Adding upstream version 115.7.0esr.upstream/115.7.0esrupstream

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

1 files changed, 1460 insertions, 0 deletions

diff --git a/intl/icu/source/common/udata.cpp b/intl/icu/source/common/udata.cpp
new file mode 100644
index 0000000000..76d970f3f2
--- /dev/null
+++ b/intl/icu/source/common/udata.cpp
@@ -0,0 +1,1460 @@
+// © 2016 and later: Unicode, Inc. and others.
+// License & terms of use: http://www.unicode.org/copyright.html
+/*
+******************************************************************************
+*
+*   Copyright (C) 1999-2016, International Business Machines
+*   Corporation and others.  All Rights Reserved.
+*
+******************************************************************************
+*   file name:  udata.cpp
+*   encoding:   UTF-8
+*   tab size:   8 (not used)
+*   indentation:4
+*
+*   created on: 1999oct25
+*   created by: Markus W. Scherer
+*/
+
+#include "unicode/utypes.h"  /* U_PLATFORM etc. */
+
+#ifdef __GNUC__
+/* if gcc
+#define ATTRIBUTE_WEAK __attribute__ ((weak))
+might have to #include some other header
+*/
+#endif
+
+#include "unicode/putil.h"
+#include "unicode/udata.h"
+#include "unicode/uversion.h"
+#include "charstr.h"
+#include "cmemory.h"
+#include "cstring.h"
+#include "mutex.h"
+#include "putilimp.h"
+#include "restrace.h"
+#include "uassert.h"
+#include "ucln_cmn.h"
+#include "ucmndata.h"
+#include "udatamem.h"
+#include "uhash.h"
+#include "umapfile.h"
+#include "umutex.h"
+
+/***********************************************************************
+*
+*   Notes on the organization of the ICU data implementation
+*
+*      All of the public API is defined in udata.h
+*
+*      The implementation is split into several files...
+*
+*         - udata.c  (this file) contains higher level code that knows about
+*                     the search paths for locating data, caching opened data, etc.
+*
+*         - umapfile.c  contains the low level platform-specific code for actually loading
+*                     (memory mapping, file reading, whatever) data into memory.
+*
+*         - ucmndata.c  deals with the tables of contents of ICU data items within
+*                     an ICU common format data file.  The implementation includes
+*                     an abstract interface and support for multiple TOC formats.
+*                     All knowledge of any specific TOC format is encapsulated here.
+*
+*         - udatamem.c has code for managing UDataMemory structs.  These are little
+*                     descriptor objects for blocks of memory holding ICU data of
+*                     various types.
+*/
+
+/* configuration ---------------------------------------------------------- */
+
+/* If you are excruciatingly bored turn this on .. */
+/* #define UDATA_DEBUG 1 */
+
+#if defined(UDATA_DEBUG)
+#   include <stdio.h>
+#endif
+
+U_NAMESPACE_USE
+
+/*
+ *  Forward declarations
+ */
+static UDataMemory *udata_findCachedData(const char *path, UErrorCode &err);
+
+/***********************************************************************
+*
+*    static (Global) data
+*
+************************************************************************/
+
+/*
+ * Pointers to the common ICU data.
+ *
+ * We store multiple pointers to ICU data packages and iterate through them
+ * when looking for a data item.
+ *
+ * It is possible to combine this with dependency inversion:
+ * One or more data package libraries may export
+ * functions that each return a pointer to their piece of the ICU data,
+ * and this file would import them as weak functions, without a
+ * strong linker dependency from the common library on the data library.
+ *
+ * Then we can have applications depend on only that part of ICU's data
+ * that they really need, reducing the size of binaries that take advantage
+ * of this.
+ */
+static UDataMemory *gCommonICUDataArray[10] = { nullptr };   // Access protected by icu global mutex.
+
+static u_atomic_int32_t gHaveTriedToLoadCommonData {0};  //  See extendICUData().
+
+static UHashtable  *gCommonDataCache = nullptr;  /* Global hash table of opened ICU data files.  */
+static icu::UInitOnce gCommonDataCacheInitOnce {};
+
+#if !defined(ICU_DATA_DIR_WINDOWS)
+static UDataFileAccess  gDataFileAccess = UDATA_DEFAULT_ACCESS;  // Access not synchronized.
+                                                                 // Modifying is documented as thread-unsafe.
+#else
+// If we are using the Windows data directory, then look in one spot only.
+static UDataFileAccess  gDataFileAccess = UDATA_NO_FILES;
+#endif
+
+static UBool U_CALLCONV
+udata_cleanup()
+{
+    int32_t i;
+
+    if (gCommonDataCache) {             /* Delete the cache of user data mappings.  */
+        uhash_close(gCommonDataCache);  /*   Table owns the contents, and will delete them. */
+        gCommonDataCache = nullptr;        /*   Cleanup is not thread safe.                */
+    }
+    gCommonDataCacheInitOnce.reset();
+
+    for (i = 0; i < UPRV_LENGTHOF(gCommonICUDataArray) && gCommonICUDataArray[i] != nullptr; ++i) {
+        udata_close(gCommonICUDataArray[i]);
+        gCommonICUDataArray[i] = nullptr;
+    }
+    gHaveTriedToLoadCommonData = 0;
+
+    return true;                   /* Everything was cleaned up */
+}
+
+static UBool U_CALLCONV
+findCommonICUDataByName(const char *inBasename, UErrorCode &err)
+{
+    UBool found = false;
+    int32_t i;
+
+    UDataMemory  *pData = udata_findCachedData(inBasename, err);
+    if (U_FAILURE(err) || pData == nullptr)
+        return false;
+
+    {
+        Mutex lock;
+        for (i = 0; i < UPRV_LENGTHOF(gCommonICUDataArray); ++i) {
+            if ((gCommonICUDataArray[i] != nullptr) && (gCommonICUDataArray[i]->pHeader == pData->pHeader)) {
+                /* The data pointer is already in the array. */
+                found = true;
+                break;
+            }
+        }
+    }
+    return found;
+}
+
+
+/*
+ * setCommonICUData.   Set a UDataMemory to be the global ICU Data
+ */
+static UBool
+setCommonICUData(UDataMemory *pData,     /*  The new common data.  Belongs to caller, we copy it. */
+                 UBool       warn,       /*  If true, set USING_DEFAULT warning if ICUData was    */
+                                         /*    changed by another thread before we got to it.     */
+                 UErrorCode *pErr)
+{
+    UDataMemory  *newCommonData = UDataMemory_createNewInstance(pErr);
