env: Add environment variable flags

Currently just validates variable types as decimal, hexidecimal,
boolean, ip address, and mac address.

If the entry is not found in the env ".flags", then look in the static
one. This allows the env to override the static definitions, but prevents
the need to have every definition in the environment distracting you.

Signed-off-by: Joe Hershberger <joe.hershberger@ni.com>

1 files changed, 319 insertions, 0 deletions

diff --git a/common/env_flags.c b/common/env_flags.c
new file mode 100644
index 0000000..a58d614
--- /dev/null
+++ b/common/env_flags.c
@@ -0,0 +1,319 @@
+/*
+ * (C) Copyright 2012
+ * Joe Hershberger, National Instruments, joe.hershberger@ni.com
+ *
+ * See file CREDITS for list of people who contributed to this
+ * project.
+ *
+ * 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 2 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, write to the Free Software
+ * Foundation, Inc., 59 Temple Place, Suite 330, Boston,
+ * MA 02111-1307 USA
+ */
+
+#include <linux/string.h>
+#include <linux/ctype.h>
+
+#include <common.h>
+#include <environment.h>
+
+#ifdef CONFIG_CMD_NET
+#define ENV_FLAGS_NET_VARTYPE_REPS "im"
+#else
+#define ENV_FLAGS_NET_VARTYPE_REPS ""
+#endif
+
+static const char env_flags_vartype_rep[] = "sdxb" ENV_FLAGS_NET_VARTYPE_REPS;
+
+/*
+ * Parse the flags string from a .flags attribute list into the vartype enum.
+ */
+enum env_flags_vartype env_flags_parse_vartype(const char *flags)
+{
+	char *type;
+
+	if (strlen(flags) <= ENV_FLAGS_VARTYPE_LOC)
+		return env_flags_vartype_string;
+
+	type = strchr(env_flags_vartype_rep,
+		flags[ENV_FLAGS_VARTYPE_LOC]);
+
+	if (type != NULL)
+		return (enum env_flags_vartype)
+			(type - &env_flags_vartype_rep[0]);
+
+	printf("## Warning: Unknown environment variable type '%c'\n",
+		flags[ENV_FLAGS_VARTYPE_LOC]);
+	return env_flags_vartype_string;
+}
+
+static inline int is_hex_prefix(const char *value)
+{
+	return value[0] == '0' && (value[1] == 'x' || value[1] == 'X');
+}
+
+static void skip_num(int hex, const char *value, const char **end,
+	int max_digits)
+{
+	int i;
+
+	if (hex && is_hex_prefix(value))
+		value += 2;
+
+	for (i = max_digits; i != 0; i--) {
+		if (hex && !isxdigit(*value))
+			break;
+		if (!hex && !isdigit(*value))
+			break;
+		value++;
+	}
+	if (end != NULL)
+		*end = value;
+}
+
+/*
+ * Based on the declared type enum, validate that the value string complies
+ * with that format
+ */
+static int _env_flags_validate_type(const char *value,
+	enum env_flags_vartype type)
+{
+	const char *end;
+#ifdef CONFIG_CMD_NET
+	const char *cur;
+	int i;
+#endif
+
+	switch (type) {
+	case env_flags_vartype_string:
+		break;
+	case env_flags_vartype_decimal:
+		skip_num(0, value, &end, -1);
+		if (*end != '\0')
+			return -1;
+		break;
+	case env_flags_vartype_hex:
+		skip_num(1, value, &end, -1);
+		if (*end != '\0')
+			return -1;
+		if (value + 2 == end && is_hex_prefix(value))
+			return -1;
+		break;
+	case env_flags_vartype_bool:
+		if (value[0] != '1' && value[0] != 'y' && value[0] != 't' &&
+		    value[0] != 'Y' && value[0] != 'T' &&
+		    value[0] != '0' && value[0] != 'n' && value[0] != 'f' &&
+		    value[0] != 'N' && value[0] != 'F')
+			return -1;
+		if (value[1] != '\0')
+			return -1;
+		break;
+#ifdef CONFIG_CMD_NET
+	case env_flags_vartype_ipaddr:
+		cur = value;
+		for (i = 0; i < 4; i++) {
+			skip_num(0, cur, &end, 3);
+			if (cur == end)
+				return -1;
+			if (i != 3 && *end != '.')
+				return -1;
+			if (i == 3 && *end != '\0')
+				return -1;
+			cur = end + 1;
+		}
+		break;
+	case env_flags_vartype_macaddr:
+		cur = value;
+		for (i = 0; i < 6; i++) {
+			skip_num(1, cur, &end, 2);
+			if (cur == end)
+				return -1;
+			if (cur + 2 == end && is_hex_prefix(cur))
+				return -1;
+			if (i != 5 && *end != ':')
+				return -1;
+			if (i == 5 && *end != '\0')
+				return -1;
+			cur = end + 1;
+		}
+		break;
+#endif
+	case env_flags_vartype_end:
+		return -1;
+	}
+
+	/* OK */
+	return 0;
+}
+
+/*
+ * Look for flags in a provided list and failing that the static list
+ */
+static inline int env_flags_lookup(const char *flags_list, const char *name,
+	char *flags)
+{
+	int ret = 1;
+
+	if (!flags)
