| 1 | //! Which license a repository's LICENSE file holds: an `SPDX-License-Identifier` |
| 2 | //! line when it has one, else the phrases each common license is known by. |
| 3 | //! A text none of them match is "Other": the file is still linked. |
| 4 | |
| 5 | use g1t_contracts::about::License; |
| 6 | |
| 7 | /// The names a license file goes by, at the root, best first. |
| 8 | const PREFERRED: &[&str] = &["license", "license.md", "license.txt", "licence", "licence.md", "licence.txt", "copying", "copying.md", "copying.txt", "unlicense"]; |
| 9 | |
| 10 | /// Whether a root file is a license file: `LICENSE`, `LICENCE.md`, |
| 11 | /// `COPYING`, `LICENSE-MIT` and the like. |
| 12 | pub fn is_license_file(name: &str) -> bool { |
| 13 | let lower = name.to_ascii_lowercase(); |
| 14 | ["license", "licence", "copying", "unlicense"].iter().any(|start| lower.starts_with(start)) |
| 15 | && !lower.ends_with(".html") |
| 16 | && lower.len() <= 40 |
| 17 | } |
| 18 | |
| 19 | /// The root files to read for a license, best first. |
| 20 | pub fn candidates<'a>(names: impl IntoIterator<Item = &'a str>) -> Vec<&'a str> { |
| 21 | let mut found: Vec<&str> = names.into_iter().filter(|name| is_license_file(name)).collect(); |
| 22 | found.sort_by_key(|name| { |
| 23 | let lower = name.to_ascii_lowercase(); |
| 24 | (PREFERRED.iter().position(|preferred| *preferred == lower).unwrap_or(PREFERRED.len()), lower) |
| 25 | }); |
| 26 | found |
| 27 | } |
| 28 | |
| 29 | /// One license: its SPDX id, its name, and phrases its text holds (all of |
| 30 | /// `all`, none of `none`), lowercase with spaces collapsed. |
| 31 | struct Known { |
| 32 | id: &'static str, |
| 33 | name: &'static str, |
| 34 | all: &'static [&'static str], |
| 35 | none: &'static [&'static str], |
| 36 | } |
| 37 | |
| 38 | /// Most specific first: AGPL and LGPL before GPL, MIT-0 before MIT. |
| 39 | const KNOWN: &[Known] = &[ |
| 40 | Known { id: "AGPL-3.0", name: "GNU Affero General Public License v3.0", all: &["gnu affero general public license"], none: &[] }, |
| 41 | Known { id: "LGPL-3.0", name: "GNU Lesser General Public License v3.0", all: &["gnu lesser general public license", "version 3"], none: &[] }, |
| 42 | Known { id: "LGPL-2.1", name: "GNU Lesser General Public License v2.1", all: &["gnu lesser general public license", "version 2.1"], none: &[] }, |
| 43 | Known { id: "GPL-3.0", name: "GNU General Public License v3.0", all: &["gnu general public license", "version 3"], none: &[] }, |
| 44 | Known { id: "GPL-2.0", name: "GNU General Public License v2.0", all: &["gnu general public license", "version 2"], none: &[] }, |
| 45 | Known { id: "Apache-2.0", name: "Apache License 2.0", all: &["apache license", "version 2.0"], none: &[] }, |
| 46 | Known { id: "MPL-2.0", name: "Mozilla Public License 2.0", all: &["mozilla public license", "2.0"], none: &[] }, |
| 47 | Known { id: "EPL-2.0", name: "Eclipse Public License 2.0", all: &["eclipse public license", "2.0"], none: &[] }, |
| 48 | Known { id: "EPL-1.0", name: "Eclipse Public License 1.0", all: &["eclipse public license", "1.0"], none: &[] }, |
| 49 | Known { id: "BSL-1.0", name: "Boost Software License 1.0", all: &["boost software license"], none: &[] }, |
| 50 | Known { id: "BUSL-1.1", name: "Business Source License 1.1", all: &["business source license"], none: &[] }, |
| 51 | Known { id: "Elastic-2.0", name: "Elastic License 2.0", all: &["elastic license 2.0"], none: &[] }, |
| 52 | Known { id: "SSPL-1.0", name: "Server Side Public License v1", all: &["server side public license"], none: &[] }, |
| 53 | Known { id: "Unlicense", name: "The Unlicense", all: &["this is free and unencumbered software released into the public domain"], none: &[] }, |
| 54 | Known { id: "CC0-1.0", name: "Creative Commons Zero v1.0 Universal", all: &["cc0 1.0 universal"], none: &[] }, |
| 55 | Known { id: "CC-BY-4.0", name: "Creative Commons Attribution 4.0 International", all: &["attribution 4.0 international"], none: &["sharealike", "noncommercial"] }, |
| 56 | Known { id: "WTFPL", name: "Do What The F*ck You Want To Public License", all: &["do what the fuck you want to public license"], none: &[] }, |
| 57 | Known { |
| 58 | id: "MIT-0", |
