PR #5358 reintroduced a version of the TIOCGPGRP ioctl call that works
on all Unix platforms except Linux, due to a bug/inconsistency in
x/sys/unix. This commit fixes that by introducing termstatus.Tcgetpgrp.
It also introduces termstatus.Getpgrp and termstatus.Tcsetpgrp to deal
with the different signature of unix.Getpgrp in Solaris vs. all other
Unix platforms and an int-overflowing constant on AIX, so that some
AIX/Solaris-specific code can be removed elsewhere and
foreground/background detection is done the same everywhere except on
Windows.
To clear the status lines, they should be set to an empty array to
prevent future updates of those lines. Setting the status lines to an
array containing an empty string is wrong as this causes the output to
continuously add that empty status line after each message.
`writeStatus` also cleans no longer used status lines.
The old code actually cleaned one line too much. However, as that line
was never used it makes no difference.
x/text/width.LookupRune has to re-encode its argument as UTF-8,
while LookupString operates on the UTF-8 directly.
The uint casts get rid of a bounds check.
Benchmark results, with b.ResetTimer introduced first:
name old time/op new time/op delta
TruncateASCII-8 69.7ns ± 1% 55.2ns ± 1% -20.90% (p=0.000 n=20+18)
TruncateUnicode-8 350ns ± 1% 171ns ± 1% -51.05% (p=0.000 n=20+19)
mintty on windows always uses pipes to connect stdout between processes
and for the terminal output. The previous implementation always assumed
that stdout connected to a pipe means that stdout is displayed on a
mintty terminal. However, this detection breaks when using pipes to
connect processes and for powershell which uses pipes when redirecting
to a file.
Now the pipe filename is queried and matched against the pattern used by
msys / cygwin when connected to the terminal. In all other cases assume
that a pipe is just a regular pipe.
Previously the progress bar / status update interval used
stdoutIsTerminal to determine whether it is possible to update the
progress bar or not. However, its implementation differed from the
detection within the backup command which included additional checks to
detect the presence of mintty on Windows. mintty behaves like a terminal
but uses pipes for communication.
This adds stdoutCanUpdateStatus() which calls the same terminal detection
code used by backup. This ensures that all commands consistently switch
between interactive and non-interactive terminal mode.
stdoutIsTerminal() now also returns true whenever stdoutCanUpdateStatus()
does so. This is required to properly handle the special case of mintty.
