Adding upstream version 2.4.57.upstream/2.4.57

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 788 insertions, 0 deletions

diff --git a/modules/slotmem/mod_slotmem_shm.c b/modules/slotmem/mod_slotmem_shm.c
new file mode 100644
index 0000000..f4eaa84
--- /dev/null
+++ b/modules/slotmem/mod_slotmem_shm.c
@@ -0,0 +1,788 @@
+/* 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.
+ */
+
+/* Memory handler for a shared memory divided in slot.
+ * This one uses shared memory.
+ *
+ * Shared memory is cleaned-up for each restart, graceful or
+ * otherwise.
+ */
+
+#include  "ap_slotmem.h"
+
+#include "httpd.h"
+#include "http_main.h"
+#include "ap_mpm.h" /* for ap_mpm_query() */
+
+#define AP_SLOTMEM_IS_PREGRAB(t)    (t->desc->type & AP_SLOTMEM_TYPE_PREGRAB)
+#define AP_SLOTMEM_IS_PERSIST(t)    (t->desc->type & AP_SLOTMEM_TYPE_PERSIST)
+#define AP_SLOTMEM_IS_CLEARINUSE(t) (t->desc->type & AP_SLOTMEM_TYPE_CLEARINUSE)
+
+/* The description of the slots to reuse the slotmem */
+typedef struct {
+    apr_size_t size;             /* size of each memory slot */
+    unsigned int num;            /* number of mem slots */
+    ap_slotmem_type_t type;      /* type-specific flags */
+} sharedslotdesc_t;
+
+#define AP_SLOTMEM_OFFSET (APR_ALIGN_DEFAULT(sizeof(sharedslotdesc_t)))
+#define AP_UNSIGNEDINT_OFFSET (APR_ALIGN_DEFAULT(sizeof(unsigned int)))
+
+struct ap_slotmem_instance_t {
+    char                 *name;       /* file based SHM path/name */
+    char                 *pname;      /* persisted file path/name */
+    int                  fbased;      /* filebased? */
+    void                 *shm;        /* ptr to memory segment (apr_shm_t *) */
+    void                 *base;       /* data set start */
+    apr_pool_t           *gpool;      /* per segment pool (generation cleared) */
+    char                 *inuse;      /* in-use flag table*/
+    unsigned int         *num_free;   /* slot free count for this instance */
+    void                 *persist;    /* persist dataset start */
+    const sharedslotdesc_t *desc;     /* per slot desc */
+    struct ap_slotmem_instance_t  *next;       /* location of next allocated segment */
+};
+
+/*
+ * Layout for SHM and persisted file :
+ *
+ *   +-------------------------------------------------------------+~>
+ *   | desc | num_free | base (slots) | inuse (array) | md5 | desc | compat..
+ *   +------+-----------------------------------------+------------+~>
+ *   ^      ^                                         ^    \ /     ^   :
+ *   |______|_____________ SHM (mem->@) ______________|     | _____|__/
+ *          |                                               |/     |
+ *          |                                         ^     v      |
+ *          |_____________________ File (mem->persist +  [meta]) __|
+ */
+
+/* global pool and list of slotmem we are handling */
+static struct ap_slotmem_instance_t *globallistmem = NULL;
+static apr_pool_t *gpool = NULL;
+
+#define DEFAULT_SLOTMEM_PREFIX "slotmem-shm-"
+#define DEFAULT_SLOTMEM_SUFFIX ".shm"
+#define DEFAULT_SLOTMEM_PERSIST_SUFFIX ".persist"
+
+/*
+ * Persist the slotmem in a file
+ * slotmem name and file name.
+ * none      : no persistent data
+ * rel_name  : $server_root/rel_name
+ * /abs_name : $abs_name
+ *
+ */
+static int slotmem_filenames(apr_pool_t *pool,
+                             const char *slotname,
+                             const char **filename,
+                             const char **persistname)
+{
+    const char *fname = NULL, *pname = NULL;
+
+    if (slotname && *slotname && strcasecmp(slotname, "none") != 0) {
+        if (slotname[0] != '/') {
+            /* Each generation needs its own file name. */
+            int generation = 0;
+            ap_mpm_query(AP_MPMQ_GENERATION, &generation);
+            fname = apr_psprintf(pool, "%s%s_%x%s", DEFAULT_SLOTMEM_PREFIX,
+                                 slotname, generation, DEFAULT_SLOTMEM_SUFFIX);
+            fname = ap_runtime_dir_relative(pool, fname);
+        }
+        else {
+            /* Don't mangle the file name if given an absolute path, it's
+             * up to the caller to provide a unique name when necessary.
