Finish the env re-implementation

* NEWS: Document the "env" statement and the PIES_MASTER_PID
environment variable.
Version 1.3.91
* configure.ac: Version 1.3.91
* doc/pies.texi: Document the new "env" statement syntax. Provide
instructions on how to convert legacy "env" statement to the new
form.
* lib/envop.c (environ_unset): Take reference value as argument.
If supplied, unset the variable only if its value matches the
reference one.
* lib/envop.h (environ_unset): Change proto.
* src/pies.c (parse_legacy_env): Minor changes.
(_cb_env_unset): Allow to specify value.
* src/progman.c (run_command): Define PIES_MASTER_PID.
* tests/env.at: Check the legacy env syntax.
* tests/envop.at: Additional checks.

9 files changed, 361 insertions, 27 deletions

diff --git a/NEWS b/NEWS
index f34a6f0..db79097 100644
--- a/NEWS
+++ b/NEWS
@@ -1,13 +1,13 @@
-GNU Pies NEWS -- history of user-visible changes. 2019-05-31
+GNU Pies NEWS -- history of user-visible changes. 2019-06-03
 See the end of file for copying conditions.
 
 Please send Pies bug reports to <bug-pies@gnu.org> or
 <bug-pies@gnu.org.ua>
 
-Version 1.3.90 (git)
+Version 1.3.91 (git)
 
 * New option --no-init
 
 The --no-init option instructs pies not to switch to init mode if its
 PID is 1.  Use this option if you run pies as a process manager in a
 docker container.
@@ -35,21 +35,61 @@ contains redirections, pipes, etc. E.g.
     flags shell;
     command "if [ -n "$X" ]; then foo; else bar; fi"
   }
 
 * Improved cyclic dependency diagnostics
 
-* Fix a bug in 'env' statement
+* New 'env' statement
+
+The 'env' statement has been re-implemented as a compound statement.
+It can contain the following sub-statements:
+
+** clear yes
+Clears the environment
+
+** keep NAME
+Keeps the variable NAME when clearing the environment. Implies
+"clear yes". NAME can be a globbing pattern, in which case all
+variables matching the pattern are retained.
+
+** set "NAME=VALUE"
+Sets the environment variable for the component. VALUE is subject
+to variable expansion.
+
+** unset NAME
+Unsets the variable. NAME can be a globbing pattern, in which case all
+variables matching the pattern are unset.
+
+Example:
+
+ env {
+   clear yes
+   keep PATH
+   keep MANPATH
+   keep "LC_*"
+   set "MANPATH=$MANPATH${MANPATH:+:}/usr/local/man"
+ }
+
+* Legacy 'env' statement.
+
+Support for the old one-line syntax of "env" is retained for
+backward compatibility.
 
 Previous versions applied unnecessary word splitting if given a
 single argument. This is now fixed, so that e.g. the following
 statement is processed correctly and defines a single variable
 X to have the value "foo bar":
 
   env "X=foo bar"
 
+* New environment variable available in commands started from return-code
+
+Programs started via "exec" statement in the "return-code" block
+obtain the PID of the master pies process in environment variable
+PIES_MASTER_PID.
+
 
 Version 1.3, 2016-10-01
 
 * SysV-style Init 
 
 GNU Pies can now be used as init process daemon - the first process
diff --git a/configure.ac b/configure.ac
index a3c0b34..ccfd9fc 100644
--- a/configure.ac
+++ b/configure.ac
@@ -12,13 +12,13 @@
 # GNU General Public License for more details.
 #
 # You should have received a copy of the GNU General Public License
 # along with GNU Pies.  If not, see <http://www.gnu.org/licenses/>.
 
