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| 1 | +// SPDX-License-Identifier: AGPL-3.0-or-later |
| 2 | + |
| 3 | +package git |
| 4 | + |
| 5 | +import ( |
| 6 | + "bytes" |
| 7 | + "context" |
| 8 | + "errors" |
| 9 | + "fmt" |
| 10 | + "os" |
| 11 | + "os/exec" |
| 12 | + "path/filepath" |
| 13 | + "strconv" |
| 14 | + "strings" |
| 15 | + "time" |
| 16 | +) |
| 17 | + |
| 18 | +// ResolveRefOID returns the full SHA for `ref` via `git rev-parse`. |
| 19 | +// Returns ErrRefNotFound when git can't resolve. |
| 20 | +func ResolveRefOID(ctx context.Context, gitDir, ref string) (string, error) { |
| 21 | + cmd := exec.CommandContext(ctx, "git", "-C", gitDir, "rev-parse", "--verify", ref+"^{commit}") |
| 22 | + out, err := cmd.Output() |
| 23 | + if err != nil { |
| 24 | + var ee *exec.ExitError |
| 25 | + if errors.As(err, &ee) { |
| 26 | + return "", ErrRefNotFound |
| 27 | + } |
| 28 | + return "", wrapExecErr(err) |
| 29 | + } |
| 30 | + return strings.TrimSpace(string(out)), nil |
| 31 | +} |
| 32 | + |
| 33 | +// MergeTreeResult captures the output of `git merge-tree --write-tree |
| 34 | +// --merge-base=<base> <base> <head>`. ConflictPaths is empty when the |
| 35 | +// merge is clean. Git ≥ 2.38 required. |
| 36 | +type MergeTreeResult struct { |
| 37 | + TreeOID string |
| 38 | + ConflictPaths []string |
| 39 | + HasConflict bool |
| 40 | +} |
| 41 | + |
| 42 | +// ProbeMerge runs `git merge-tree --write-tree --no-messages <base> |
| 43 | +// <head>` and lets git auto-compute the merge base. Exit 0 = clean |
| 44 | +// merge (TreeOID set); exit 1 = conflicts (ConflictPaths populated). |
| 45 | +// Anything else is wrapped. |
| 46 | +func ProbeMerge(ctx context.Context, gitDir, baseOID, headOID string) (MergeTreeResult, error) { |
| 47 | + cmd := exec.CommandContext(ctx, "git", "-C", gitDir, |
| 48 | + "merge-tree", "--write-tree", "--no-messages", |
| 49 | + baseOID, headOID) |
| 50 | + var stdout, stderr bytes.Buffer |
| 51 | + cmd.Stdout = &stdout |
| 52 | + cmd.Stderr = &stderr |
| 53 | + err := cmd.Run() |
| 54 | + out := strings.TrimRight(stdout.String(), "\n") |
| 55 | + if err == nil { |
| 56 | + return MergeTreeResult{TreeOID: out}, nil |
| 57 | + } |
| 58 | + var ee *exec.ExitError |
| 59 | + if errors.As(err, &ee) && ee.ExitCode() == 1 { |
| 60 | + // First line is the tree OID even on conflict; subsequent lines |
| 61 | + // list conflicting paths (one per line) when --no-messages is set. |
| 62 | + lines := strings.Split(out, "\n") |
| 63 | + res := MergeTreeResult{HasConflict: true} |
| 64 | + if len(lines) > 0 { |
| 65 | + res.TreeOID = lines[0] |
| 66 | + } |
| 67 | + for _, l := range lines[1:] { |
| 68 | + if l = strings.TrimSpace(l); l != "" { |
| 69 | + res.ConflictPaths = append(res.ConflictPaths, l) |
| 70 | + } |
| 71 | + } |
| 72 | + return res, nil |
| 73 | + } |
| 74 | + return MergeTreeResult{}, fmt.Errorf("merge-tree: %w (%s)", err, stderr.String()) |
| 75 | +} |
| 76 | + |
| 77 | +// CommitsBetweenDetail returns commits unique to head, with author + |
| 78 | +// committer + body, suitable for refreshing pull_request_commits. The |
| 79 | +// result preserves head-side oldest-first ordering by inverting log's |
| 80 | +// default newest-first via --reverse. |
