/*
 * CDDL HEADER START
 *
 * The contents of this file are subject to the terms of the
 * Common Development and Distribution License (the "License").
 * You may not use this file except in compliance with the License.
 *
 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
 * or http://www.opensolaris.org/os/licensing.
 * See the License for the specific language governing permissions
 * and limitations under the License.
 *
 * When distributing Covered Code, include this CDDL HEADER in each
 * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
 * If applicable, add the following below this CDDL HEADER, with the
 * fields enclosed by brackets "[]" replaced with your own identifying
 * information: Portions Copyright [yyyy] [name of copyright owner]
 *
 * CDDL HEADER END
 */

/*
 * Copyright 2009 Sun Microsystems, Inc.  All rights reserved.
 * Use is subject to license terms.
 */

/*
 * Error handling support for directory lookup.
 * Actually, this is intended to be a very generic and extensible error
 * reporting mechanism.
 */

#include <stdio.h>
#include <stdlib.h>
#include <thread.h>
#include <errno.h>
#include <stdarg.h>
#include <malloc.h>
#include <string.h>
#include <ctype.h>
#include <syslog.h>
#include <idmap_impl.h>
#include <rpcsvc/idmap_prot.h>
#include <libintl.h>
#include "directory.h"

/*
 * This is the actual implementation of the opaque directory_error_t structure.
 */
struct directory_error {
        /*
         * True if this directory_error_t is statically allocated.  Used to
         * handle out of memory errors during error reporting.
         */
        boolean_t       is_static;

        /*
         * The error code.  This is a locale-independent string that
         * represents the precise error (to some level of granularity)
         * that occurred.  Internationalization processing could map it
         * to an message.  Errors may be subclassed by appending a dot
         * and a name for the subclass.
         *
         * Note that this code plus the parameters allows for structured
         * processing of error results.
         */
        char            *code;

        /*
         * The default (in the absence of internationalization) format for
         * the error message.  %n interposes params[n - 1].
         */
        char            *fmt;

        /*
         * Parameters to the error message.  Note that subclasses are
         * required to have the same initial parameters as their superclasses,
         * so that code that processes the superclass can work on the subclass.
         */
        int             nparams;
        char            **params;

        /*
         * Cached printable form (that is, with params[] interpolated into
         * fmt) of the error message.  Created when requested.
         */
        char            *printable;
};

static directory_error_t directory_error_internal_error(int err);

/*
 * For debugging, reference count of directory_error instances still in
 * existence.  When the system is idle, this should be zero.
 * Note that no attempt is made to make this MT safe, so it is not reliable
 * in an MT environment.
 */
static int directory_errors_outstanding = 0;

/*
 * Free the specified directory_error_t.  Note that this invalidates all strings
 * returned based on it.
 *
 * Does nothing when de==NULL.
 */
void
directory_error_free(directory_error_t de)
{
        int i;

        if (de == NULL)
                return;

        /* Don't free our internal static directory_error_ts! */
        if (de->is_static)
                return;

        free(de->code);
        de->code = NULL;
        free(de->fmt);
        de->fmt = NULL;

        /* Free parameters, if any */
        if (de->params != NULL) {
                for (i = 0; i < de->nparams; i++) {
                        free(de->params[i]);
                        de->params[i] = NULL;
                }
                free(de->params);
                de->params = NULL;
        }

        /* Free cached printable */
        free(de->printable);
        de->printable = NULL;

        free(de);

        directory_errors_outstanding--;
}

/*
 * de = directory_error(code, fmt [, arg1 ... ]);
 * Code, fmt, and arguments must be strings and will be copied.
 */
directory_error_t
directory_error(const char *code, const char *fmt, ...)
{
        directory_error_t de = NULL;
        va_list va;
        int i;

        de = calloc(1, sizeof (*de));
        if (de == NULL)
                goto nomem;

        directory_errors_outstanding++;

        de->is_static = B_FALSE;

        de->code = strdup(code);
        if (de->code == NULL)
                goto nomem;

        de->fmt = strdup(fmt);
        if (de->fmt == NULL)
                goto nomem;

        /* Count our parameters */
        va_start(va, fmt);
        for (i = 0; va_arg(va, char *) != NULL; i++)
                /* LOOP */;
        va_end(va);

        de->nparams = i;