+             */
+            fname = slotname;
+        }
+
+        if (persistname) {
+            /* Persisted file names are immutable... */
+            if (slotname[0] != '/') {
+                pname = apr_pstrcat(pool, DEFAULT_SLOTMEM_PREFIX,
+                                    slotname, DEFAULT_SLOTMEM_SUFFIX,
+                                    DEFAULT_SLOTMEM_PERSIST_SUFFIX,
+                                    NULL);
+                pname = ap_runtime_dir_relative(pool, pname);
+            }
+            else {
+                pname = apr_pstrcat(pool, slotname,
+                                    DEFAULT_SLOTMEM_PERSIST_SUFFIX,
+                                    NULL);
+            }
+        }
+    }
+
+    *filename = fname;
+    if (persistname) {
+        *persistname = pname;
+    }
+    return (fname != NULL);
+}
+
+static void slotmem_clearinuse(ap_slotmem_instance_t *slot)
+{
+    unsigned int i;
+    char *inuse;
+    
+    if (!slot) {
+        return;
+    }
+    
+    inuse = slot->inuse;
+    
+    for (i = 0; i < slot->desc->num; i++, inuse++) {
+        if (*inuse) {
+            *inuse = 0;
+            (*slot->num_free)++;
+        }
+    }
+}
+
+static void store_slotmem(ap_slotmem_instance_t *slotmem)
+{
+    apr_file_t *fp;
+    apr_status_t rv;
+    apr_size_t nbytes;
+    unsigned char digest[APR_MD5_DIGESTSIZE];
+    const char *storename = slotmem->pname;
+
+    ap_log_error(APLOG_MARK, APLOG_DEBUG, 0, ap_server_conf, APLOGNO(02334)
+                 "storing %s", storename);
+
+    if (storename) {
+        rv = apr_file_open(&fp, storename, APR_CREATE | APR_READ | APR_WRITE,
+                           APR_OS_DEFAULT, slotmem->gpool);
+        if (APR_STATUS_IS_EEXIST(rv)) {
+            apr_file_remove(storename, slotmem->gpool);
+            rv = apr_file_open(&fp, storename, APR_CREATE | APR_READ | APR_WRITE,
+                               APR_OS_DEFAULT, slotmem->gpool);
+        }
+        if (rv != APR_SUCCESS) {
+            return;
+        }
+        if (AP_SLOTMEM_IS_CLEARINUSE(slotmem)) {
+            slotmem_clearinuse(slotmem);
+        }
+        nbytes = (slotmem->desc->size * slotmem->desc->num) +
+                 (slotmem->desc->num * sizeof(char)) + AP_UNSIGNEDINT_OFFSET;
+        apr_md5(digest, slotmem->persist, nbytes);
+        rv = apr_file_write_full(fp, slotmem->persist, nbytes, NULL);
+        if (rv == APR_SUCCESS) {
+            rv = apr_file_write_full(fp, digest, APR_MD5_DIGESTSIZE, NULL);
+        }
+        if (rv == APR_SUCCESS) {
+            rv = apr_file_write_full(fp, slotmem->desc, AP_SLOTMEM_OFFSET,
+                                     NULL);
+        }
+        apr_file_close(fp);
+        if (rv != APR_SUCCESS) {
+            apr_file_remove(storename, slotmem->gpool);
+        }
+    }
+}
+
+static apr_status_t restore_slotmem(sharedslotdesc_t *desc,
+                                    const char *storename, apr_size_t size,
+                                    apr_pool_t *pool)
+{
+    apr_file_t *fp;
+    apr_status_t rv = APR_ENOTIMPL;
+    void *ptr = (char *)desc + AP_SLOTMEM_OFFSET;
+    apr_size_t nbytes = size - AP_SLOTMEM_OFFSET;
+    unsigned char digest[APR_MD5_DIGESTSIZE];
+    unsigned char digest2[APR_MD5_DIGESTSIZE];