 AC_PREREQ([2.63])
-AC_INIT([GNU Pies], [1.3.90], [bug-pies@gnu.org.ua])
+AC_INIT([GNU Pies], [1.3.91], [bug-pies@gnu.org.ua])
 AC_CONFIG_SRCDIR([src/pies.h])
 AC_CONFIG_AUX_DIR([build-aux])
 AC_CONFIG_HEADERS([config.h])
 AM_INIT_AUTOMAKE([1.11 gnits tar-ustar dist-bzip2 std-options silent-rules])
 
 # Enable silent rules by default:
diff --git a/doc/pies.texi b/doc/pies.texi
index b77a40c..ccb9f0e 100644
--- a/doc/pies.texi
+++ b/doc/pies.texi
@@ -119,12 +119,13 @@ Configuration File Syntax
 
 Component Statement
 
 * Prerequisites::
 * Component Privileges::
 * Resources::
+* Environment::
 * Actions Before Startup::
 * Exit Actions::
 * Output Redirectors::
 * Inetd-Style Components::
 * Meta1-Style Components::
 * Visibility::
@@ -709,13 +710,13 @@ If the latter is absent, the remembered file name does not change.
 @item # @var{num} "@var{file}"
   This is a special form of @code{#line} statement, understood for
 compatibility with the @sc{c} preprocessor.
 @end table
 
 @node Component Statement
-@section Component Statement
+@section The @code{component} Statement
 @kwindex component
 
 @deffn {Config} component
   The @code{component} statement defines a new component:
 @end deffn
 
@@ -934,12 +935,13 @@ The following subsections describe the rest of @samp{component}
 substatements.
 
 @menu
 * Prerequisites::
 * Component Privileges::
 * Resources::
+* Environment::
 * Actions Before Startup::
 * Exit Actions::
 * Output Redirectors::
 * Inetd-Style Components::
 * Meta1-Style Components::
 * Visibility::
@@ -1035,34 +1037,195 @@ in version @value{VERSION}.
 
 @deffn {Config: component} umask @var{number}
 Set the umask.  The @var{number} must be an octal value not greater
 than @samp{777}.  The default umask is inherited at startup.
 @end deffn
 
-@deffn {Config: component} env @var{args}
+@deffn {Config: component} max-instances @var{n}
+Sets the maximum number of simultaneously running instances of this
+component. 
+@end deffn
+
+@node Environment
+@subsection Environment
+Normally all components inherit the environment of the master
+@command{pies} process.  You can modify this environment using
+the @code{env} statement.  It has two variants: @dfn{compound} and @dfn{legacy}.
+The legacy one-line statement was used in @command{pies} versions
+up to 1.3 and is still retained for backward compatibility.  It is
+described in @ref{env legacy syntax}.  This subsection describes the
+modern compount syntax.
+
+@deffn {Config: component} env @{ ... @}
+The compound @code{env} statement has the following syntax:
+
+@example
+@group
+env @{
+   clear @var{bool};
+   keep @var{pattern};
+   set "@var{name}=@var{value}";
+   unset @var{pattern};
+@}
+@end group
+@end example
+@end deffn
+
+Statements inside the @code{env} block define operations that
+modify the environment.  The @code{clear} and @code{keep} statements
+are executed first.  Then, the @code{set} and @code{unset} statements
+are applied in the order of their appearance in the configuration.
+
+@deffn {env} clear @var{bool}
+If @var{bool} is @samp{yes}, all environment variables will be cleared
+(unset).  The resulting environment will be empty, unless one or more
+@code{keep} statements are also given (see below).  The @code{clear}
+statement is always executed first.
+@end deffn
+
+@deffn {env} keep @var{pattern}
+Declares variables matching @var{pattern} (a globbing pattern) as
+exempt from clearing.  This statement implies @code{clear}.
+
+For example, the following configuration fragment removes from the
+environment all variables except @samp{HOME}, @samp{USER},
+@samp{PATH}, and variables beginning with @samp{LC_}:
+
+@example
+@group
+env @{
+  clear yes;
+  keep HOME;
+  keep USER;
+  keep PATH;
+  keep "LC_*";
+@}
+@end group
+@end example
+@end deffn
+
+@deffn {env} keep "@var{name}=@var{value}"
+Retains the variable @var{name}, if it has the given value. Note, that
+the argument must be quoted.
+@end deffn
+
+@deffn {env} set "@var{name}=@var{value}"
+Assigns @var{value} to environment variable @var{name}.  The value is
+subject to @dfn{variable expansion} using the same syntax as in shell.
+The @code{set} and @code{unset} (see below) statements are executed in
+order of their appearance.  For example
+
+@example
+@group
+env @{
+  set "MYLIB=$HOME/lib";
+  set "LD_LIBRARY_PATH=$LD_LIBRARY_PATH$@{LD_LIBRARY_PATH:+:@}$MYLIB";
+@}
+@end group
+@end example
+@end deffn
+
+@deffn {env} unset @var{pattern}
+Unset environment variables matching @var{pattern}.  The following
+will unset the @env{LOGIN} variable:
+
+@example
+unset LOGIN;
+@end example
+
+@noindent
+The following will unset all variables starting with @samp{LD_}:
+
+@example
+unset "LD_*";
+@end example
+
+@noindent
+Notice, that patterns containing wildcard characters must be quoted.
+@end deffn
+
+@menu
+* env legacy syntax::
+@end menu
+
+@node env legacy syntax
+@subsubsection @code{env}: legacy syntax.
+Up to version 1.3 @command{pies} implemented the one-line variant of
+the @code{env} statement.  The use of this legacy syntax is
+discouraged.  It is supported for backward compatibility only and will
+be removed in future versions.  This subsection describes the legacy
+syntax.
+
+@deffn {legacy syntax} env @var{args}
 Set program environment.
 
