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scsidump: Allow to start at a specific offset #1633

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Merged
rdmark merged 1 commit into from
Jan 6, 2026
Merged

scsidump: Allow to start at a specific offset #1633

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27 changes: 19 additions & 8 deletions cpp/scsidump/scsidump_core.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -93,7 +93,7 @@ void ScsiDump::ParseArguments(span<char *> args)
int buffer_size = DEFAULT_BUFFER_SIZE;

opterr = 0;
while ((opt = getopt(static_cast<int>(args.size()), args.data(), "i:f:s:t:rvpIS")) != -1) {
while ((opt = getopt(static_cast<int>(args.size()), args.data(), "i:f:o:s:t:rvpIS")) != -1) {
switch (opt) {
case 'i':
if (!GetAsUnsignedInt(optarg, initiator_id) || initiator_id > 7) {
Expand All @@ -116,6 +116,10 @@ void ScsiDump::ParseArguments(span<char *> args)

break;

case 'o':
start_sector = static_cast<uint64_t>(strtoull(optarg, NULL, 0));
break;

case 'S':
scan_bus = true;
break;
Expand Down Expand Up @@ -549,8 +553,18 @@ int ScsiDump::DumpRestore()
return EXIT_FAILURE;
}

// Dump by buffer size
auto dsiz = static_cast<int>(buffer.size());
const int duni = dsiz / inq_info.sector_size;
auto dnum = static_cast<int>((inq_info.capacity * inq_info.sector_size) / dsiz);

// Verify start sector.
if (start_sector % duni != 0) {
throw parser_exception("Start sector must be a multiple of " + to_string(duni) + " (= bufsize / sectsize)");
}

fstream fs;
fs.open(filename, (restore ? ios::in : ios::out) | ios::binary);
fs.open(filename, (restore ? ios::in : ios::out) | ios::binary | ios::app);

if (fs.fail()) {
throw parser_exception("Can't open image file '" + filename + "'");
Expand All @@ -573,19 +587,16 @@ int ScsiDump::DumpRestore()
} else if (size < (off_t)(inq_info.sector_size * inq_info.capacity)) {
throw parser_exception("File size is smaller than disk size");
}
fs.seekg(start_sector * inq_info.sector_size);
} else {
fs.seekp(start_sector * inq_info.sector_size);
cout << "Starting dump\n" << flush;
}

// Dump by buffer size
auto dsiz = static_cast<int>(buffer.size());
const int duni = dsiz / inq_info.sector_size;
auto dnum = static_cast<int>((inq_info.capacity * inq_info.sector_size) / dsiz);

const auto start_time = chrono::high_resolution_clock::now();

int i;
for (i = 0; i < dnum; i++) {
for (i = start_sector / duni; i < dnum; i++) {
if (restore) {
fs.read((char*)buffer.data(), dsiz);
Write10(i * duni, duni, dsiz);
Expand Down
2 changes: 2 additions & 0 deletions cpp/scsidump/scsidump_core.h
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Expand Up @@ -87,6 +87,8 @@ class ScsiDump

string filename;

uint64_t start_sector = 0;

bool inquiry = false;

bool scan_bus = false;
Expand Down
6 changes: 4 additions & 2 deletions doc/scsidump.1
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Expand Up @@ -33,6 +33,8 @@ If the generated drive image is intended to be used with PiSCSI, the drive image
Display INQUIRY data of ID[:LUN].
.It Fl i Ar BID
SCSI ID of the PiSCSI device. If not specified, the PiSCSI device will use ID 7. The PiSCSI host will be functioning as the "Initiator" device.
.It Fl o Ar offs
Use `offs` as the sector offset to start dumping. It must be aligned to the buffer size. Can be used to resume an aborted transfer from/to a somewhat broken device by specifying the last shown sector number.
.It Fl f Ar FILE
Path to the dump file.
.It Fl p
Expand All @@ -52,12 +54,12 @@ Enable verbose logging.
Dump Mode: [SCSI Drive] ---> [PiSCSI host]
.Pp
Launch scsidump to dump an all data from SCSI ID 3 with block size 64 KiB, store it to the local filesystem as a drive image named outimage.hda, and generate the outimage.hda.properties file with the drive's INQUIRY information:
.Dl Nm scsidump Fl t 3 Fl f ./outimage.hda Fl s 65536 Fl p
.Dl Nm scsidump -t 3 -f ./outimage.hda -s 65536 -p
.Pp
Restore Mode: [PiSCSI host] ---> [SCSI Drive]
.Pp
Launch scsidump to restore/upload a drive image from the local file system to SCSI ID 0 with block size 1MiB:
.Dl Nm scsidump Fl r Fl t 0 Fl f ./outimage.hda Fl s 1048576
.Dl Nm scsidump -r -t 0 -f ./outimage.hda -s 1048576
.Sh SEE ALSO
.Xr scsictl 1 ,
.Xr piscsi 1 ,
Expand Down