ISO disc images

Arca reads ISO 9660 images (.iso): CD/DVD images, Linux installation media, software bundles. It is built in, needs no Cargo feature and is read-only: Arca never creates or modifies an ISO.

arca list ubuntu.isoarca test ubuntu.isoarca extract ubuntu.iso -o ubuntu/

In the window, open the image like any archive. The title says ISO: read-only; previews, extraction and testing work, while add, delete, rename, move, new folder and password are refused before the image is touched.

What is read

• Names: Rock Ridge (NM) first, then Joliet (UTF-16), then plain ISO 9660 with the ;1 version and the trailing dot removed.
• Directories relocated by Rock Ridge (CL/RE, the rr_moved trick for deep trees) appear in their real place.
• Files larger than 4 GiB, stored as several extents, come out as one file.
• Dates come from the directory records.

ISO 9660 stores no checksums. arca test proves every byte of every file can be read from the image, not that the bytes are the original ones.

What is left out, and said so

• Symbolic links, devices, FIFOs and sockets from Rock Ridge are neither listed nor extracted. The CLI prints note: skipped N symbolic links or special files: ... on stderr; the window shows the same line.
• UDF. Images that also carry UDF (DVD/Blu-ray, Windows installation media) are read through their ISO 9660 side, with a note that files stored only in UDF are not listed. On Windows media sources/install.wim is usually one of them. UDF-only images are rejected.
• Not supported: El Torito boot images as files, associated files, interleaved files, logical blocks other than 2048 bytes, mounting.

Safety

The parser is safe Rust with no dependencies. A damaged image gives an error, never a crash. Each image is checked for:

• volume descriptors, truncation and extents past the end of the file;
• directory records that are malformed or cross a sector boundary;
• directory loops, nesting deeper than 64 levels, more than 256 MiB of directory data, and Rock Ridge continuation chains longer than 32 areas or 64 KiB;
• names that escape the destination or are unsafe on Windows (.., /, \, drive letters, :<>"|?*, control characters, CON, NUL, COM1, trailing dots or spaces);
• duplicate paths, including names that differ only in case, and file/directory collisions.

Extraction streams each file in 256 KiB chunks into a temporary file next to its destination and renames it into place once complete. Every folder is opened by handle without following links, so a link already inside the destination tree, or one swapped in while extracting, is refused instead of followed. Skip, rename, overwrite and cancel conflicts are honored. A failure or cancellation can leave files that were already finished. Previews are limited to 64 MiB.

Checking it against other tools

bash interop.sh builds images with genisoimage and xorriso (plain, Joliet, Rock Ridge, relocated directories) and compares what Arca extracts with bsdtar and 7z, byte for byte. Set ARCA_TEST_ISO_BIG=1 to also build a 4.7 GB sparse image and check a multi-extent file; it needs about 5 GB of free disk space.