| 81 | +func CommitsBetweenDetail(ctx context.Context, gitDir, baseOID, headOID string, max int) ([]CommitDetail, error) { |
| 82 | + if max <= 0 { |
| 83 | + max = 250 |
| 84 | + } |
| 85 | + const sep = "\x1f" |
| 86 | + const recordEnd = "\x1e" |
| 87 | + format := strings.Join([]string{ |
| 88 | + "%H", "%h", |
| 89 | + "%an", "%ae", "%at", |
| 90 | + "%cn", "%ce", "%ct", |
| 91 | + "%s", |
| 92 | + }, sep) + sep + "%b" + recordEnd |
| 93 | + cmd := exec.CommandContext(ctx, "git", "-C", gitDir, |
| 94 | + "log", "--reverse", |
| 95 | + "--max-count="+strconv.Itoa(max), |
| 96 | + "--format="+format, |
| 97 | + baseOID+".."+headOID, |
| 98 | + ) |
| 99 | + out, err := cmd.Output() |
| 100 | + if err != nil { |
| 101 | + var ee *exec.ExitError |
| 102 | + if errors.As(err, &ee) && strings.Contains(string(ee.Stderr), "unknown revision") { |
| 103 | + return nil, ErrRefNotFound |
| 104 | + } |
| 105 | + return nil, wrapExecErr(err) |
| 106 | + } |
| 107 | + return parseCommitDetail(out), nil |
| 108 | +} |
| 109 | + |
| 110 | +func parseCommitDetail(out []byte) []CommitDetail { |
| 111 | + const sep = "\x1f" |
| 112 | + const recordEnd = "\x1e" |
| 113 | + body := bytes.TrimRight(out, "\n") |
| 114 | + records := bytes.Split(body, []byte(recordEnd)) |
| 115 | + cs := make([]CommitDetail, 0, len(records)) |
| 116 | + for _, rec := range records { |
| 117 | + rec = bytes.TrimLeft(rec, "\n") |
| 118 | + if len(rec) == 0 { |
| 119 | + continue |
| 120 | + } |
| 121 | + parts := strings.SplitN(string(rec), sep, 10) |
| 122 | + if len(parts) < 10 { |
| 123 | + continue |
| 124 | + } |
| 125 | + ats, _ := strconv.ParseInt(parts[4], 10, 64) |
| 126 | + cts, _ := strconv.ParseInt(parts[7], 10, 64) |
| 127 | + cs = append(cs, CommitDetail{ |
| 128 | + Commit: Commit{ |
| 129 | + OID: parts[0], |
| 130 | + ShortOID: parts[1], |
| 131 | + AuthorName: parts[2], |
| 132 | + AuthorEmail: parts[3], |
| 133 | + AuthorWhen: time.Unix(ats, 0).UTC(), |
| 134 | + Subject: parts[8], |
| 135 | + Body: strings.TrimSpace(parts[9]), |
| 136 | + }, |
| 137 | + CommitterName: parts[5], |
| 138 | + CommitterEmail: parts[6], |
| 139 | + CommitterWhen: time.Unix(cts, 0).UTC(), |
| 140 | + }) |
| 141 | + } |
| 142 | + return cs |
| 143 | +} |
| 144 | + |
| 145 | +// FilesChangedBetween returns the change set head-side, computed as |
| 146 | +// `git diff --name-status --numstat <base>...<head>` (three-dot: |
| 147 | +// changes from merge-base to head). Status is git's letter code, |
| 148 | +// renames carry the old path as the second column. |
| 149 | +func FilesChangedBetween(ctx context.Context, gitDir, baseOID, headOID string) ([]PRFileChange, error) { |
| 150 | + cmd := exec.CommandContext(ctx, "git", "-C", gitDir, |
| 151 | + "diff", "--name-status", "-M", "-C", |
| 152 | + baseOID+"..."+headOID, |
| 153 | + ) |
| 154 | + statusOut, err := cmd.Output() |
| 155 | + if err != nil { |
| 156 | + var ee *exec.ExitError |
| 157 | + if errors.As(err, &ee) && strings.Contains(string(ee.Stderr), "unknown revision") { |
| 158 | + return nil, ErrRefNotFound |
| 159 | + } |
| 160 | + return nil, wrapExecErr(err) |
| 161 | + } |
| 162 | + cmd = exec.CommandContext(ctx, "git", "-C", gitDir, |