 Arguments are a whitespace-delimited list of specifiers.  The
 following specifiers are understood: 
 
 @table @asis
 @item - (a dash)
 Clear the environment.  This is understood only when used as a first
 word in @var{args}.
 
+The modern syntax equivalent is:
+
+@example
+@group
+env @{
+  clear yes;
+@}
+@end group
+@end example
+
 @item -@var{name}
-Unset the environment variable @var{name}.
+Unset the environment variable @var{name}.  The modern syntax
+equivalent is
+
+@example
+@group
+env @{
+  unset @var{name};
+@}
+@end group
+@end example
 
 @item -@var{name}=@var{val}
 Unset the environment variable @var{name} only if its value is @var{val}.
+The modern syntax equivalent is:
+
+@example
+@group
+env @{
+  unset "@var{name}=@var{val}";
+@}
+@end group
+@end example
 
 @item @var{name}
-Retain the environment variable @var{name}.
+Retain the environment variable @var{name}.  The modern syntax
+equivalent is
+
+@example
+@group
+env @{
+  keep @var{name};
+@}
+@end group
+@end example
 
 @item @var{name}=@var{value}
-Define environment variable @var{name} to have given @var{value}.
+Define environment variable @var{name} to have given @var{value}.  The
+modern syntax equivalent is:
+
+@example
+@group
+env @{
+  keep "@var{name}=@var{value}";
+@}
+@end group
+@end example
 
 @item @var{name}+=@var{value}
 Retain variable @var{name} and append @var{value} to its existing
 value.  If no such variable is present in the environment, it is
 created and @var{value} is assigned to it.  However, if @var{value}
 begins with a punctuation character, this character is removed from it
@@ -1074,24 +1237,48 @@ PATH+=:/sbin
 @end example
 
 In this example, if @env{PATH} exists, @samp{:/sbin} will be appended
 to it.  Otherwise, it will be created and @samp{/sbin} will be
 assigned to it.
 
+In modern syntax, use shell variable references, e.g.:
+
+@example
+@group
+env @{
+  set "PATH=$@{PATH@}$@{PATH:+:@}/sbin";
+@}
+@end group
+@end example
+
 @item @var{name}=+@var{value}
 Retain variable @var{name} and prepend @var{value} to its existing
 value.  If no such variable is present in the environment, it is
 created and @var{value} is assigned to it.  However, if @var{value}
 ends with a punctuation character, this character is removed from it
-before assignment. 
-@end table
-@end deffn
+before assignment.
 
-@deffn {Config: component} max-instances @var{n}
-Sets the maximum number of simultaneously running instances of this
-component. 
+In modern syntax, use shell variable references, e.g. instead of
+doing
+
+@example
+env PATH=+/sbin:
+@end example
+
+@noindent
+use
+
+@example
+@group
+env @{
+  set "PATH=/sbin$@{PATH:+:@}$PATH";
+@}
+@end group
+@end example
+
+@end table
 @end deffn
 
 @node Actions Before Startup
 @subsection Actions Before Startup
 
   The statements described in this subsection specify actions to perform
@@ -1183,12 +1370,15 @@ environment from the main @command{pies} process with the following
 additional variables:
 
 @table @env
 @item PIES_VERSION
 The @command{pies} version number (@value{VERSION}).
 
