[0/5] Tighten patch header parsing in patch-id

Message

Junio C Hamano June 21, 2024, 11:18 p.m. UTC

The patch-id command loops over a series of patches, picking up the
origin commit object name (which is on the "patch header" line) and
then computing the patch identifier out of the "patch" (series of
"diff") that follows the "patch header".

The parser is structured in a bit "strange" way.  It repeatedly
calls a single helper function get_one_patchid() that returns when a
patch header is recognised, or skips until the "patch" part begins
and then computes the "patch id" over the "patch" part, until it
sees a patch header.  The caller knows that it gets just the "patch
header" for the first patch with its first call, and the second call
is about computing the patch id for the first patch, whose
originating commit was obtained from the first call, etc.

During the second and subsequent call (i.e. after finding a patch
header which caused the get_one_patchid() to return, calling the
helper again, expecting it to skip the commit log and find the patch
for which we are asked to compute the patch id), we shouldn't look
for the patch header at all.  Otherwise, a line that looks like a
patch header in the log message can easily be mistaken to be the
beginning of a new patch header, as if the current message did not
have any patch text.

This 5-patch series is organized as follows:

 - patch 1 is about setting the baseline.  We need to recognise the
   patch header produced by format-patch, log, and diff-tree --stdin.

 - patch 2 to patch 4 are bit of code restructuring without changing
   the behaviour.

 - patch 5 stops looking for a patch header when we shouldn't, and
   adds tests.

Junio C Hamano (5):
  t4204: patch-id supports various input format
  patch-id: call flush_current_id() only when needed
  patch-id: make get_one_patchid() more extensible
  patch-id: rewrite code that detects the beginning of a patch
  patch-id: tighten code to detect the patch header

 builtin/patch-id.c  | 82 +++++++++++++++++++++++++++++++++------------
 t/t4204-patch-id.sh | 40 ++++++++++++++++++++++
 2 files changed, 101 insertions(+), 21 deletions(-)