helpers/mode: Parse

4 files changed, 330 insertions, 1 deletions

diff --git a/helpers/defs.h b/helpers/defs.h
new file mode 100644
index 0000000..24e9776
--- /dev/null
+++ b/helpers/defs.h
@@ -0,0 +1,27 @@
+/*
+ * Copyright (C) 2023  Patrick McDermott
+ *
+ * This file is part of opkg-opk.
+ *
+ * opkg-opk 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.
+ *
+ * opkg-opk 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 opkg-opk.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#ifndef OPKG_OPK_DEFS_H_
+#define OPKG_OPK_DEFS_H_
+
+#define OPKG_OPK_OK     0
+#define OPKG_OPK_END    1
+#define OPKG_OPK_ERROR -1
+
+#endif  /* OPKG_OPK_DEFS_H_ */
diff --git a/helpers/local.mk b/helpers/local.mk
index ce5ecc7..c4b248e 100644
--- a/helpers/local.mk
+++ b/helpers/local.mk
@@ -1 +1,5 @@
-mknod_SOURCES = %reldir%/mknod.c
+mknod_SOURCES = \
+	%reldir%/defs.h \
+	%reldir%/mknod.c \
+	%reldir%/mode.c \
+	%reldir%/mode.h
diff --git a/helpers/mode.c b/helpers/mode.c
new file mode 100644
index 0000000..e3e4878
--- /dev/null
+++ b/helpers/mode.c
@@ -0,0 +1,269 @@
+/*
+ * Copyright (C) 2023  Patrick McDermott
+ *
+ * This file is part of opkg-opk.
+ *
+ * opkg-opk 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.
+ *
+ * opkg-opk 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 opkg-opk.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#include <stdlib.h>
+#include <sys/stat.h>
+#include "defs.h"
+#include "mode.h"
+
+static const mode_t OPKG_OPK_HELPER_MODE_U_ = 04700;
+static const mode_t OPKG_OPK_HELPER_MODE_G_ = 02070;
+static const mode_t OPKG_OPK_HELPER_MODE_O_ = 00007;
+static const mode_t OPKG_OPK_HELPER_MODE_A_ = 00777;
+
+struct _opkg_opk_helper_mode {
+	mode_t      umask;
+	mode_t      cur_mode;
+	const char *sym_mode;
+	mode_t     *new_mode;
+	mode_t      who;
+	char        op;
+};
+
+/*
+ * Grammar and operations from POSIX chown utility:
+ * https://pubs.opengroup.org/onlinepubs/9699919799/utilities/chmod.html
+ */
+
+static void
+_opkg_opk_helper_mode_chmod(struct _opkg_opk_helper_mode *mode, mode_t perm)
+{
+	switch (mode->op) {
+		case '+':
+			*mode->new_mode |= (mode->who & perm);
+			break;
+		case '-':
+		default:  /* Should be unreachable */
+			*mode->new_mode ^= (mode->who & perm);
+			break;
+	}
+}
+
+static int
+_opkg_opk_helper_mode_parse_perm(struct _opkg_opk_helper_mode *mode)
+{
+	switch (*mode->sym_mode) {
+		case 'r':
+			_opkg_opk_helper_mode_chmod(mode, 00444);
+			break;
+		case 'w':
+			_opkg_opk_helper_mode_chmod(mode, 00222);
+			break;
+		case 'x':
+			_opkg_opk_helper_mode_chmod(mode, 00111);
+			break;
+		case 'X':
+			if (S_ISDIR(mode->cur_mode)
+					|| mode->cur_mode & 00111) {
+				_opkg_opk_helper_mode_chmod(mode, 00111);
+			}
+			break;
+		case 's':
+			_opkg_opk_helper_mode_chmod(mode, 06000);
+			break;
+		case 't':
+			if (S_ISDIR(mode->cur_mode)
+					&& (mode->who & OPKG_OPK_HELPER_MODE_A_)
+					== OPKG_OPK_HELPER_MODE_A_) {
+				_opkg_opk_helper_mode_chmod(mode, 01000);
+			}
+			break;
+		default:
+			return OPKG_OPK_ERROR;
+	}
+	++mode->sym_mode;
+	return OPKG_OPK_OK;
+}
+
+static int
+_opkg_opk_helper_mode_parse_permlist(struct _opkg_opk_helper_mode *mode)
+{
+	if (_opkg_opk_helper_mode_parse_perm(mode) != OPKG_OPK_OK) {
+		return OPKG_OPK_ERROR;
+	}
+	_opkg_opk_helper_mode_parse_permlist(mode);
+	return OPKG_OPK_OK;
+}
+
+static int
+_opkg_opk_helper_mode_parse_op(struct _opkg_opk_helper_mode *mode)
+{
+	switch (*mode->sym_mode) {
+		case '+':
+		case '-':
+			mode->op = *mode->sym_mode;
+			break;
+		case '=':
+			if (mode->who == 0000) {
+				*mode->new_mode &= ~07777;
+			} else {
+				*mode->new_mode &= ~mode->who;
+			}
+			mode->op = '+';
+			break;
+		default:
+			return OPKG_OPK_ERROR;
+	}
+	if (mode->who == 0000) {
+		mode->who = OPKG_OPK_HELPER_MODE_A_ ^ mode->umask;
+	}
+	++mode->sym_mode;
+	return OPKG_OPK_OK;
+}
+
+static int
+_opkg_opk_helper_mode_parse_permcopy(struct _opkg_opk_helper_mode *mode)
