document_svg/document/
op2.rs

1//! Bounded Nastran Output2 (OP2) binary preflight.
2//!
3//! OP2 files contain solver model/results tables in a record-framed binary
4//! stream.  Full interpretation depends on table-specific element and result
5//! schemas, so this adapter validates only conservative record framing in a
6//! bounded prefix and reports recognizable table names.  It never decodes
7//! result vectors, executes a solver, or follows referenced files.
8
9use std::fs::{self, File};
10use std::io::Read;
11use std::path::Path;
12
13use crate::convert::{ConvertOptions, PageConsumer};
14use crate::document::html::{HtmlBlock, render_blocks_to_pages};
15use crate::error::{Error, Result};
16use crate::table::{TableAlign, TableData};
17
18const MAX_OP2_BYTES: u64 = 2 * 1024 * 1024 * 1024;
19const MAX_OP2_SCAN_BYTES: usize = 16 * 1024 * 1024;
20const MAX_OP2_RECORD_BYTES: usize = 64 * 1024 * 1024;
21const MAX_OP2_TABLES: usize = 1000;
22
23const TABLE_NAMES: &[&[u8]] = &[
24    b"GEOM1",
25    b"GEOM2",
26    b"GEOM3",
27    b"GEOM4",
28    b"GEOMM1",
29    b"OUGV1",
30    b"OES1",
31    b"OQG1",
32    b"OGPWG",
33    b"OEF1",
34    b"OAG1",
35    b"OPG1",
36    b"MAT1",
37    b"KELM",
38    b"XSOP2DIR",
39];
40
41#[derive(Clone, Copy, Debug, Eq, PartialEq)]
42enum Endian {
43    Little,
44    Big,
45}
46
47impl Endian {
48    fn name(self) -> &'static str {
49        match self {
50            Self::Little => "little-endian",
51            Self::Big => "big-endian",
52        }
53    }
54    fn u32(self, bytes: &[u8]) -> Option<u32> {
55        let array: [u8; 4] = bytes.get(..4)?.try_into().ok()?;
56        Some(match self {
57            Self::Little => u32::from_le_bytes(array),
58            Self::Big => u32::from_be_bytes(array),
59        })
60    }
61}
62
63struct Op2PageSink<'a> {
64    inner: &'a mut dyn PageConsumer,
65    warnings: &'a [String],
66}
67
68impl PageConsumer for Op2PageSink<'_> {
69    fn consume(&mut self, mut page: crate::ir::Page) -> Result<()> {
70        page.source_format = "op2".into();
71        if page.title.is_empty() {
72            page.title = "Nastran OP2 preflight".into();
73        }
74        page.description = "Nastran Output2 record metadata is rendered as bounded inert rows; model/result payloads are not decoded".into();
75        for warning in self.warnings {
76            page.warn(warning.clone());
77        }
78        self.inner.consume(page)
79    }
80}
81
82pub(crate) fn looks_like_prefix(prefix: &[u8]) -> bool {
83    TABLE_NAMES
84        .iter()
85        .any(|name| prefix.windows(name.len()).any(|window| window == *name))
86        && detect_endian(prefix).is_some()
87}
88
89pub(crate) fn convert(
90    path: &Path,
91    options: &ConvertOptions,
92    sink: &mut dyn PageConsumer,
93) -> Result<Vec<String>> {
94    let metadata = fs::metadata(path)?;
95    let max_bytes = options.max_input_bytes.min(MAX_OP2_BYTES);
96    if metadata.len() > max_bytes {
97        return Err(Error::LimitExceeded(format!(
98            "OP2 input exceeds maximum bytes ({max_bytes})"
99        )));
100    }
101    let scan_len = metadata.len().min(MAX_OP2_SCAN_BYTES as u64) as usize;
102    let mut file = File::open(path)?;
103    let mut bytes = vec![0u8; scan_len];
104    file.read_exact(&mut bytes)?;
105    let endian = detect_endian(&bytes).ok_or_else(|| {
106        Error::InvalidInput("OP2 record framing was not recognized in the bounded prefix".into())
107    })?;
108    let (records, scanned_bytes) = scan_records(&bytes, endian);
109    let mut tables = Vec::new();
110    for name in TABLE_NAMES {