+@item PIES_MASTER_PID
+PID of the master @command{pies} process.
+
 @item PIES_COMPONENT
 Tag of the terminated component (@pxref{Component Statement, tag}).
 
 @item PIES_PID
 PID of the terminated component.
 
diff --git a/lib/envop.c b/lib/envop.c
index 79083f7..80a8b6c 100644
--- a/lib/envop.c
+++ b/lib/envop.c
@@ -170,13 +170,13 @@ environ_set (environ_t *env, char const *name, char const *value)
   if (!name)
     {
       errno = EINVAL;
       return -1;
     }
   if (!value)
-    return environ_unset (env, name);
+    return environ_unset (env, name, value);
 
   ws.ws_env = (char const **) env->env_base;
   if (wordsplit (value, &ws,
 		 WRDSF_NOSPLIT
 		 | WRDSF_QUOTE
 		 | WRDSF_NOCMD /* FIXME */
@@ -215,24 +215,27 @@ environ_set (environ_t *env, char const *name, char const *value)
       return -1;
     }
   return 0;
 }
   
 int
-environ_unset (environ_t *env, char const *name)
+environ_unset (environ_t *env, char const *name, char const *refval)
 {
   ssize_t n;
+  char *val;
 
   if (!env || !name)
     {
       errno = EINVAL;
       return -1;
     }
-  n = getenvind (env, name, NULL);
+  n = getenvind (env, name, &val);
   if (n == -1)
     return ENOENT;
+  if (refval && strcmp (val, refval))
+    return ENOENT;
 
   free (env->env_base[n]);
   memmove (env->env_base + n, env->env_base + n + 1,
 	   (env->env_count - n) * sizeof (env->env_base[0]));
   env->env_count--;
   return 0;
@@ -454,13 +457,16 @@ envop_exec (struct envop_entry *op, environ_t *env)
 	case envop_set:
 	  if (environ_set (env, op->name, op->value))
 	    return -1;
 	  break;
 		   
 	case envop_unset:
-	  environ_unset_glob (env, op->name);
+	  if (op->value)
+	    environ_unset (env, op->name, op->value);
+	  else
+	    environ_unset_glob (env, op->name);
 	  break;
 
 	case envop_keep:
 	  break;
 	  
 	default:
diff --git a/lib/envop.h b/lib/envop.h
index 054152e..82be3a5 100644
--- a/lib/envop.h
+++ b/lib/envop.h
@@ -24,13 +24,13 @@ struct environ
 typedef struct environ environ_t;
 
 environ_t *environ_create (char **);
 void environ_free (environ_t *env);
 int environ_add (environ_t *env, char const *def);
 int environ_set (environ_t *env, char const *name, char const *val);
-int environ_unset (environ_t *env, char const *name);
+int environ_unset (environ_t *env, char const *name, char const *val);
 int environ_unset_glob (environ_t *env, const char *pattern);
 static inline char **
 environ_ptr (environ_t *env)
 {
   return env->env_base;
 }
diff --git a/src/pies.c b/src/pies.c
index 2387cef..fe8d9b4 100644
--- a/src/pies.c
+++ b/src/pies.c
@@ -610,13 +610,13 @@ parse_legacy_env (char **argv, envop_t **envop)
 	    {
 	      name[--len] = 0;
 	      if (c_ispunct (value[0]))
 		{
 		  msize = 2*len + 9 + vlen + 1;
 		  mem = grecs_malloc (msize);
-		  snprintf (mem, msize, "${%s:-}${%s+%c}%s",
+		  snprintf (mem, msize, "${%s:-}${%s:+%c}%s",
 			    name, name, value[0], value + 1);
 		}
 	      else
 		{
 		  msize = len + vlen + 6;
 		  snprintf (mem, msize, "${%s:-}%s", name, value);
@@ -632,13 +632,13 @@ parse_legacy_env (char **argv, envop_t **envop)
 		{
 		  int c = value[vlen-1];
 		  value[--vlen] = 0;
 