+		/* bad parameter */
+		return -1;
+
+	/* try the env first */
+	if (flags_list)
+		ret = env_attr_lookup(flags_list, name, flags);
+
+	if (ret != 0)
+		/* if not found in the env, look in the static list */
+		ret = env_attr_lookup(ENV_FLAGS_LIST_STATIC, name, flags);
+
+	return ret;
+}
+
+/*
+ * Parse the flag charachters from the .flags attribute list into the binary
+ * form to be stored in the environment entry->flags field.
+ */
+static int env_parse_flags_to_bin(const char *flags)
+{
+	return env_flags_parse_vartype(flags) & ENV_FLAGS_VARTYPE_BIN_MASK;
+}
+
+/*
+ * Look for possible flags for a newly added variable
+ * This is called specifically when the variable did not exist in the hash
+ * previously, so the blanket update did not find this variable.
+ */
+void env_flags_init(ENTRY *var_entry)
+{
+	const char *var_name = var_entry->key;
+	const char *flags_list = getenv(ENV_FLAGS_VAR);
+	char flags[ENV_FLAGS_ATTR_MAX_LEN + 1] = "";
+	int ret = 1;
+
+	/* look in the ".flags" and static for a reference to this variable */
+	ret = env_flags_lookup(flags_list, var_name, flags);
+
+	/* if any flags were found, set the binary form to the entry */
+	if (!ret && strlen(flags))
+		var_entry->flags = env_parse_flags_to_bin(flags);
+}
+
+/*
+ * Called on each existing env var prior to the blanket update since removing
+ * a flag in the flag list should remove its flags.
+ */
+static int clear_flags(ENTRY *entry)
+{
+	entry->flags = 0;
+
+	return 0;
+}
+
+/*
+ * Call for each element in the list that defines flags for a variable
+ */
+static int set_flags(const char *name, const char *value)
+{
+	ENTRY e, *ep;
+
+	e.key	= name;
+	e.data	= NULL;
+	hsearch_r(e, FIND, &ep, &env_htab, 0);
+
+	/* does the env variable actually exist? */
+	if (ep != NULL) {
+		/* the flag list is empty, so clear the flags */
+		if (value == NULL || strlen(value) == 0)
+			ep->flags = 0;
+		else
+			/* assign the requested flags */
+			ep->flags = env_parse_flags_to_bin(value);
+	}
+
+	return 0;
+}
+
+static int on_flags(const char *name, const char *value, enum env_op op,
+	int flags)
+{
+	/* remove all flags */
+	hwalk_r(&env_htab, clear_flags);
+
+	/* configure any static flags */
+	env_attr_walk(ENV_FLAGS_LIST_STATIC, set_flags);
+	/* configure any dynamic flags */
+	env_attr_walk(value, set_flags);
+
+	return 0;
+}
+U_BOOT_ENV_CALLBACK(flags, on_flags);
+
+/*
+ * Perform consistency checking before creating, overwriting, or deleting an
+ * environment variable. Called as a callback function by hsearch_r() and
+ * hdelete_r(). Returns 0 in case of success, 1 in case of failure.
+ * When (flag & H_FORCE) is set, do not print out any error message and force
+ * overwriting of write-once variables.
+ */
+
+int env_flags_validate(const ENTRY *item, const char *newval, enum env_op op,
+	int flag)
+{
+	const char *name;
+#if !defined(CONFIG_ENV_OVERWRITE) && defined(CONFIG_OVERWRITE_ETHADDR_ONCE) \
+&& defined(CONFIG_ETHADDR)
+	const char *oldval = NULL;
+
+	if (op != env_op_create)
+		oldval = item->data;
+#endif
+
+	name = item->key;
+
+	/* Default value for NULL to protect string-manipulating functions */
+	newval = newval ? : "";
+
+#ifndef CONFIG_ENV_OVERWRITE
+	/*
+	 * Some variables like "ethaddr" and "serial#" can be set only once and
+	 * cannot be deleted, unless CONFIG_ENV_OVERWRITE is defined.
+	 */
+	if (op != env_op_create &&		/* variable exists */
+		(flag & H_FORCE) == 0) {	/* and we are not forced */
+		if (strcmp(name, "serial#") == 0 ||
+		    (strcmp(name, "ethaddr") == 0
+#if defined(CONFIG_OVERWRITE_ETHADDR_ONCE) && defined(CONFIG_ETHADDR)
+		     && strcmp(oldval, __stringify(CONFIG_ETHADDR)) != 0
+#endif	/* CONFIG_OVERWRITE_ETHADDR_ONCE && CONFIG_ETHADDR */
+			)) {
+			printf("Can't overwrite \"%s\"\n", name);
+			return 1;
+		}
+	}
+#endif
+
+	/* validate the value to match the variable type */
+	if (op != env_op_delete) {
+		enum env_flags_vartype type = (enum env_flags_vartype)
+			(ENV_FLAGS_VARTYPE_BIN_MASK & item->flags);
+
+		if (_env_flags_validate_type(newval, type) < 0) {
+			printf("## Error: flags type check failure for "
+				"\"%s\" <= \"%s\" (type: %c)\n",
+				name, newval, env_flags_vartype_rep[type]);
+			return -1;
+		}
+	}
+
+	return 0;
+}