| 163 | + "diff", "--numstat", "-M", "-C", |
| 164 | + baseOID+"..."+headOID, |
| 165 | + ) |
| 166 | + numOut, err := cmd.Output() |
| 167 | + if err != nil { |
| 168 | + return nil, wrapExecErr(err) |
| 169 | + } |
| 170 | + return parseFilesChanged(statusOut, numOut), nil |
| 171 | +} |
| 172 | + |
| 173 | +// PRFileChange is a per-file row for pull_request_files. Status mirrors |
| 174 | +// the migration enum; OldPath is non-empty for renames + copies. |
| 175 | +type PRFileChange struct { |
| 176 | + Path string |
| 177 | + OldPath string |
| 178 | + Status string // "added" | "modified" | "deleted" | "renamed" | "copied" |
| 179 | + Additions int |
| 180 | + Deletions int |
| 181 | +} |
| 182 | + |
| 183 | +func parseFilesChanged(statusOut, numOut []byte) []PRFileChange { |
| 184 | + type stats struct{ adds, dels int } |
| 185 | + numByPath := map[string]stats{} |
| 186 | + for _, line := range strings.Split(string(numOut), "\n") { |
| 187 | + fields := strings.Split(strings.TrimSpace(line), "\t") |
| 188 | + if len(fields) < 3 { |
| 189 | + continue |
| 190 | + } |
| 191 | + // "-" appears for binary files; treat as 0/0 counts. |
| 192 | + a, _ := strconv.Atoi(fields[0]) |
| 193 | + d, _ := strconv.Atoi(fields[1]) |
| 194 | + // For renames/copies the path field is `old\x00new`-ish via {oldpath => newpath}; |
| 195 | + // numstat's last field is just the new path when -M is applied. |
| 196 | + key := fields[len(fields)-1] |
| 197 | + numByPath[key] = stats{a, d} |
| 198 | + } |
| 199 | + out := []PRFileChange{} |
| 200 | + for _, line := range strings.Split(string(statusOut), "\n") { |
| 201 | + fields := strings.Split(strings.TrimSpace(line), "\t") |
| 202 | + if len(fields) < 2 { |
| 203 | + continue |
| 204 | + } |
| 205 | + statusLetter := fields[0] |
| 206 | + var fc PRFileChange |
| 207 | + switch { |
| 208 | + case strings.HasPrefix(statusLetter, "R") && len(fields) >= 3: |
| 209 | + fc.Status = "renamed" |
| 210 | + fc.OldPath = fields[1] |
| 211 | + fc.Path = fields[2] |
| 212 | + case strings.HasPrefix(statusLetter, "C") && len(fields) >= 3: |
| 213 | + fc.Status = "copied" |
| 214 | + fc.OldPath = fields[1] |
| 215 | + fc.Path = fields[2] |
| 216 | + case statusLetter == "A": |
| 217 | + fc.Status = "added" |
| 218 | + fc.Path = fields[1] |
| 219 | + case statusLetter == "D": |
| 220 | + fc.Status = "deleted" |
| 221 | + fc.Path = fields[1] |
| 222 | + case statusLetter == "M": |
| 223 | + fc.Status = "modified" |
| 224 | + fc.Path = fields[1] |
| 225 | + default: |
| 226 | + fc.Status = "modified" |
| 227 | + fc.Path = fields[len(fields)-1] |
| 228 | + } |
| 229 | + s := numByPath[fc.Path] |
| 230 | + fc.Additions = s.adds |
| 231 | + fc.Deletions = s.dels |
| 232 | + out = append(out, fc) |
| 233 | + } |
| 234 | + return out |
| 235 | +} |
| 236 | + |
| 237 | +// MergeOptions configures a worktree-based merge. |
| 238 | +type MergeOptions struct { |
| 239 | + GitDir string |
| 240 | + BaseRef string // e.g. "refs/heads/trunk" |
| 241 | + BaseOID string |
| 242 | + HeadOID string |
| 243 | + Method string // "merge" | "squash" | "rebase" |
| 244 | + AuthorName string |
| 245 | + AuthorEmail string |
| 246 | + CommitterName string |
| 247 | + CommitterEmail string |
