Toggle diff (272 lines)
diff --git a/doc/guix.texi b/doc/guix.texi
index dabd7fea1e..e860ccc9b2 100644
--- a/doc/guix.texi
+++ b/doc/guix.texi
@@ -5640,17 +5640,11 @@ environment, where the new packages are added to search path environment
variables such as @code{PATH}. You can, instead, choose to create an
@emph{isolated} environment containing nothing but the packages you
asked for. Passing the @option{--pure} option clears environment
-variable definitions found in the parent environment@footnote{Users
-sometimes wrongfully augment environment variables such as @env{PATH} in
-their @file{~/.bashrc} file. As a consequence, when @command{guix
-environment} launches it, Bash may read @file{~/.bashrc}, thereby
-introducing ``impurities'' in these environment variables. It is an
-error to define such environment variables in @file{.bashrc}; instead,
-they should be defined in @file{.bash_profile}, which is sourced only by
-log-in shells. @xref{Bash Startup Files,,, bash, The GNU Bash Reference
-Manual}, for details on Bash start-up files.}; passing
-@option{--container} goes one step further by spawning a @dfn{container}
-isolated from the rest of the system:
+variable definitions found in the parent environment@footnote{Be sure to
+use the @option{--check} option the first time you use @command{guix
+shell} interactively to make sure the shell does not undo the effect of
+@option{--pure}.}; passing @option{--container} goes one step further by
+spawning a @dfn{container} isolated from the rest of the system:
@example
guix shell --container emacs gcc-toolchain
@@ -5699,6 +5693,24 @@ $ ls "$GUIX_ENVIRONMENT/bin"
The available options are summarized below.
@table @code
+@item --check
+Set up the environment and check whether the shell would clobber
+environment variables. It's a good idea to use this option the first
+time you run @command{guix shell} for an interactive session to make
+sure your setup is correct.
+
+For example, if the shell modifies the @env{PATH} environment variable,
+report it since you would get a different environment than what you
+asked for.
+
+Such problems usually indicate that the shell startup files are
+unexpectedly modifying those environment variables. For example, if you
+are using Bash, make sure that environment variables are set or modified
+in @file{~/.bash_profile} and @emph{not} in @file{~/.bashrc}---the
+former is sourced only by log-in shells. @xref{Bash Startup Files,,,
+bash, The GNU Bash Reference Manual}, for details on Bash start-up
+files.
+
@item --development
@itemx -D
Cause @command{guix shell} to include in the environment the
@@ -6065,6 +6077,11 @@ guix environment --preserve='^DISPLAY$' --container --network \
The available options are summarized below.
@table @code
+@item --check
+Set up the environment and check whether the shell would clobber
+environment variables. @xref{Invoking guix shell, @option{--check}},
+for more info.
+
@item --root=@var{file}
@itemx -r @var{file}
@cindex persistent environment
diff --git a/guix/scripts/environment.scm b/guix/scripts/environment.scm
index 05a43659da..7b97a8e39a 100644
--- a/guix/scripts/environment.scm
+++ b/guix/scripts/environment.scm
@@ -41,12 +41,14 @@ (define-module (guix scripts environment)
#:autoload (gnu build accounts) (password-entry group-entry
password-entry-name password-entry-directory
write-passwd write-group)
- #:autoload (guix build syscalls) (set-network-interface-up)
+ #:autoload (guix build syscalls) (set-network-interface-up openpty login-tty)
#:use-module (gnu system file-systems)
#:autoload (gnu packages) (specification->package+output)
#:autoload (gnu packages bash) (bash)
#:autoload (gnu packages bootstrap) (bootstrap-executable %bootstrap-guile)
#:use-module (ice-9 match)
+ #:autoload (ice-9 rdelim) (read-line)
+ #:use-module (ice-9 vlist)
#:use-module (srfi srfi-1)
#:use-module (srfi srfi-11)
#:use-module (srfi srfi-26)
@@ -83,6 +85,8 @@ (define (show-environment-options-help)
-m, --manifest=FILE create environment with the manifest from FILE"))
(display (G_ "
-p, --profile=PATH create environment from profile at PATH"))
+ (display (G_ "
+ --check check if the shell clobbers environment variables"))
(display (G_ "
--pure unset existing environment variables"))
(display (G_ "
@@ -178,6 +182,9 @@ (define %options
(option '(#\V "version") #f #f
(lambda args
(show-version-and-exit "guix environment")))
+ (option '("check") #f #f
+ (lambda (opt name arg result)
+ (alist-cons 'check? #t result)))
(option '("pure") #f #f
(lambda (opt name arg result)
(alist-cons 'pure #t result)))
@@ -396,6 +403,155 @@ (define* (launch-environment command profile manifest
((program . args)
(apply execlp program program args))))
+(define (child-shell-environment shell profile manifest)
+ "Create a child process, load PROFILE and MANIFEST, and then run SHELL in
+interactive mode in it. Return a name/value vhash for all the variables shown
+by running 'set' in the shell."
+ (define-values (controller inferior)
+ (openpty))
+
+ (define script
+ ;; Script to obtain the list of environment variable values. On a POSIX
+ ;; shell we can rely on 'set', but on fish we have to use 'env' (fish's
+ ;; 'set' truncates values and prints them in a different format.)
