slave: unset TERM_PROGRAM{,_VERSION}

Foot’s policy is to not set environment variables that identifies
it (except the well-known and established `TERM` variable).

We encourage applications to use terminfo to determine capabilities,
or terminal queries, when available. Or, at least use terminal queries
to detect the terminal and its version.

Setting environment variables is a bad idea since they are inherited
by all applications started by the terminal (which is the whole
point). But, this includes other terminal emulators, making it very
possible a terminal emulator gets mis-detected just because it was
started from another terminal.

Since there are a couple of terminal emulators that _do_ set
TERM_PROGRAM and TERM_PROGRAM_VERSION, unset these environment
variables to avoid being misdetected.

Closes #1349

CHANGELOG.md

@@ -93,7 +93,7 @@
 * “Report DA2” terminfo entries (`RV`/`rv`).
 * `XF` terminfo capability (focus in/out events available).
 * `$TERM_PROGRAM` and `$TERM_PROGRAM_VERSION` environment variables
-  set in the slave process.
+  unset in the slave process.
 
 [1136]: https://codeberg.org/dnkl/foot/issues/1136
 [1225]: https://codeberg.org/dnkl/foot/issues/1225

doc/foot.1.scd

@@ -546,17 +546,6 @@ In all other cases, the exit code is that of the client application
 	This variable is set to *truecolor*, to indicate to client
 	applications that 24-bit RGB colors are supported.
 
-*TERM_PROGRAM*
-	Always set to *foot*. This can be used by client applications to
-	check which terminal is in use, but with the caveat that it may
-	have been inherited from a parent process in other terminals that
-	aren't known to set the variable.
-
-*TERM_PROGRAM_VERSION*
-	Set to the foot version string, in the format _major_*.*_minor_*.*_patch_
-	or _major_*.*_minor_*.*_patch_*-*_revision_*-\g*_commit_ for inter-release
-	builds. The same caveat as for *TERM_PROGRAM* applies.
-
 In addition to the variables listed above, custom environment
 variables may be defined in *foot.ini*(5).
 

doc/footclient.1.scd

@@ -158,17 +158,6 @@ terminfo entries manually, by copying *foot* and *foot-direct* to
 	This variable is set to *truecolor*, to indicate to client
 	applications that 24-bit RGB colors are supported.
 
-*TERM_PROGRAM*
-	Always set to *foot*. This can be used by client applications to
-	check which terminal is in use, but with the caveat that it may
-	have been inherited from a parent process in other terminals that
-	aren't known to set the variable.
-
-*TERM_PROGRAM_VERSION*
-	Set to the foot version string, in the format _major_*.*_minor_*.*_patch_
-	or _major_*.*_minor_*.*_patch_*-*_revision_*-\g*_commit_ for inter-release
-	builds. The same caveat as for *TERM_PROGRAM* applies.
-
 In addition to the variables listed above, custom environment
 variables may be defined in *foot.ini*(5).
 

generate-version.sh

@@ -41,7 +41,6 @@ patch=$(echo "${new_version}" | sed -r 's/([0-9]+)\.([0-9]+)\.([0-9]+).*/\3/')
 extra=$(echo "${new_version}" | sed -r 's/([0-9]+)\.([0-9]+)\.([0-9]+)(-([0-9]+-g[a-z0-9]+) .*)?.*/\5/')
 
 new_version="#define FOOT_VERSION \"${new_version}\"
-#define FOOT_VERSION_SHORT \"${git_version:-${default_version}}\"
 #define FOOT_MAJOR ${major}
 #define FOOT_MINOR ${minor}
 #define FOOT_PATCH ${patch}

slave.c

@@ -21,7 +21,6 @@
 #include "macros.h"
 #include "terminal.h"
 #include "tokenize.h"
-#include "version.h"
 #include "xmalloc.h"
 
 extern char **environ;
@@ -352,11 +351,12 @@ slave_spawn(int ptmx, int argc, const char *cwd, char *const *argv,
         }
 
         setenv("TERM", term_env, 1);
-        setenv("TERM_PROGRAM", "foot", 1);
-        setenv("TERM_PROGRAM_VERSION", FOOT_VERSION_SHORT, 1);
         setenv("COLORTERM", "truecolor", 1);
         setenv("PWD", cwd, 1);
 
+        unsetenv("TERM_PROGRAM");
+        unsetenv("TERM_PROGRAM_VERSION");
+
 #if defined(FOOT_TERMINFO_PATH)
         setenv("TERMINFO", FOOT_TERMINFO_PATH, 1);
 #endif