| 59 | name: "MIT No Attribution", |
| 60 | all: &["permission is hereby granted, free of charge, to any person obtaining a copy"], |
| 61 | none: &["the above copyright notice and this permission notice shall be included"], |
| 62 | }, |
| 63 | Known { |
| 64 | id: "MIT", |
| 65 | name: "MIT License", |
| 66 | all: &["permission is hereby granted, free of charge, to any person obtaining a copy", "the above copyright notice and this permission notice shall be included"], |
| 67 | none: &[], |
| 68 | }, |
| 69 | Known { |
| 70 | id: "ISC", |
| 71 | name: "ISC License", |
| 72 | all: &["permission to use, copy, modify, and/or distribute this software for any purpose", "the above copyright notice and this permission notice appear in all copies"], |
| 73 | none: &[], |
| 74 | }, |
| 75 | Known { |
| 76 | id: "0BSD", |
| 77 | name: "BSD Zero Clause License", |
| 78 | all: &["permission to use, copy, modify, and/or distribute this software for any purpose with or without fee is hereby granted"], |
| 79 | none: &["the above copyright notice and this permission notice appear in all copies"], |
| 80 | }, |
| 81 | Known { |
| 82 | id: "BSD-4-Clause", |
| 83 | name: "BSD 4-Clause \"Original\" License", |
| 84 | all: &["redistribution and use in source and binary forms", "all advertising materials mentioning features"], |
| 85 | none: &[], |
| 86 | }, |
| 87 | Known { |
| 88 | id: "BSD-3-Clause", |
| 89 | name: "BSD 3-Clause \"New\" or \"Revised\" License", |
| 90 | all: &["redistribution and use in source and binary forms", "neither the name of"], |
| 91 | none: &[], |
| 92 | }, |
| 93 | Known { |
| 94 | id: "BSD-3-Clause", |
| 95 | name: "BSD 3-Clause \"New\" or \"Revised\" License", |
| 96 | all: &["redistribution and use in source and binary forms", "may be used to endorse or promote products derived from this software without specific prior written permission"], |
| 97 | none: &[], |
| 98 | }, |
| 99 | Known { |
| 100 | id: "BSD-2-Clause", |
| 101 | name: "BSD 2-Clause \"Simplified\" License", |
| 102 | all: &["redistribution and use in source and binary forms"], |
| 103 | none: &[], |
| 104 | }, |
| 105 | Known { |
| 106 | id: "Zlib", |
| 107 | name: "zlib License", |
| 108 | all: &["altered source versions must be plainly marked as such"], |
| 109 | none: &[], |
| 110 | }, |
| 111 | ]; |
| 112 | |
| 113 | /// Lowercase, quotes made plain, and whitespace collapsed to single spaces. |
| 114 | fn normalize(text: &str) -> String { |
| 115 | let mut out = String::with_capacity(text.len()); |
| 116 | let mut space = false; |
| 117 | for c in text.chars() { |
| 118 | let c = match c { |
| 119 | '\u{2018}' | '\u{2019}' => '\'', |
| 120 | '\u{201c}' | '\u{201d}' => '"', |
| 121 | c => c, |
| 122 | }; |
| 123 | if c.is_whitespace() || c == '*' || c == '#' { |
| 124 | // Comment markers of a header copied from source count as space. |
| 125 | space = !out.is_empty(); |
| 126 | continue; |
| 127 | } |
| 128 | if space { |
| 129 | out.push(' '); |
| 130 | space = false; |
| 131 | } |
| 132 | out.extend(c.to_lowercase()); |
| 133 | } |
| 134 | out |
| 135 | } |
| 136 | |
| 137 | /// An `SPDX-License-Identifier:` line's expression. |
| 138 | fn spdx_line(text: &str) -> Option<String> { |
| 139 | text.lines().take(20).find_map(|line| { |
| 140 | let (_, rest) = line.split_once("SPDX-License-Identifier:")?; |
| 141 | let id = rest.trim().trim_end_matches("*/").trim(); |
| 142 | (!id.is_empty() && id.len() <= 100).then(|| id.to_owned()) |
| 143 | }) |
| 144 | } |
| 145 | |
| 146 | /// The license in a license file's text; "Other" when it is not one g1t |
| 147 | /// recognizes. |
| 148 | pub fn detect(path: &str, text: &str) -> License { |
| 149 | // Enough of the text to find each license's phrases: they come early. |
| 150 | let head: String = text.chars().take(24_000).collect(); |
| 151 | if let Some(id) = spdx_line(&head) { |
| 152 | let name = KNOWN.iter().find(|known| known.id.eq_ignore_ascii_case(&id)).map_or_else(|| id.clone(), |known| known.name.to_owned()); |
| 153 | return License { spdx_id: Some(id), name, path: path.to_owned() }; |
| 154 | } |
| 155 | let normal = normalize(&head); |
| 156 | match KNOWN.iter().find(|known| known.all.iter().all(|phrase| normal.contains(phrase)) && !known.none.iter().any(|phrase| normal.contains(phrase))) { |