        /*
         * Note that we do not copy the terminating NULL because we have
         * a count.
         */
        de->params = calloc(de->nparams, sizeof (char *));
        if (de->params == NULL)
                goto nomem;

        va_start(va, fmt);
        for (i = 0; i < de->nparams; i++) {
                de->params[i] = strdup((char *)va_arg(va, char *));
                if (de->params[i] == NULL) {
                        va_end(va);
                        goto nomem;
                }
        }
        va_end(va);

        return (de);

nomem:;
        int err = errno;
        directory_error_free(de);
        return (directory_error_internal_error(err));
}

/*
 * Transform a directory_error returned by RPC into a directory_error_t.
 */
directory_error_t
directory_error_from_rpc(directory_error_rpc *de_rpc)
{
        directory_error_t de;
        int i;

        de = calloc(1, sizeof (*de));
        if (de == NULL)
                goto nomem;

        directory_errors_outstanding++;

        de->is_static = B_FALSE;
        de->code = strdup(de_rpc->code);
        if (de->code == NULL)
                goto nomem;
        de->fmt = strdup(de_rpc->fmt);
        if (de->fmt == NULL)
                goto nomem;

        de->nparams = de_rpc->params.params_len;

        de->params = calloc(de->nparams, sizeof (char *));
        if (de->params == NULL)
                goto nomem;

        for (i = 0; i < de->nparams; i++) {
                de->params[i] = strdup(de_rpc->params.params_val[i]);
                if (de->params[i] == NULL)
                        goto nomem;
        }

        return (de);

nomem:;
        int err = errno;
        directory_error_free(de);
        return (directory_error_internal_error(err));
}

/*
 * Convert a directory_error_t into a directory_error to send over RPC.
 *
 * Returns TRUE on successful conversion, FALSE on failure.
 *
 * Frees the directory_error_t.
 *
 * Note that most functions in this suite return boolean_t, as defined
 * by types.h.  This function is intended to be used directly as the
 * return value from an RPC service function, and so it returns bool_t.
 */
bool_t
directory_error_to_rpc(directory_error_rpc *de_rpc, directory_error_t de)
{
        int i;
        idmap_utf8str *params;

        de_rpc->code = strdup(de->code);
        if (de_rpc->code == NULL)
                goto nomem;

        de_rpc->fmt = strdup(de->fmt);
        if (de_rpc->fmt == NULL)
                goto nomem;

        params = calloc(de->nparams, sizeof (idmap_utf8str));
        if (params == NULL)
                goto nomem;
        de_rpc->params.params_val = params;
        de_rpc->params.params_len = de->nparams;

        for (i = 0; i < de->nparams; i++) {
                params[i] = strdup(de->params[i]);
                if (params[i] == NULL)
                        goto nomem;
        }

        directory_error_free(de);
        return (TRUE);

nomem:
        logger(LOG_ERR, "Warning:  failed to convert error for RPC\n"
            "Original error:  %s\n"
            "Conversion error:  %s\n",
            strerror(errno),
            directory_error_printable(de));
        directory_error_free(de);
        return (FALSE);
}

/*
 * Determines whether this directory_error_t is an instance of the
 * particular error, or a subclass of that error.
 */
boolean_t
directory_error_is_instance_of(directory_error_t de, char *code)
{
        int len;

        if (de == NULL || de->code == NULL)
                return (B_FALSE);

        len = strlen(code);

        if (strncasecmp(de->code, code, len) != 0)
                return (B_FALSE);

        if (de->code[len] == '\0' || de->code[len] == '.')
                return (B_TRUE);

        return (B_FALSE);
}

/*
 * Expand the directory_error_t in de into buf, returning the size of the
 * resulting string including terminating \0.  If buf is NULL, just
 * return the size.
 *
 * Return -1 if there are no substitutions, so that the caller can
 * avoid memory allocation.
 */
static
int
directory_error_expand(char *buf, directory_error_t de)
{
        int bufsiz;
        boolean_t has_subst;
        const char *p;
        char c;
        long n;
        const char *s;
        char *newp;

        bufsiz = 0;
        has_subst = B_FALSE;