+{
+	mode_t perm;
+
+	switch (*mode->sym_mode) {
+		case 'u':
+			perm = (mode->cur_mode & 0700)
+			     | (mode->cur_mode & 0700) >> 001
+			     | (mode->cur_mode & 0700) >> 010;
+			break;
+		case 'g':
+			perm = (mode->cur_mode & 0070) << 001
+			     | (mode->cur_mode & 0070)
+			     | (mode->cur_mode & 0070) >> 001;
+			break;
+		case 'o':
+			perm = (mode->cur_mode & 0007) << 010
+			     | (mode->cur_mode & 0007) << 001
+			     | (mode->cur_mode & 0007);
+			break;
+		default:
+			return OPKG_OPK_ERROR;
+	}
+	_opkg_opk_helper_mode_chmod(mode, perm);
+	++mode->sym_mode;
+	return OPKG_OPK_OK;
+}
+
+static int
+_opkg_opk_helper_mode_parse_action(struct _opkg_opk_helper_mode *mode)
+{
+	if (_opkg_opk_helper_mode_parse_op(mode) != OPKG_OPK_OK) {
+		return OPKG_OPK_ERROR;
+	}
+	if (_opkg_opk_helper_mode_parse_permlist(mode) != OPKG_OPK_OK) {
+		_opkg_opk_helper_mode_parse_permcopy(mode);
+	}
+	return OPKG_OPK_OK;
+}
+
+static int
+_opkg_opk_helper_mode_parse_actionlist(struct _opkg_opk_helper_mode *mode)
+{
+	if (_opkg_opk_helper_mode_parse_action(mode) != OPKG_OPK_OK) {
+		return OPKG_OPK_ERROR;
+	}
+	_opkg_opk_helper_mode_parse_actionlist(mode);
+	return OPKG_OPK_OK;
+}
+
+static int
+_opkg_opk_helper_mode_parse_who(struct _opkg_opk_helper_mode *mode)
+{
+	switch (*mode->sym_mode) {
+		case 'u':
+			mode->who |= OPKG_OPK_HELPER_MODE_U_;
+			break;
+		case 'g':
+			mode->who |= OPKG_OPK_HELPER_MODE_G_;
+			break;
+		case 'o':
+			mode->who |= OPKG_OPK_HELPER_MODE_O_;
+			break;
+		case 'a':
+			mode->who |= OPKG_OPK_HELPER_MODE_A_;
+			break;
+		default:
+			return OPKG_OPK_ERROR;
+	}
+	++mode->sym_mode;
+	return OPKG_OPK_OK;
+}
+
+static int
+_opkg_opk_helper_mode_parse_wholist(struct _opkg_opk_helper_mode *mode)
+{
+	if (_opkg_opk_helper_mode_parse_who(mode) != OPKG_OPK_OK) {
+		return OPKG_OPK_ERROR;
+	}
+	_opkg_opk_helper_mode_parse_wholist(mode);
+	return OPKG_OPK_OK;
+}
+
+static int
+_opkg_opk_helper_mode_parse_clause(struct _opkg_opk_helper_mode *mode)
+{
+	mode->who = 0000;
+	mode->op  = '\0';
+	_opkg_opk_helper_mode_parse_wholist(mode);
+	if (_opkg_opk_helper_mode_parse_actionlist(mode) != OPKG_OPK_OK) {
+		return OPKG_OPK_ERROR;
+	}
+	return OPKG_OPK_OK;
+}
+
+static int
+_opkg_opk_helper_mode_parse_symbolic_mode(struct _opkg_opk_helper_mode *mode)
+{
+	if (_opkg_opk_helper_mode_parse_clause(mode) != OPKG_OPK_OK) {
+		return OPKG_OPK_ERROR;
+	}
+	if (*mode->sym_mode != ',') {
+		return OPKG_OPK_OK;
+	}
+	++mode->sym_mode;
+	if (_opkg_opk_helper_mode_parse_symbolic_mode(mode) != OPKG_OPK_OK) {
+		return OPKG_OPK_ERROR;
+	}
+	return OPKG_OPK_OK;
+}
+
+int
+opkg_opk_helper_mode_parse(mode_t cur_mode, const char *mode_str,
+		mode_t *new_mode)
+{
+	char                         *end;
+	long int                      mode_long;
+	struct _opkg_opk_helper_mode  mode;
+
+	mode_long = strtol(mode_str, &end, 8);
+	if (*end == '\0') {
+		if ((mode_long & 07777) != mode_long) {
+			return OPKG_OPK_ERROR;
+		}
+		*new_mode = (mode_long & 07777);
+		return OPKG_OPK_OK;
+	}
+
+	mode.umask = umask(0);
+	umask(mode.umask);
+
+	mode.cur_mode = cur_mode;
+	mode.sym_mode = mode_str;
+	mode.new_mode = new_mode;
+
+	*new_mode = 00000;
+
+	return _opkg_opk_helper_mode_parse_symbolic_mode(&mode);
+}
diff --git a/helpers/mode.h b/helpers/mode.h
new file mode 100644
index 0000000..b332268
--- /dev/null
+++ b/helpers/mode.h
@@ -0,0 +1,29 @@
+/*
+ * Copyright (C) 2023  Patrick McDermott
+ *
+ * This file is part of opkg-opk.
+ *
+ * opkg-opk 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.
+ *
+ * opkg-opk 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 opkg-opk.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#ifndef OPKG_OPK_HELPER_MODE_H_
+#define OPKG_OPK_HELPER_MODE_H_
+
+#include <sys/stat.h>
+
+int
+opkg_opk_helper_mode_parse(mode_t cur_mode, const char *mode_str,
+		mode_t *new_mode);
+
+#endif  /* OPKG_OPK_HELPER_MODE_H_ */