[gdm] gdm-common: Add gdm_shell_expand() and tests

[Alexander Larsson <alexl src gnome org>]

commit 6e26045943d27656b4444e157d0d10c025aa69db
Author: Alexander Larsson <alexl redhat com>
Date:   Thu Jun 18 11:57:12 2015 +0200

    gdm-common: Add gdm_shell_expand() and tests
    
    This allows shell-like expansion of strings. It will be later
    used to allow configuring the environment via config files.
    
    https://bugzilla.gnome.org/show_bug.cgi?id=751158

 common/gdm-common.c |   87 ++++++++++++++++++++++++++++++++++++++++
 common/gdm-common.h |    9 ++++
 tests/Makefile.am   |    2 +
 tests/m-common.c    |   11 +++++
 tests/s-common.c    |  110 +++++++++++++++++++++++++++++++++++++++++++++++++++
 tests/s-common.h    |   28 +++++++++++++
 6 files changed, 247 insertions(+), 0 deletions(-)
---
diff --git a/common/gdm-common.c b/common/gdm-common.c
index 5beeebf..a96b30f 100644
--- a/common/gdm-common.c
+++ b/common/gdm-common.c
@@ -710,3 +710,90 @@ gdm_run_script (const char *dir,
 
         return ret;
 }
+
+gboolean
+gdm_shell_var_is_valid_char (gchar c, gboolean first)
+{
+        return (!first && g_ascii_isdigit (c)) ||
+                c == '_' ||
+                g_ascii_isalpha (c);
+}
+
+/* This expands a string somewhat similar to how a shell would do it
+   if it was enclosed inside double quotes.  It handles variable
+   expansion like $FOO and ${FOO}, single-char escapes using \, and
+   non-escaped # at the begining of a word is taken as a comment and ignored */
+char *
+gdm_shell_expand (const char *str,
+                  GdmExpandVarFunc expand_var_func,
+                  gpointer user_data)
+{
+        GString *s = g_string_new("");
+        const gchar *p, *start;
+        gchar c;
+        gboolean at_new_word;
+
+        p = str;
+        at_new_word = TRUE;
+        while (*p) {
+                c = *p;
+                if (c == '\\') {
+                        p++;
+                        c = *p;
+                        if (c != '\0') {
+                                p++;
+                                switch (c) {
+                                case '\\':
+                                        g_string_append_c (s, '\\');
+                                        break;
+                                case '$':
+                                        g_string_append_c (s, '$');
+                                        break;
+                                case '#':
+                                        g_string_append_c (s, '#');
+                                        break;
+                                default:
+                                        g_string_append_c (s, '\\');
+                                        g_string_append_c (s, c);
+                                        break;
+                                }
+                        }
+                } else if (c == '#' && at_new_word) {
+                        break;
+                } else if (c == '$') {
+                        gboolean brackets = FALSE;
+                        p++;
+                        if (*p == '{') {
+                                brackets = TRUE;
+                                p++;
+                        }
+                        start = p;
+                        while (*p != '\0' &&
+                               gdm_shell_var_is_valid_char (*p, p == start))
+                                p++;
+                        if (p == start || (brackets && *p != '}')) {
+                                /* Invalid variable, use as-is */
+                                g_string_append_c (s, '$');
+                                if (brackets)
+                                        g_string_append_c (s, '{');
+                                g_string_append_len (s, start, p - start);
+                        } else {
+                                gchar *expanded;
+                                gchar *var = g_strndup (start, p - start);
+                                if (brackets && *p == '}')
+                                        p++;
+
+                                expanded = expand_var_func (var, user_data);
+                                if (expanded)
+                                        g_string_append (s, expanded);
+                                g_free (var);
+                                g_free (expanded);
+                        }
+                } else {
+                        p++;
+                        g_string_append_c (s, c);
+                        at_new_word = g_ascii_isspace (c);
+                }
+        }
+        return g_string_free (s, FALSE);
+}
diff --git a/common/gdm-common.h b/common/gdm-common.h
index 3302afe..d0812ed 100644
--- a/common/gdm-common.h
+++ b/common/gdm-common.h
@@ -36,6 +36,9 @@
 GQuark gdm_common_error_quark (void);
 #define GDM_COMMON_ERROR gdm_common_error_quark()
 
