git/Documentation/git-merge-file.txt
Jeff King e34f80278e merge-file: clamp exit code to maximum 127
Git-merge-file is documented to return one of three exit
codes:

  - zero means the merge was successful

  - a negative number means an error occurred

  - a positive number indicates the number of conflicts

Unfortunately, this all gets stuffed into an 8-bit return
code. Which means that if you have 256 conflicts, this wraps
to zero, and the merge appears to succeed (and commits a
blob full of conflict-marker cruft!).

This patch clamps the return value to a maximum of 127,
which we should be able to safely represent everywhere. This
also leaves 128-255 for other values. Shells (and some parts
of git) will typically represent signal death as 128 plus
the signal number. And negative values are typically coerced
to an 8-bit unsigned value (so "return -1" ends up as 255).

Technically negative returns have the same problem (e.g.,
"-256" wraps back to 0), but this is not a problem in
practice, as the only negative value we use is "-1".

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2015-10-29 12:10:23 -07:00

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git-merge-file(1)
=================
NAME
----
git-merge-file - Run a three-way file merge
SYNOPSIS
--------
[verse]
'git merge-file' [-L <current-name> [-L <base-name> [-L <other-name>]]]
[--ours|--theirs|--union] [-p|--stdout] [-q|--quiet] [--marker-size=<n>]
[--[no-]diff3] <current-file> <base-file> <other-file>
DESCRIPTION
-----------
'git merge-file' incorporates all changes that lead from the `<base-file>`
to `<other-file>` into `<current-file>`. The result ordinarily goes into
`<current-file>`. 'git merge-file' is useful for combining separate changes
to an original. Suppose `<base-file>` is the original, and both
`<current-file>` and `<other-file>` are modifications of `<base-file>`,
then 'git merge-file' combines both changes.
A conflict occurs if both `<current-file>` and `<other-file>` have changes
in a common segment of lines. If a conflict is found, 'git merge-file'
normally outputs a warning and brackets the conflict with lines containing
<<<<<<< and >>>>>>> markers. A typical conflict will look like this:
<<<<<<< A
lines in file A
=======
lines in file B
>>>>>>> B
If there are conflicts, the user should edit the result and delete one of
the alternatives. When `--ours`, `--theirs`, or `--union` option is in effect,
however, these conflicts are resolved favouring lines from `<current-file>`,
lines from `<other-file>`, or lines from both respectively. The length of the
conflict markers can be given with the `--marker-size` option.
The exit value of this program is negative on error, and the number of
conflicts otherwise (truncated to 127 if there are more than that many
conflicts). If the merge was clean, the exit value is 0.
'git merge-file' is designed to be a minimal clone of RCS 'merge'; that is, it
implements all of RCS 'merge''s functionality which is needed by
linkgit:git[1].
OPTIONS
-------
-L <label>::
This option may be given up to three times, and
specifies labels to be used in place of the
corresponding file names in conflict reports. That is,
`git merge-file -L x -L y -L z a b c` generates output that
looks like it came from files x, y and z instead of
from files a, b and c.
-p::
Send results to standard output instead of overwriting
`<current-file>`.
-q::
Quiet; do not warn about conflicts.
--diff3::
Show conflicts in "diff3" style.
--ours::
--theirs::
--union::
Instead of leaving conflicts in the file, resolve conflicts
favouring our (or their or both) side of the lines.
EXAMPLES
--------
`git merge-file README.my README README.upstream`::
combines the changes of README.my and README.upstream since README,
tries to merge them and writes the result into README.my.
`git merge-file -L a -L b -L c tmp/a123 tmp/b234 tmp/c345`::
merges tmp/a123 and tmp/c345 with the base tmp/b234, but uses labels
`a` and `c` instead of `tmp/a123` and `tmp/c345`.
GIT
---
Part of the linkgit:git[1] suite