New configuration statement for manipulating the environment.

The "env" statement is now a compound statement. It can contain four
substatements: "clear" to clear the environment, "keep" to retain
certain variable while clearing it, "set" to set a variable, and
"unset" to unset a variable or variables.

Both "keep" and "unset" can take globbing pattern as their argument,
in which case they affect all variable matching that pattern.

The value part in the "set" statement is subject to variable expansion,
e.g.

   set "MANPATH=$MANPATH${MANPATH:+:}/usr/local/man"

The support for the old one-line syntax of "env" is retained for
backward compatibility.

This commit also fixes redirection to a file: new data are appended
to the file, instead of overwriting it.

* lib/Makefile.am: Add new files.
* lib/envop.c: New file.
* lib/envop.h: New file.
* lib/wildmatch.c: New file.

* src/comp.c (component_free): Update.
* src/pies.c (argv_free): New function.
(parse_legacy_env): New function.
(_cb_env): Remove.
(cb_env_section_parser): New function.
(cb_env_keywords): New keywords for the "env" block statement:
clear, keep, set, unset.
(component_keywords): New compount statement: env.
Old usage retained for backward compatibility.
* src/pies.h: Include "envop.h"
(component)<env>: Remove.
<envop>: New field.
* src/prog.h (prog)<env>: New field.
* src/progman.c (redirect_to_file): Position to the end of file.
(DEBUG_ENVIRON): Remove macro.
(debug_environ): New function.
(environ_setup): Remove.
(prog_sockenv): Use environ_set to modify local copy of environment.
(prog_start_prologue): Use environ_create + envop_exec to create and
modify the environment.
(prog_execute): Set environment to prog-local copy.

* tests/.gitignore: Build envtest
* tests/Makefile.am: Add new tests.
* tests/testsuite.at: Add environment tests.
* tests/envop.at: New file.
* tests/envtest.c: New file.
* tests/env.at: New file.
* tests/redirect.at: Check first two lines of the output file.

16 files changed, 1410 insertions, 289 deletions

diff --git a/lib/Makefile.am b/lib/Makefile.am
index 4aa9d3e..7b4eb42 100644
--- a/lib/Makefile.am
+++ b/lib/Makefile.am
@@ -21,6 +21,8 @@ noinst_HEADERS = libpies.h grecsasrt.h
 libpies_a_SOURCES=\
  addrfmt.c\
  arraymember.c\
+ envop.c\
+ envop.h\
  grecsasrt.c\
  mkfilename.c\
  netrc.c\
@@ -30,7 +32,8 @@ libpies_a_SOURCES=\
  safe_strcmp.c\
  split3.c\
  strtotok.c\
- url.c
+ url.c\
+ wildmatch.c
 
