lvm2/libdm/libdm-config.c

/*
 * Copyright (C) 2001-2004 Sistina Software, Inc. All rights reserved.
 * Copyright (C) 2004-2011 Red Hat, Inc. All rights reserved.
 *
 * This file is part of LVM2.
 *
 * This copyrighted material is made available to anyone wishing to use,
 * modify, copy, or redistribute it subject to the terms and conditions
 * of the GNU Lesser General Public License v.2.1.
 *
 * You should have received a copy of the GNU Lesser General Public License
 * along with this program; if not, write to the Free Software Foundation,
 * Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
 */

#include "libdm/misc/dmlib.h"

#include <sys/stat.h>
#include <sys/mman.h>
#include <unistd.h>
#include <fcntl.h>
#include <ctype.h>
#include <stdarg.h>

#define SECTION_B_CHAR '{'
#define SECTION_E_CHAR '}'

enum {
	TOK_INT,
	TOK_FLOAT,
	TOK_STRING,		/* Single quotes */
	TOK_STRING_ESCAPED,	/* Double quotes */
	TOK_STRING_BARE,	/* No quotes */
	TOK_EQ,
	TOK_SECTION_B,
	TOK_SECTION_E,
	TOK_ARRAY_B,
	TOK_ARRAY_E,
	TOK_IDENTIFIER,
	TOK_COMMA,
	TOK_EOF
};

struct parser {
	const char *fb, *fe;		/* file limits */

	int t;			/* token limits and type */
	const char *tb, *te;

	int line;		/* line number we are on */

	struct dm_pool *mem;
	int no_dup_node_check;	/* whether to disable dup node checking */
	const char *key;        /* last obtained key */
	unsigned ignored_creation_time;
};

struct config_output {
	struct dm_pool *mem;
	dm_putline_fn putline;
	const struct dm_config_node_out_spec *spec;
	void *baton;
};

static void _get_token(struct parser *p, int tok_prev);
static void _eat_space(struct parser *p);
static struct dm_config_node *_file(struct parser *p);
static struct dm_config_node *_section(struct parser *p, struct dm_config_node *parent);
static struct dm_config_value *_value(struct parser *p);
static struct dm_config_value *_type(struct parser *p);
static int _match_aux(struct parser *p, int t);
static struct dm_config_value *_create_value(struct dm_pool *mem);
static struct dm_config_node *_create_node(struct dm_pool *mem);
static char *_dup_tok(struct parser *p);
static char *_dup_token(struct dm_pool *mem, const char *b, const char *e);

#define MAX_INDENT 32

#define match(t) do {\
   if (!_match_aux(p, (t))) {\
	log_error("Parse error at byte %" PRIptrdiff_t " (line %d): unexpected token", \
		  p->tb - p->fb + 1, p->line); \
      return 0;\
   } \
} while(0)

static int _tok_match(const char *str, const char *b, const char *e)
{
	while (*str && (b != e)) {
		if (*str++ != *b++)
			return 0;
	}

	return !(*str || (b != e));
}

struct dm_config_tree *dm_config_create(void)
{
	struct dm_config_tree *cft;
	struct dm_pool *mem = dm_pool_create("config", 10 * 1024);

	if (!mem) {
		log_error("Failed to allocate config pool.");
		return 0;
	}

	if (!(cft = dm_pool_zalloc(mem, sizeof(*cft)))) {
		log_error("Failed to allocate config tree.");
		dm_pool_destroy(mem);
		return 0;
	}
	cft->mem = mem;

	return cft;
}

void dm_config_set_custom(struct dm_config_tree *cft, void *custom)
{
	cft->custom = custom;
}

void *dm_config_get_custom(struct dm_config_tree *cft)
{
	return cft->custom;
}

void dm_config_destroy(struct dm_config_tree *cft)
{
	dm_pool_destroy(cft->mem);
}

