53 lines
1.3 KiB
Rust
53 lines
1.3 KiB
Rust
//! Macintosh archived format header utilities.
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use crate::durandal::bin::*;
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/// Checks for an AppleSingle header. Returns offset to the resource fork.
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pub fn check_apple_single(b: &[u8]) -> Option<usize>
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{
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if b.o_u32b(0)? != 0x51600 || b.o_u32b(4)? != 0x20000 {return None}
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let num = b.o_u16b(24)? as usize;
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for i in 0..num
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{
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let p = 26 + (12 * i);
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let fid = b.o_u32b(p )?;
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let ofs = b.o_u32b(p+4)? as usize;
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let len = b.o_u32b(p+8)? as usize;
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if fid == 1 {return if ofs + len > b.len() {None} else {Some(ofs)}}
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}
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None
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}
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/// Checks for a MacBin header. Returns offset to the resource fork.
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pub fn check_mac_bin(b: &[u8]) -> Option<usize>
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{
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if b[0] != 0 || b[1] > 63 || b[74] != 0 || b[123] > 0x81 {return None}
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let mut crc = 0;
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for i in 0..124 {
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for j in 8..16
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{
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let d = b[i] as (u16) << j;
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if (d ^ crc) & 0x8000 != 0 {crc = crc << 1 ^ 0x1021}
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else {crc <<= 1}
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}
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}
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if crc == b.o_u16b(124)? {Some(128)} else {None}
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}
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/// Reads a MacBin or AppleSingle header if there is one and returns the
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/// offset from the start of the header to the resource fork (if one is found.)
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pub fn try_mac_header(b: &[u8]) -> usize
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{
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let ofs = check_mac_bin(b).unwrap_or(0);
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if ofs != 0 {ofs} else {check_apple_single(b).unwrap_or(0)}
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}
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// EOF
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