lvm2/lib/config/config.c

/*
 * Copyright (C) 2001-2004 Sistina Software, Inc. All rights reserved.
 * Copyright (C) 2004 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 General Public License v.2.
 *
 * 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 "lib.h"
#include "config.h"
#include "crc.h"
#include "device.h"
#include "str_list.h"
#include "toolcontext.h"
#include "lvm-string.h"
#include "lvm-file.h"

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

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

enum {
	TOK_INT,
	TOK_FLOAT,
	TOK_STRING,
	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 fd;			/* descriptor for file being parsed */
	int line;		/* line number we are on */

	struct dm_pool *mem;
};

struct cs {
	struct config_tree cft;
	struct dm_pool *mem;
	time_t timestamp;
	char *filename;
	int exists;
	int keep_open;
	struct device *dev;
};

struct output_line {
	FILE *fp;
	struct dm_pool *mem;
};

static void _get_token(struct parser *p, int tok_prev);
static void _eat_space(struct parser *p);
static struct config_node *_file(struct parser *p);
static struct config_node *_section(struct parser *p);
static struct config_value *_value(struct parser *p);
static struct config_value *_type(struct parser *p);
static int _match_aux(struct parser *p, int t);
static struct config_value *_create_value(struct parser *p);
static struct config_node *_create_node(struct parser *p);
static char *_dup_tok(struct parser *p);

static const int sep = '/';

#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));
}

/*
 * public interface
 */
struct config_tree *create_config_tree(const char *filename, int keep_open)
{
	struct cs *c;
	struct dm_pool *mem = dm_pool_create("config", 10 * 1024);

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

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

	c->mem = mem;
	c->cft.root = (struct config_node *) NULL;
	c->timestamp = 0;
	c->exists = 0;
	c->keep_open = keep_open;
	c->dev = 0;
	if (filename)
		c->filename = dm_pool_strdup(c->mem, filename);
	return &c->cft;
}

void destroy_config_tree(struct config_tree *cft)
{
	struct cs *c = (struct cs *) cft;

	if (c->dev)
		dev_close(c->dev);

	dm_pool_destroy(c->mem);
}

static int _parse_config_file(struct parser *p, struct config_tree *cft)
{
	p->tb = p->te = p->fb;
	p->line = 1;
	_get_token(p, TOK_SECTION_E);
	if (!(cft->root = _file(p)))
		return_0;

	return 1;
}

struct config_tree *create_config_tree_from_string(struct cmd_context *cmd,
						   const char *config_settings)
{
	struct cs *c;
	struct config_tree *cft;
	struct parser *p;

	if (!(cft = create_config_tree(NULL, 0)))
		return_NULL;

	c = (struct cs *) cft;
	if (!(p = dm_pool_alloc(c->mem, sizeof(*p)))) {
		log_error("Failed to allocate config tree parser.");
		destroy_config_tree(cft);
		return NULL;
	}

	p->mem = c->mem;
	p->fb = config_settings;
	p->fe = config_settings + strlen(config_settings);

	if (!_parse_config_file(p, cft)) {
		destroy_config_tree(cft);
		return_NULL;
	}

	return cft;
}

int read_config_fd(struct config_tree *cft, struct device *dev,
		   off_t offset, size_t size, off_t offset2, size_t size2,
		   checksum_fn_t checksum_fn, uint32_t checksum)
{
	struct cs *c = (struct cs *) cft;
	struct parser *p;
	int r = 0;
	int use_mmap = 1;
	off_t mmap_offset = 0;
	char *buf = NULL;

	if (!(p = dm_pool_alloc(c->mem, sizeof(*p)))) {
		stack;
		return 0;
	}
	p->mem = c->mem;

	/* Only use mmap with regular files */
	if (!(dev->flags & DEV_REGULAR) || size2)
		use_mmap = 0;

	if (use_mmap) {
		mmap_offset = offset % lvm_getpagesize();
		/* memory map the file */
		p->fb = mmap((caddr_t) 0, size + mmap_offset, PROT_READ,
			     MAP_PRIVATE, dev_fd(dev), offset - mmap_offset);
		if (p->fb == (caddr_t) (-1)) {
			log_sys_error("mmap", dev_name(dev));
			goto out;
		}
		p->fb = p->fb + mmap_offset;
	} else {
		if (!(buf = dm_malloc(size + size2))) {
			stack;
			return 0;
		}
		if (!dev_read_circular(dev, (uint64_t) offset, size,
				       (uint64_t) offset2, size2, buf)) {
			goto out;
		}
		p->fb = buf;
	}

	if (checksum_fn && checksum !=
	    (checksum_fn(checksum_fn(INITIAL_CRC, p->fb, size),
			 p->fb + size, size2))) {
		log_error("%s: Checksum error", dev_name(dev));
		goto out;
	}

	p->fe = p->fb + size + size2;

	if (!_parse_config_file(p, cft)) {
		stack;
		goto out;
	}

	r = 1;