| 248 | + When time.Time |
| 249 | + Subject string |
| 250 | + Body string |
| 251 | + WorktreesDir string // parent dir for the temp worktree (must share volume with GitDir) |
| 252 | +} |
| 253 | + |
| 254 | +// MergeResult is what PerformMerge returns on success. |
| 255 | +type MergeResult struct { |
| 256 | + NewBaseOID string // the new tip of base_ref after the merge |
| 257 | + MergedOID string // for "merge" method: the merge commit; "squash"/"rebase": same as NewBaseOID |
| 258 | +} |
| 259 | + |
| 260 | +// PerformMerge executes the requested merge strategy in a temp worktree |
| 261 | +// rooted at WorktreesDir. The worktree is removed on every exit path |
| 262 | +// (success or failure). Returns the new base-ref tip. |
| 263 | +func PerformMerge(ctx context.Context, opts MergeOptions) (MergeResult, error) { |
| 264 | + if opts.WorktreesDir == "" { |
| 265 | + opts.WorktreesDir = filepath.Join(filepath.Dir(opts.GitDir), ".tmp-worktrees") |
| 266 | + } |
| 267 | + if err := os.MkdirAll(opts.WorktreesDir, 0o750); err != nil { |
| 268 | + return MergeResult{}, fmt.Errorf("worktrees dir: %w", err) |
| 269 | + } |
| 270 | + wt, err := os.MkdirTemp(opts.WorktreesDir, "merge-*") |
| 271 | + if err != nil { |
| 272 | + return MergeResult{}, fmt.Errorf("mktemp worktree: %w", err) |
| 273 | + } |
| 274 | + cleanup := func() { |
| 275 | + // `git worktree remove --force` ignores stale entries; --force |
| 276 | + // also drops the directory contents so a leftover after a panic |
| 277 | + // gets reaped on the next attempt. |
| 278 | + _ = exec.Command("git", "-C", opts.GitDir, "worktree", "remove", "--force", wt).Run() |
| 279 | + _ = os.RemoveAll(wt) |
| 280 | + } |
| 281 | + defer cleanup() |
| 282 | + |
| 283 | + // Set up the worktree at base_oid (detached). Using detached HEAD |
| 284 | + // keeps the worktree from polluting the bare repo's branch refs; |
| 285 | + // we only push the resulting commit back to base_ref at the end. |
| 286 | + addCmd := exec.CommandContext(ctx, "git", "-C", opts.GitDir, |
| 287 | + "worktree", "add", "--detach", wt, opts.BaseOID) |
| 288 | + if out, err := addCmd.CombinedOutput(); err != nil { |
| 289 | + return MergeResult{}, fmt.Errorf("worktree add: %w (%s)", err, out) |
| 290 | + } |
| 291 | + |
| 292 | + // Identity for the merge commit. `--no-edit` + a baked subject |
| 293 | + // keeps the merge non-interactive. |
| 294 | + envBase := append(os.Environ(), |
| 295 | + "GIT_AUTHOR_NAME="+opts.AuthorName, |
| 296 | + "GIT_AUTHOR_EMAIL="+opts.AuthorEmail, |
| 297 | + "GIT_COMMITTER_NAME="+opts.CommitterName, |
| 298 | + "GIT_COMMITTER_EMAIL="+opts.CommitterEmail, |
| 299 | + ) |
| 300 | + if !opts.When.IsZero() { |
| 301 | + envBase = append(envBase, |
| 302 | + "GIT_AUTHOR_DATE="+opts.When.Format(time.RFC3339), |
| 303 | + "GIT_COMMITTER_DATE="+opts.When.Format(time.RFC3339), |
| 304 | + ) |
| 305 | + } |
| 306 | + |
| 307 | + switch opts.Method { |
| 308 | + case "merge": |
| 309 | + // Non-fast-forward merge so we always get a merge commit, even |
| 310 | + // when the head is strictly ahead of base. |
| 311 | + msg := strings.TrimSpace(opts.Subject) |
| 312 | + if opts.Body != "" { |
| 313 | + msg += "\n\n" + opts.Body |
| 314 | + } |
