Install pipeline

Overview

All sources converge on the same install orchestrator (install.cpp):

1. Prepare - read CNMT NCAs, install content meta to NCM DB, push application record to NS
2. Begin - import tickets/certs via ES, stream each content NCA into storage

.nsz / .xcz are not decompressed as whole files - they use the same PFS0/HFS0 layout with .ncz entries instead of .nca.

install.cpp, install_nsp.cpp, install_xci.cpp

NSP / NSZ - PFS0 container

• Magic PFS0 (0x30534650)
• File table: PFS0BaseHeader + entries + string table
• NCA entries: {id}.nca, {id}.cnmt.nca, {id}.ncz, {id}.cnmt.ncz
• Ticket pairs: .tik + .cert → esImportTicket

Streaming (HTTP / USB)

Dual-thread pipeline in http_nsp.cpp / usb_nsp.cpp:

• Thread 1: HTTP/USB range read → BufferedPlaceholderWriter
• Thread 2: flush 8 MB segments → NcaWriter → NCM placeholder
• Ring buffer: 8 MB × 128 segments (2 in applet mode)

Per-NCA steps (NSPInstall::InstallNCA)

1. Delete stale placeholder
2. Optional RSA-PSS signature verify (validateNCAs)
3. Stream to placeholder via NcaWriter
4. Register placeholder → final NCA id
5. Delete placeholder; rollback on error

nsp.cpp, install_nsp.cpp, http_nsp.cpp, buffered_placeholder_writer.cpp

XCI / XCZ - HFS0 container

• Root HFS0 at offset 0xF000 or 0x10000, magic HFS0 (0x30534648)
• secure partition holds NCAs, tickets, certs
• Same Prepare/Begin flow as NSP but reads HFS0 entries

Streaming differences

• HTTP XCI: 4 MB chunks, NcaWriter direct (no ring buffer) - http_xci.cpp
• SD/USB XCI: same as local NSP pattern via sdmc_xci.cpp

xci.cpp, install_xci.cpp, http_xci.cpp

NCZ decompression (.nsz / .xcz inner NCAs)

Handled inside NcaWriter / nca_writer.cpp while streaming:

After decompress, section data is re-encrypted (AES-128-CTR) and written to the NCM placeholder in 8 MB flushes.

nca_writer.cpp

NCM placeholder API

Wrapper around Switch ncmContentStorage* in ncm.cpp:

ncm.cpp, nx/ncm.cpp

NCA signature verification

When validateNCAs is true (default in config):

• Decrypt NCA header (AES-XTS with headerKey)
• Check magic NCA3
• RSA-2048-PSS verify first 0x200 bytes of header
• On failure: warning dialog - user can abort or continue

install_nsp.cpp, optionsPage.cpp (validateNCAs)

Shop XCI - special HTTP stream

Shop XCI items bypass the generic XCIInstallTask and use InstallXciHttpStream in shopInstall.cpp:

• Detect XCI: extension .xci/.xcz or HFS0 magic at 0xF000/0x10000
• Parse HFS0 via HTTP range with 16 MB read-ahead cache
• Write NCAs through NcaWriter, commit CNMT incrementally
• Import tickets at end - single continuous HTTP connection

NSP/NSZ shop items use standard HTTPNSP + NSPInstall.

shopInstall.cpp - installTitleShop, InstallXciHttpStream