Replace groups.sh with groups.c.

* src/groups.c (main): New file, replacing groups.sh.
* src/group-list.c, src/group-list.h: New files, factored out of id.c,
implementing the functionality that "id" and "groups" have in common.
* src/id.c (print_full_info): Avoid a segfault when trying to print
an error message if getgroups fails.
(print_group_list): Move to group-list.c.
(print_group): Likewise.
* man/Makefile.am: When building groups.1, obtain the help text
from src/groups.c, not src/groups.sh.
(noinst_HEADERS): Add group-list.h.
(group): Remove rule.
(dist_man_MANS): Remove groups.1.
* doc/coreutils.texi (groups: Print group names a user is in):
Explain why "groups" and "groups $(id -un)" give different results
in existing login sessions after you change the group database.
(id: Print user identity): Likewise for "id".
* po/POTFILES.in: Add src/group-list.c and src/groups.c.
* NEWS: mention this.
* AUTHORS: Update.

6 files changed, 339 insertions, 181 deletions

diff --git a/src/Makefile.am b/src/Makefile.am
index a0b1d0c0c..155f22bf3 100644
--- a/src/Makefile.am
+++ b/src/Makefile.am
@@ -33,7 +33,7 @@ EXTRA_PROGRAMS = \
   ginstall link ln dir vdir ls mkdir \
   mkfifo mknod mktemp \
   mv nohup readlink rm rmdir shred stat sync touch unlink \
-  cat cksum comm csplit cut expand fmt fold head join md5sum \
+  cat cksum comm csplit cut expand fmt fold head join groups md5sum \
   nl od paste pr ptx sha1sum sha224sum sha256sum sha384sum sha512sum \
   shuf sort split sum tac tail tr tsort unexpand uniq wc \
   basename date dirname echo env expr factor false \
@@ -42,7 +42,6 @@ EXTRA_PROGRAMS = \
   test true tty whoami yes \
   base64
 
-bin_SCRIPTS = groups
 bin_PROGRAMS = $(OPTIONAL_BIN_PROGS)
 
 noinst_PROGRAMS = setuidgid
@@ -53,6 +52,7 @@ noinst_HEADERS = \
   cp-hash.h \
   dircolors.h \
   fs.h \
+  group-list.h \
   ls.h \
   remove.h \
   system.h \
@@ -61,7 +61,7 @@ noinst_HEADERS = \
   uname.h
 
 EXTRA_DIST = dcgen dircolors.hin tac-pipe.c \
-  groups.sh wheel-gen.pl extract-magic c99-to-c89.diff
+  wheel-gen.pl extract-magic c99-to-c89.diff
 BUILT_SOURCES =
 CLEANFILES = $(SCRIPTS) su
 
@@ -142,20 +142,6 @@ RELEASE_YEAR = \
   `sed -n '/.*COPYRIGHT_YEAR = \([0-9][0-9][0-9][0-9]\) };/s//\1/p' \
     $(top_srcdir)/lib/version-etc.c`
 
-# This depends on 'Makefile', so that version changes
-#(reflected in Makefile's VERSION definition)
-# are reflected into groups --version also between releases.
-groups: groups.sh Makefile
-	rm -f $@ $@-t
-	sed \
-	  -e 's!@''bindir''@!$(bindir)!' \
-	  -e 's/@''RELEASE_YEAR'@/$(RELEASE_YEAR)/ \
-	  -e 's/@''PACKAGE_NAME''@/$(PACKAGE_NAME)/' \
-	  -e 's/@''PACKAGE_BUGREPORT''@/$(PACKAGE_BUGREPORT)/' \
-	  -e 's/@''VERSION''@/$(VERSION)/' $(srcdir)/groups.sh > $@-t
-	chmod +x $@-t
-	mv $@-t $@
-
 all-local: su$(EXEEXT)
 