/*
 * If there's a cascaded dm_config_tree, remove and return it, otherwise
 * return NULL.
 */
struct dm_config_tree *dm_config_remove_cascaded_tree(struct dm_config_tree *cft)
{
	struct dm_config_tree *second_cft;

	if (!cft)
		return NULL;

	second_cft = cft->cascade;
	cft->cascade = NULL;

	return second_cft;
}

/*
 * When searching, first_cft is checked before second_cft.
 */
struct dm_config_tree *dm_config_insert_cascaded_tree(struct dm_config_tree *first_cft, struct dm_config_tree *second_cft)
{
	first_cft->cascade = second_cft;

	return first_cft;
}

static struct dm_config_node *_config_reverse(struct dm_config_node *head)
{
	struct dm_config_node *left = head, *middle = NULL, *right = NULL;

	while (left) {
		right = middle;
		middle = left;
		left = left->sib;
		middle->sib = right;
		middle->child = _config_reverse(middle->child);
	}

	return middle;
}

static int _do_dm_config_parse(struct dm_config_tree *cft, const char *start, const char *end, int no_dup_node_check)
{
	/* TODO? if (start == end) return 1; */

	struct parser p = {
		.mem = cft->mem,
		.tb = start,
		.te = start,
		.fb = start,
		.fe = end,
		.line = 1,
		.no_dup_node_check = no_dup_node_check
	};

	_get_token(&p, TOK_SECTION_E);
	if (!(cft->root = _file(&p)))
		return_0;

	cft->root = _config_reverse(cft->root);

	return 1;
}

int dm_config_parse(struct dm_config_tree *cft, const char *start, const char *end)
{
	return _do_dm_config_parse(cft, start, end, 0);
}

int dm_config_parse_without_dup_node_check(struct dm_config_tree *cft, const char *start, const char *end)
{
	return _do_dm_config_parse(cft, start, end, 1);
}

struct dm_config_tree *dm_config_from_string(const char *config_settings)
{
	struct dm_config_tree *cft;

	if (!(cft = dm_config_create()))
		return_NULL;

	if (!dm_config_parse(cft, config_settings, config_settings + strlen(config_settings))) {
		dm_config_destroy(cft);
		return_NULL;
	}

	return cft;
}

static int _line_start(struct config_output *out)
{
	if (!dm_pool_begin_object(out->mem, 128)) {
		log_error("dm_pool_begin_object failed for config line");
		return 0;
	}

	return 1;
}

__attribute__ ((format(printf, 2, 3)))
static int _line_append(struct config_output *out, const char *fmt, ...)
{
	char buf[4096];
	char *dyn_buf = NULL;
	va_list ap;
	int n;

	/*
	 * We should be fine with the 4096 char buffer 99% of the time,
	 * but if we need to go beyond that, allocate the buffer dynamically.
	 */

	va_start(ap, fmt);
	n = vsnprintf(buf, sizeof(buf), fmt, ap);
	va_end(ap);

	if (n < 0) {
		log_error("vsnprintf failed for config line");
		return 0;
	}

	if (n > (int) sizeof buf - 1) {
		/*
		 * Fixed size buffer with sizeof buf is not enough,
		 * so try dynamically allocated buffer now...
		 */
		va_start(ap, fmt);
		n = dm_vasprintf(&dyn_buf, fmt, ap);
		va_end(ap);

		if (n < 0) {
			log_error("dm_vasprintf failed for config line");
			return 0;
		}
	}

	if (!dm_pool_grow_object(out->mem, dyn_buf ? : buf, 0)) {
		log_error("dm_pool_grow_object failed for config line");
		dm_free(dyn_buf);
		return 0;
	}

	dm_free(dyn_buf);

	return 1;
}

#define line_append(args...) do {if (!_line_append(out, args)) {return_0;}} while (0)

static int _line_end(const struct dm_config_node *cn, struct config_output *out)
{
	const char *line;

	if (!dm_pool_grow_object(out->mem, "\0", 1)) {
		log_error("dm_pool_grow_object failed for config line");
		return 0;
	}

	line = dm_pool_end_object(out->mem);

	if (!out->putline && !out->spec)
		return 0;

	if (out->putline)
		out->putline(line, out->baton);

	if (out->spec && out->spec->line_fn)
		out->spec->line_fn(cn, line, out->baton);

	return 1;
}

static int _write_value(struct config_output *out, const struct dm_config_value *v)
{
	char *buf;
	const char *s;

	switch (v->type) {
	case DM_CFG_STRING:
		buf = alloca(dm_escaped_len(v->v.str));
		s = (v->format_flags & DM_CONFIG_VALUE_FMT_STRING_NO_QUOTES) ? "" : "\"";
		line_append("%s%s%s", s, dm_escape_double_quotes(buf, v->v.str), s);
		break;