+ "env || /usr/bin/env || set; echo GUIX-CHECK-DONE; read x; exit\n")
+
+ (define lines
+ (match (primitive-fork)
+ (0
+ (catch #t
+ (lambda ()
+ (load-profile profile manifest #:pure? #t)
+ (setenv "GUIX_ENVIRONMENT" profile)
+ (close-fdes controller)
+ (login-tty inferior)
+ (execl shell shell))
+ (lambda _
+ (primitive-exit 127))))
+ (pid
+ (close-fdes inferior)
+ (let* ((port (fdopen controller "r+l"))
+ (result (begin
+ (display script port)
+ (let loop ((lines '()))
+ (match (read-line port)
+ ((? eof-object?) (reverse lines))
+ ("GUIX-CHECK-DONE\r"
+ (display "done\n" port)
+ (reverse lines))
+ (line
+ ;; Drop the '\r' from LINE.
+ (loop (cons (string-drop-right line 1)
+ lines))))))))
+ (close-port port)
+ (waitpid pid)
+ result))))
+
+ (fold (lambda (line table)
+ ;; Note: 'set' in fish outputs "NAME VALUE" instead of "NAME=VALUE"
+ ;; but it also truncates values anyway, so don't try to support it.
+ (let ((index (string-index line #\=)))
+ (if index
+ (vhash-cons (string-take line index)
+ (string-drop line (+ 1 index))
+ table)
+ table)))
+ vlist-null
+ lines))
+
+(define* (validate-child-shell-environment profile manifest
+ #:optional (shell %default-shell))
+ "Run SHELL in interactive mode in an environment for PROFILE and MANIFEST
+and report clobbered environment variables."
+ (define warned? #f)
+ (define-syntax-rule (warn exp ...)
+ (begin
+ (set! warned? #t)
+ (warning exp ...)))
+
+ (info (G_ "checking the environment variables visible from shell '~a'...~%")
+ shell)
+ (let ((actual (child-shell-environment shell profile manifest)))
+ (when (vlist-null? actual)
+ (leave (G_ "failed to determine environment of shell '~a'~%")
+ shell))
+ (for-each (match-lambda
+ ((spec . expected)
+ (let ((name (search-path-specification-variable spec)))
+ (match (vhash-assoc name actual)
+ (#f
+ (warn (G_ "variable '~a' is missing from shell \
+environment~%")
+ name))
+ ((_ . actual)
+ (cond ((string=? expected actual)
+ #t)
+ ((string-prefix? expected actual)
+ (warn (G_ "variable '~a' has unexpected \
+suffix '~a'~%")
+ name
+ (string-drop actual
+ (string-length expected))))
+ (else
+ (warn (G_ "variable '~a' is clobbered: '~a'~%")
+ name actual))))))))
+ (profile-search-paths profile manifest))
+
+ ;; Special case.
+ (match (vhash-assoc "GUIX_ENVIRONMENT" actual)
+ (#f
+ (warn (G_ "'GUIX_ENVIRONMENT' is missing from the shell \
+environment~%")))
+ ((_ . value)
+ (unless (string=? value profile)
+ (warn (G_ "'GUIX_ENVIRONMENT' is set to '~a' instead of '~a'~%")
+ value profile))))
+
+ ;; Check the prompt unless we have more important warnings.
+ (unless warned?
+ (match (vhash-assoc "PS1" actual)
+ (#f #f)
+ (str
+ (when (and (getenv "PS1") (string=? str (getenv "PS1")))
+ (warning (G_ "'PS1' is the same in sub-shell~%"))
+ (display-hint (G_ "Consider setting a different prompt for
+environment shells to make them distinguishable.
+
+If you are using Bash, you can do that by adding these lines to
+@file{~/.bashrc}:
+
+@example
+if [ -n \"$GUIX_ENVIRONMENT\" ]
+then
+ export PS1=\"\\u@@\\h \\w [env]\\$ \"
+fi
+@end example
+"))))))
+
+ (if warned?
+ (begin
+ (display-hint (G_ "One or more environment variables have a
+different value in the shell than the one we set. This means that you may
+find yourself running code in an environment different from the one you asked
+Guix to prepare.
+
+This usually indicates that your shell startup files are unexpectedly
+modifying those environment variables. For example, if you are using Bash,
+make sure that environment variables are set or modified in
+@file{~/.bash_profile} and @emph{not} in @file{~/.bashrc}. For more
+information on Bash startup files, run:
+
+@example
+info \"(bash) Bash Startup Files\"
+@end example
+
+Alternatively, you can avoid the problem by passing the @option{--container}
+or @option{-C} option. That will give you a fully isolated environment
+running in a \"container\", immune to the issue described above."))
+ (exit 1))
+ (info (G_ "All is good! The shell gets correct environment \
+variables.~%")))))
+
(define* (launch-environment/fork command profile manifest
#:key pure? (white-list '()))
"Run COMMAND in a new process with an environment containing PROFILE, with
@@ -775,6 +931,10 @@ (define manifest
(mwhen gc-root
(register-gc-root profile gc-root))
+ (mwhen (assoc-ref opts 'check?)
+ (return
+ (validate-child-shell-environment profile manifest)))
+
(cond
((assoc-ref opts 'search-paths)
(show-search-paths profile manifest #:pure? pure?)
--
2.33.0