| 315 | + mergeCmd := exec.CommandContext(ctx, "git", "-C", wt, |
| 316 | + "merge", "--no-ff", "--no-edit", "-m", msg, opts.HeadOID) |
| 317 | + mergeCmd.Env = envBase |
| 318 | + if out, err := mergeCmd.CombinedOutput(); err != nil { |
| 319 | + return MergeResult{}, fmt.Errorf("merge --no-ff: %w (%s)", err, out) |
| 320 | + } |
| 321 | + case "squash": |
| 322 | + // `git merge --squash` stages the squashed change without |
| 323 | + // committing; `git commit` makes the squash commit with a |
| 324 | + // single author/committer pair. |
| 325 | + squashCmd := exec.CommandContext(ctx, "git", "-C", wt, |
| 326 | + "merge", "--squash", opts.HeadOID) |
| 327 | + squashCmd.Env = envBase |
| 328 | + if out, err := squashCmd.CombinedOutput(); err != nil { |
| 329 | + return MergeResult{}, fmt.Errorf("merge --squash: %w (%s)", err, out) |
| 330 | + } |
| 331 | + msg := strings.TrimSpace(opts.Subject) |
| 332 | + if opts.Body != "" { |
| 333 | + msg += "\n\n" + opts.Body |
| 334 | + } |
| 335 | + commitCmd := exec.CommandContext(ctx, "git", "-C", wt, |
| 336 | + "commit", "-m", msg) |
| 337 | + commitCmd.Env = envBase |
| 338 | + if out, err := commitCmd.CombinedOutput(); err != nil { |
| 339 | + return MergeResult{}, fmt.Errorf("squash commit: %w (%s)", err, out) |
| 340 | + } |
| 341 | + case "rebase": |
| 342 | + // Replay head_oid onto base_oid. --rebase-merges off means we |
| 343 | + // flatten merge commits into linear history; this matches the |
| 344 | + // standard "rebase merge" UX. |
| 345 | + rebaseCmd := exec.CommandContext(ctx, "git", "-C", wt, |
| 346 | + "rebase", "--onto", opts.BaseOID, opts.BaseOID, opts.HeadOID) |
| 347 | + rebaseCmd.Env = envBase |
| 348 | + if out, err := rebaseCmd.CombinedOutput(); err != nil { |
| 349 | + // Best-effort abort so the worktree is reusable for the |
| 350 | + // cleanup step (cleanup deletes anyway, but keeps logs sane). |
| 351 | + _ = exec.Command("git", "-C", wt, "rebase", "--abort").Run() |
| 352 | + return MergeResult{}, fmt.Errorf("rebase --onto: %w (%s)", err, out) |
| 353 | + } |
| 354 | + default: |
| 355 | + return MergeResult{}, fmt.Errorf("unknown merge method %q", opts.Method) |
| 356 | + } |
| 357 | + |
| 358 | + // Capture the resulting tip of HEAD in the worktree. |
| 359 | + revOut, err := exec.CommandContext(ctx, "git", "-C", wt, "rev-parse", "HEAD").Output() |
| 360 | + if err != nil { |
| 361 | + return MergeResult{}, fmt.Errorf("rev-parse HEAD: %w", err) |
| 362 | + } |
| 363 | + newOID := strings.TrimSpace(string(revOut)) |
| 364 | + |
| 365 | + // Update base_ref atomically via update-ref, gated on the expected |
| 366 | + // old OID to defend against concurrent pushes during the merge. |
| 367 | + updateCmd := exec.CommandContext(ctx, "git", "-C", opts.GitDir, |
| 368 | + "update-ref", opts.BaseRef, newOID, opts.BaseOID) |
| 369 | + if out, err := updateCmd.CombinedOutput(); err != nil { |
| 370 | + return MergeResult{}, fmt.Errorf("update-ref %s: %w (%s)", opts.BaseRef, err, out) |
| 371 | + } |
| 372 | + |
| 373 | + // For "merge" method the merge commit is HEAD; for squash and |
| 374 | + // rebase it's the same as the new base tip. |
| 375 | + return MergeResult{NewBaseOID: newOID, MergedOID: newOID}, nil |
| 376 | +} |