+    int32_t i;
+    UBool didUpdate = false;
+    if (U_FAILURE(*pErr)) {
+        return false;
+    }
+
+    /*  For the assignment, other threads must cleanly see either the old            */
+    /*    or the new, not some partially initialized new.  The old can not be        */
+    /*    deleted - someone may still have a pointer to it lying around in           */
+    /*    their locals.                                                              */
+    UDatamemory_assign(newCommonData, pData);
+    umtx_lock(nullptr);
+    for (i = 0; i < UPRV_LENGTHOF(gCommonICUDataArray); ++i) {
+        if (gCommonICUDataArray[i] == nullptr) {
+            gCommonICUDataArray[i] = newCommonData;
+            didUpdate = true;
+            break;
+        } else if (gCommonICUDataArray[i]->pHeader == pData->pHeader) {
+            /* The same data pointer is already in the array. */
+            break;
+        }
+    }
+    umtx_unlock(nullptr);
+
+    if (i == UPRV_LENGTHOF(gCommonICUDataArray) && warn) {
+        *pErr = U_USING_DEFAULT_WARNING;
+    }
+    if (didUpdate) {
+        ucln_common_registerCleanup(UCLN_COMMON_UDATA, udata_cleanup);
+    } else {
+        uprv_free(newCommonData);
+    }
+    return didUpdate;
+}
+
+#if !defined(ICU_DATA_DIR_WINDOWS)
+
+static UBool
+setCommonICUDataPointer(const void *pData, UBool /*warn*/, UErrorCode *pErrorCode) {
+    UDataMemory tData;
+    UDataMemory_init(&tData);
+    UDataMemory_setData(&tData, pData);
+    udata_checkCommonData(&tData, pErrorCode);
+    return setCommonICUData(&tData, false, pErrorCode);
+}
+
+#endif
+
+static const char *
+findBasename(const char *path) {
+    const char *basename=uprv_strrchr(path, U_FILE_SEP_CHAR);
+    if(basename==nullptr) {
+        return path;
+    } else {
+        return basename+1;
+    }
+}
+
+#ifdef UDATA_DEBUG
+static const char *
+packageNameFromPath(const char *path)
+{
+    if((path == nullptr) || (*path == 0)) {
+        return U_ICUDATA_NAME;
+    }
+
+    path = findBasename(path);
+
+    if((path == nullptr) || (*path == 0)) {
+        return U_ICUDATA_NAME;
+    }
+
+    return path;
+}
+#endif
+
+/*----------------------------------------------------------------------*
+ *                                                                      *
+ *   Cache for common data                                              *
+ *      Functions for looking up or adding entries to a cache of        *
+ *      data that has been previously opened.  Avoids a potentially     *
+ *      expensive operation of re-opening the data for subsequent       *
+ *      uses.                                                           *
+ *                                                                      *
+ *      Data remains cached for the duration of the process.            *
+ *                                                                      *
+ *----------------------------------------------------------------------*/
+
+typedef struct DataCacheElement {
+    char          *name;
+    UDataMemory   *item;
+} DataCacheElement;
+
+
+
+/*
+ * Deleter function for DataCacheElements.
+ *         udata cleanup function closes the hash table; hash table in turn calls back to
+ *         here for each entry.
+ */
+static void U_CALLCONV DataCacheElement_deleter(void *pDCEl) {
+    DataCacheElement *p = (DataCacheElement *)pDCEl;
+    udata_close(p->item);              /* unmaps storage */
+    uprv_free(p->name);                /* delete the hash key string. */
+    uprv_free(pDCEl);                  /* delete 'this'          */
+}
+
+static void U_CALLCONV udata_initHashTable(UErrorCode &err) {
+    U_ASSERT(gCommonDataCache == nullptr);
+    gCommonDataCache = uhash_open(uhash_hashChars, uhash_compareChars, nullptr, &err);
+    if (U_FAILURE(err)) {
+       return;
+    }
+    U_ASSERT(gCommonDataCache != nullptr);
+    uhash_setValueDeleter(gCommonDataCache, DataCacheElement_deleter);
+    ucln_common_registerCleanup(UCLN_COMMON_UDATA, udata_cleanup);
+}
+
+ /*   udata_getCacheHashTable()
+  *     Get the hash table used to store the data cache entries.
+  *     Lazy create it if it doesn't yet exist.
+  */
+static UHashtable *udata_getHashTable(UErrorCode &err) {
+    umtx_initOnce(gCommonDataCacheInitOnce, &udata_initHashTable, err);
+    return gCommonDataCache;
+}
+
+
+
+static UDataMemory *udata_findCachedData(const char *path, UErrorCode &err)
+{
+    UHashtable        *htable;
+    UDataMemory       *retVal = nullptr;
+    DataCacheElement  *el;
+    const char        *baseName;
+
+    htable = udata_getHashTable(err);
+    if (U_FAILURE(err)) {
+        return nullptr;
+    }
+
+    baseName = findBasename(path);   /* Cache remembers only the base name, not the full path. */
+    umtx_lock(nullptr);
+    el = (DataCacheElement *)uhash_get(htable, baseName);
+    umtx_unlock(nullptr);
+    if (el != nullptr) {
+        retVal = el->item;
+    }
+#ifdef UDATA_DEBUG
+    fprintf(stderr, "Cache: [%s] -> %p\n", baseName, (void*) retVal);
+#endif
+    return retVal;
+}
+
+
+static UDataMemory *udata_cacheDataItem(const char *path, UDataMemory *item, UErrorCode *pErr) {
+    DataCacheElement *newElement;
+    const char       *baseName;
+    int32_t           nameLen;
+    UHashtable       *htable;
+    DataCacheElement *oldValue = nullptr;
+    UErrorCode        subErr = U_ZERO_ERROR;
+
+    htable = udata_getHashTable(*pErr);
+    if (U_FAILURE(*pErr)) {
+        return nullptr;
+    }
+
+    /* Create a new DataCacheElement - the thingy we store in the hash table -
+     * and copy the supplied path and UDataMemoryItems into it.
+     */
+    newElement = (DataCacheElement *)uprv_malloc(sizeof(DataCacheElement));
+    if (newElement == nullptr) {
+        *pErr = U_MEMORY_ALLOCATION_ERROR;
+        return nullptr;
+    }
+    newElement->item = UDataMemory_createNewInstance(pErr);
+    if (U_FAILURE(*pErr)) {
+        uprv_free(newElement);
+        return nullptr;
+    }
+    UDatamemory_assign(newElement->item, item);
+
+    baseName = findBasename(path);
+    nameLen = (int32_t)uprv_strlen(baseName);
+    newElement->name = (char *)uprv_malloc(nameLen+1);
+    if (newElement->name == nullptr) {
+        *pErr = U_MEMORY_ALLOCATION_ERROR;
+        uprv_free(newElement->item);
+        uprv_free(newElement);
+        return nullptr;
+    }
+    uprv_strcpy(newElement->name, baseName);
+
+    /* Stick the new DataCacheElement into the hash table.