 		  msize = 2*len + 10 + vlen + 1;
 		  mem = grecs_malloc (msize);
-		  snprintf (mem, msize, "%s${%s+%c}${%s:-}",
+		  snprintf (mem, msize, "%s${%s:+%c}${%s:-}",
 			    value, name, c, name);
 		}
 	      else
 		{
 		  msize = len + vlen + 6;
 		  snprintf (mem, msize, "%s${%s:-}", value, name);
@@ -782,17 +782,21 @@ _cb_env_set (enum grecs_callback_command cmd,
 static int
 _cb_env_unset (enum grecs_callback_command cmd,
 	       grecs_locus_t *locus,
 	       void *varptr, grecs_value_t *value, void *cb_data)
 {
   struct component *comp = varptr;
+  char *p;
 
   if (assert_scalar_stmt (locus, cmd)
       || assert_grecs_value_type (locus, value, GRECS_TYPE_STRING))
     return 1;
-  if (envop_entry_add (&comp->envop, envop_unset, value->v.string, NULL))
+  p = strchr (value->v.string, '=');
+  if (p)
+    *p++ = 0;
+  if (envop_entry_add (&comp->envop, envop_unset, value->v.string, p))
     grecs_error (locus, errno, "envop_entry_add");
   return 0;
 }
 
 struct grecs_keyword cb_env_keywords[] = {
   { "clear",
diff --git a/src/progman.c b/src/progman.c
index b75a2db..a6dc418 100644
--- a/src/progman.c
+++ b/src/progman.c
@@ -818,13 +818,13 @@ prog_start_prologue (struct prog *prog)
 
   prog->v.p.env = environ_create (environ);
   if (prog->v.p.comp->flags & CF_SOCKENV)
     {
       size_t i;
       for (i = 0; sockenv_var[i]; i++)
-	environ_unset (prog->v.p.env, sockenv_var[i]);
+	environ_unset (prog->v.p.env, sockenv_var[i], NULL);
     }
   envop_exec (prog->v.p.comp->envop, prog->v.p.env);
   if (init_process)
     {
       size_t i;
       for (i = 0; sysvinit_environ_hint[i]; i++)
@@ -1975,16 +1975,18 @@ status_matches_p (struct action *act, unsigned status)
 }
 
 static void
 run_command (struct action *act, struct prog *prog, unsigned retcode,
 	     pid_t child_pid)
 {
-  pid_t pid;
+  pid_t pid, master_pid;
   char *argv[4];
   char buf[INT_BUFSIZE_BOUND (uintmax_t)];
 
+  master_pid = getpid ();
+
   /* FIXME: optionally set output redirectors for this command? */
   pid = fork ();
 
   if (pid == (pid_t) -1)
     {
       logmsg (LOG_ERR, "fork: %s", strerror (errno));
@@ -1995,12 +1997,13 @@ run_command (struct action *act, struct prog *prog, unsigned retcode,
     {
       debug (1, (_("executing %s"), act->command));
       /* Child */
       setsid ();
       setenv ("PIES_VERSION", PACKAGE_VERSION, 1);
       setenv ("PIES_COMPONENT", prog_tag (prog), 1);
+      setenv ("PIES_MASTER_PID", umaxtostr (master_pid, buf), 1);
       setenv ("PIES_PID", umaxtostr (child_pid, buf), 1);
       if (retcode & STATUS_SIG_BIT)
 	setenv ("PIES_SIGNAL", umaxtostr (STATUS_CODE (retcode), buf), 1);
       else
 	setenv ("PIES_STATUS", umaxtostr (STATUS_CODE (retcode), buf), 1);
 
diff --git a/tests/env.at b/tests/env.at
index 18b0e52..430bf10 100644
--- a/tests/env.at
+++ b/tests/env.at
@@ -12,21 +12,21 @@ component envtest {
   }
   command "$abs_builddir/envtest -clone";
   chdir $PWD;
   stdout file "$PWD/log";
   return-code 0 {
     action disable;
-    exec "piesctl --url unix:///$PWD/pies.ctl --no-netrc shutdown";
+    exec "$abs_top_builddir/src/piesctl --url unix:///$PWD/pies.ctl --no-netrc shutdown";
   }
 }
 _EOT
 
 to 5 \
   envtest -exec \
     $abs_top_builddir/src/pies --foreground --stderr \
-                --config-file control.conf --config-file envtest.conf 2>errlog
+                --config-file control.conf --config-file envtest.conf --debug 1 2>errlog
 cat log
 ],
 [0],
 [$4])
 AT_CLEANUP])
 
