dbm.c

linux网络服务器工具

/* Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License.  You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

/*
** DAV extension module for Apache 2.0.*
**  - Database support using DBM-style databases,
**    part of the filesystem repository implementation
*/

/*
** This implementation uses a SDBM database per file and directory to
** record the properties. These databases are kept in a subdirectory (of
** the directory in question or the directory that holds the file in
** question) named by the macro DAV_FS_STATE_DIR (.DAV). The filename of the
** database is equivalent to the target filename, and is
** DAV_FS_STATE_FILE_FOR_DIR (.state_for_dir) for the directory itself.
*/

#include "apr_strings.h"
#include "apr_file_io.h"

#include "apr_dbm.h"

#define APR_WANT_BYTEFUNC
#include "apr_want.h"       /* for ntohs and htons */

#include "mod_dav.h"
#include "repos.h"


struct dav_db {
    apr_pool_t *pool;
    apr_dbm_t *file;

    /* when used as a property database: */

    int version;                /* *minor* version of this db */

    dav_buffer ns_table;        /* table of namespace URIs */
    short ns_count;             /* number of entries in table */
    int ns_table_dirty;         /* ns_table was modified */
    apr_hash_t *uri_index;      /* map URIs to (1-based) table indices */

    dav_buffer wb_key;          /* work buffer for dav_gdbm_key */

    apr_datum_t iter;           /* iteration key */
};

/* -------------------------------------------------------------------------
 *
 * GENERIC DBM ACCESS
 *
 * For the most part, this just uses the APR DBM functions. They are wrapped
 * a bit with some error handling (using the mod_dav error functions).
 */

void dav_dbm_get_statefiles(apr_pool_t *p, const char *fname,
                            const char **state1, const char **state2)
{
    if (fname == NULL)
        fname = DAV_FS_STATE_FILE_FOR_DIR;

    apr_dbm_get_usednames(p, fname, state1, state2);
}

static dav_error * dav_fs_dbm_error(dav_db *db, apr_pool_t *p,
                                    apr_status_t status)
{
    int save_errno = errno;
    int errcode;
    const char *errstr;
    dav_error *err;
    char errbuf[200];

    if (status == APR_SUCCESS)
        return NULL;

    p = db ? db->pool : p;

    /* There might not be a <db> if we had problems creating it. */
    if (db == NULL) {
        errcode = 1;
        errstr = "Could not open property database.";
    }
    else {
        (void) apr_dbm_geterror(db->file, &errcode, errbuf, sizeof(errbuf));
        errstr = apr_pstrdup(p, errbuf);
    }

    err = dav_new_error(p, HTTP_INTERNAL_SERVER_ERROR, errcode, errstr);
    err->save_errno = save_errno;
    return err;
}

/* ensure that our state subdirectory is present */
/* ### does this belong here or in dav_fs_repos.c ?? */
void dav_fs_ensure_state_dir(apr_pool_t * p, const char *dirname)
{
    const char *pathname = apr_pstrcat(p, dirname, "/" DAV_FS_STATE_DIR, NULL);

    /* ### do we need to deal with the umask? */

    /* just try to make it, ignoring any resulting errors */
    (void) apr_dir_make(pathname, APR_OS_DEFAULT, p);
}

/* dav_dbm_open_direct:  Opens a *dbm database specified by path.
 *    ro = boolean read-only flag.
 */
dav_error * dav_dbm_open_direct(apr_pool_t *p, const char *pathname, int ro,
                                dav_db **pdb)
{
    apr_status_t status;
    apr_dbm_t *file;

    *pdb = NULL;

    if ((status = apr_dbm_open(&file, pathname,
                               ro ? APR_DBM_READONLY : APR_DBM_RWCREATE,
                               APR_OS_DEFAULT, p))
                != APR_SUCCESS
        && !ro) {
        /* ### do something with 'status' */

        /* we can't continue if we couldn't open the file
           and we need to write */
        return dav_fs_dbm_error(NULL, p, status);
    }

    /* may be NULL if we tried to open a non-existent db as read-only */
    if (file != NULL) {
        /* we have an open database... return it */
        *pdb = apr_pcalloc(p, sizeof(**pdb));
        (*pdb)->pool = p;
        (*pdb)->file = file;
    }

    return NULL;
}

static dav_error * dav_dbm_open(apr_pool_t * p, const dav_resource *resource,
                                int ro, dav_db **pdb)
{
    const char *dirpath;
    const char *fname;
    const char *pathname;

    /* Get directory and filename for resource */
    /* ### should test this result value... */
    (void) dav_fs_dir_file_name(resource, &dirpath, &fname);

    /* If not opening read-only, ensure the state dir exists */
    if (!ro) {
        /* ### what are the perf implications of always checking this? */
        dav_fs_ensure_state_dir(p, dirpath);
    }

    pathname = apr_pstrcat(p, dirpath, "/" DAV_FS_STATE_DIR "/",
                              fname ? fname : DAV_FS_STATE_FILE_FOR_DIR,
                              NULL);

    /* ### readers cannot open while a writer has this open; we should
       ### perform a few retries with random pauses. */