+    */
+    umtx_lock(nullptr);
+    oldValue = (DataCacheElement *)uhash_get(htable, path);
+    if (oldValue != nullptr) {
+        subErr = U_USING_DEFAULT_WARNING;
+    }
+    else {
+        uhash_put(
+            htable,
+            newElement->name,               /* Key   */
+            newElement,                     /* Value */
+            &subErr);
+    }
+    umtx_unlock(nullptr);
+
+#ifdef UDATA_DEBUG
+    fprintf(stderr, "Cache: [%s] <<< %p : %s. vFunc=%p\n", newElement->name, 
+    (void*) newElement->item, u_errorName(subErr), (void*) newElement->item->vFuncs);
+#endif
+
+    if (subErr == U_USING_DEFAULT_WARNING || U_FAILURE(subErr)) {
+        *pErr = subErr; /* copy sub err unto fillin ONLY if something happens. */
+        uprv_free(newElement->name);
+        uprv_free(newElement->item);
+        uprv_free(newElement);
+        return oldValue ? oldValue->item : nullptr;
+    }
+
+    return newElement->item;
+}
+
+/*----------------------------------------------------------------------*==============
+ *                                                                      *
+ *  Path management.  Could be shared with other tools/etc if need be   *
+ * later on.                                                            *
+ *                                                                      *
+ *----------------------------------------------------------------------*/
+
+U_NAMESPACE_BEGIN
+
+class UDataPathIterator
+{
+public:
+    UDataPathIterator(const char *path, const char *pkg,
+                      const char *item, const char *suffix, UBool doCheckLastFour,
+                      UErrorCode *pErrorCode);
+    const char *next(UErrorCode *pErrorCode);
+
+private:
+    const char *path;                              /* working path (u_icudata_Dir) */
+    const char *nextPath;                          /* path following this one */
+    const char *basename;                          /* item's basename (icudt22e_mt.res)*/
+
+    StringPiece suffix;                            /* item suffix (can be null) */
+
+    uint32_t    basenameLen;                       /* length of basename */
+
+    CharString  itemPath;                          /* path passed in with item name */
+    CharString  pathBuffer;                        /* output path for this it'ion */
+    CharString  packageStub;                       /* example:  "/icudt28b". Will ignore that leaf in set paths. */
+
+    UBool       checkLastFour;                     /* if true then allow paths such as '/foo/myapp.dat'
+                                                    * to match, checks last 4 chars of suffix with
+                                                    * last 4 of path, then previous chars. */
+};
+
+/**
+ * @param iter    The iterator to be initialized. Its current state does not matter.
+ * @param inPath  The full pathname to be iterated over.  If nullptr, defaults to U_ICUDATA_NAME 
+ * @param pkg     Package which is being searched for, ex "icudt28l".  Will ignore leaf directories such as /icudt28l 
+ * @param item    Item to be searched for.  Can include full path, such as /a/b/foo.dat 
+ * @param inSuffix  Optional item suffix, if not-null (ex. ".dat") then 'path' can contain 'item' explicitly.
+ *             Ex:   'stuff.dat' would be found in '/a/foo:/tmp/stuff.dat:/bar/baz' as item #2.   
+ *                   '/blarg/stuff.dat' would also be found.
+ *  Note: inSuffix may also be the 'item' being searched for as well, (ex: "ibm-5348_P100-1997.cnv"), in which case 
+ *        the 'item' parameter is often the same as pkg. (Though sometimes might have a tree part as well, ex: "icudt62l-curr").
+ */
+UDataPathIterator::UDataPathIterator(const char *inPath, const char *pkg,
+                                     const char *item, const char *inSuffix, UBool doCheckLastFour,
+                                     UErrorCode *pErrorCode)
+{
+#ifdef UDATA_DEBUG
+        fprintf(stderr, "SUFFIX1=%s PATH=%s\n", inSuffix, inPath);
+#endif
+    /** Path **/
+    if(inPath == nullptr) {
+        path = u_getDataDirectory();
+    } else {
+        path = inPath;
+    }
+
+    /** Package **/
+    if(pkg != nullptr) {
+      packageStub.append(U_FILE_SEP_CHAR, *pErrorCode).append(pkg, *pErrorCode);
+#ifdef UDATA_DEBUG
+      fprintf(stderr, "STUB=%s [%d]\n", packageStub.data(), packageStub.length());
+#endif
+    }
+
+    /** Item **/
+    basename = findBasename(item);
+    basenameLen = (int32_t)uprv_strlen(basename);
+
+    /** Item path **/
+    if(basename == item) {
+        nextPath = path;
+    } else {
+        itemPath.append(item, (int32_t)(basename-item), *pErrorCode);
+        nextPath = itemPath.data();
+    }
+#ifdef UDATA_DEBUG
+    fprintf(stderr, "SUFFIX=%s [%p]\n", inSuffix, (void*) inSuffix);
+#endif
+
+    /** Suffix  **/
+    if(inSuffix != nullptr) {
+        suffix = inSuffix;
+    } else {
+        suffix = "";
+    }
+
+    checkLastFour = doCheckLastFour;
+
+    /* pathBuffer will hold the output path strings returned by this iterator */
+
+#ifdef UDATA_DEBUG
+    fprintf(stderr, "0: init %s -> [path=%s], [base=%s], [suff=%s], [itempath=%s], [nextpath=%s], [checklast4=%s]\n",
+            item,
+            path,
+            basename,
+            suffix.data(),
+            itemPath.data(),
+            nextPath,
+            checkLastFour?"true":"false");
+#endif
+}
+
+/**
+ * Get the next path on the list.
+ *
+ * @param iter The Iter to be used 
+ * @param len  If set, pointer to the length of the returned path, for convenience. 
+ * @return Pointer to the next path segment, or nullptr if there are no more.
+ */
+const char *UDataPathIterator::next(UErrorCode *pErrorCode)
+{
+    if(U_FAILURE(*pErrorCode)) {
+        return nullptr;
+    }
+
+    const char *currentPath = nullptr;
+    int32_t     pathLen = 0;
+    const char *pathBasename;
+
+    do
+    {
+        if( nextPath == nullptr ) {
+            break;
+        }
+        currentPath = nextPath;
+
+        if(nextPath == itemPath.data()) { /* we were processing item's path. */
+            nextPath = path; /* start with regular path next tm. */
+            pathLen = (int32_t)uprv_strlen(currentPath);
+        } else {
+            /* fix up next for next time */
+            nextPath = uprv_strchr(currentPath, U_PATH_SEP_CHAR);
+            if(nextPath == nullptr) {
+                /* segment: entire path */
+                pathLen = (int32_t)uprv_strlen(currentPath); 
+            } else {
+                /* segment: until next segment */
+                pathLen = (int32_t)(nextPath - currentPath);
+                /* skip divider */
+                nextPath ++;
+            }
+        }
+
+        if(pathLen == 0) {
+            continue;
+        }
+
+#ifdef UDATA_DEBUG
+        fprintf(stderr, "rest of path (IDD) = %s\n", currentPath);
+        fprintf(stderr, "                     ");
+        { 
+            int32_t qqq;
+            for(qqq=0;qqq<pathLen;qqq++)
+            {
+                fprintf(stderr, " ");
+            }
+
+            fprintf(stderr, "^\n");
+        }
+#endif
+        pathBuffer.clear().append(currentPath, pathLen, *pErrorCode);
+
+        /* check for .dat files */
+        pathBasename = findBasename(pathBuffer.data());
+
+        if(checkLastFour && 
+           (pathLen>=4) &&
+           uprv_strncmp(pathBuffer.data() +(pathLen-4), suffix.data(), 4)==0 && /* suffix matches */
+           uprv_strncmp(findBasename(pathBuffer.data()), basename, basenameLen)==0  && /* base matches */
+           uprv_strlen(pathBasename)==(basenameLen+4)) { /* base+suffix = full len */
+
+#ifdef UDATA_DEBUG
+            fprintf(stderr, "Have %s file on the path: %s\n", suffix.data(), pathBuffer.data());
+#endif
+            /* do nothing */
+        }
+        else 
+        {       /* regular dir path */
+            if(pathBuffer[pathLen-1] != U_FILE_SEP_CHAR) {
+                if((pathLen>=4) &&
+                   uprv_strncmp(pathBuffer.data()+(pathLen-4), ".dat", 4) == 0)
+                {
+#ifdef UDATA_DEBUG
+                    fprintf(stderr, "skipping non-directory .dat file %s\n", pathBuffer.data());
+#endif
+                    continue;
+                }
+
+                /* Check if it is a directory with the same name as our package */
+                if(!packageStub.isEmpty() &&
+                   (pathLen > packageStub.length()) &&
+                   !uprv_strcmp(pathBuffer.data() + pathLen - packageStub.length(), packageStub.data())) {
+#ifdef UDATA_DEBUG
+                  fprintf(stderr, "Found stub %s (will add package %s of len %d)\n", packageStub.data(), basename, basenameLen);
+#endif
+                  pathBuffer.truncate(pathLen - packageStub.length());
+                }
+                pathBuffer.append(U_FILE_SEP_CHAR, *pErrorCode);
+            }
+
+            /* + basename */
+            pathBuffer.append(packageStub.data()+1, packageStub.length()-1, *pErrorCode);
+
+            if (!suffix.empty())  /* tack on suffix */
+            {
+                if (suffix.length() > 4) {
+                    // If the suffix is actually an item ("ibm-5348_P100-1997.cnv") and not an extension (".res")
+                    // then we need to ensure that the path ends with a separator.
