[BUG]: Filename shortening if file is created by imager

[paulober]

What happened?

Cloud-init network-config can't be created by imager only edited if already present in the imager because it would shorten the filename which results in an invalid filename for the cloud-init datasource.

Version

1.9.2 (Default)

What host operating system were you using?

Windows

Host OS Version

24H2

Selected OS

Raspberry Pi OS Bookworm Lite (64-bit)

Which Raspberry Pi Device are you using?

Raspberry Pi 5

What kind of storage device are you using?

microSD Card in a USB reader

OS Customisation

• Yes, I was using OS Customisation when the bug occurred.

Relevant log output

rpi-imager/src/devicewrapperfatpartition.cpp

Lines 402 to 483 in 879b89c

	if (createIfNotExist)
	{
	QByteArray shortFilename;
	uint8_t shortFileNameChecksum = 0;
	struct longfn_entry longEntry;
	if (longFilename.count(".") == 1)
	{
	QList<QByteArray> fnParts = longFilename.toLatin1().toUpper().split('.');
	shortFilename = fnParts[0].leftJustified(8, ' ', true)+fnParts[1].leftJustified(3, ' ', true);
	}
	else
	{
	shortFilename = longFilename.toLatin1().leftJustified(11, ' ', true);
	}
	/* Verify short file name has not been taken yet, and if not try inserting numbers into the name */
	if (dirNameExists(shortFilename))
	{
	for (int i=0; i<100; i++)
	{
	shortFilename = shortFilename.left( (i < 10 ? 7 : 6) )+QByteArray::number(i)+shortFilename.right(3);
	if (!dirNameExists(shortFilename))
	{
	break;
	}
	else if (i == 99)
	{
	throw std::runtime_error("Error finding available short filename");
	}
	}
	}
	for(int i = 0; i < shortFilename.length(); i++)
	{
	shortFileNameChecksum = ((shortFileNameChecksum & 1) ? 0x80 : 0) + (shortFileNameChecksum >> 1) + shortFilename[i];
	}
	QString longFilenameWithNull = longFilename + QChar::Null;
	char *longFilenameStr = (char *) longFilenameWithNull.data();
	int lfnFragments = (longFilenameWithNull.length()+12)/13;
	int lenBytes = longFilenameWithNull.length()*2;
	/* long file name directory entries are added in reverse order before the 8.3 entry */
	for (int i = lfnFragments; i > 0; i--)
	{
	memset(&longEntry, 0xff, sizeof(longEntry));
	longEntry.LDIR_Attr = ATTR_LONG_NAME;
	longEntry.LDIR_Chksum = shortFileNameChecksum;
	longEntry.LDIR_Ord = (i == lfnFragments) ? lfnFragments | LAST_LONG_ENTRY : lfnFragments;
	longEntry.LDIR_FstClusLO = 0;
	longEntry.LDIR_Type = 0;
	size_t start = (i-1) * 26;
	memcpy(longEntry.LDIR_Name1, longFilenameStr+start, qMin(lenBytes-start, sizeof(longEntry.LDIR_Name1)));
	start += sizeof(longEntry.LDIR_Name1);
	if (start < lenBytes)
	{
	memcpy(longEntry.LDIR_Name2, longFilenameStr+start, qMin(lenBytes-start, sizeof(longEntry.LDIR_Name2)));
	start += sizeof(longEntry.LDIR_Name2);
	if (start < lenBytes)
	{
	memcpy(longEntry.LDIR_Name3, longFilenameStr+start, qMin(lenBytes-start, sizeof(longEntry.LDIR_Name3)));
	}
	}
	writeDirEntryAtCurrentPos((struct dir_entry *) &longEntry);
	}
	memset(entry, 0, sizeof(*entry));
	memcpy(entry->DIR_Name, shortFilename.data(), sizeof(entry->DIR_Name));
	entry->DIR_Attr = ATTR_ARCHIVE;
	entry->DIR_CrtDate = QDateToFATdate( QDate::currentDate() );
	entry->DIR_CrtTime = QTimeToFATtime( QTime::currentTime() );
	writeDirEntryAtCurrentPos(entry);
	/* Add an end-of-directory marker after our newly appended file */
	struct dir_entry endOfDir = {0};
	writeDirEntryAtCurrentPos(&endOfDir);
	}

[paulober]

@tdewey-rpi Seems like it worked on other images because they already pre-created the modified files and therefore this part does not execute.

[lurch]

What filename is it supposed to have? What does it get shortened to?

[tdewey-rpi]

What filename is it supposed to have? What does it get shortened to?

In practice, we see Imager producing short filenames essentially all the time. This first manifested with user-data, and affects the default names for each of the cloud-init configuration files.

[maxnet]

In practice, we see Imager producing short filenames essentially all the time.

Pretty sure it did generate new files like "firstrun.sh" (lowercase) correctly in the past.
If storing long file name entries would not work at all, I would expect it to show up as FIRSTRUN.SH instead, as the 8.3 short name is stored in uppercase.