nodejs/node · error

U_INDEX_OUTOFBOUNDS_ERROR

U_INDEX_OUTOFBOUNDS_ERROR

Error message

icupkg: too few bytes (%ld after header) for a .dat package\n

What it means

Thrown by Package::readPackage() when the remaining data after the header (length - headerLength) is less than the computed minimum offset. The minimum offset is the larger of: the space needed for the item count int32, the full ToC table (4 + 8*itemCount bytes), or the last item's data offset plus 20 bytes for its header. This means the file is truncated relative to what its ToC claims.

Solutions

1. Verify file integrity: compare file size against expected size from the build system.
2. Re-download or rebuild the .dat file.
3. Check the file is not truncated: ls -l and compare against a known-good copy.
4. If modifying .dat files, use icupkg itself rather than manual binary editing.

// Verify file size is plausible for a .dat package
#include <sys/stat.h>
#include <fstream>
bool isPlausibleDatSize(const char* filename) {
    struct stat st;
    if (stat(filename, &st) != 0) return false;
    // A valid .dat must have at least a header + 4 bytes for item count
    if (st.st_size < 32) return false;
    // Read item count and check ToC plausibility
    std::ifstream f(filename, std::ios::binary);
    f.seekg(20); // approximate offset past header
    int32_t itemCount = 0;
    f.read(reinterpret_cast<char*>(&itemCount), 4);
    // ToC must fit: 4 + 8*itemCount < remaining file
    return itemCount >= 0 && (4 + 8 * static_cast<int64_t>(itemCount)) < st.st_size;
}

When it happens

Trigger: A .dat file whose header and ToC entries describe more data than the file actually contains. Specifically: length < 4 (no item count), or length < 4+8*itemCount (ToC table incomplete), or length < 20+lastItemDataOffset (last item header missing). The offset is set to 0x7fffffff (effectively infinite) when the ToC cannot fit, guaranteeing the check fails.

Common situations: Truncated .dat files from interrupted builds or incomplete downloads; corrupt ToC entries with inflated dataOffset values; manual editing of binary .dat files that changed the structure without updating offsets; filesystem corruption.

Related errors

• U_INVALID_FORMAT_ERROR
• U_UNSUPPORTED_ERROR
• 0
• errorCode
• icupkg: udata_openSwapper

AI-assisted analysis of nodejs/node@1b2de5e052 (2026-08-13). Data as JSON: /api/errors/6210f754771ca3b8. Report an issue: GitHub.

Appendix: source

Thrown at deps/icu-small/source/tools/toolutil/package.cpp:528

    length-=headerLength;
    if(length<4) {
        /* itemCount does not fit */
        offset=0x7fffffff;
    } else {
        itemCount = udata_readInt32(ds, *reinterpret_cast<const int32_t*>(inBytes));
        setItemCapacity(itemCount); /* resize so there's space */
        if(itemCount==0) {
            offset=4;
        } else if(length<(4+8*itemCount)) {
            /* ToC table does not fit */
            offset=0x7fffffff;
        } else {
            /* offset of the last item plus at least 20 bytes for its header */
            offset = 20 + static_cast<int32_t>(ds->readUInt32(inEntries[itemCount - 1].dataOffset));
        }
    }
    if(length<offset) {
        fprintf(stderr, "icupkg: too few bytes (%ld after header) for a .dat package\n",
                        static_cast<long>(length));
        exit(U_INDEX_OUTOFBOUNDS_ERROR);
    }
    /* do not modify the package length variable until the last item's length is set */

    if(itemCount<=0) {
        if(doAutoPrefix) {
            fprintf(stderr, "icupkg: --auto_toc_prefix[_with_type] but the input package is empty\n");
            exit(U_INVALID_FORMAT_ERROR);
        }
    } else {
        char prefix[MAX_PKG_NAME_LENGTH+4];
        char *s, *inItemStrings;

        if(itemCount>itemMax) {
            fprintf(stderr, "icupkg: too many items, maximum is %d\n", itemMax);
            exit(U_BUFFER_OVERFLOW_ERROR);
        }

View on GitHub (pinned to 1b2de5e052)