+typedef char * (*GdmExpandVarFunc) (const char *var,
+                                    gpointer user_data);
+
 G_BEGIN_DECLS
 
 int            gdm_wait_on_pid           (int pid);
@@ -64,6 +67,12 @@ gboolean       gdm_run_script             (const char *dir,
                                            const char *display_hostname,
                                            const char *display_x11_authority_file);
 
+gboolean      gdm_shell_var_is_valid_char (char c,
+                                           gboolean first);
+char *        gdm_shell_expand            (const char *str,
+                                           GdmExpandVarFunc expand_func,
+                                           gpointer user_data);
+
 G_END_DECLS
 
 #endif /* _GDM_COMMON_H */
diff --git a/tests/Makefile.am b/tests/Makefile.am
index 63fc198..c6475af 100644
--- a/tests/Makefile.am
+++ b/tests/Makefile.am
@@ -21,6 +21,8 @@ m_common_SOURCES =            \
        m-common.c              \
        s-common-address.c      \
        s-common-address.h      \
+       s-common.c              \
+       s-common.h              \
        $(NULL)
 
 m_common_CFLAGS =              \
diff --git a/tests/m-common.c b/tests/m-common.c
index c5ff2f4..62f1f44 100644
--- a/tests/m-common.c
+++ b/tests/m-common.c
@@ -24,6 +24,7 @@
 #include <glib-object.h>
 
 #include "s-common-address.h"
+#include "s-common.h"
 
 static gboolean no_fork = FALSE;
 static gboolean verbose = FALSE;
@@ -66,5 +67,15 @@ main (int argc, char **argv)
         failed = srunner_ntests_failed (r);
         srunner_free (r);
 