| 157 | Some(known) => License { spdx_id: Some(known.id.to_owned()), name: known.name.to_owned(), path: path.to_owned() }, |
| 158 | None => License { spdx_id: None, name: "Other".to_owned(), path: path.to_owned() }, |
| 159 | } |
| 160 | } |
| 161 | |
| 162 | #[cfg(test)] |
| 163 | mod tests { |
| 164 | use super::*; |
| 165 | |
| 166 | const MIT: &str = "MIT License\n\nCopyright (c) 2026 Flagon, Inc.\n\nPermission is hereby granted, free of charge, to any person obtaining a copy\nof this software and associated documentation files (the \"Software\"), to deal\nin the Software without restriction, including without limitation the rights\nto use, copy, modify, merge, publish, distribute, sublicense, and/or sell\ncopies of the Software, and to permit persons to whom the Software is\nfurnished to do so, subject to the following conditions:\n\nThe above copyright notice and this permission notice shall be included in all\ncopies or substantial portions of the Software.\n\nTHE SOFTWARE IS PROVIDED \"AS IS\", WITHOUT WARRANTY OF ANY KIND."; |
| 167 | |
| 168 | fn id(text: &str) -> Option<String> { |
| 169 | detect("LICENSE", text).spdx_id |
| 170 | } |
| 171 | |
| 172 | #[test] |
| 173 | fn common_licenses_are_recognized() { |
| 174 | assert_eq!(id(MIT).as_deref(), Some("MIT")); |
| 175 | assert_eq!(detect("LICENSE", MIT).name, "MIT License"); |
| 176 | assert_eq!(id(" Apache License\n Version 2.0, January 2004\n").as_deref(), Some("Apache-2.0")); |
| 177 | assert_eq!(id("GNU GENERAL PUBLIC LICENSE\nVersion 3, 29 June 2007").as_deref(), Some("GPL-3.0")); |
| 178 | assert_eq!(id("GNU GENERAL PUBLIC LICENSE\nVersion 2, June 1991").as_deref(), Some("GPL-2.0")); |
| 179 | assert_eq!(id("GNU AFFERO GENERAL PUBLIC LICENSE\nVersion 3, 19 November 2007").as_deref(), Some("AGPL-3.0")); |
| 180 | assert_eq!(id("GNU LESSER GENERAL PUBLIC LICENSE\nVersion 2.1, February 1999").as_deref(), Some("LGPL-2.1")); |
| 181 | assert_eq!(id("Mozilla Public License Version 2.0\n==================================").as_deref(), Some("MPL-2.0")); |
| 182 | assert_eq!(id("This is free and unencumbered software released into the public domain.").as_deref(), Some("Unlicense")); |
| 183 | assert_eq!( |
| 184 | id("Redistribution and use in source and binary forms, with or without\nmodification, are permitted provided that ...\n3. Neither the name of the copyright holder nor ...").as_deref(), |
| 185 | Some("BSD-3-Clause") |
| 186 | ); |
| 187 | assert_eq!(id("Redistribution and use in source and binary forms, with or without modification").as_deref(), Some("BSD-2-Clause")); |
| 188 | assert_eq!( |
| 189 | id("Permission to use, copy, modify, and/or distribute this software for any purpose with or without fee is hereby granted, provided that the above copyright notice and this permission notice appear in all copies.").as_deref(), |
| 190 | Some("ISC") |
| 191 | ); |
| 192 | } |
| 193 | |
| 194 | #[test] |
| 195 | fn mit_without_its_notice_clause_is_mit_0() { |
| 196 | let text = MIT.replace("The above copyright notice and this permission notice shall be included in all\ncopies or substantial portions of the Software.", ""); |
| 197 | assert_eq!(id(&text).as_deref(), Some("MIT-0")); |
| 198 | } |
| 199 | |
| 200 | #[test] |
| 201 | fn an_spdx_line_says_it_outright() { |
| 202 | assert_eq!(id("// SPDX-License-Identifier: Apache-2.0 OR MIT\n").as_deref(), Some("Apache-2.0 OR MIT")); |
| 203 | assert_eq!(detect("LICENSE", "SPDX-License-Identifier: MIT").name, "MIT License"); |
| 204 | } |
| 205 | |
| 206 | #[test] |
| 207 | fn anything_else_is_other() { |
| 208 | let other = detect("COPYING", "All rights reserved. Do not copy."); |
| 209 | assert_eq!(other.spdx_id, None); |
| 210 | assert_eq!(other.name, "Other"); |
| 211 | assert_eq!(other.path, "COPYING"); |
| 212 | } |
| 213 | |
| 214 | #[test] |
| 215 | fn license_files_are_found_best_first() { |
| 216 | let names = ["README.md", "LICENSE-MIT", "COPYING", "LICENSE.md", "license.html", "src"]; |
| 217 | assert_eq!(candidates(names), vec!["LICENSE.md", "COPYING", "LICENSE-MIT"]); |
| 218 | assert!(candidates(["Cargo.toml"]).is_empty()); |
| 219 | } |
| 220 | } |