credential: add method for querying capabilities

[thirdparty/git.git] / Documentation / git-credential.txt

diff --git a/Documentation/git-credential.txt b/Documentation/git-credential.txt
index 3d3accc273294dc6acfb27f40a962d7b7f58fbd5..e41493292f6f84b36a782bf0eee063da11072465 100644 (file)
--- a/Documentation/git-credential.txt
+++ b/Documentation/git-credential.txt
@@ -8,7 +8,7 @@ git-credential - Retrieve and store user credentials
 SYNOPSIS
 --------
 ------------------
-'git credential' (fill|approve|reject)
+'git credential' (fill|approve|reject|capability)
 ------------------
 
 DESCRIPTION
@@ -41,6 +41,9 @@ If the action is `reject`, git-credential will send the description to
 any configured credential helpers, which may erase any stored
 credentials matching the description.
 
+If the action is `capability`, git-credential will announce any capabilities
+it supports to standard output.
+
 If the action is `approve` or `reject`, no output should be emitted.
 
 TYPICAL USE OF GIT CREDENTIAL
@@ -263,6 +266,29 @@ is supported, but they should not be provided without the capability.
 
 Unrecognised attributes and capabilities are silently discarded.
 
+[[CAPA-IOFMT]]
+CAPABILITY INPUT/OUTPUT FORMAT
+------------------------------
+
+For `git credential capability`, the format is slightly different. First, a
+`version 0` announcement is made to indicate the current version of the
+protocol, and then each capability is announced with a line like `capability
+authtype`. Credential helpers may also implement this format, again with the
+`capability` argument. Additional lines may be added in the future; callers
+should ignore lines which they don't understand.
+
+Because this is a new part of the credential helper protocol, older versions of
+Git, as well as some credential helpers, may not support it.  If a non-zero
+exit status is received, or if the first line doesn't start with the word
+`version` and a space, callers should assume that no capabilities are supported.
+
+The intention of this format is to differentiate it from the credential output
+in an unambiguous way.  It is possible to use very simple credential helpers
+(e.g., inline shell scripts) which always produce identical output.  Using a
+distinct format allows users to continue to use this syntax without having to
+worry about correctly implementing capability advertisements or accidentally
+confusing callers querying for capabilities.
+
 GIT
 ---
 Part of the linkgit:git[1] suite