 installed_su = $(DESTDIR)$(bindir)/`echo su|sed '$(transform)'`
@@ -225,6 +211,8 @@ __SOURCES = lbracket.c
 cp_SOURCES = cp.c $(copy_sources)
 dir_SOURCES = ls.c ls-dir.c
 vdir_SOURCES = ls.c ls-vdir.c
+id_SOURCES = id.c group-list.c
+groups_SOURCES = groups.c group-list.c
 ln_SOURCES = ln.c
 ls_SOURCES = ls.c ls-ls.c
 chown_SOURCES = chown.c chown-core.c
diff --git a/src/group-list.c b/src/group-list.c
new file mode 100644
index 000000000..e788f8e87
--- /dev/null
+++ b/src/group-list.c
@@ -0,0 +1,134 @@
+/* group-list.c --Print a list of group IDs or names.
+   Copyright (C) 1989-2008 Free Software Foundation, Inc.
+
+   This program 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 of the License, or
+   (at your option) any later version.
+
+   This program 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 this program.  If not, see <http://www.gnu.org/licenses/>.  */
+
+/* Written by Arnold Robbins.
+   Major rewrite by David MacKenzie, djm@gnu.ai.mit.edu.
+   Extracted from id.c by James Youngman. */
+
+#include <config.h>
+#include <stdio.h>
+#include <sys/types.h>
+#include <getopt.h>
+#include <pwd.h>
+#include <grp.h>
+
+#include "system.h"
+#include "error.h"
+#include "mgetgroups.h"
+#include "quote.h"
+#include "group-list.h"
+
+
+/* Print all of the distinct groups the user is in. */
+extern bool
+print_group_list (const char *username,
+                  uid_t ruid, gid_t rgid, gid_t egid,
+                  bool use_names)
+{
+  bool ok = true;
+  struct passwd *pwd;
+
+  pwd = getpwuid (ruid);
+  if (pwd == NULL)
+    ok = false;
+
+  if (!print_group (rgid, use_names))
+    ok = false;
+
+  if (egid != rgid)
+    {
+      putchar (' ');
+      if (!print_group (egid, use_names))
+        ok = false;
+    }
+
+#if HAVE_GETGROUPS
+  {
+    GETGROUPS_T *groups;
+    size_t i;
+
+    int n_groups = mgetgroups (username, (pwd ? pwd->pw_gid : (gid_t) -1),
+                               &groups);
+    if (n_groups < 0)
+      {
+        if (username)
+          {
+            error (0, errno, _("failed to get groups for user %s"),
+                   quote (username));
+          }
+        else
+          {
+            error (0, errno, _("failed to get groups for the current process"));
+          }
+        return false;
+      }
+
+    for (i = 0; i < n_groups; i++)
+      if (groups[i] != rgid && groups[i] != egid)
+        {
+          putchar (' ');
+          if (!print_group (groups[i], use_names))
+            ok = false;
+        }
+    free (groups);
+    return ok;
+  }
+#endif /* HAVE_GETGROUPS */
+}
+
+
+/* Print the name or value of group ID GID. */
+extern bool
+print_group (gid_t gid, bool use_name)
+{
+  struct group *grp = NULL;
+  bool ok = true;
+
+  if (use_name)
+    {
+      grp = getgrgid (gid);
+      if (grp == NULL)
+        {
+          error (0, 0, _("cannot find name for group ID %lu"),
+                 (unsigned long int) gid);
+          ok = false;
+        }
+    }
+
+  if (grp == NULL)
+    {
+      if (printf ("%lu", (unsigned long int) gid) < 0)
+        {
+          error (0, errno, _("write error"));
+          ok = false;
+        }
+    }
+  else
+    {
+      if (printf ("%s", grp->gr_name) < 0)
+        {
+          error (0, errno, _("write error"));
+          ok = false;
+        }
+    }
+  return ok;
+}
+
+/*
+ * Local variables:
+ *  indent-tabs-mode: nil
+ * End:
+ */