+    char desc_buf[AP_SLOTMEM_OFFSET];
+
+    ap_log_error(APLOG_MARK, APLOG_DEBUG, 0, ap_server_conf, APLOGNO(02335)
+                 "restoring %s", storename);
+
+    if (storename) {
+        rv = apr_file_open(&fp, storename, APR_READ | APR_WRITE, APR_OS_DEFAULT,
+                           pool);
+        if (rv == APR_SUCCESS) {
+            rv = apr_file_read_full(fp, ptr, nbytes, NULL);
+            if (rv == APR_SUCCESS || rv == APR_EOF) {
+                /*
+                 * if at EOF, don't bother checking md5
+                 *  - backwards compatibility
+                 *  */
+                if (apr_file_eof(fp) != APR_EOF) {
+                    rv = apr_file_read_full(fp, digest, APR_MD5_DIGESTSIZE, NULL);
+                    if (rv == APR_SUCCESS || rv == APR_EOF) {
+                        apr_md5(digest2, ptr, nbytes);
+                        if (memcmp(digest, digest2, APR_MD5_DIGESTSIZE)) {
+                            rv = APR_EMISMATCH;
+                        }
+                        /*
+                         * if at EOF, don't bother checking desc
+                         *  - backwards compatibility
+                         *  */
+                        else if (apr_file_eof(fp) != APR_EOF) {
+                            rv = apr_file_read_full(fp, desc_buf, sizeof(desc_buf), NULL);
+                            if (rv == APR_SUCCESS || rv == APR_EOF) {
+                                if (memcmp(desc, desc_buf, sizeof(desc_buf))) {
+                                    rv = APR_EMISMATCH;
+                                }
+                                else {
+                                    rv = APR_SUCCESS;
+                                }
+                            }
+                            else {
+                                rv = APR_INCOMPLETE;
+                            }
+                        }
+                        else {
+                            rv = APR_EOF;
+                        }
+                    }
+                    else {
+                        rv = APR_INCOMPLETE;
+                    }
+                }
+                else {
+                    rv = APR_EOF;
+                }
+                if (rv == APR_EMISMATCH) {
+                    ap_log_error(APLOG_MARK, APLOG_ERR, 0, ap_server_conf, APLOGNO(02551)
+                                 "persisted slotmem md5/desc mismatch");
+                }
+                else if (rv == APR_EOF) {
+                    ap_log_error(APLOG_MARK, APLOG_NOTICE, 0, ap_server_conf, APLOGNO(02552)
+                                 "persisted slotmem at EOF... bypassing md5/desc match check "
+                                 "(old persist file?)");
+                    rv = APR_SUCCESS;
+                }
+            }
+            else {
+                rv = APR_INCOMPLETE;
+            }
+            if (rv == APR_INCOMPLETE) {
+                ap_log_error(APLOG_MARK, APLOG_ERR, 0, ap_server_conf, APLOGNO(02553)
+                             "persisted slotmem read had unexpected size");
+            }
+            apr_file_close(fp);
+        }
+    }
+    return rv;
+}
+
+/*
+ * Whether the module is called from a MPM that re-enter main() and
+ * pre/post_config phases.
