libidmap/common/directory_error.c

/*
 * 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);
    }
}