 libpies_a_LIBADD=\
  $(LIBOBJS)\
diff --git a/lib/envop.c b/lib/envop.c
new file mode 100644
index 0000000..79083f7
--- /dev/null
+++ b/lib/envop.c
@@ -0,0 +1,484 @@
+/* Environment modification functions for GNU Pies.
+   Copyright (C) 2019 Sergey Poznyakoff
+
+   GNU Pies is free software; you can redistribute it and/or modify
+   it under the terms of the GNU General Public License as published by
+   the Free Software Foundation; either version 3, or (at your option)
+   any later version.
+
+   GNU Pies is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+   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/>. */
+
+#ifdef HAVE_CONFIG_H
+# include <config.h>
+#endif
+#include <stdlib.h>
+#include <string.h>
+#include <errno.h>
+#include <ctype.h>
+#include "envop.h"
+#include "wordsplit.h"
+
+environ_t *
+environ_create (char **def)
+{
+  size_t i;
+  environ_t *env = malloc (sizeof (*env));
+
+  if (!env)
+    return NULL;
+
+  if (!def)
+    {
+      static char *nullenv[] = { NULL };
+      def = nullenv;
+    }
+  
+  for (i = 0; def[i]; i++)
+    ;
+  env->env_count = 0;
+  env->env_max = i + 1;
+  env->env_base = calloc (env->env_max, sizeof (env->env_base[0]));
+  if (!env->env_base)
+    {
+      free (env);
+      return NULL;
+    }
+  
+  for (i = 0; def[i]; i++)
+    {
+      if (!(env->env_base[i] = strdup (def[i])))
+        {
+          environ_free (env);
+          return NULL;
+        }
+      env->env_count++;
+    }
+  env->env_base[i] = NULL;
+  return env;
+}
+
+void
+environ_free (environ_t *env)
+{
+  size_t i;
+  for (i = 0; i < env->env_count; i++)
+    free (env->env_base[i]);
+  free (env->env_base);
+}
+
+static ssize_t
+getenvind (environ_t *env, char const *name, char **pval)
+{
+  size_t i;
+  
+  for (i = 0; i < env->env_count; i++)
+    {
+      char const *p;
+      char *q;
+      
+      for (p = name, q = env->env_base[i]; *p == *q; p++, q++)
+        if (*p == '=')
+          break;
+      if ((*p == 0 || *p == '=') && *q == '=')
+        {
+          if (pval)
+            *pval = q + 1;
+          return i;
+        }
+    }
+  return -1;
+}
+
+static ssize_t
+environ_alloc (environ_t *env)
+{
+  size_t n;
+  if (env->env_count + 1 >= env->env_max)
+    {
+      char **p;
+      if (env->env_base == NULL)
+        {
+          n = 64;
+          p = calloc (n, sizeof (p[0]));
+          if (!p)
+            return -1;
+        }
+      else
+        {
+          n = env->env_max;
+          if ((size_t) -1 / 3 * 2 / sizeof (p[0]) <= n)
+            {
+              errno = ENOMEM;
+              return -1;
+            }
+          n += (n + 1) / 2;
+          p = realloc (env->env_base, n * sizeof (p[0]));
+          if (!p)
+            return -1;
+        }
+      env->env_base = p;
+      env->env_max = n;
+    }
+  n = env->env_count++;
+  env->env_base[env->env_count] = NULL;
+  return n;
+}
+
+static int
+environ_add_alloced (environ_t *env, char *def)
+{
+  ssize_t n;
+  n = getenvind (env, def, NULL);
+  if (n == -1)
+    {
+      n = environ_alloc (env);
+      if (n == -1)
+        return -1;
+    }
+  free (env->env_base[n]);
+  env->env_base[n] = def;
+  return 0;
+}
+
+int
+environ_add (environ_t *env, char const *def)
+{
+  char *defcp = strdup (def);
+  if (!defcp)
+    return -1;
+  if (environ_add_alloced (env, defcp))
+    {
+      free (defcp);
+      return -1;
+    }
+  return 0;
+}
+  
+int
+environ_set (environ_t *env, char const *name, char const *value)
+{
+  size_t len;
+  char *def;
+  struct wordsplit ws;
+
+  if (!name)
+    {
+      errno = EINVAL;
+      return -1;
+    }
+  if (!value)
+    return environ_unset (env, name);
+
+  ws.ws_env = (char const **) env->env_base;
+  if (wordsplit (value, &ws,
+                 WRDSF_NOSPLIT
+                 | WRDSF_QUOTE
+                 | WRDSF_NOCMD /* FIXME */
+                 | WRDSF_SQUEEZE_DELIMS
+                 | WRDSF_CESCAPES
+                 | WRDSF_ENV
+                 | WRDSF_PATHEXPAND))
+    {
+      int ec = errno;
+      if (ws.ws_errno != WRDSE_USAGE) /* FIXME */
+        wordsplit_free (&ws);
+      errno = ec;
+      return -1;
+    }
+
+  if (strcmp (name, ":") == 0)
+    {
+      wordsplit_free (&ws);
+      return 0;
+    }