      out:
	if (!use_mmap)
		dm_free(buf);
	else {
		/* unmap the file */
		if (munmap((char *) (p->fb - mmap_offset), size + mmap_offset)) {
			log_sys_error("munmap", dev_name(dev));
			r = 0;
		}
	}

	return r;
}

int read_config_file(struct config_tree *cft)
{
	struct cs *c = (struct cs *) cft;
	struct stat info;
	int r = 1;

	if (stat(c->filename, &info)) {
		log_sys_error("stat", c->filename);
		c->exists = 0;
		return 0;
	}

	if (!S_ISREG(info.st_mode)) {
		log_error("%s is not a regular file", c->filename);
		c->exists = 0;
		return 0;
	}

	c->exists = 1;

	if (info.st_size == 0) {
		log_verbose("%s is empty", c->filename);
		return 1;
	}

	if (!c->dev) {
		if (!(c->dev = dev_create_file(c->filename, NULL, NULL, 1)))
			return_0;

		if (!dev_open_flags(c->dev, O_RDONLY, 0, 0))
			return_0;
	}

	r = read_config_fd(cft, c->dev, 0, (size_t) info.st_size, 0, 0,
			   (checksum_fn_t) NULL, 0);

	if (!c->keep_open) {
		dev_close(c->dev);
		c->dev = 0;
	}

	c->timestamp = info.st_ctime;

	return r;
}

time_t config_file_timestamp(struct config_tree *cft)
{
	struct cs *c = (struct cs *) cft;

	return c->timestamp;
}

/*
 * Return 1 if config files ought to be reloaded
 */
int config_file_changed(struct config_tree *cft)
{
	struct cs *c = (struct cs *) cft;
	struct stat info;

	if (!c->filename)
		return 0;

	if (stat(c->filename, &info) == -1) {
		/* Ignore a deleted config file: still use original data */
		if (errno == ENOENT) {
			if (!c->exists)
				return 0;
			log_very_verbose("Config file %s has disappeared!",
					 c->filename);
			goto reload;
		}
		log_sys_error("stat", c->filename);
		log_error("Failed to reload configuration files");
		return 0;
	}

	if (!S_ISREG(info.st_mode)) {
		log_error("Configuration file %s is not a regular file",
			  c->filename);
		goto reload;
	}

	/* Unchanged? */
	if (c->timestamp == info.st_ctime)
		return 0;

      reload:
	log_verbose("Detected config file change to %s", c->filename);
	return 1;
}

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

	return 1;
}

static int _line_append(struct output_line *outline, const char *fmt, ...)
  __attribute__ ((format(printf, 2, 3)));
static int _line_append(struct output_line *outline, const char *fmt, ...)
{
	char buf[4096];
	va_list ap;
	int n;

	va_start(ap, fmt);
	n = vsnprintf(&buf[0], sizeof buf - 1, fmt, ap);
	if (n < 0 || n > sizeof buf - 1) {
		log_error("vsnprintf failed for config line");
		return 0;
	}
	va_end(ap);

	if (!dm_pool_grow_object(outline->mem, &buf[0], strlen(buf))) {
		log_error("dm_pool_grew_object failed for config line");
		return 0;
	}

	return 1;
}

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

static int _line_end(struct output_line *outline)
{
	const char *line;

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

	line = dm_pool_end_object(outline->mem);
	if (!outline->fp)
		log_print("%s", line);
	else
		fprintf(outline->fp, "%s\n", line);

	return 1;
}

static int _write_value(struct output_line *outline, struct config_value *v)
{
	switch (v->type) {
	case CFG_STRING:
		line_append("\"%s\"", v->v.str);
		break;

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

	case CFG_INT:
		line_append("%" PRId64, v->v.i);
		break;

	case CFG_EMPTY_ARRAY:
		line_append("[]");
		break;

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

	}

	return 1;
}

static int _write_config(struct config_node *n, int only_one,
			 struct output_line *outline, int level)
{
	char space[MAX_INDENT + 1];
	int l = (level < MAX_INDENT) ? level : MAX_INDENT;
	int i;

	if (!n)
		return 1;

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

	do {
		if (!_line_start(outline))
			return_0;
		line_append("%s%s", space, n->key);
		if (!n->v) {
			/* it's a sub section */
			line_append(" {");
			if (!_line_end(outline))
				return_0;
			if (!_line_start(outline))
				return_0;
			_write_config(n->child, 0, outline, level + 1);
			line_append("%s}", space);
		} else {
			/* it's a value */
			struct config_value *v = n->v;
			line_append("=");
			if (v->next) {
				line_append("[");
				while (v) {
					if (!_write_value(outline, v))
						return_0;
					v = v->next;
					if (v)
						line_append(", ");
				}
				line_append("]");
			} else
				if (!_write_value(outline, v))
					return_0;
		}
		if (!_line_end(outline))
			return_0;
		n = n->sib;
	} while (n && !only_one);
	/* FIXME: add error checking */
	return 1;
}