diff --git a/src/group-list.h b/src/group-list.h
new file mode 100644
index 000000000..868585ede
--- /dev/null
+++ b/src/group-list.h
@@ -0,0 +1,19 @@
+/* group-list.h -- prototypes shared by id and groups.
+
+   Copyright (C) 2008 Free Software Foundation.
+
+   This program 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 of the License, or
+   (at your option) any later version.
+
+   This program 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 this program.  If not, see <http://www.gnu.org/licenses/>.  */
+
+bool print_group (gid_t, bool);
+bool print_group_list (const char *, uid_t, gid_t, gid_t, bool);
diff --git a/src/groups.c b/src/groups.c
new file mode 100644
index 000000000..8a4673ced
--- /dev/null
+++ b/src/groups.c
@@ -0,0 +1,153 @@
+/* groups -- print the groups a user is in
+   Copyright (C) 1989-2008 Free Software Foundation, Inc.
+
+   This program 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 of the License, or
+   (at your option) any later version.
+
+   This program 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 this program.  If not, see <http://www.gnu.org/licenses/>.  */
+
+/* Written by James Youngman based on id.c and groups.sh,
+   which were written by Arnold Robbins and David MacKenzie. */
+
+#include <config.h>
+#include <stdio.h>
+#include <getopt.h>
+#include <sys/types.h>
+#include <pwd.h>
+#include <grp.h>
+#include <getopt.h>
+
+#include "system.h"
+#include "error.h"
+#include "group-list.h"
+
+/* The name this program was run with. */
+char *program_name;
+
+/* The official name of this program (e.g., no `g' prefix).  */
+#define PROGRAM_NAME "groups"
+
+#define AUTHORS "David MacKenzie", "James Youngman"
+
+
+static struct option const longopts[] =
+{
+  {GETOPT_HELP_OPTION_DECL},
+  {GETOPT_VERSION_OPTION_DECL},
+  {NULL, 0, NULL, 0}
+};
+
+void
+usage (int status)
+{
+  if (status != EXIT_SUCCESS)
+    fprintf (stderr, _("Try `%s --help' for more information.\n"),
+             program_name);
+  else
+    {
+      printf (_("Usage: %s [OPTION]... [USERNAME]\n"), program_name);
+      fputs (_("\
+Print information for USERNAME or, if no USERNAME is specified,\n\
+the current process (which is different if the groups database has changed).\n"),
+             stdout);
+      fputs (HELP_OPTION_DESCRIPTION, stdout);
+      fputs (VERSION_OPTION_DESCRIPTION, stdout);
+      emit_bug_reporting_address ();
+    }
+  exit (status);
+}
+
+static void
+write_error (void)
+{
+  error (0, errno, _("write error"));
+}
+
+
+int
+main (int argc, char **argv)
+{
+  int optc;
+  bool ok = true;
+  gid_t rgid, egid;
+  uid_t ruid;
+
+  initialize_main (&argc, &argv);
+  program_name = argv[0];
+  setlocale (LC_ALL, "");
+  bindtextdomain (PACKAGE, LOCALEDIR);
+  textdomain (PACKAGE);
+
+  atexit (close_stdout);
+
+  /* Processing the arguments this way makes groups.c behave differently to
+   * groups.sh if one of the arguments is "--".
+   */
+  while ((optc = getopt_long (argc, argv, "", longopts, NULL)) != -1)
+    {
+      switch (optc)
+        {
+        case_GETOPT_HELP_CHAR;
+        case_GETOPT_VERSION_CHAR (PROGRAM_NAME, AUTHORS);
+        default:
+          usage (EXIT_FAILURE);
+        }
+    }
+
+  if (optind == argc)
+    {
+      /* No arguments.  Divulge the details of the current process. */
+      ruid = getuid ();
+      egid = getegid ();
+      rgid = getgid ();
+
+      if (!print_group_list (NULL, ruid, rgid, egid, true))
