git_policy_cli/
standards_review_source.rs

1//! What:
2//!  The Git reads of the standards-review shadow run, in as few real-Git starts as the data allows: one `git show`
3//!  for the patch and one `git cat-file --batch` for the new-side text of the excerpted code files.
4//! Why:
5//!  The root `mise.toml` task `shadow-review` starts Git twenty-odd times per landing (`rev-parse`, `log`, `show`,
6//!  `diff-tree`, then `show` and `diff -U0` for each of up to eight files). The landing already knows the commit name,
7//!  its message and the changed names, so the subject and the names need no start, the zero-context ranges come out of
8//!  the patch, and the file texts come in one batch. A commit with no code files costs no start at all.
9//!
10//! In TS you'd write (pseudocode):
11//! ```ts
12//! const patch = git('show', '--format=', '--patch', sha); const blobs = catFileBatch(codeFiles.map((name) => `${sha}:${name}`));
13//! ```
14
15use super::standards_review_input::{LandedCommit, MAX_EXCERPT_FILES};
16use super::transaction_git::{GitContext, GitRequest, run_git};
17use std::collections::BTreeMap;
18use std::ffi::OsString;
19use std::path::Path;
20
21/// The most patch bytes read, the script's `maxBuffer` of 64 MiB.
22pub const MAX_PATCH_BYTES: usize = 1 << 26;
23
24/// What:
25///  Read the patch of `sha` with one `git show`.
26/// Why:
27///   Color and external diff drivers are switched off so the text does not depend on the account's configuration.
28///
29/// In TS you'd write (pseudocode):
30/// ```ts
31/// git('show', '--format=', '--patch', sha)
32/// ```
33fn read_patch(context: &GitContext, cwd: &Path, sha: &str) -> Result<String, String> {
34    let request: GitRequest = GitRequest::new(cwd, &["show", "--format=", "--patch", "--no-color", "--no-ext-diff", sha]);
35    let output = run_git(context, &request).map_err(|error| return format!("starting git show failed: {error}"))?;
36    if !output.succeeded() {
37        return Err(format!("git show {sha} failed: {}", output.error_text()));
38    }
39    if output.stdout.len() > MAX_PATCH_BYTES {
40        return Err(format!("the patch of {sha} is over {MAX_PATCH_BYTES} bytes"));
41    }
42    return Ok(String::from_utf8_lossy(output.stdout.as_slice()).into_owned());
43}
44
45/// What:
46///  Split `git cat-file --batch` output for the requested names into texts; a name Git reports `missing` has none.
47/// Why:
48///   A file the commit deleted has no new-side text, and a size says where content ends, never a delimiter.
49///
50/// In TS you'd write (pseudocode):
51/// ```ts
52/// parseBatch({ output, names }): Map<string, string>
53/// ```
54pub fn parse_batch(output: &[u8], names: &[String]) -> Result<BTreeMap<String, String>, String> {
55    let mut texts: BTreeMap<String, String> = BTreeMap::new();
56    let mut offset: usize = 0;
57    for name in names {
58        let Some(relative) = output[offset..].iter().position(|byte| return *byte == b'\n') else {
59            return Err(format!("git cat-file omitted the header for {name}"));
60        };
61        let header: String = String::from_utf8_lossy(&output[offset..offset + relative]).into_owned();
62        offset += relative + 1;
63        let fields: Vec<&str> = header.split(' ').collect();
64        if fields.len() == 2 && fields[1] == "missing" {
65            continue;
66        }
67        let size: usize = match (fields.len(), fields.get(1), fields.get(2).and_then(|text| return text.parse::<usize>().ok())) {
68            (3, Some(&"blob"), Some(size)) => size,
69            _ => return Err(format!("git cat-file returned an unexpected header for {name}: {header}")),
70        };
71        let end: usize = offset.checked_add(size).filter(|end| return *end < output.len() && output[*end] == b'\n').ok_or_else(|| return format!("git cat-file returned truncated content for {name}"))?;
72        texts.insert(name.clone(), String::from_utf8_lossy(&output[offset..end]).into_owned());
73        offset = end + 1;
74    }
75    return Ok(texts);
76}
77
78/// What:
79///  Read the patch and the excerpted files' new-side texts of a landed commit.
80///  `code_files` are the code names in name order; only the first `MAX_EXCERPT_FILES` are fetched.
81/// Why:
82///   It is the whole of the review's Git use: two starts.
83///
84/// In TS you'd write (pseudocode):
85/// ```ts
86/// const commit = await readLandedCommit({ context, cwd, sha, subject, codeFiles });
87/// ```
88pub fn read_landed_commit(context: &GitContext, cwd: &Path, sha: &str, subject: &str, code_files: &[String]) -> Result<LandedCommit, String> {
89    let patch: String = read_patch(context, cwd, sha)?;
90    let wanted: Vec<String> = code_files.iter().take(MAX_EXCERPT_FILES).cloned().collect();
91    let specs: String = wanted.iter().map(|name| return format!("{sha}:{name}\n")).collect();
92    let mut request: GitRequest = GitRequest::new(cwd, &[OsString::from("cat-file"), OsString::from("--batch")]);
93    request.input = Some(specs.into_bytes());
94    let output = run_git(context, &request).map_err(|error| return format!("starting git cat-file failed: {error}"))?;
95    if !output.succeeded() {
96        return Err(format!("git cat-file failed: {}", output.error_text()));
97    }
98    let contents: BTreeMap<String, String> = parse_batch(output.stdout.as_slice(), wanted.as_slice())?;
99    return Ok(LandedCommit { sha: String::from(sha), subject: String::from(subject), patch, contents });
100}
101
102/// Controls stay out of the release executable.
103#[cfg(test)]
104#[path = "standards_review_source_tests.rs"]
105mod tests;
git_policy_cli/standards_review_source.rs

git_policy_cli/
standards_review_source.rs
