path: root/shmem/win32/shm.c

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#include "apr_general.h"
#include "apr_errno.h"
#include "apr_file_io.h"
#include "apr_shm.h"
#include "fileio.h"

typedef struct memblock_t {
    apr_size_t size;
    apr_size_t length;
} memblock_t;

struct apr_shm_t {
    apr_pool_t *pool;
    memblock_t *memblk;
    void       *usrmem;
    apr_size_t  size;
    apr_size_t  length;
    HANDLE      hMap;
};

static apr_status_t shm_cleanup(void* shm)
{
    apr_status_t rv = APR_SUCCESS;
    apr_shm_t *m = shm;
    
    if (UnmapViewOfFile(m->memblk)) {
        rv = apr_get_os_error();
    }
    if (CloseHandle(m->hMap)) {
        return (rv != APR_SUCCESS) ? rv : apr_get_os_error();
    }
    /* ### Do we want to make a point of unlinking m->file here? 
     * Need to add the fname to the apr_shm_t, in that case.
     */
    return rv;
}

APR_DECLARE(apr_status_t) apr_shm_create(apr_shm_t **m,
                                         apr_size_t reqsize,
                                         const char *file,
                                         apr_pool_t *pool)
{
    static apr_size_t memblock = 0;
    SECURITY_ATTRIBUTES sec, *psec;
    HANDLE hMap, hFile;
    apr_status_t rv;
    apr_size_t size;
    apr_file_t *f;
    void *base;
    void *mapkey;
    DWORD err;

    reqsize += sizeof(memblock_t);

    if (!memblock)
    {
        SYSTEM_INFO si;
        GetSystemInfo(&si);
        memblock = si.dwAllocationGranularity;
    }   

    /* Compute the granualar multiple of the pagesize */
    size = memblock * (1 + (reqsize - 1) / memblock);

    if (!file) {
        /* Do Anonymous, which will be an inherited handle */
        hFile = INVALID_HANDLE_VALUE;
        sec.nLength = sizeof(SECURITY_ATTRIBUTES);
        sec.lpSecurityDescriptor = NULL;
        sec.bInheritHandle = TRUE;
        mapkey = NULL;
        psec = &sec;
    }
    else {
        /* Do file backed, which is not an inherited handle 
         * While we could open APR_EXCL, it doesn't seem that Unix
         * ever did.  Ignore that error here, but fail later when
         * we discover we aren't the creator of the file map object.
         */
        rv = apr_file_open(&f, file,
                           APR_READ | APR_WRITE | APR_BINARY | APR_CREATE,
                           APR_UREAD | APR_UWRITE, pool);
        if ((rv != APR_SUCCESS)
                || ((rv = apr_os_file_get(&hFile, f)) != APR_SUCCESS)) {
            return rv;
        }
        rv = apr_file_trunc(f, size);
        mapkey = res_name_from_filename(file, 1, pool);
        psec = NULL;
    }

    /* XXX: I had nothing but utter failure on WinNT attempting to specify
     * the size of the CreateFileMapping() calls below (given in DWORDs
     * as hi-DWORD, lo-DWORD where you see the 0, 0 args.)  Consistently,
     * Win2K reported insufficient disk space, when that is obviously not
     * the case.  I'm suspecting size should have been in pages (???) but
     * there was no docs in the PSDK that made that implication.
     *
     * The XXX above is due to the fact that anon allocation dies right now,
     * since we can't create a filemapping with size zero, when we don't
     * back it with a file.  Since I clearly don't understand what Win32
     * has done with this size arg, I'm loath to make the obvious fix.
     * Let it fail until I, or someone with time on their hands, wants to
     * research, experiment and fix this for good.
     */
#if APR_HAS_UNICODE_FS
    if (apr_os_level >= APR_WIN_NT) 
    {
        hMap = CreateFileMappingW(hFile, psec, PAGE_READWRITE, 0, 0, mapkey);
    }
    else
#endif
    {
        hMap = CreateFileMappingA(hFile, psec, PAGE_READWRITE, 0, 0, mapkey);
    }
    err = apr_get_os_error();

    if (file) {
        apr_file_close(f);
    }

    if (hMap && err == ERROR_ALREADY_EXISTS) {
        CloseHandle(hMap);
        return APR_EEXIST;
    }
    if (!hMap) {
        return err;
    }
    
    base = MapViewOfFile(hMap, FILE_MAP_READ | FILE_MAP_WRITE,
                         0, 0, size);
    if (!base) {
        CloseHandle(hMap);
        return apr_get_os_error();
    }
    
    *m = (apr_shm_t *) apr_palloc(pool, sizeof(apr_shm_t));
    (*m)->pool = pool;
    (*m)->hMap = hMap;
    (*m)->memblk = base;
    (*m)->size = size;

    (*m)->usrmem = (char*)base + sizeof(memblock_t);
    (*m)->length = reqsize - sizeof(memblock_t);;
    
    (*m)->memblk->length = (*m)->length;
    (*m)->memblk->size = (*m)->size;

    apr_pool_cleanup_register((*m)->pool, *m, 
                              shm_cleanup, apr_pool_cleanup_null);
    return APR_SUCCESS;
}

APR_DECLARE(apr_status_t) apr_shm_destroy(apr_shm_t *m) 
{
    apr_status_t rv = shm_cleanup(m);
    apr_pool_cleanup_kill(m->pool, m, shm_cleanup);
    return rv;
}

APR_DECLARE(apr_status_t) apr_shm_attach(apr_shm_t **m,
                                         const char *file,
                                         apr_pool_t *pool)
{
    HANDLE hMap;
    void *mapkey;
    void *base;

    if (!file) {
        return APR_EINVAL;
    }
    else {
        mapkey = res_name_from_filename(file, 1, pool);
    }

#if APR_HAS_UNICODE_FS
    if (apr_os_level >= APR_WIN_NT) 
    {
        hMap = OpenFileMappingW(FILE_MAP_READ | FILE_MAP_WRITE, FALSE, mapkey);
    }
    else
#endif
    {
        hMap = OpenFileMappingA(FILE_MAP_READ | FILE_MAP_WRITE, FALSE, mapkey);
    }

    if (!hMap) {
        return apr_get_os_error();
    }
    
    base = MapViewOfFile(hMap, FILE_MAP_READ | FILE_MAP_WRITE, 0, 0, 0);
    if (!base) {
        CloseHandle(hMap);
        return apr_get_os_error();
    }
    
    *m = (apr_shm_t *) apr_palloc(pool, sizeof(apr_shm_t));
    (*m)->pool = pool;
    (*m)->hMap = hMap;
    (*m)->memblk = base;
    (*m)->usrmem = (char*)base + sizeof(memblock_t);
    /* Real (*m)->mem->size could be recovered with VirtualQuery */
    (*m)->size = (*m)->memblk->size;
    (*m)->length = (*m)->memblk->length;

    apr_pool_cleanup_register((*m)->pool, *m, 
                              shm_cleanup, apr_pool_cleanup_null);
    return APR_SUCCESS;
}

APR_DECLARE(apr_status_t) apr_shm_detach(apr_shm_t *m)
{
    apr_status_t rv = shm_cleanup(m);
    apr_pool_cleanup_kill(m->pool, m, shm_cleanup);
    return rv;
}

APR_DECLARE(void *) apr_shm_baseaddr_get(const apr_shm_t *m)
{
    return m->usrmem;
}

APR_DECLARE(apr_size_t) apr_shm_size_get(const apr_shm_t *m)
{
    return m->length;
}