+        ok = false;
+      if (EOF == putchar ('\n'))
+        {
+          write_error ();
+          ok = false;
+        }
+    }
+  else
+    {
+      /* At least one argument.  Divulge the details of the specified users. */
+      while (optind < argc)
+        {
+          struct passwd *pwd = getpwnam (argv[optind]);
+          if (pwd == NULL)
+            error (EXIT_FAILURE, 0, _("%s: No such user"), argv[optind]);
+          ruid = pwd->pw_uid;
+          rgid = egid = pwd->pw_gid;
+
+          if (printf ("%s : ", argv[optind]) < 0)
+            {
+              write_error ();
+              ok = false;
+            }
+          if (!print_group_list (argv[optind++], ruid, rgid, egid, true))
+            ok = false;
+          if (EOF == putchar ('\n'))
+            {
+              write_error ();
+              ok = false;
+            }
+        }
+    }
+
+  exit (ok ? EXIT_SUCCESS : EXIT_FAILURE);
+}
+
+/*
+ * Local variables:
+ *  indent-tabs-mode: nil
+ * End:
+ */
diff --git a/src/groups.sh b/src/groups.sh
deleted file mode 100755
index 7afe52e71..000000000
--- a/src/groups.sh
+++ /dev/null
@@ -1,84 +0,0 @@
-#!/bin/sh
-# groups -- print the groups a user is in
-# Copyright (C) 1991, 1997, 2000, 2002, 2004-2007 Free Software Foundation, Inc.
-
-# This program 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 of the License, or
-# (at your option) any later version.
-
-# This program 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 this program.  If not, see <http://www.gnu.org/licenses/>.
-
-# Written by David MacKenzie <djm@gnu.ai.mit.edu>.
-
-# Make sure we get GNU id, if possible; also allow
-# it to be somewhere else in PATH if not installed yet.
-PATH=@bindir@:$PATH
-
-usage="Usage: $0 [OPTION]... [USERNAME]...
-
-  --help      display this help and exit
-  --version   output version information and exit
-
-Same as id -Gn.  If no USERNAME, use current process.
-
-Report bugs to <@PACKAGE_BUGREPORT@>."
-
-version='groups (@PACKAGE_NAME@) @VERSION@
-Copyright (C) @RELEASE_YEAR@ Free Software Foundation, Inc.
-License GPLv3+: GNU GPL version 3 or later <http://gnu.org/licenses/gpl.html>
-This is free software: you are free to change and redistribute it.
-There is NO WARRANTY, to the extent permitted by law.
-
-Written by David MacKenzie.'
-
-
-for arg
-do
-  case $arg in
-    --help | --hel | --he | --h)
-      exec echo "$usage" ;;
-    --version | --versio | --versi | --vers | --ver | --ve | --v)
-      exec echo "$version" ;;
-    --)
-      shift
-      break ;;
-    -*)
-      echo "$0: invalid option: $arg" >&2
-      exit 1 ;;
-    *)
-      break ;;
-  esac
-done
-
-# With fewer than two arguments, simply exec "id".
-case $# in
-  0|1) exec id -Gn -- "$@" ;;
-esac
-
-# With more, we need a loop, and be sure to exit nonzero upon failure.
-status=0
-write_error=0
-
-for name
-do
-  if groups=`id -Gn -- "$name"`; then
-    echo "$name : $groups" || {
-      status=$?
-      if test $write_error = 0; then
-	echo "$0: write error" >&2
-	write_error=1
-      fi
-    }
-  else
-    status=$?
-  fi
-done
-
-exit $status
diff --git a/src/id.c b/src/id.c
index caf71e8c0..e4eda4071 100644
--- a/src/id.c
+++ b/src/id.c
@@ -1,5 +1,5 @@
 /* id -- print real and effective UIDs and GIDs
-   Copyright (C) 1989-2007 Free Software Foundation, Inc.
+   Copyright (C) 1989-2008 Free Software Foundation, Inc.
 