+                    pathBuffer.ensureEndsWithFileSeparator(*pErrorCode);
+                }
+                pathBuffer.append(suffix, *pErrorCode);
+            }
+        }
+
+#ifdef UDATA_DEBUG
+        fprintf(stderr, " -->  %s\n", pathBuffer.data());
+#endif
+
+        return pathBuffer.data();
+
+    } while(path);
+
+    /* fell way off the end */
+    return nullptr;
+}
+
+U_NAMESPACE_END
+
+/* ==================================================================================*/
+
+
+/*----------------------------------------------------------------------*
+ *                                                                      *
+ *  Add a static reference to the common data library                   *
+ *   Unless overridden by an explicit udata_setCommonData, this will be *
+ *      our common data.                                                *
+ *                                                                      *
+ *----------------------------------------------------------------------*/
+#if !defined(ICU_DATA_DIR_WINDOWS)
+// When using the Windows system data, we expect only a single data file.
+extern "C" const DataHeader U_DATA_API U_ICUDATA_ENTRY_POINT;
+#endif
+
+/*
+ * This would be a good place for weak-linkage declarations of
+ * partial-data-library access functions where each returns a pointer
+ * to its data package, if it is linked in.
+ */
+/*
+extern const void *uprv_getICUData_collation() ATTRIBUTE_WEAK;
+extern const void *uprv_getICUData_conversion() ATTRIBUTE_WEAK;
+*/
+
+/*----------------------------------------------------------------------*
+ *                                                                      *
+ *   openCommonData   Attempt to open a common format (.dat) file       *
+ *                    Map it into memory (if it's not there already)    *
+ *                    and return a UDataMemory object for it.           *
+ *                                                                      *
+ *                    If the requested data is already open and cached  *
+ *                       just return the cached UDataMem object.        *
+ *                                                                      *
+ *----------------------------------------------------------------------*/
+static UDataMemory *
+openCommonData(const char *path,          /*  Path from OpenChoice?          */
+               int32_t commonDataIndex,   /*  ICU Data (index >= 0) if path == nullptr */
+               UErrorCode *pErrorCode)
+{
+    UDataMemory tData;
+    const char *pathBuffer;
+    const char *inBasename;
+
+    if (U_FAILURE(*pErrorCode)) {
+        return nullptr;
+    }
+
+    UDataMemory_init(&tData);
+
+    /* ??????? TODO revisit this */ 
+    if (commonDataIndex >= 0) {
+        /* "mini-cache" for common ICU data */
+        if(commonDataIndex >= UPRV_LENGTHOF(gCommonICUDataArray)) {
+            return nullptr;
+        }
+        {
+            Mutex lock;
+            if(gCommonICUDataArray[commonDataIndex] != nullptr) {
+                return gCommonICUDataArray[commonDataIndex];
+            }
+#if !defined(ICU_DATA_DIR_WINDOWS)
+// When using the Windows system data, we expect only a single data file.
+            int32_t i;
+            for(i = 0; i < commonDataIndex; ++i) {
+                if(gCommonICUDataArray[i]->pHeader == &U_ICUDATA_ENTRY_POINT) {
+                    /* The linked-in data is already in the list. */
+                    return nullptr;
+                }
+            }
+#endif
+        }
+
+        /* Add the linked-in data to the list. */
+        /*
+         * This is where we would check and call weakly linked partial-data-library
+         * access functions.
+         */
+        /*
+        if (uprv_getICUData_collation) {
+            setCommonICUDataPointer(uprv_getICUData_collation(), false, pErrorCode);
+        }
+        if (uprv_getICUData_conversion) {
+            setCommonICUDataPointer(uprv_getICUData_conversion(), false, pErrorCode);
+        }
+        */
+#if !defined(ICU_DATA_DIR_WINDOWS)
+// When using the Windows system data, we expect only a single data file.
+        setCommonICUDataPointer(&U_ICUDATA_ENTRY_POINT, false, pErrorCode);
+        {
+            Mutex lock;
+            return gCommonICUDataArray[commonDataIndex];
+        }
+#endif
+    }
+
+
+    /* request is NOT for ICU Data.  */
+
+    /* Find the base name portion of the supplied path.   */
+    /*   inBasename will be left pointing somewhere within the original path string.      */
+    inBasename = findBasename(path);
+#ifdef UDATA_DEBUG
+    fprintf(stderr, "inBasename = %s\n", inBasename);
+#endif
+
+    if(*inBasename==0) {
+        /* no basename.     This will happen if the original path was a directory name,   */
+        /*    like  "a/b/c/".   (Fallback to separate files will still work.)             */
+#ifdef UDATA_DEBUG
+        fprintf(stderr, "ocd: no basename in %s, bailing.\n", path);
+#endif
+        if (U_SUCCESS(*pErrorCode)) {
+            *pErrorCode=U_FILE_ACCESS_ERROR;
+        }
+        return nullptr;
+    }
+
+   /* Is the requested common data file already open and cached?                     */
+   /*   Note that the cache is keyed by the base name only.  The rest of the path,   */
+   /*     if any, is not considered.                                                 */
+    UDataMemory  *dataToReturn = udata_findCachedData(inBasename, *pErrorCode);
+    if (dataToReturn != nullptr || U_FAILURE(*pErrorCode)) {
+        return dataToReturn;
+    }
+
+    /* Requested item is not in the cache.