+ */
+static APR_INLINE int is_child_process(void)
+{
+#ifdef WIN32
+    return getenv("AP_PARENT_PID") != NULL;
+#else
+    return 0;
+#endif
+}
+
+static apr_status_t cleanup_slotmem(void *param)
+{
+    int is_child = is_child_process();
+    ap_slotmem_instance_t *next = globallistmem;
+
+    while (next) {
+        if (!is_child && AP_SLOTMEM_IS_PERSIST(next)) {
+            store_slotmem(next);
+        }
+        apr_shm_destroy(next->shm);
+        apr_shm_remove(next->name, next->gpool);
+        next = next->next;
+    }
+
+    globallistmem = NULL;
+    return APR_SUCCESS;
+}
+
+static apr_status_t slotmem_doall(ap_slotmem_instance_t *mem,
+                                  ap_slotmem_callback_fn_t *func,
+                                  void *data, apr_pool_t *pool)
+{
+    unsigned int i;
+    char *ptr;
+    char *inuse;
+    apr_status_t retval = APR_SUCCESS;
+
+    if (!mem) {
+        return APR_ENOSHMAVAIL;
+    }
+
+    ptr = (char *)mem->base;
+    inuse = mem->inuse;
+    for (i = 0; i < mem->desc->num; i++, inuse++) {
+        if (!AP_SLOTMEM_IS_PREGRAB(mem) || *inuse) {
+            retval = func((void *) ptr, data, pool);
+            if (retval != APR_SUCCESS)
+                break;
+        }
+        ptr += mem->desc->size;
+    }
+    return retval;
+}
+
+static apr_status_t slotmem_create(ap_slotmem_instance_t **new,
+                                   const char *name, apr_size_t item_size,
+                                   unsigned int item_num,
+                                   ap_slotmem_type_t type, apr_pool_t *pool)
+{
+    int fbased = 1;
+    int restored = 0;
+    char *ptr;
+    sharedslotdesc_t *desc;
+    ap_slotmem_instance_t *res;
+    ap_slotmem_instance_t *next = globallistmem;
+    const char *fname, *pname = NULL;
+    apr_shm_t *shm;
+    apr_size_t basesize = (item_size * item_num);
+    apr_size_t size = AP_SLOTMEM_OFFSET + AP_UNSIGNEDINT_OFFSET +
+                      (item_num * sizeof(char)) + basesize;
+    int persist = (type & AP_SLOTMEM_TYPE_PERSIST) != 0;
+    apr_status_t rv;
+
+    *new = NULL;
+    if (gpool == NULL) {
+        return APR_ENOSHMAVAIL;
+    }
+    if (slotmem_filenames(pool, name, &fname, persist ? &pname : NULL)) {
+        /* first try to attach to existing slotmem */
+        if (next) {
+            for (;;) {
+                if (strcmp(next->name, fname) == 0) {
+                    /* we already have it */
+                    *new = next;
+                    ap_log_error(APLOG_MARK, APLOG_DEBUG, 0, ap_server_conf, APLOGNO(02603)
+                                 "create found %s in global list", fname);
+                    return APR_SUCCESS;
+                }
+                if (!next->next) {
+                     break;
+                }
+                next = next->next;
+            }
+        }
+        ap_log_error(APLOG_MARK, APLOG_DEBUG, 0, ap_server_conf, APLOGNO(02602)
+                     "create didn't find %s in global list", fname);
+    }
+    else {
+        fbased = 0;
+        fname = "none";
+    }
+
+    /* first try to attach to existing shared memory */
+    ap_log_error(APLOG_MARK, APLOG_DEBUG, 0, ap_server_conf, APLOGNO(02300)
+                 "create %s: %"APR_SIZE_T_FMT"/%u", fname, item_size,
+                 item_num);
+
+    {
+        /* For MPMs that run pre/post_config() phases in both the parent
+         * and children processes (e.g. winnt), SHMs created by the
+         * parent exist in the children already; attach them.
+         */
+        if (fbased) {
+            if (is_child_process()) {
+                rv = apr_shm_attach(&shm, fname, gpool);
+            }
+            else {
+                apr_shm_remove(fname, pool);
+                rv = apr_shm_create(&shm, size, fname, gpool);
+            }
+        }
+        else {
+            rv = apr_shm_create(&shm, size, NULL, gpool);
+        }
+        ap_log_error(APLOG_MARK, rv == APR_SUCCESS ? APLOG_DEBUG : APLOG_ERR,
+                     rv, ap_server_conf, APLOGNO(02611)
+                     "create: apr_shm_%s(%s) %s",
+                     fbased && is_child_process() ? "attach" : "create",
+                     fname, rv == APR_SUCCESS ? "succeeded" : "failed");
+        if (rv != APR_SUCCESS) {
+            return rv;
+        }
+
+        desc = (sharedslotdesc_t *)apr_shm_baseaddr_get(shm);
+        memset(desc, 0, size);
+        desc->size = item_size;
+        desc->num = item_num;
+        desc->type = type;
+
+        /*
+         * TODO: Error check the below... What error makes
+         * sense if the restore fails? Any?
