\n 6\\n 7\\n 8\\n \\t0 \\t1 \\t2 \\t3 \\t4 \\t5 \\t6 \ > \t733 \\t8 20 7172 5448Ki CPU23 23 0:00 0.04% top -HiSCazopid > > Note how \n turned into \\n , taking an extra character for > each \n . Similarly for \t vs. \\t . (Other examples do > similarly.) > > The tab characters really do use more than one character cell > on the display (sometimes). > > The text from the tr command ends up spread across 2 lines > as things look like in the window where top is running. > > I ran top in another ssh session first and then the tr command. > Before running the tr command, top showed as: > > 33019 root 20 0 17172Ki 5448Ki CPU24 24 0:00 0.05% top -HiSCazopid > > If you do not end up with top listed just after tr in top's output, > then it will not be top's line that ends up partially overwritten. > > If you have wider windows, you may need more text in the tr quoted > strings. > > In another experiment I inserted a large number of backspace characters > (control-H's) at the front of the first quoted string in the tr command. > The top output displayed: > > 0\\n5 ro1\\n 2\\93 3\\n12764\\n 25\\ni CP6\\n 97\\n:12 100.00\t0r \nHiS\\t1pid \\t2 \\t3 \\t4 \\t5 \\t6 \\t > 33094 root 20 0 17172Ki 5488Ki CPU21 21 0:00 0.06% top -HiSCazopid > > In other words, backspace moved the cursor position back over prior > fields on the line and then the later line content overwrote those > fields instead of being after "tr" someplace (or truncated off). > > Note that part of "-HiSCazopid" shows up on both lines. The extra > is from when top was running but tr had not started yet. top is > not managing text replacement correctly for output characters that > end up not being just "in" the next character-cell on the terminal. > > The same sort of result happens when instead adding just one > carriage return (control-M) in front of that first quuoted > string instead: > > 0\\n8 ro1\\n 2\\92 3\\n12764\\n 25\\ni CP6\\n 117\\n:11 100.00\t0r \nHiS\\t1pid \\t2 \\t3 \\t4 \\t5 \\t6 \\t > 33094 root 20 0 17172Ki 5488Ki CPU23 23 0:00 0.04% top -HiSCazopid > > I do not intend to try to find all examples of characters that > cause problems but used to not cause problems. > > From what I've seen, cursor positioning escape character sequences > seem to be sent through and cause overwrites at arbitrary places > on screen, based on the escape sequence content. There are command > lines around that contain such sequences. So I sometimes see the > first few lines of top's output have garbage text from commands > that were listed below at some point overwriting the top text. > > Part of what is going on is top avoiding rewriting characters > that its tracking indicates have not been updated. When the > actual display and that supposed-tracking mismatch, the > display ends up wrong when updated (bad text continues to > display). > > The text in commands should not make "top -a" output mess up > the display of other lines in top's output, nor of other > top output fields on the same line. In my view, if some usage > contexts need otherwise, it should take an extra command line > option to put top in a mode that might do such things. The > default behavior should strictly avoid having such things > happen. Thanks. The attached diff seems to take care of the issue for me, adding VIS_TAB and removing VIS_SAFE, which can be blamed for passing through the following: VIS_SAFE Currently this form allows space, tab, newline, backspace, bell, and return — in addition to all graphic characters — unencoded.
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