+     * Hunt it down, trying all the path locations
+     */
+
+    UDataPathIterator iter(u_getDataDirectory(), inBasename, path, ".dat", true, pErrorCode);
+
+    while ((UDataMemory_isLoaded(&tData)==false) && (pathBuffer = iter.next(pErrorCode)) != nullptr)
+    {
+#ifdef UDATA_DEBUG
+        fprintf(stderr, "ocd: trying path %s - ", pathBuffer);
+#endif
+        uprv_mapFile(&tData, pathBuffer, pErrorCode);
+#ifdef UDATA_DEBUG
+        fprintf(stderr, "%s\n", UDataMemory_isLoaded(&tData)?"LOADED":"not loaded");
+#endif
+    }
+    if (U_FAILURE(*pErrorCode)) {
+        return nullptr;
+    }
+
+#if defined(OS390_STUBDATA) && defined(OS390BATCH)
+    if (!UDataMemory_isLoaded(&tData)) {
+        char ourPathBuffer[1024];
+        /* One more chance, for extendCommonData() */
+        uprv_strncpy(ourPathBuffer, path, 1019);
+        ourPathBuffer[1019]=0;
+        uprv_strcat(ourPathBuffer, ".dat");
+        uprv_mapFile(&tData, ourPathBuffer, pErrorCode);
+    }
+#endif
+
+    if (U_FAILURE(*pErrorCode)) {
+        return nullptr;
+    }
+    if (!UDataMemory_isLoaded(&tData)) {
+        /* no common data */
+        *pErrorCode=U_FILE_ACCESS_ERROR;
+        return nullptr;
+    }
+
+    /* we have mapped a file, check its header */
+    udata_checkCommonData(&tData, pErrorCode);
+
+
+    /* Cache the UDataMemory struct for this .dat file,
+     *   so we won't need to hunt it down and map it again next time
+     *   something is needed from it.                */
+    return udata_cacheDataItem(inBasename, &tData, pErrorCode);
+}
+
+
+/*----------------------------------------------------------------------*
+ *                                                                      *
+ *   extendICUData   If the full set of ICU data was not loaded at      *
+ *                   program startup, load it now.  This function will  *
+ *                   be called when the lookup of an ICU data item in   *
+ *                   the common ICU data fails.                         *
+ *                                                                      *
+ *                   return true if new data is loaded, false otherwise.*
+ *                                                                      *
+ *----------------------------------------------------------------------*/
+static UBool extendICUData(UErrorCode *pErr)
+{
+    UDataMemory   *pData;
+    UDataMemory   copyPData;
+    UBool         didUpdate = false;
+
+    /*
+     * There is a chance for a race condition here.
+     * Normally, ICU data is loaded from a DLL or via mmap() and
+     * setCommonICUData() will detect if the same address is set twice.
+     * If ICU is built with data loading via fread() then the address will
+     * be different each time the common data is loaded and we may add
+     * multiple copies of the data.
+     * In this case, use a mutex to prevent the race.
+     * Use a specific mutex to avoid nested locks of the global mutex.
+     */
+#if MAP_IMPLEMENTATION==MAP_STDIO
+    static UMutex extendICUDataMutex;
+    umtx_lock(&extendICUDataMutex);
+#endif
+    if(!umtx_loadAcquire(gHaveTriedToLoadCommonData)) {
+        /* See if we can explicitly open a .dat file for the ICUData. */
+        pData = openCommonData(
+                   U_ICUDATA_NAME,            /*  "icudt20l" , for example.          */
+                   -1,                        /*  Pretend we're not opening ICUData  */
+                   pErr);
+
+        /* How about if there is no pData, eh... */
+
+       UDataMemory_init(&copyPData);
+       if(pData != nullptr) {
+          UDatamemory_assign(&copyPData, pData);
+          copyPData.map = 0;              /* The mapping for this data is owned by the hash table */
+          copyPData.mapAddr = 0;          /*   which will unmap it when ICU is shut down.         */
+                                          /* CommonICUData is also unmapped when ICU is shut down.*/
+                                          /* To avoid unmapping the data twice, zero out the map  */
+                                          /*   fields in the UDataMemory that we're assigning     */
+                                          /*   to CommonICUData.                                  */
+
+          didUpdate = /* no longer using this result */
+              setCommonICUData(&copyPData,/*  The new common data.                                */
+                       false,             /*  No warnings if write didn't happen                  */
+                       pErr);             /*  setCommonICUData honors errors; NOP if error set    */
+        }
+
+        umtx_storeRelease(gHaveTriedToLoadCommonData, 1);
+    }
+
+    didUpdate = findCommonICUDataByName(U_ICUDATA_NAME, *pErr);  /* Return 'true' when a racing writes out the extended                 */
+                                                          /* data after another thread has failed to see it (in openCommonData), so     */
+                                                          /* extended data can be examined.                                             */
+                                                          /* Also handles a race through here before gHaveTriedToLoadCommonData is set. */
+
+#if MAP_IMPLEMENTATION==MAP_STDIO
+    umtx_unlock(&extendICUDataMutex);
+#endif
+    return didUpdate;               /* Return true if ICUData pointer was updated.   */
+                                    /*   (Could potentially have been done by another thread racing */
+                                    /*   us through here, but that's fine, we still return true    */
+                                    /*   so that current thread will also examine extended data.   */
+}
+
+/*----------------------------------------------------------------------*
+ *                                                                      *
+ *   udata_setCommonData                                                *
+ *                                                                      *
+ *----------------------------------------------------------------------*/
+U_CAPI void U_EXPORT2
+udata_setCommonData(const void *data, UErrorCode *pErrorCode) {
+    UDataMemory dataMemory;
+
+    if(pErrorCode==nullptr || U_FAILURE(*pErrorCode)) {
+        return;
+    }
+
+    if(data==nullptr) {
+        *pErrorCode=U_ILLEGAL_ARGUMENT_ERROR;
+        return;
+    }
+
+    /* set the data pointer and test for validity */
+    UDataMemory_init(&dataMemory);
+    UDataMemory_setData(&dataMemory, data);
+    udata_checkCommonData(&dataMemory, pErrorCode);
+    if (U_FAILURE(*pErrorCode)) {return;}
+
+    /* we have good data */
+    /* Set it up as the ICU Common Data.  */
+    setCommonICUData(&dataMemory, true, pErrorCode);
+}
+
+/*---------------------------------------------------------------------------
+ *
+ *  udata_setAppData
+ *
+ *---------------------------------------------------------------------------- */
+U_CAPI void U_EXPORT2
+udata_setAppData(const char *path, const void *data, UErrorCode *err)
+{
+    UDataMemory     udm;
+
+    if(err==nullptr || U_FAILURE(*err)) {
+        return;
+    }
+    if(data==nullptr) {
+        *err=U_ILLEGAL_ARGUMENT_ERROR;
+        return;
+    }
+
+    UDataMemory_init(&udm);
+    UDataMemory_setData(&udm, data);
+    udata_checkCommonData(&udm, err);
+    udata_cacheDataItem(path, &udm, err);
+}
+
+/*----------------------------------------------------------------------------*
+ *                                                                            *
+ *  checkDataItem     Given a freshly located/loaded data item, either        *
+ *                    an entry in a common file or a separately loaded file,  *
+ *                    sanity check its header, and see if the data is         *
+ *                    acceptable to the app.                                  *
+ *                    If the data is good, create and return a UDataMemory    *
+ *                    object that can be returned to the application.         *
+ *                    Return nullptr on any sort of failure.                     *