        for (p = dgettext(TEXT_DOMAIN, de->fmt); *p != '\0'; ) {
                c = *p++;
                if (c == '%') {
                        has_subst = B_TRUE;
                        if (isdigit(*p)) {
                                n = strtol(p, &newp, 10);
                                p = newp;
                                if (de->params == NULL ||
                                    n < 1 ||
                                    n > de->nparams)
                                        s = dgettext(TEXT_DOMAIN, "(missing)");
                                else
                                        s = de->params[n - 1];
                                if (buf != NULL)
                                        (void) strcpy(buf + bufsiz, s);
                                bufsiz += strlen(s);
                                continue;
                        }
                }
                if (buf != NULL)
                        buf[bufsiz] = c;
                bufsiz++;
        }

        if (buf != NULL)
                buf[bufsiz] = '\0';
        bufsiz++;

        return (has_subst ? bufsiz : -1);
}

/*
 * Returns a printable version of this directory_error_t, suitable for
 * human consumption.
 *
 * The value returned is valid as long as the directory_error_t is valid,
 * and is freed when the directory_error_t is freed.
 */
const char *
directory_error_printable(directory_error_t de)
{
        char *s;
        int bufsiz;

        if (de->printable != NULL)
                return (de->printable);

        bufsiz = directory_error_expand(NULL, de);

        /*
         * Short circuit case to avoid memory allocation when there is
         * no parameter substitution.
         */
        if (bufsiz < 0)
                return (dgettext(TEXT_DOMAIN, de->fmt));

        s = malloc(bufsiz);
        if (s == NULL) {
                return (dgettext(TEXT_DOMAIN,
                    "Out of memory while expanding directory_error_t"));
        }

        (void) directory_error_expand(s, de);

        /*
         * Stash the expansion away for later free, and to short-circuit
         * repeated expansions.
         */
        de->printable = s;

        return (de->printable);
}

/*
 * Returns the error code for the particular error, as a string.
 * Note that this function should not normally be used to answer
 * the question "did error X happen", since the value returned
 * could be a subclass of X.  directory_error_is_instance_of is intended
 * to answer that question.
 *
 * The value returned is valid as long as the directory_error_t is valid,
 * and is freed when the directory_error_t is freed.
 */
const char *
directory_error_code(directory_error_t de)
{
        return (de->code);
}

/*
 * Returns one of the parameters of the directory_error_t, or NULL if
 * the parameter does not exist.
 *
 * Note that it is required that error subclasses have initial parameters
 * the same as their superclasses.
 *
 * The value returned is valid as long as the directory_error_t is valid,
 * and is freed when the directory_error_t is freed.
 */
const char *
directory_error_param(directory_error_t de, int param)
{
        if (param >= de->nparams)
                return (NULL);
        return (de->params[param]);
}

/*
 * Here are some (almost) constant directory_error_t structures
 * for use in reporting errors encountered while creating a
 * directory_error_t structure.  Unfortunately, the original error
 * report is lost.
 */
#define gettext(x)      x       /* let xgettext see these messages */
static struct directory_error directory_error_ENOMEM = {
        B_TRUE,
        "ENOMEM.directory_error_t",
        gettext("Out of memory while creating a directory_error_t"),
        0, NULL,
        NULL,
};

static struct directory_error directory_error_EAGAIN = {
        B_TRUE,
        "EAGAIN.directory_error_t",
        gettext("Out of resources while creating a directory_error_t"),
        0, NULL,
        NULL,
};

/* 40 is big enough for even 128 bits */
static char directory_error_unknown_errno[40] = "0";
static char *directory_error_unknown_params[] = {
    directory_error_unknown_errno
};
static struct directory_error directory_error_unknown = {
        B_TRUE,
        "Unknown.directory_error_t",
        gettext("Unknown error (%1) while creating a directory_error_t"),
        1, directory_error_unknown_params,
        NULL,
};
#undef  gettext

static
directory_error_t
directory_error_internal_error(int err)
{
        switch (err) {
        case ENOMEM:    return (&directory_error_ENOMEM);
        case EAGAIN:    return (&directory_error_EAGAIN);
        default:
                /* Pray that we don't have a reentrancy problem ... */
                (void) sprintf(directory_error_unknown_errno, "%u", err);
                return (&directory_error_unknown);
        }
}