+         * For now, we continue with a fresh new slotmem,
+         * but NOTICE in the log.
+         */
+        if (persist) {
+            rv = restore_slotmem(desc, pname, size, pool);
+            if (rv == APR_SUCCESS) {
+                restored = 1;
+            }
+            else {
+                /* just in case, re-zero */
+                ap_log_error(APLOG_MARK, APLOG_DEBUG, 0, ap_server_conf,
+                             APLOGNO(02554) "could not restore %s", fname);
+                memset((char *)desc + AP_SLOTMEM_OFFSET, 0,
+                       size - AP_SLOTMEM_OFFSET);
+            }
+        }
+    }
+
+    ptr = (char *)desc + AP_SLOTMEM_OFFSET;
+
+    /* For the chained slotmem stuff */
+    res = apr_pcalloc(gpool, sizeof(ap_slotmem_instance_t));
+    res->name = apr_pstrdup(gpool, fname);
+    res->pname = apr_pstrdup(gpool, pname);
+    res->fbased = fbased;
+    res->shm = shm;
+    res->persist = (void *)ptr;
+    res->num_free = (unsigned int *)ptr;
+    ptr += AP_UNSIGNEDINT_OFFSET;
+    if (!restored) {
+        *res->num_free = item_num;
+    }
+    res->base = (void *)ptr;
+    res->desc = desc;
+    res->gpool = gpool;
+    res->next = NULL;
+    res->inuse = ptr + basesize;
+    if (fbased) {
+        if (globallistmem == NULL) {
+            globallistmem = res;
+        }
+        else {
+            next->next = res;
+        }
+    }
+
+    *new = res;
+    return APR_SUCCESS;
+}
+
+static apr_status_t slotmem_attach(ap_slotmem_instance_t **new,
+                                   const char *name, apr_size_t *item_size,
+                                   unsigned int *item_num, apr_pool_t *pool)
+{
+    char *ptr;
+    ap_slotmem_instance_t *res;
+    ap_slotmem_instance_t *next = globallistmem;
+    sharedslotdesc_t *desc;
+    const char *fname;
+    apr_shm_t *shm;
+    apr_status_t rv;
+
+    if (gpool == NULL) {
+        return APR_ENOSHMAVAIL;
+    }
+    if (!slotmem_filenames(pool, name, &fname, NULL)) {
+        return APR_ENOSHMAVAIL;
+    }
+
+    ap_log_error(APLOG_MARK, APLOG_DEBUG, 0, ap_server_conf, APLOGNO(02301)
+                 "attach looking for %s", fname);
+
+    /* first try to attach to existing slotmem */
+    if (next) {
+        for (;;) {
+            if (strcmp(next->name, fname) == 0) {
+                /* we already have it */
+                *new = next;
+                *item_size = next->desc->size;
+                *item_num = next->desc->num;
+                ap_log_error(APLOG_MARK, APLOG_DEBUG, 0, ap_server_conf,
+                             APLOGNO(02302)
+                             "attach found %s: %"APR_SIZE_T_FMT"/%u", fname,
+                             *item_size, *item_num);
+                return APR_SUCCESS;
+            }
+            if (!next->next) {
+                 break;
+            }
+            next = next->next;
+        }
+    }
+
+    /* next try to attach to existing shared memory */
+    rv = apr_shm_attach(&shm, fname, gpool);
+    if (rv != APR_SUCCESS) {
+        return rv;
+    }
+
+    /* Read the description of the slotmem */
+    desc = (sharedslotdesc_t *)apr_shm_baseaddr_get(shm);
+    ptr = (char *)desc + AP_SLOTMEM_OFFSET;
+
+    /* For the chained slotmem stuff */
+    res = apr_pcalloc(gpool, sizeof(ap_slotmem_instance_t));
+    res->name = apr_pstrdup(gpool, fname);
+    res->fbased = 1;
+    res->shm = shm;