	case DM_CFG_FLOAT:
		line_append("%f", v->v.f);
		break;

	case DM_CFG_INT:
		if (v->format_flags & DM_CONFIG_VALUE_FMT_INT_OCTAL)
			line_append("0%" PRIo64, v->v.i);
		else
			line_append(FMTd64, v->v.i);
		break;

	case DM_CFG_EMPTY_ARRAY:
		s = (v->format_flags & DM_CONFIG_VALUE_FMT_COMMON_EXTRA_SPACES) ? " " : "";
		line_append("[%s]", s);
		break;

	default:
		log_error("_write_value: Unknown value type: %d", v->type);

	}

	return 1;
}

static int _write_config(const struct dm_config_node *n, int only_one,
			 struct config_output *out, int level)
{
	const char *extra_space;
	int format_array;
	char space[MAX_INDENT + 1];
	int l = (level < MAX_INDENT) ? level : MAX_INDENT;
	int i;
	char *escaped_key = NULL;

	if (!n)
		return 1;

	for (i = 0; i < l; i++)
		space[i] = '\t';
	space[i] = '\0';

	do {
		extra_space = (n->v && (n->v->format_flags & DM_CONFIG_VALUE_FMT_COMMON_EXTRA_SPACES)) ? " " : "";
		format_array = (n->v && (n->v->format_flags & DM_CONFIG_VALUE_FMT_COMMON_ARRAY));

		if (out->spec && out->spec->prefix_fn)
			out->spec->prefix_fn(n, space, out->baton);

		if (!_line_start(out))
			return_0;
		if (strchr(n->key, '#') || strchr(n->key, '"') || strchr(n->key, '!')) {
			escaped_key = alloca(dm_escaped_len(n->key) + 2);
			*escaped_key = '"';
			dm_escape_double_quotes(escaped_key + 1, n->key);
			strcat(escaped_key, "\"");
		}
		line_append("%s%s", space, escaped_key ? escaped_key : n->key);
		escaped_key = NULL;
		if (!n->v) {
			/* it's a sub section */
			line_append(" {");
			if (!_line_end(n, out))
				return_0;
			if (!_write_config(n->child, 0, out, level + 1))
				return_0;
			if (!_line_start(out))
				return_0;
			line_append("%s}", space);
		} else {
			/* it's a value */
			const struct dm_config_value *v = n->v;
			line_append("%s=%s", extra_space, extra_space);
			if (v->next) {
				line_append("[%s", extra_space);
				while (v && v->type != DM_CFG_EMPTY_ARRAY) {
					if (!_write_value(out, v))
						return_0;
					v = v->next;
					if (v && v->type != DM_CFG_EMPTY_ARRAY)
						line_append(",%s", extra_space);
				}
				line_append("%s]", extra_space);
			} else {
				if (format_array && (v->type != DM_CFG_EMPTY_ARRAY))
					line_append("[%s", extra_space);
				if (!_write_value(out, v))
					return_0;
				if (format_array && (v->type != DM_CFG_EMPTY_ARRAY))
					line_append("%s]", extra_space);
			}
		}
		if (!_line_end(n, out))
			return_0;

		if (out->spec && out->spec->suffix_fn)
			out->spec->suffix_fn(n, space, out->baton);

		n = n->sib;
	} while (n && !only_one);
	/* FIXME: add error checking */
	return 1;
}

static int _write_node(const struct dm_config_node *cn, int only_one,
		       dm_putline_fn putline,
		       const struct dm_config_node_out_spec *out_spec,
		       void *baton)
{
	struct config_output out = {
		.mem = dm_pool_create("config_output", 1024),
		.putline = putline,
		.spec = out_spec,
		.baton = baton
	};

	if (!out.mem)
		return_0;

	if (!_write_config(cn, only_one, &out, 0)) {
		dm_pool_destroy(out.mem);
		return_0;
	}
	dm_pool_destroy(out.mem);
	return 1;
}

int dm_config_write_one_node(const struct dm_config_node *cn, dm_putline_fn putline, void *baton)
{
	return _write_node(cn, 1, putline, NULL, baton);
}

int dm_config_write_node(const struct dm_config_node *cn, dm_putline_fn putline, void *baton)
{
	return _write_node(cn, 0, putline, NULL, baton);
}

int dm_config_write_one_node_out(const struct dm_config_node *cn,
				 const struct dm_config_node_out_spec *out_spec,
				 void *baton)
{
	return _write_node(cn, 1, NULL, out_spec, baton);
}

int dm_config_write_node_out(const struct dm_config_node *cn,
			     const struct dm_config_node_out_spec *out_spec,
			     void *baton)
{
	return _write_node(cn, 0, NULL, out_spec, baton);
}

