From c5766eae6f2b002396b6cd4f85b62317b707174e Mon Sep 17 00:00:00 2001 From: Johannes Schindelin Date: Sun, 4 Dec 2022 22:56:08 +0100 Subject: [PATCH] is_Cygwin: avoid `exec`ing anything The `is_Cygwin` function is used, among other things, to determine how executables are discovered in the `PATH` list by the `_which` function. We are about to change the behavior of the `_which` function on Windows (but not Cygwin): On Windows, we want it to ignore empty elements of the `PATH` instead of treating them as referring to the current directory (which is a "legacy feature" according to https://pubs.opengroup.org/onlinepubs/9699919799/basedefs/V1_chap08.html#tag_08_03, but apparently not explicitly deprecated, the POSIX documentation is quite unclear on that even if the Cygwin project itself considers it to be deprecated: https://github.com/cygwin/cygwin/commit/fc74dbf22f5c). This is important because on Windows, `exec` does something very unsafe by default (unless we're running a Cygwin version of Tcl, which follows Unix semantics). However, we try to `exec` something _inside_ `is_Cygwin` to determine whether we're running within Cygwin or not, i.e. before we determined whether we need to handle `PATH` specially or not. That's a Catch-22. Therefore, and because it is much cleaner anyway, use the `$::tcl_platform(os)` value which is guaranteed to start with `CYGWIN_` when running a Cygwin variant of Tcl/Tk, instead of executing `cygpath --windir`. Signed-off-by: Johannes Schindelin Signed-off-by: Pratyush Yadav --- git-gui.sh | 12 ++---------- 1 file changed, 2 insertions(+), 10 deletions(-) diff --git a/git-gui.sh b/git-gui.sh index 0cf625ca01..0fe60f80cc 100755 --- a/git-gui.sh +++ b/git-gui.sh @@ -269,16 +269,8 @@ proc is_Windows {} { proc is_Cygwin {} { global _iscygwin if {$_iscygwin eq {}} { - if {$::tcl_platform(platform) eq {windows}} { - if {[catch {set p [exec cygpath --windir]} err]} { - set _iscygwin 0 - } else { - set _iscygwin 1 - # Handle MSys2 which is only cygwin when MSYSTEM is MSYS. - if {[info exists ::env(MSYSTEM)] && $::env(MSYSTEM) ne "MSYS"} { - set _iscygwin 0 - } - } + if {[string match "CYGWIN_*" $::tcl_platform(os)]} { + set _iscygwin 1 } else { set _iscygwin 0 } -- 2.39.5