tar_header.nx
buildroot/runtime/tar_header.nx
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tar_header.nx -- parse POSIX ustar tar headers (IEEE 1003.1).
Each tar entry is a 512-byte header followed by its file data
padded to a 512-byte boundary. The archive ends with at least
two zero-filled 512-byte blocks.
Header layout:
offset size field
0 100 name (NUL-terminated if shorter)
100 8 mode (octal ASCII)
108 8 uid (octal ASCII)
116 8 gid (octal ASCII)
124 12 size (octal ASCII, bytes of file data)
136 12 mtime (octal ASCII seconds since epoch)
148 8 header checksum (octal ASCII)
156 1 typeflag ('0'=regular, '5'=dir, '2'=symlink,
'1'=hardlink, 'x'=pax extended, 'g'=pax global)
157 100 linkname
257 6 magic "ustar\0" (POSIX) or "ustar " (GNU)
263 2 version "00" (POSIX) or " \0" (GNU)
265 32 uname (owner name)
297 32 gname (group name)
329 8 devmajor (octal)
337 8 devminor (octal)
345 155 prefix (prepended to name for long paths)
Invariants:
T1 Magic must be "ustar" -- the first 5 bytes at offset 257.
T2 Size fields are parsed as big-endian octal ASCII. GNU tar
optionally encodes large sizes as binary with MSB=0x80;
we reject those (caller can detect and extend).
T3 Checksum verification not performed here (future work);
we parse the field value but don't validate.
dependencies 1 imports · 0 importers
imports: syscalls.nx
imported by: nobody (leaf or entry point)
call flow from main pre-order; caps 40 nodes / depth 6 declared; ↻ = already shown
structs
| 43 | struct TarHeader { |
consts
| 37 | const TAR_BLOCK: i64 = 512 |
| 39 | const TAR_ERR_FORMAT: i64 = -1 |
| 40 | const TAR_ERR_SHORT: i64 = -2 |
| 41 | const TAR_ERR_OCTAL: i64 = -3 |
functions
| 62 | func tar_parse_octal(buf: *u8, off: i64, n: i64) -> i64 {
called by 1: tar_parse_header |
| 80 | func tar_scan_nul(buf: *u8, off: i64, max: i64) -> i64 {
called by 1: tar_parse_header |
| 91 | func tar_is_zero_block(buf: *u8, off: i64) -> i64 {
called by 1: main |
| 102 | func tar_parse_header(buf: *u8, n: i64, off: i64, h: *TarHeader) -> i64 { |
| 138 | func main() -> i64 { |