@@ -65,6 +65,74 @@ LOGIN="user"
 PATH="/usr/local/bin:/usr/bin:/bin"
 PIES_INSTANCE="pies"
 USER="user"
 ])
 
 m4_popdef([ENVTEST])
+
+# ##############################
+# Legacy syntax
+# ##############################
+
+AT_BANNER([env: legacy syntax])
+
+m4_pushdef([ENVTEST],
+[AT_SETUP([$1])
+AT_KEYWORDS([env $2])
+AT_CHECK([
+PIES_XFAIL_CHECK
+PIES_CONTROL_INIT
+cat > envtest.conf <<_EOT
+component envtest {
+  env $3;
+  command "$abs_builddir/envtest -clone";
+  chdir $PWD;
+  stdout file "$PWD/log";
+  return-code 0 {
+    action disable;
+    exec "$abs_top_builddir/src/piesctl --url unix:///$PWD/pies.ctl --no-netrc shutdown";
+  }
+}
+_EOT
+
+to 5 \
+  envtest -exec \
+    $abs_top_builddir/src/pies --foreground --stderr \
+                --config-file control.conf --config-file envtest.conf --debug 1 2>errlog
+cat log
+],
+[0],
+[$4])
+AT_CLEANUP])
+
+ENVTEST([clear],[clear],[-],[])
+ENVTEST([keep],[keep],[- USER LOGIN],
+[LOGIN="user"
+USER="user"
+])
+
+ENVTEST([set],[set],["FOO=bar" "BAR=bar"],
+[BAR="bar"
+FOO="bar"
+HOME="/home/user"
+LC_ALL="C"
+LC_CTYPE="C"
+LC_MESSAGES="C"
+LC_NUMERIC="C"
+LOGIN="user"
+PATH="/usr/local/bin:/usr/bin:/bin"
+PIES_INSTANCE="pies"
+PWD="/home"
+USER="user"
+])
+
+ENVTEST([unset],[unset],["-LC_NUMERIC" "-LC_CTYPE" "-LC_MESSAGES"],
+[HOME="/home/user"
+LC_ALL="C"
+LOGIN="user"
+PATH="/usr/local/bin:/usr/bin:/bin"
+PIES_INSTANCE="pies"
+PWD="/home"
+USER="user"
+])
+
+
diff --git a/tests/envop.at b/tests/envop.at
index 6f634fb..2b857f5 100644
--- a/tests/envop.at
+++ b/tests/envop.at
@@ -94,8 +94,31 @@ ENVTEST([unset wildcard],[unset],[-unset 'LC_*'],
 LOGIN="user"
 PATH="/usr/local/bin:/usr/bin:/bin"
 PWD="/home"
 USER="user"
 ])
 
+ENVTEST([unset with value],[unset],[-unset 'LOGIN=user'],
+[HOME="/home/user"
+LC_ALL="C"
+LC_CTYPE="C"
+LC_MESSAGES="C"
+LC_NUMERIC="C"
+PATH="/usr/local/bin:/usr/bin:/bin"
+PWD="/home"
+USER="user"
+])
+
+ENVTEST([unset with value (mismatch)],[unset],[-unset 'LOGIN=another'],
+[HOME="/home/user"
+LC_ALL="C"
+LC_CTYPE="C"
+LC_MESSAGES="C"
+LC_NUMERIC="C"
+LOGIN="user"
+PATH="/usr/local/bin:/usr/bin:/bin"
+PWD="/home"
+USER="user"
+])
+
 m4_popdef([ENVTEST])