111        if bytes.windows(name.len()).any(|window| window == *name) {
112            tables.push(std::str::from_utf8(name).unwrap_or("table"));
113            if tables.len() >= MAX_OP2_TABLES {
114                break;
115            }
116        }
117    }
118    let table_text = if tables.is_empty() {
119        "none recognized".into()
120    } else {
121        tables.join(", ")
122    };
123    let rows = vec![
124        vec!["File bytes".into(), metadata.len().to_string()],
125        vec!["Scan bytes".into(), scanned_bytes.to_string()],
126        vec!["Record byte order".into(), endian.name().into()],
127        vec!["Framed records".into(), records.to_string()],
128        vec!["Recognized tables".into(), table_text],
129    ];
130    let mut warnings = vec![
131        "OP2 table schemas, model geometry, element connectivity, result vectors, precision variants, and subcase semantics are not decoded".into(),
132        "External references, solver commands, DMAP/user code, file paths, and result post-processing remain inert and are never executed".into(),
133    ];
134    if scan_len < metadata.len() as usize {
135        warnings.push(format!(
136            "OP2 preflight scanned only the first {MAX_OP2_SCAN_BYTES} bytes"
137        ));
138    }
139    let blocks = vec![
140        HtmlBlock::Heading {
141            level: 1,
142            text: "Nastran OP2 preflight".into(),
143        },
144        HtmlBlock::Paragraph {
145            text: "The bounded prefix is checked for conservative OP2 record framing and known table labels. Binary model and result payloads are never expanded.".into(),
146        },
147        HtmlBlock::Table(TableData {
148            headers: vec!["Metric".into(), "Value".into()],
149            rows,
150            alignments: vec![TableAlign::Left, TableAlign::Right],
151            raw_source: String::new(),
152        }),
153    ];
154    let mut page_sink = Op2PageSink {
155        inner: sink,
156        warnings: &warnings,
157    };
158    render_blocks_to_pages(&blocks, &mut page_sink, options)?;
159    warnings.sort();
160    warnings.dedup();
161    Ok(warnings)
162}
163
164fn detect_endian(bytes: &[u8]) -> Option<Endian> {
165    [Endian::Little, Endian::Big].into_iter().find(|endian| {
166        (0..bytes.len().saturating_sub(12))
167            .step_by(4)
168            .take(256)
169            .any(|offset| valid_record(bytes, *endian, offset).is_some())
170    })
171}
172
173fn valid_record(bytes: &[u8], endian: Endian, offset: usize) -> Option<usize> {
174    let record_len = usize::try_from(endian.u32(bytes.get(offset..offset + 4)?)?).ok()?;
175    if record_len == 0 || record_len > MAX_OP2_RECORD_BYTES {
176        return None;
177    }
178    let trailer_offset = offset.checked_add(4)?.checked_add(record_len)?;
179    let trailer = endian.u32(bytes.get(trailer_offset..trailer_offset + 4)?)?;
180    (trailer as usize == record_len).then_some(record_len + 8)
181}
182
183fn scan_records(bytes: &[u8], endian: Endian) -> (usize, usize) {
184    let mut offset = 0usize;
185    let mut records = 0usize;
186    while offset.saturating_add(8) <= bytes.len() && records < MAX_OP2_TABLES * 100 {
187        if let Some(consumed) = valid_record(bytes, endian, offset) {
188            records = records.saturating_add(1);
189            offset = offset.saturating_add(consumed);
190        } else {
191            offset = offset.saturating_add(4);
192        }
193    }
194    (records, offset.min(bytes.len()))
195}
document_svg/document/op2.rs

document_svg/document/
op2.rs