+        r = srunner_create (suite_common ());
+
+        if (no_fork) {
+                srunner_set_fork_status (r, CK_NOFORK);
+        }
+
+        srunner_run_all (r, verbose ? CK_VERBOSE : CK_NORMAL);
+        failed |= srunner_ntests_failed (r);
+        srunner_free (r);
+
         return failed != 0;
 }
diff --git a/tests/s-common.c b/tests/s-common.c
new file mode 100644
index 0000000..c91306f
--- /dev/null
+++ b/tests/s-common.c
@@ -0,0 +1,110 @@
+/* -*- Mode: C; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 8 -*-
+ *
+ * Copyright (C) 2007 Andrew Ziem <ahz001 gmail com>
+ * Copyright (C) 2007 William Jon McCann <mccann jhu edu>
+ * Copyright (C) 2015 Alexander Larsson <alexl redhat com>
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Library General Public
+ * License as published by the Free Software Foundation; either
+ * version 2 of the License, or (at your option) any later version.
+ *
+ * This library 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
+ * Library General Public License for more details.
+ *
+ * You should have received a copy of the GNU Library General Public
+ * License along with this library; if not, write to the
+ * Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
+ * Boston, MA 02110-1301, USA.
+ */
+
+#include <stdlib.h>
+#include <string.h>
+#include <stdio.h>
+#include <glib.h>
+#include <check.h>
+
+#include "gdm-common.h"
+#include "s-common.h"
+
+static void
+setup (void)
+{
+}
+
+static void
+teardown (void)
+{
+}
+
+static char *
+expand_fn (const char *var, gpointer data)
+{
+        if (strcmp (var, "FOO") == 0)
+                return g_strdup ("BAR");
+        if (strcmp (var, "FOO9") == 0)
+                return g_strdup ("XXX");
+        if (strcmp (var, "_FOO") == 0)
+                return g_strdup ("YYY");
+        if (strcmp (var, "FOO_FOO") == 0)
+                return g_strdup ("ZZZ");
+        return NULL;
+}
+
+static gboolean expands_to (const char *to_expand, const char *expanded)
+{
+        return strcmp (gdm_shell_expand (to_expand, expand_fn, NULL), expanded) == 0;
+}
+
+START_TEST (test_gdm_shell_expand)
+{
+        fail_unless (expands_to ("foo", "foo"));
+        fail_unless (expands_to ("foo ", "foo "));
+        fail_unless (expands_to ("foo#bar", "foo#bar"));
+        fail_unless (expands_to ("foo #bar", "foo "));
+        fail_unless (expands_to ("#bar", ""));
+        fail_unless (expands_to ("foo #bar gazonk", "foo "));
+        fail_unless (expands_to ("foo #bar gazonk", "foo "));
+        fail_unless (expands_to ("foo #bar gazonk", "foo "));
+        fail_unless (expands_to ("$FOO", "BAR"));
+        fail_unless (expands_to ("$9FOO", "$9FOO"));
+        fail_unless (expands_to ("$FOO9", "XXX"));
+        fail_unless (expands_to ("${FOO}9", "BAR9"));
+        fail_unless (expands_to ("$_FOO", "YYY"));
+        fail_unless (expands_to ("$FOO_FOO", "ZZZ"));
+        fail_unless (expands_to ("${FOO}", "BAR"));
+        fail_unless (expands_to ("$FOO$FOO", "BARBAR"));
+        fail_unless (expands_to ("${FOO}${FOO}", "BARBAR"));
+        fail_unless (expands_to ("$FOO${FOO}", "BARBAR"));
+        fail_unless (expands_to ("$foo", ""));
+        fail_unless (expands_to ("$FOOBAR", ""));
+        fail_unless (expands_to ("$FOO/BAR", "BAR/BAR"));
+        fail_unless (expands_to ("${FOO}BAR", "BARBAR"));
+        fail_unless (expands_to ("$/BAR", "$/BAR"));
+        fail_unless (expands_to ("${FOO BAR}BAR", "${FOO BAR}BAR"));
+        fail_unless (expands_to ("${}BAR", "${}BAR"));
+        fail_unless (expands_to ("${$FOO}BAR", "${BAR}BAR"));
+        fail_unless (expands_to ("\\$foo", "$foo"));
+        fail_unless (expands_to ("a\\\\b", "a\\b"));
+        fail_unless (expands_to ("a\\b", "a\\b"));
+        fail_unless (expands_to ("a\\#b", "a#b"));
+}
+END_TEST
+
+Suite *
+suite_common (void)
+{
+        Suite *s;
+        TCase *tc_core;
+
+        s = suite_create ("gdm-common");
+        tc_core = tcase_create ("core");
+
+        tcase_add_checked_fixture (tc_core, setup, teardown);
+        tcase_add_test (tc_core, test_gdm_shell_expand);
+        suite_add_tcase (s, tc_core);
+
+        return s;
+}
diff --git a/tests/s-common.h b/tests/s-common.h
new file mode 100644
index 0000000..561186f
--- /dev/null
+++ b/tests/s-common.h
@@ -0,0 +1,28 @@
+/* -*- Mode: C; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 8 -*-
+ *
+ * Copyright (C) 2015 Alexander Larsson <alexl redhat com>
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Library General Public
+ * License as published by the Free Software Foundation; either
+ * version 2 of the License, or (at your option) any later version.
+ *
+ * This library 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
+ * Library General Public License for more details.
+ *
+ * You should have received a copy of the GNU Library General Public
+ * License along with this library; if not, write to the
+ * Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
+ * Boston, MA 02110-1301, USA.
+ */
+
+#ifndef __S_COMMON_H
+#define __S_COMMON_H
+
+#include <check.h>
+
+Suite   *suite_common                 (void);
+
+#endif /* __S_COMMON_H */