+ *                                                                            *
+ *----------------------------------------------------------------------------*/
+static UDataMemory *
+checkDataItem
+(
+ const DataHeader         *pHeader,         /* The data item to be checked.                */
+ UDataMemoryIsAcceptable  *isAcceptable,    /* App's call-back function                    */
+ void                     *context,         /*   pass-thru param for above.                */
+ const char               *type,            /*   pass-thru param for above.                */
+ const char               *name,            /*   pass-thru param for above.                */
+ UErrorCode               *nonFatalErr,     /* Error code if this data was not acceptable  */
+                                            /*   but openChoice should continue with       */
+                                            /*   trying to get data from fallback path.    */
+ UErrorCode               *fatalErr         /* Bad error, caller should return immediately */
+ )
+{
+    UDataMemory  *rDataMem = nullptr;          /* the new UDataMemory, to be returned.        */
+
+    if (U_FAILURE(*fatalErr)) {
+        return nullptr;
+    }
+
+    if(pHeader->dataHeader.magic1==0xda &&
+        pHeader->dataHeader.magic2==0x27 &&
+        (isAcceptable==nullptr || isAcceptable(context, type, name, &pHeader->info))
+    ) {
+        rDataMem=UDataMemory_createNewInstance(fatalErr);
+        if (U_FAILURE(*fatalErr)) {
+            return nullptr;
+        }
+        rDataMem->pHeader = pHeader;
+    } else {
+        /* the data is not acceptable, look further */
+        /* If we eventually find something good, this errorcode will be */
+        /*    cleared out.                                              */
+        *nonFatalErr=U_INVALID_FORMAT_ERROR;
+    }
+    return rDataMem;
+}
+
+/**
+ * @return 0 if not loaded, 1 if loaded or err 
+ */
+static UDataMemory *doLoadFromIndividualFiles(const char *pkgName, 
+        const char *dataPath, const char *tocEntryPathSuffix,
+            /* following arguments are the same as doOpenChoice itself */
+            const char *path, const char *type, const char *name,
+             UDataMemoryIsAcceptable *isAcceptable, void *context,
+             UErrorCode *subErrorCode,
+             UErrorCode *pErrorCode)
+{
+    const char         *pathBuffer;
+    UDataMemory         dataMemory;
+    UDataMemory *pEntryData;
+
+    /* look in ind. files: package\nam.typ  ========================= */
+    /* init path iterator for individual files */
+    UDataPathIterator iter(dataPath, pkgName, path, tocEntryPathSuffix, false, pErrorCode);
+
+    while ((pathBuffer = iter.next(pErrorCode)) != nullptr)
+    {
+#ifdef UDATA_DEBUG
+        fprintf(stderr, "UDATA: trying individual file %s\n", pathBuffer);
+#endif
+        if (uprv_mapFile(&dataMemory, pathBuffer, pErrorCode))
+        {
+            pEntryData = checkDataItem(dataMemory.pHeader, isAcceptable, context, type, name, subErrorCode, pErrorCode);
+            if (pEntryData != nullptr) {
+                /* Data is good.
+                *  Hand off ownership of the backing memory to the user's UDataMemory.
+                *  and return it.   */
+                pEntryData->mapAddr = dataMemory.mapAddr;
+                pEntryData->map     = dataMemory.map;
+
+#ifdef UDATA_DEBUG
+                fprintf(stderr, "** Mapped file: %s\n", pathBuffer);
+#endif
+                return pEntryData;
+            }
+
+            /* the data is not acceptable, or some error occurred.  Either way, unmap the memory */
+            udata_close(&dataMemory);
+
+            /* If we had a nasty error, bail out completely.  */
+            if (U_FAILURE(*pErrorCode)) {
+                return nullptr;
+            }
+
+            /* Otherwise remember that we found data but didn't like it for some reason  */
+            *subErrorCode=U_INVALID_FORMAT_ERROR;
+        }
+#ifdef UDATA_DEBUG
+        fprintf(stderr, "%s\n", UDataMemory_isLoaded(&dataMemory)?"LOADED":"not loaded");
+#endif
+    }
+    return nullptr;
+}
+
+/**
+ * @return 0 if not loaded, 1 if loaded or err 
+ */
+static UDataMemory *doLoadFromCommonData(UBool isICUData, const char * /*pkgName*/, 
+        const char * /*dataPath*/, const char * /*tocEntryPathSuffix*/, const char *tocEntryName,
+            /* following arguments are the same as doOpenChoice itself */
+            const char *path, const char *type, const char *name,
+             UDataMemoryIsAcceptable *isAcceptable, void *context,
+             UErrorCode *subErrorCode,
+             UErrorCode *pErrorCode)
+{
+    UDataMemory        *pEntryData;
+    const DataHeader   *pHeader;
+    UDataMemory        *pCommonData;
+    int32_t            commonDataIndex;
+    UBool              checkedExtendedICUData = false;
+    /* try to get common data.  The loop is for platforms such as the 390 that do
+     *  not initially load the full set of ICU data.  If the lookup of an ICU data item
+     *  fails, the full (but slower to load) set is loaded, the and the loop repeats,
+     *  trying the lookup again.  Once the full set of ICU data is loaded, the loop wont
+     *  repeat because the full set will be checked the first time through.
+     *
+     *  The loop also handles the fallback to a .dat file if the application linked
+     *   to the stub data library rather than a real library.
+     */
+    for (commonDataIndex = isICUData ? 0 : -1;;) {
+        pCommonData=openCommonData(path, commonDataIndex, subErrorCode); /** search for pkg **/
+
+        if(U_SUCCESS(*subErrorCode) && pCommonData!=nullptr) {
+            int32_t length;
+
+            /* look up the data piece in the common data */
+            pHeader=pCommonData->vFuncs->Lookup(pCommonData, tocEntryName, &length, subErrorCode);
+#ifdef UDATA_DEBUG
+            fprintf(stderr, "%s: pHeader=%p - %s\n", tocEntryName, (void*) pHeader, u_errorName(*subErrorCode));
+#endif
+
+            if(pHeader!=nullptr) {
+                pEntryData = checkDataItem(pHeader, isAcceptable, context, type, name, subErrorCode, pErrorCode);
+#ifdef UDATA_DEBUG
+                fprintf(stderr, "pEntryData=%p\n", (void*) pEntryData);
+#endif
+                if (U_FAILURE(*pErrorCode)) {
+                    return nullptr;
+                }
+                if (pEntryData != nullptr) {
+                    pEntryData->length = length;
+                    return pEntryData;
+                }
+            }
+        }
+        // If we failed due to being out-of-memory, then stop early and report the error.
+        if (*subErrorCode == U_MEMORY_ALLOCATION_ERROR) {
+            *pErrorCode = *subErrorCode;
+            return nullptr;
+        }
+        /* Data wasn't found.  If we were looking for an ICUData item and there is
+         * more data available, load it and try again,
+         * otherwise break out of this loop. */
+        if (!isICUData) {
+            return nullptr;
+        } else if (pCommonData != nullptr) {
+            ++commonDataIndex;  /* try the next data package */
+        } else if ((!checkedExtendedICUData) && extendICUData(subErrorCode)) {
+            checkedExtendedICUData = true;
+            /* try this data package slot again: it changed from nullptr to non-nullptr */
+        } else {
+            return nullptr;
+        }
+    }
+}
+
+/*
+ * Identify the Time Zone resources that are subject to special override data loading.
+ */
+static UBool isTimeZoneFile(const char *name, const char *type) {
+    return ((uprv_strcmp(type, "res") == 0) &&
+            (uprv_strcmp(name, "zoneinfo64") == 0 ||
+             uprv_strcmp(name, "timezoneTypes") == 0 ||
+             uprv_strcmp(name, "windowsZones") == 0 ||
+             uprv_strcmp(name, "metaZones") == 0));
+}
+
+/*
+ *  A note on the ownership of Mapped Memory
+ *
+ *  For common format files, ownership resides with the UDataMemory object
+ *    that lives in the cache of opened common data.  These UDataMemorys are private
+ *    to the udata implementation, and are never seen directly by users.