    This program is free software: you can redistribute it and/or modify
    it under the terms of the GNU General Public License as published by
@@ -19,7 +19,6 @@
 
 #include <config.h>
 #include <stdio.h>
-#include <getopt.h>
 #include <sys/types.h>
 #include <pwd.h>
 #include <grp.h>
@@ -28,9 +27,9 @@
 
 #include "system.h"
 #include "error.h"
-#include "getugroups.h"
 #include "mgetgroups.h"
 #include "quote.h"
+#include "group-list.h"
 
 /* The official name of this program (e.g., no `g' prefix).  */
 #define PROGRAM_NAME "id"
@@ -41,8 +40,6 @@
 static int just_context = 0;
 
 static void print_user (uid_t uid);
-static void print_group (gid_t gid);
-static void print_group_list (const char *username);
 static void print_full_info (const char *username);
 
 /* The name this program was run with. */
@@ -216,15 +213,27 @@ of a different user"));
     }
 
   if (just_user)
-    print_user (use_real ? ruid : euid);
+    {
+      print_user (use_real ? ruid : euid);
+    }
   else if (just_group)
-    print_group (use_real ? rgid : egid);
+    {
+      if (!print_group (use_real ? rgid : egid, use_name))
+	ok = false;
+    }
   else if (just_group_list)
-    print_group_list (argv[optind]);
+    {
+      if (!print_group_list (argv[optind], ruid, rgid, egid, use_name))
+	ok = false;
+    }
   else if (just_context)
-    fputs (context, stdout);
+    {
+      fputs (context, stdout);
+    }
   else
-    print_full_info (argv[optind]);
+    {
+      print_full_info (argv[optind]);
+    }
   putchar ('\n');
 
   exit (ok ? EXIT_SUCCESS : EXIT_FAILURE);
@@ -254,74 +263,6 @@ print_user (uid_t uid)
     printf ("%s", pwd->pw_name);
 }
 
-/* Print the name or value of group ID GID. */
-
-static void
-print_group (gid_t gid)
-{
-  struct group *grp = NULL;
-
-  if (use_name)
-    {
-      grp = getgrgid (gid);
-      if (grp == NULL)
-	{
-	  error (0, 0, _("cannot find name for group ID %lu"),
-		 (unsigned long int) gid);
-	  ok = false;
-	}
-    }
-
-  if (grp == NULL)
-    printf ("%lu", (unsigned long int) gid);
-  else
-    printf ("%s", grp->gr_name);
-}
-
-/* Print all of the distinct groups the user is in. */
-
-static void
-print_group_list (const char *username)
-{
-  struct passwd *pwd;
-
-  pwd = getpwuid (ruid);
-  if (pwd == NULL)
-    ok = false;
-
-  print_group (rgid);
-  if (egid != rgid)
-    {
-      putchar (' ');
-      print_group (egid);
-    }
-
-#if HAVE_GETGROUPS
-  {
-    GETGROUPS_T *groups;
-    size_t i;
-
-    int n_groups = mgetgroups (username, (pwd ? pwd->pw_gid : (gid_t) -1),
-			       &groups);
-    if (n_groups < 0)
-      {
-	error (0, errno, _("failed to get groups for user %s"),
-	       quote (username));
-	ok = false;
-	return;
-      }
-
-    for (i = 0; i < n_groups; i++)
-      if (groups[i] != rgid && groups[i] != egid)
-	{
-	  putchar (' ');
-	  print_group (groups[i]);
-	}
-    free (groups);
-  }
-#endif /* HAVE_GETGROUPS */
-}
-
 /* Print all of the info about the user's user and group IDs. */
 
 static void
@@ -365,8 +306,15 @@ print_full_info (const char *username)
 			       &groups);
     if (n_groups < 0)
       {
-	error (0, errno, _("failed to get groups for user %s"),
-	       quote (username));
+	if (username)
+	  {
+	    error (0, errno, _("failed to get groups for user %s"),
+		   quote (username));
+	  }
+	else
+	  {
+	    error (0, errno, _("failed to get groups for the current process"));
+	  }
 	ok = false;
 	return;
       }