    /* ### do we need to deal with the umask? */

    return dav_dbm_open_direct(p, pathname, ro, pdb);
}

void dav_dbm_close(dav_db *db)
{
    apr_dbm_close(db->file);
}

dav_error * dav_dbm_fetch(dav_db *db, apr_datum_t key, apr_datum_t *pvalue)
{
    apr_status_t status = apr_dbm_fetch(db->file, key, pvalue);

    return dav_fs_dbm_error(db, NULL, status);
}

dav_error * dav_dbm_store(dav_db *db, apr_datum_t key, apr_datum_t value)
{
    apr_status_t status = apr_dbm_store(db->file, key, value);

    return dav_fs_dbm_error(db, NULL, status);
}

dav_error * dav_dbm_delete(dav_db *db, apr_datum_t key)
{
    apr_status_t status = apr_dbm_delete(db->file, key);

    return dav_fs_dbm_error(db, NULL, status);
}

int dav_dbm_exists(dav_db *db, apr_datum_t key)
{
    return apr_dbm_exists(db->file, key);
}

static dav_error * dav_dbm_firstkey(dav_db *db, apr_datum_t *pkey)
{
    apr_status_t status = apr_dbm_firstkey(db->file, pkey);

    return dav_fs_dbm_error(db, NULL, status);
}

static dav_error * dav_dbm_nextkey(dav_db *db, apr_datum_t *pkey)
{
    apr_status_t status = apr_dbm_nextkey(db->file, pkey);

    return dav_fs_dbm_error(db, NULL, status);
}

void dav_dbm_freedatum(dav_db *db, apr_datum_t data)
{
    apr_dbm_freedatum(db->file, data);
}

/* -------------------------------------------------------------------------
 *
 * PROPERTY DATABASE FUNCTIONS
 */


#define DAV_GDBM_NS_KEY         "METADATA"
#define DAV_GDBM_NS_KEY_LEN     8

typedef struct {
    unsigned char major;
#define DAV_DBVSN_MAJOR         4
    /*
    ** V4 -- 0.9.9 ..
    **       Prior versions could have keys or values with invalid
    **       namespace prefixes as a result of the xmlns="" form not
    **       resetting the default namespace to be "no namespace". The
    **       namespace would be set to "" which is invalid; it should
    **       be set to "no namespace".
    **
    ** V3 -- 0.9.8
    **       Prior versions could have values with invalid namespace
    **       prefixes due to an incorrect mapping of input to propdb
    **       namespace indices. Version bumped to obsolete the old
    **       values.
    **
    ** V2 -- 0.9.7
    **       This introduced the xml:lang value into the property value's
    **       record in the propdb.
    **
    ** V1 -- .. 0.9.6
    **       Initial version.
    */


    unsigned char minor;
#define DAV_DBVSN_MINOR         0

    short ns_count;

} dav_propdb_metadata;

struct dav_deadprop_rollback {
    apr_datum_t key;
    apr_datum_t value;
};

struct dav_namespace_map {
    int *ns_map;
};

/*
** Internal function to build a key
**
** WARNING: returns a pointer to a "static" buffer holding the key. The
**          value must be copied or no longer used if this function is
**          called again.
*/
static apr_datum_t dav_build_key(dav_db *db, const dav_prop_name *name)
{
    char nsbuf[20];
    apr_size_t l_ns, l_name = strlen(name->name);
    apr_datum_t key = { 0 };

    /*
     * Convert namespace ID to a string. "no namespace" is an empty string,
     * so the keys will have the form ":name". Otherwise, the keys will
     * have the form "#:name".
     */
    if (*name->ns == '\0') {
        nsbuf[0] = '\0';
        l_ns = 0;
    }
    else {
        long ns_id = (long)apr_hash_get(db->uri_index, name->ns,
                                      APR_HASH_KEY_STRING);


        if (ns_id == 0) {
            /* the namespace was not found(!) */
            return key;         /* zeroed */
        }

        l_ns = sprintf(nsbuf, "%ld", ns_id - 1);
    }

    /* assemble: #:name */
    dav_set_bufsize(db->pool, &db->wb_key, l_ns + 1 + l_name + 1);
    memcpy(db->wb_key.buf, nsbuf, l_ns);
    db->wb_key.buf[l_ns] = ':';
    memcpy(&db->wb_key.buf[l_ns + 1], name->name, l_name + 1);

    /* build the database key */
    key.dsize = l_ns + 1 + l_name + 1;
    key.dptr = db->wb_key.buf;

    return key;
}

static void dav_append_prop(apr_pool_t *pool,
                            const char *name, const char *value,
                            apr_text_header *phdr)
{
    const char *s;
    const char *lang = value;

    /* skip past the xml:lang value */
    value += strlen(lang) + 1;

    if (*value == '\0') {
        /* the property is an empty value */
        if (*name == ':') {
            /* "no namespace" case */
            s = apr_psprintf(pool, "<%s/>" DEBUG_CR, name+1);
        }
        else {
            s = apr_psprintf(pool, "<ns%s/>" DEBUG_CR, name);
        }
    }
    else if (*lang != '\0') {
        if (*name == ':') {
            /* "no namespace" case */
            s = apr_psprintf(pool, "<%s xml:lang=\"%s\">%s</%s>" DEBUG_CR,
                             name+1, lang, value, name+1);
        }
        else {
            s = apr_psprintf(pool, "<ns%s xml:lang=\"%s\">%s</ns%s>" DEBUG_CR,
                             name, lang, value, name);
        }
    }
    else if (*name == ':') {
        /* "no namespace" case */
        s = apr_psprintf(pool, "<%s>%s</%s>" DEBUG_CR, name+1, value, name+1);
    }
    else {
        s = apr_psprintf(pool, "<ns%s>%s</ns%s>" DEBUG_CR, name, value, name);
    }

    apr_text_append(pool, phdr, s);
}

static dav_error * dav_propdb_open(apr_pool_t *pool,
                                   const dav_resource *resource, int ro,
                                   dav_db **pdb)
{