+ *
+ *    The UDataMemory objects returned to users will have the address of some desired
+ *    data within the mapped region, but they wont have the mapping info itself, and thus
+ *    won't cause anything to be removed from memory when they are closed.
+ *
+ *  For individual data files, the UDataMemory returned to the user holds the
+ *  information necessary to unmap the data on close.  If the user independently
+ *  opens the same data file twice, two completely independent mappings will be made.
+ *  (There is no cache of opened data items from individual files, only a cache of
+ *   opened Common Data files, that is, files containing a collection of data items.)
+ *
+ *  For common data passed in from the user via udata_setAppData() or
+ *  udata_setCommonData(), ownership remains with the user.
+ *
+ *  UDataMemory objects themselves, as opposed to the memory they describe,
+ *  can be anywhere - heap, stack/local or global.
+ *  They have a flag to indicate when they're heap allocated and thus
+ *  must be deleted when closed.
+ */
+
+
+/*----------------------------------------------------------------------------*
+ *                                                                            *
+ * main data loading functions                                                *
+ *                                                                            *
+ *----------------------------------------------------------------------------*/
+static UDataMemory *
+doOpenChoice(const char *path, const char *type, const char *name,
+             UDataMemoryIsAcceptable *isAcceptable, void *context,
+             UErrorCode *pErrorCode)
+{
+    UDataMemory         *retVal = nullptr;
+
+    const char         *dataPath;
+
+    int32_t             tocEntrySuffixIndex;
+    const char         *tocEntryPathSuffix;
+    UErrorCode          subErrorCode=U_ZERO_ERROR;
+    const char         *treeChar;
+
+    UBool               isICUData = false;
+
+
+    FileTracer::traceOpen(path, type, name);
+
+
+    /* Is this path ICU data? */
+    if(path == nullptr ||
+       !strcmp(path, U_ICUDATA_ALIAS) ||  /* "ICUDATA" */
+       !uprv_strncmp(path, U_ICUDATA_NAME U_TREE_SEPARATOR_STRING, /* "icudt26e-" */
+                     uprv_strlen(U_ICUDATA_NAME U_TREE_SEPARATOR_STRING)) ||  
+       !uprv_strncmp(path, U_ICUDATA_ALIAS U_TREE_SEPARATOR_STRING, /* "ICUDATA-" */
+                     uprv_strlen(U_ICUDATA_ALIAS U_TREE_SEPARATOR_STRING))) {
+      isICUData = true;
+    }
+
+#if (U_FILE_SEP_CHAR != U_FILE_ALT_SEP_CHAR)  /* Windows:  try "foo\bar" and "foo/bar" */
+    /* remap from alternate path char to the main one */
+    CharString altSepPath;
+    if(path) {
+        if(uprv_strchr(path,U_FILE_ALT_SEP_CHAR) != nullptr) {
+            altSepPath.append(path, *pErrorCode);
+            char *p;
+            while ((p = uprv_strchr(altSepPath.data(), U_FILE_ALT_SEP_CHAR)) != nullptr) {
+                *p = U_FILE_SEP_CHAR;
+            }
+#if defined (UDATA_DEBUG)
+            fprintf(stderr, "Changed path from [%s] to [%s]\n", path, altSepPath.s);
+#endif
+            path = altSepPath.data();
+        }
+    }
+#endif
+
+    CharString tocEntryName; /* entry name in tree format. ex:  'icudt28b/coll/ar.res' */
+    CharString tocEntryPath; /* entry name in path format. ex:  'icudt28b\\coll\\ar.res' */
+
+    CharString pkgName;
+    CharString treeName;
+
+    /* ======= Set up strings */
+    if(path==nullptr) {
+        pkgName.append(U_ICUDATA_NAME, *pErrorCode);
+    } else {
+        const char *pkg;
+        const char *first;
+        pkg = uprv_strrchr(path, U_FILE_SEP_CHAR);
+        first = uprv_strchr(path, U_FILE_SEP_CHAR);
+        if(uprv_pathIsAbsolute(path) || (pkg != first)) { /* more than one slash in the path- not a tree name */
+            /* see if this is an /absolute/path/to/package  path */
+            if(pkg) {
+                pkgName.append(pkg+1, *pErrorCode);
+            } else {
+                pkgName.append(path, *pErrorCode);
+            }
+        } else {
+            treeChar = uprv_strchr(path, U_TREE_SEPARATOR);
+            if(treeChar) { 
+                treeName.append(treeChar+1, *pErrorCode); /* following '-' */
+                if(isICUData) {
+                    pkgName.append(U_ICUDATA_NAME, *pErrorCode);
+                } else {
+                    pkgName.append(path, (int32_t)(treeChar-path), *pErrorCode);
+                    if (first == nullptr) {
+                        /*
+                        This user data has no path, but there is a tree name.
+                        Look up the correct path from the data cache later.
+                        */
+                        path = pkgName.data();
+                    }
+                }
+            } else {
+                if(isICUData) {
+                    pkgName.append(U_ICUDATA_NAME, *pErrorCode);
+                } else {
+                    pkgName.append(path, *pErrorCode);
+                }
+            }
+        }
+    }
+
+#ifdef UDATA_DEBUG
+    fprintf(stderr, " P=%s T=%s\n", pkgName.data(), treeName.data());
+#endif
+
+    /* setting up the entry name and file name 
+     * Make up a full name by appending the type to the supplied
+     *  name, assuming that a type was supplied.
+     */
+
+    /* prepend the package */
+    tocEntryName.append(pkgName, *pErrorCode);
+    tocEntryPath.append(pkgName, *pErrorCode);
+    tocEntrySuffixIndex = tocEntryName.length();
+
+    if(!treeName.isEmpty()) {
+        tocEntryName.append(U_TREE_ENTRY_SEP_CHAR, *pErrorCode).append(treeName, *pErrorCode);
+        tocEntryPath.append(U_FILE_SEP_CHAR, *pErrorCode).append(treeName, *pErrorCode);
+    }
+
+    tocEntryName.append(U_TREE_ENTRY_SEP_CHAR, *pErrorCode).append(name, *pErrorCode);
+    tocEntryPath.append(U_FILE_SEP_CHAR, *pErrorCode).append(name, *pErrorCode);
+    if(type!=nullptr && *type!=0) {
+        tocEntryName.append(".", *pErrorCode).append(type, *pErrorCode);
+        tocEntryPath.append(".", *pErrorCode).append(type, *pErrorCode);
+    }
+    // The +1 is for the U_FILE_SEP_CHAR that is always appended above.
+    tocEntryPathSuffix = tocEntryPath.data() + tocEntrySuffixIndex + 1; /* suffix starts here */
+
+#ifdef UDATA_DEBUG
+    fprintf(stderr, " tocEntryName = %s\n", tocEntryName.data());
+    fprintf(stderr, " tocEntryPath = %s\n", tocEntryName.data());
+#endif
+
+#if !defined(ICU_DATA_DIR_WINDOWS)
+    if(path == nullptr) {
+        path = COMMON_DATA_NAME; /* "icudt26e" */
+    }
+#else
+    // When using the Windows system data, we expects only a single data file.
