[PATCH 0/4] rev-list: introduce NUL-delimited output mode

When walking objects, git-rev-list(1) prints each object entry on a separate line in the form:

        <oid> LF

Some options, such as `--objects`, may print additional information about the object on the same line:

        <oid> SP [<path>] LF

In this mode, if the object path contains a newline it is truncated at the newline.

When the `--missing={print,print-info}` option is provided, information about any missing objects encountered during the object walk are also printed in the form:

        ?<oid> [SP <token>=<value>]... LF

where values containing LF or SP are printed in a token specific fashion so that the resulting encoded value does not contain either of these two problematic bytes. For example, missing object paths are quoted in the C style so they contain LF or SP.

To make machine parsing easier, this series introduces a NUL-delimited output mode for git-rev-list(1) via a `-z` option following a suggestion from Junio in a previous thread[1]. In this mode, instead of LF, each object is delimited with two NUL bytes and any object metadata is separated with a single NUL byte. Examples:

        <oid> NUL NUL
        <oid> [NUL <path>] NUL NUL
        ?<oid> [NUL <token>=<value>]... NUL NUL

In this mode, path and value info are printed as-is without any special encoding or truncation.

For now this series only adds support for use with the `--objects` and `--missing` options. Usage of `-z` with other options is rejected, so it can potentially be added in the future.

One idea I had, but did not implement in this version, was to also use the `<token>=<value>` format for regular non-missing object info while in the NUL-delimited mode. I could see this being a bit more flexible instead of relying strictly on order. Interested if anyone has thoughts on this. :)

This series is structured as follows:

        - Patches 1 and 2 do some minor preparatory refactors.

        - Patch 3 adds the `-z` option to git-rev-list(1) to print
          objects in a NUL-delimited fashion. Printed object paths with
          the `--objects` option are also handled.

        - Patch 4 teaches the `--missing` option how to print info in a
          NUL-delimited fashion.

Thanks for taking a look, -Justin

[1]: <xmqq5xlor0la.fsf@gitster.g>

Justin Tobler (4):
  rev-list: inline `show_object_with_name()` in `show_object()`
  rev-list: refactor early option parsing
  rev-list: support delimiting objects with NUL bytes
  rev-list: support NUL-delimited --missing option

 Documentation/rev-list-options.adoc | 26 +++++++++
 builtin/rev-list.c                  | 86 ++++++++++++++++++++++-------
 revision.c                          |  8 ---
 revision.h                          |  2 -
 t/t6000-rev-list-misc.sh            | 34 ++++++++++++
 t/t6022-rev-list-missing.sh         | 30 ++++++++++
 6 files changed, 155 insertions(+), 31 deletions(-)

base-commit: 87a0bdbf0f72b7561f3cd50636eee33dcb7dbcc3