Module format_patch 

git format-patch mail-rendering primitives.

The full format-patch command in the grit binary parses argv, walks the revision range, reads config, runs rename detection, talks to the notes / range-diff machinery, decides on output files vs. stdout, prints the written filenames, and maps exit codes. Those responsibilities — argv parsing, revision selection, config/env resolution, file output, terminal printing, and the crate-internal log/range-diff dispatch — stay in the CLI.

What lives here is the self-contained, presentation-free core of mbox patch assembly: the byte-exact RFC 2047 / RFC 822 header encoders and folders, the [PATCH n/m] subject builder, the filename sanitizer/truncator, the committer-date formatter, the threading-header writer, and the small string transforms (mboxrd escaping, ident formatting, reroll/version labels) that git’s pretty.c, utf8.c, and builtin/log.c use to turn a commit plus its diff into an email. Each function computes a result from plain strings, bytes, or a CommitData alone — no argv, no terminal output, and no process/filesystem state — so the CLI can call them while still owning every I/O and config decision.

Enums

Rfc2047Type

Functions

add_rfc822_quoted

add_rfc2047

Append line RFC2047-Q-encoded to out, folding at 76 columns with continuation lines.

add_wrapped_text

Port of git’s strbuf_add_wrapped_text for ASCII text (used for subject/From folding). indent1 negative means -indent1 columns are already consumed on the current line.

apply_rfc_prefix

Apply the --rfc[=<str>] modifier to a subject prefix. Default RFC prepends “RFC “; a value starting with - appends (...); else replaces leader.

build_patch_filename

Build the full patch basename <file_prefix><NNNN>-<sanitized-subject>.patch, truncating the whole basename to filename_max_length - 1 chars (Git’s FORMAT_PATCH_NAME_MAX, default 64).

build_patch_subject

Build a patch Subject value: [<prefix> n/m] <subject> with proper handling of empty prefix.

commit_author_timestamp

encode_display_name

Encode a display name portion of an email address.

encode_email_address

Encode an email address for use in email headers.

encode_email_address_for_charset

Like encode_email_address but uses charset_label for RFC 2047 when non-ASCII.

ensure_trailing_slash

Ensure a directory prefix ends with /.

first_subject_line

The first physical line of the subject (used for the patch filename, matching git which stops format_sanitized_subject at the first newline). Returns the whole trimmed message if single-line.

flatten_subject

Flatten a multi-line commit message into a single-line subject (paragraph join with spaces).

format_date_rfc2822

Extract date from identity string and format as RFC 2822-like.

format_ident

Format an identity string as “Name ”.

is_valid_from_ident

Validate a --from=<ident> value: must look like an email ident (contain @).

last_line_length

Length of the last line of s (bytes after the final \n).

mboxrd_escape

Apply mboxrd >From escaping to body lines if mboxrd is set.

needs_rfc822_quoting

needs_rfc2047_encoding

True if line needs RFC2047 encoding (non-ASCII, newline, or =?).

notes_value_to_ref

Map a format.notes / --notes= value to a full notes ref (refs/notes/<x> unless already a full refs/... ref). An empty value or true means the default refs/notes/commits.

path_matches_spec

prev_version_label

Interdiff against v<N-1>: label, or None if reroll is not an integer >= 2.

push_indented

Append body to out, indenting every line by two spaces (matching sed -e "s/^/ /").

rfc2047_charset_label

Charset token for RFC 2047 =?charset?q?...?= (matches Git test expectations).

rfc2047_encode

RFC 2047 UTF-8 quoted-printable encoding for an email display name.

sanitize_reroll

Sanitize a reroll-count string for use in a filename prefix (v<x>-), like git’s sanitizer.

sanitize_subject

Sanitize a subject line for use as a filename, matching Git’s format_sanitized_subject byte-for-byte: runs of non-title bytes collapse into a single -, consecutive . collapse into one, and trailing ./- are trimmed. Operates on raw bytes (non-ASCII → separators).

strip_angles

write_addr_header

Write a From:/recipient address header <Name> <mail>, encoding/folding the display name.

write_folded_header

Write a folded email header with multiple values.

write_signature

Write the trailing signature block -- \n<sig>\n\n, or nothing when suppressed.

write_subject_header

Write the Subject: header (already-built subject string), encoding/folding like git.

write_thread_headers

Write In-Reply-To / References / Message-ID threading headers.