+    path = COMMON_DATA_NAME; /* "icudt26e" */
+#endif
+
+    /************************ Begin loop looking for ind. files ***************/
+#ifdef UDATA_DEBUG
+    fprintf(stderr, "IND: inBasename = %s, pkg=%s\n", "(n/a)", packageNameFromPath(path));
+#endif
+
+    /* End of dealing with a null basename */
+    dataPath = u_getDataDirectory();
+
+    /****    Time zone individual files override  */
+    if (isICUData && isTimeZoneFile(name, type)) {
+        const char *tzFilesDir = u_getTimeZoneFilesDirectory(pErrorCode);
+        if (tzFilesDir[0] != 0) {
+#ifdef UDATA_DEBUG
+            fprintf(stderr, "Trying Time Zone Files directory = %s\n", tzFilesDir);
+#endif
+            retVal = doLoadFromIndividualFiles(/* pkgName.data() */ "", tzFilesDir, tocEntryPathSuffix,
+                            /* path */ "", type, name, isAcceptable, context, &subErrorCode, pErrorCode);
+            if((retVal != nullptr) || U_FAILURE(*pErrorCode)) {
+                return retVal;
+            }
+        }
+    }
+
+    /****    COMMON PACKAGE  - only if packages are first. */
+    if(gDataFileAccess == UDATA_PACKAGES_FIRST) {
+#ifdef UDATA_DEBUG
+        fprintf(stderr, "Trying packages (UDATA_PACKAGES_FIRST)\n");
+#endif
+        /* #2 */
+        retVal = doLoadFromCommonData(isICUData, 
+                            pkgName.data(), dataPath, tocEntryPathSuffix, tocEntryName.data(),
+                            path, type, name, isAcceptable, context, &subErrorCode, pErrorCode);
+        if((retVal != nullptr) || U_FAILURE(*pErrorCode)) {
+            return retVal;
+        }
+    }
+
+    /****    INDIVIDUAL FILES  */
+    if((gDataFileAccess==UDATA_PACKAGES_FIRST) ||
+       (gDataFileAccess==UDATA_FILES_FIRST)) {
+#ifdef UDATA_DEBUG
+        fprintf(stderr, "Trying individual files\n");
+#endif
+        /* Check to make sure that there is a dataPath to iterate over */
+        if ((dataPath && *dataPath) || !isICUData) {
+            retVal = doLoadFromIndividualFiles(pkgName.data(), dataPath, tocEntryPathSuffix,
+                            path, type, name, isAcceptable, context, &subErrorCode, pErrorCode);
+            if((retVal != nullptr) || U_FAILURE(*pErrorCode)) {
+                return retVal;
+            }
+        }
+    }
+
+    /****    COMMON PACKAGE  */
+    if((gDataFileAccess==UDATA_ONLY_PACKAGES) || 
+       (gDataFileAccess==UDATA_FILES_FIRST)) {
+#ifdef UDATA_DEBUG
+        fprintf(stderr, "Trying packages (UDATA_ONLY_PACKAGES || UDATA_FILES_FIRST)\n");
+#endif
+        retVal = doLoadFromCommonData(isICUData,
+                            pkgName.data(), dataPath, tocEntryPathSuffix, tocEntryName.data(),
+                            path, type, name, isAcceptable, context, &subErrorCode, pErrorCode);
+        if((retVal != nullptr) || U_FAILURE(*pErrorCode)) {
+            return retVal;
+        }
+    }
+    
+    /* Load from DLL.  If we haven't attempted package load, we also haven't had any chance to
+        try a DLL (static or setCommonData/etc)  load.
+         If we ever have a "UDATA_ONLY_FILES", add it to the or list here.  */  
+    if(gDataFileAccess==UDATA_NO_FILES) {
+#ifdef UDATA_DEBUG
+        fprintf(stderr, "Trying common data (UDATA_NO_FILES)\n");
+#endif
+        retVal = doLoadFromCommonData(isICUData,
+                            pkgName.data(), "", tocEntryPathSuffix, tocEntryName.data(),
+                            path, type, name, isAcceptable, context, &subErrorCode, pErrorCode);
+        if((retVal != nullptr) || U_FAILURE(*pErrorCode)) {
+            return retVal;
+        }
+    }
+
+    /* data not found */
+    if(U_SUCCESS(*pErrorCode)) {
+        if(U_SUCCESS(subErrorCode)) {
+            /* file not found */
+            *pErrorCode=U_FILE_ACCESS_ERROR;
+        } else {
+            /* entry point not found or rejected */
+            *pErrorCode=subErrorCode;
+        }
+    }
+    return retVal;
+}
+
+
+
+/* API ---------------------------------------------------------------------- */
+
+U_CAPI UDataMemory * U_EXPORT2
+udata_open(const char *path, const char *type, const char *name,
+           UErrorCode *pErrorCode) {
+#ifdef UDATA_DEBUG
+  fprintf(stderr, "udata_open(): Opening: %s : %s . %s\n", (path?path:"nullptr"), name, type);
+    fflush(stderr);
+#endif
+
+    if(pErrorCode==nullptr || U_FAILURE(*pErrorCode)) {
+        return nullptr;
+    } else if(name==nullptr || *name==0) {
+        *pErrorCode=U_ILLEGAL_ARGUMENT_ERROR;
+        return nullptr;
+    } else {
+        return doOpenChoice(path, type, name, nullptr, nullptr, pErrorCode);
+    }
+}
+
+
+
+U_CAPI UDataMemory * U_EXPORT2
+udata_openChoice(const char *path, const char *type, const char *name,
+                 UDataMemoryIsAcceptable *isAcceptable, void *context,
+                 UErrorCode *pErrorCode) {
+#ifdef UDATA_DEBUG
+  fprintf(stderr, "udata_openChoice(): Opening: %s : %s . %s\n", (path?path:"nullptr"), name, type);
+#endif
+
+    if(pErrorCode==nullptr || U_FAILURE(*pErrorCode)) {
+        return nullptr;
+    } else if(name==nullptr || *name==0 || isAcceptable==nullptr) {
+        *pErrorCode=U_ILLEGAL_ARGUMENT_ERROR;
+        return nullptr;
+    } else {
+        return doOpenChoice(path, type, name, isAcceptable, context, pErrorCode);
+    }
+}
+
+
+
+U_CAPI void U_EXPORT2
+udata_getInfo(UDataMemory *pData, UDataInfo *pInfo) {
+    if(pInfo!=nullptr) {
+        if(pData!=nullptr && pData->pHeader!=nullptr) {
+            const UDataInfo *info=&pData->pHeader->info;
+            uint16_t dataInfoSize=udata_getInfoSize(info);
+            if(pInfo->size>dataInfoSize) {
+                pInfo->size=dataInfoSize;
+            }
+            uprv_memcpy((uint16_t *)pInfo+1, (const uint16_t *)info+1, pInfo->size-2);
+            if(info->isBigEndian!=U_IS_BIG_ENDIAN) {
+                /* opposite endianness */
+                uint16_t x=info->reservedWord;
+                pInfo->reservedWord=(uint16_t)((x<<8)|(x>>8));
+            }
+        } else {
+            pInfo->size=0;
+        }
+    }
+}
+
+
+U_CAPI void U_EXPORT2 udata_setFileAccess(UDataFileAccess access, UErrorCode * /*status*/)
+{
+    // Note: this function is documented as not thread safe.
+    gDataFileAccess = access;
+}