/*
 * parser
 */
static char *_dup_string_tok(struct parser *p)
{
	char *str;

	p->tb++, p->te--;	/* strip "'s */

	if (p->te < p->tb) {
		log_error("Parse error at byte %" PRIptrdiff_t " (line %d): "
			  "expected a string token.",
			  p->tb - p->fb + 1, p->line);
		return NULL;
	}

	if (!(str = _dup_tok(p)))
		return_NULL;

	p->te++;

	return str;
}

static struct dm_config_node *_file(struct parser *p)
{
	struct dm_config_node root = { 0 };
	root.key = "<root>";

	while (p->t != TOK_EOF)
		if (!_section(p, &root))
			return_NULL;
	return root.child;
}

static struct dm_config_node *_make_node(struct dm_pool *mem,
					 const char *key_b, const char *key_e,
					 struct dm_config_node *parent)
{
	struct dm_config_node *n;

	if (!(n = _create_node(mem)))
		return_NULL;

	n->key = _dup_token(mem, key_b, key_e);
	if (parent) {
		n->parent = parent;
		n->sib = parent->child;
		parent->child = n;
	}
	return n;
}

/* when mem is not NULL, we create the path if it doesn't exist yet */
static struct dm_config_node *_find_or_make_node(struct dm_pool *mem,
						 struct dm_config_node *parent,
						 const char *path,
						 int no_dup_node_check)
{
	const int sep = '/';
	const char *e;
	struct dm_config_node *cn = parent ? parent->child : NULL;
	struct dm_config_node *cn_found = NULL;

	while (cn || mem) {
		/* trim any leading slashes */
		while (*path && (*path == sep))
			path++;

		/* find the end of this segment */
		for (e = path; *e && (*e != sep); e++) ;

		/* hunt for the node */
		cn_found = NULL;

		if (!no_dup_node_check) {
			while (cn) {
				if (_tok_match(cn->key, path, e)) {
					/* Inefficient */
					if (!cn_found)
						cn_found = cn;
					else
						log_warn("WARNING: Ignoring duplicate"
							 " config node: %s ("
							 "seeking %s)", cn->key, path);
				}

				cn = cn->sib;
			}
		}

		if (!cn_found && mem) {
			if (!(cn_found = _make_node(mem, path, e, parent)))
				return_NULL;
		}

		if (cn_found && *e) {
			parent = cn_found;
			cn = cn_found->child;
		} else
			return cn_found;
		path = e;
	}

	return NULL;
}

static struct dm_config_node *_section(struct parser *p, struct dm_config_node *parent)
{
	/* IDENTIFIER SECTION_B_CHAR VALUE* SECTION_E_CHAR */

	struct dm_config_node *root;
	struct dm_config_value *value;
	char *str;

	if (p->t == TOK_STRING_ESCAPED) {
		if (!(str = _dup_string_tok(p)))
			return_NULL;
		dm_unescape_double_quotes(str);

		match(TOK_STRING_ESCAPED);
	} else if (p->t == TOK_STRING) {
		if (!(str = _dup_string_tok(p)))
			return_NULL;

		match(TOK_STRING);
	} else {
		if (!(str = _dup_tok(p)))
			return_NULL;

		match(TOK_IDENTIFIER);
	}

	if (!strlen(str)) {
		log_error("Parse error at byte %" PRIptrdiff_t " (line %d): empty section identifier",
			  p->tb - p->fb + 1, p->line);
		return NULL;
	}

	if (!(root = _find_or_make_node(p->mem, parent, str, p->no_dup_node_check)))
		return_NULL;

	if (p->t == TOK_SECTION_B) {
		match(TOK_SECTION_B);
		while (p->t != TOK_SECTION_E) {
			if (!(_section(p, root)))
				return_NULL;
		}
		match(TOK_SECTION_E);
	} else {
		match(TOK_EQ);
		p->key = root->key;
		if (!(value = _value(p)))