int write_config_file(struct config_tree *cft, const char *file,
		      int argc, char **argv)
{
	struct config_node *cn;
	int r = 1;
	struct output_line outline;
	outline.fp = NULL;

	if (!file)
		file = "stdout";
	else if (!(outline.fp = fopen(file, "w"))) {
		log_sys_error("open", file);
		return 0;
	}

	outline.mem = dm_pool_create("config_line", 1024);

	log_verbose("Dumping configuration to %s", file);
	if (!argc) {
		if (!_write_config(cft->root, 0, &outline, 0)) {
			log_error("Failure while writing to %s", file);
			r = 0;
		}
	} else while (argc--) {
		if ((cn = find_config_node(cft->root, *argv))) {
			if (!_write_config(cn, 1, &outline, 0)) {
				log_error("Failure while writing to %s", file);
				r = 0;
			}
		} else {
			log_error("Configuration node %s not found", *argv);
			r = 0;
		}
		argv++;
	}

	if (outline.fp && lvm_fclose(outline.fp, file)) {
		stack;
		r = 0;
	}

	dm_pool_destroy(outline.mem);
	return r;
}

/*
 * parser
 */
static struct config_node *_file(struct parser *p)
{
	struct config_node *root = NULL, *n, *l = NULL;
	while (p->t != TOK_EOF) {
		if (!(n = _section(p))) {
			stack;
			return 0;
		}

		if (!root)
			root = n;
		else
			l->sib = n;
		l = n;
	}
	return root;
}

static struct config_node *_section(struct parser *p)
{
	/* IDENTIFIER SECTION_B_CHAR VALUE* SECTION_E_CHAR */
	struct config_node *root, *n, *l = NULL;
	if (!(root = _create_node(p))) {
		stack;
		return 0;
	}

	if (!(root->key = _dup_tok(p))) {
		stack;
		return 0;
	}

	match(TOK_IDENTIFIER);

	if (p->t == TOK_SECTION_B) {
		match(TOK_SECTION_B);
		while (p->t != TOK_SECTION_E) {
			if (!(n = _section(p))) {
				stack;
				return 0;
			}

			if (!root->child)
				root->child = n;
			else
				l->sib = n;
			l = n;
		}
		match(TOK_SECTION_E);
	} else {
		match(TOK_EQ);
		if (!(root->v = _value(p))) {
			stack;
			return 0;
		}
	}

	return root;
}

static struct config_value *_value(struct parser *p)
{
	/* '[' TYPE* ']' | TYPE */
	struct config_value *h = NULL, *l, *ll = NULL;
	if (p->t == TOK_ARRAY_B) {
		match(TOK_ARRAY_B);
		while (p->t != TOK_ARRAY_E) {
			if (!(l = _type(p))) {
				stack;
				return 0;
			}

			if (!h)
				h = l;
			else
				ll->next = l;
			ll = l;

			if (p->t == TOK_COMMA)
				match(TOK_COMMA);
		}
		match(TOK_ARRAY_E);
		/*
		 * Special case for an empty array.
		 */
		if (!h) {
			if (!(h = _create_value(p)))
				return NULL;

			h->type = CFG_EMPTY_ARRAY;
		}

	} else
		h = _type(p);

	return h;
}

static struct config_value *_type(struct parser *p)
{
	/* [+-]{0,1}[0-9]+ | [0-9]*\.[0-9]* | ".*" */
	struct config_value *v = _create_value(p);

	if (!v)
		return NULL;

	switch (p->t) {
	case TOK_INT:
		v->type = CFG_INT;
		v->v.i = strtoll(p->tb, NULL, 0);	/* FIXME: check error */
		match(TOK_INT);
		break;

	case TOK_FLOAT:
		v->type = CFG_FLOAT;
		v->v.r = strtod(p->tb, NULL);	/* FIXME: check error */
		match(TOK_FLOAT);
		break;

	case TOK_STRING:
		v->type = CFG_STRING;

		p->tb++, p->te--;	/* strip "'s */
		if (!(v->v.str = _dup_tok(p))) {
			stack;
			return 0;
		}
		p->te++;
		match(TOK_STRING);
		break;

	default:
		log_error("Parse error at byte %" PRIptrdiff_t " (line %d): expected a value",
			  p->tb - p->fb + 1, p->line);
		return 0;
	}
	return v;
}

static int _match_aux(struct parser *p, int t)
{
	if (p->t != t)
		return 0;

	_get_token(p, t);
	return 1;
}

/*
 * tokeniser
 */
static void _get_token(struct parser *p, int tok_prev)
{
	int values_allowed = 0;

	p->tb = p->te;
	_eat_space(p);
	if (p->tb == p->fe || !*p->tb) {
		p->t = TOK_EOF;
		return;
	}

	/* Should next token be interpreted as value instead of identifier? */
	if (