+    res->persist = (void *)ptr;
+    res->num_free = (unsigned int *)ptr;
+    ptr += AP_UNSIGNEDINT_OFFSET;
+    res->base = (void *)ptr;
+    res->desc = desc;
+    res->gpool = gpool;
+    res->inuse = ptr + (desc->size * desc->num);
+    res->next = NULL;
+
+    *new = res;
+    *item_size = desc->size;
+    *item_num = desc->num;
+    ap_log_error(APLOG_MARK, APLOG_DEBUG, 0, ap_server_conf,
+                 APLOGNO(02303)
+                 "attach found %s: %"APR_SIZE_T_FMT"/%u", fname,
+                 *item_size, *item_num);
+    return APR_SUCCESS;
+}
+
+static apr_status_t slotmem_dptr(ap_slotmem_instance_t *slot,
+                                 unsigned int id, void **mem)
+{
+    char *ptr;
+
+    if (!slot) {
+        return APR_ENOSHMAVAIL;
+    }
+    if (id >= slot->desc->num) {
+        return APR_EINVAL;
+    }
+
+    ptr = (char *)slot->base + slot->desc->size * id;
+    if (!ptr) {
+        return APR_ENOSHMAVAIL;
+    }
+    *mem = (void *)ptr;
+    return APR_SUCCESS;
+}
+
+static apr_status_t slotmem_get(ap_slotmem_instance_t *slot, unsigned int id,
+                                unsigned char *dest, apr_size_t dest_len)
+{
+    void *ptr;
+    char *inuse;
+    apr_status_t ret;
+
+    if (!slot) {
+        return APR_ENOSHMAVAIL;
+    }
+
+    inuse = slot->inuse + id;
+    if (id >= slot->desc->num) {
+        return APR_EINVAL;
+    }
+    if (AP_SLOTMEM_IS_PREGRAB(slot) && !*inuse) {
+        return APR_NOTFOUND;
+    }
+    ret = slotmem_dptr(slot, id, &ptr);
+    if (ret != APR_SUCCESS) {
+        return ret;
+    }
+    *inuse = 1;
+    memcpy(dest, ptr, dest_len); /* bounds check? */
+    return APR_SUCCESS;
+}
+
+static apr_status_t slotmem_put(ap_slotmem_instance_t *slot, unsigned int id,
+                                unsigned char *src, apr_size_t src_len)
+{
+    void *ptr;
+    char *inuse;
+    apr_status_t ret;
+
+    if (!slot) {
+        return APR_ENOSHMAVAIL;
+    }
+
+    inuse = slot->inuse + id;
+    if (id >= slot->desc->num) {
+        return APR_EINVAL;
+    }
+    if (AP_SLOTMEM_IS_PREGRAB(slot) && !*inuse) {
+        return APR_NOTFOUND;
+    }
+    ret = slotmem_dptr(slot, id, &ptr);
+    if (ret != APR_SUCCESS) {
+        return ret;
+    }
+    *inuse=1;
+    memcpy(ptr, src, src_len); /* bounds check? */
+    return APR_SUCCESS;
+}
+
+static unsigned int slotmem_num_slots(ap_slotmem_instance_t *slot)
+{
+    return slot->desc->num;
+}
+
+static unsigned int slotmem_num_free_slots(ap_slotmem_instance_t *slot)
+{
+    if (AP_SLOTMEM_IS_PREGRAB(slot))
+        return *slot->num_free;
+    else {
+        unsigned int i, counter=0;
+        char *inuse = slot->inuse;
+        for (i=0; i<slot->desc->num; i++, inuse++) {
+            if (!*inuse)
+                counter++;
+        }
+        return counter;
+    }
+}
+
+static apr_size_t slotmem_slot_size(ap_slotmem_instance_t *slot)
+{
+    return slot->desc->size;
+}
+
+static apr_status_t slotmem_grab(ap_slotmem_instance_t *slot, unsigned int *id)
+{
+    unsigned int i;
+    char *inuse;
+
+    if (!slot) {
+        return APR_ENOSHMAVAIL;
+    }
+
+    inuse = slot->inuse;
+
+    for (i = 0; i < slot->desc->num; i++, inuse++) {
+        if (!*inuse) {
+            break;
+        }
+    }
+    if (i >= slot->desc->num) {
+        ap_log_error(APLOG_MARK, APLOG_DEBUG, 0, ap_server_conf, APLOGNO(02293)
+                     "slotmem(%s) grab failed. Num %u/num_free %u",
+                     slot->name, slotmem_num_slots(slot),
+                     slotmem_num_free_slots(slot));
+        return APR_EINVAL;
+    }
+    *inuse = 1;
+    *id = i;
+    (*slot->num_free)--;
+    return APR_SUCCESS;
+}
+
+static apr_status_t slotmem_fgrab(ap_slotmem_instance_t *slot, unsigned int id)
+{
+    char *inuse;
+    
+    if (!slot) {
+        return APR_ENOSHMAVAIL;
+    }
+
+    if (id >= slot->desc->num) {
+        ap_log_error(APLOG_MARK, APLOG_DEBUG, 0, ap_server_conf, APLOGNO(02397)
+                     "slotmem(%s) fgrab failed. Num %u/num_free %u",
+                     slot->name, slotmem_num_slots(slot),
+                     slotmem_num_free_slots(slot));
+        return APR_EINVAL;
+    }
+    inuse = slot->inuse + id;
+
+    if (!*inuse) {
+        *inuse = 1;
+        (*slot->num_free)--;
+    }
+    return APR_SUCCESS;
+}
+
+static apr_status_t slotmem_release(ap_slotmem_instance_t *slot,
+                                    unsigned int id)
+{
+    char *inuse;
+
+    if (!slot) {
+        return APR_ENOSHMAVAIL;
+    }
+
+    inuse = slot->inuse;
+
+    if (id >= slot->desc->num || !inuse[id] ) {
+        ap_log_error(APLOG_MARK, APLOG_DEBUG, 0, ap_server_conf, APLOGNO(02294)
+                     "slotmem(%s) release failed. Num %u/inuse[%u] %d",
+                     slot->name, slotmem_num_slots(slot),
+                     id, (int)inuse[id]);
+        if (id >= slot->desc->num) {
+            return APR_EINVAL;
+        } else {
+            return APR_NOTFOUND;
+        }
+    }
+    inuse[id] = 0;
+    (*slot->num_free)++;
+    return APR_SUCCESS;
+}
+
+static const ap_slotmem_provider_t storage = {
+    "sharedmem",
+    &slotmem_doall,
+    &slotmem_create,
+    &slotmem_attach,
+    &slotmem_dptr,
+    &slotmem_get,
+    &slotmem_put,
+    &slotmem_num_slots,
+    &slotmem_num_free_slots,
+    &slotmem_slot_size,
+    &slotmem_grab,
+    &slotmem_release,
+    &slotmem_fgrab
+};
+
+/* make the storage usable from outside */
+static const ap_slotmem_provider_t *slotmem_shm_getstorage(void)
+{
+    return (&storage);
+}
+
+/*
+ * Make sure the shared memory is cleaned
+ */
+static int post_config(apr_pool_t *p, apr_pool_t *plog, apr_pool_t *ptemp,
+                       server_rec *s)
+{
+    apr_pool_cleanup_register(p, NULL, cleanup_slotmem, apr_pool_cleanup_null);
+    return OK;
+}
+
+static int pre_config(apr_pool_t *p, apr_pool_t *plog, apr_pool_t *ptemp)
+{
+    gpool = p;
+    globallistmem = NULL;
+    return OK;
+}
+
+static void ap_slotmem_shm_register_hook(apr_pool_t *p)
+{
+    const ap_slotmem_provider_t *storage = slotmem_shm_getstorage();
+    ap_register_provider(p, AP_SLOTMEM_PROVIDER_GROUP, "shm",
+                         AP_SLOTMEM_PROVIDER_VERSION, storage);
+    ap_hook_post_config(post_config, NULL, NULL, APR_HOOK_LAST);
+    ap_hook_pre_config(pre_config, NULL, NULL, APR_HOOK_MIDDLE);
+}
+
+AP_DECLARE_MODULE(slotmem_shm) = {
+    STANDARD20_MODULE_STUFF,
+    NULL,                       /* create per-directory config structure */
+    NULL,                       /* merge per-directory config structures */
+    NULL,                       /* create per-server config structure */
+    NULL,                       /* merge per-server config structures */
+    NULL,                       /* command apr_table_t */
+    ap_slotmem_shm_register_hook  /* register hooks */
+};