I'm developing a git
post-receive
hook in Python. Data is supplied on stdin
with lines similar to
ef4d4037f8568e386629457d4d960915a85da2ae 61a4033ccf9159ae69f951f709d9c987d3c9f580 refs/heads/master
The first hash is the old-ref, the second the new-ref and the third column is the reference being updated.
I want to split this into 3 variables, whilst also validating input. How do I validate the branch name?
I am currently using the following regular expression
^([0-9a-f]{40}) ([0-9a-f]{40}) refs/heads/([0-9a-zA-Z]+)$
This doesn't accept all possible branch names, as set out by man git-check-ref-format. For example, it excludes a branch by the name of build-master
, which is valid.
I actually want to exclude any branch that starts with "build-". Can this be done in the same regex?
Given the great answers below, I wrote some tests, which can be found at https://github.com/alexchamberlain/githooks/blob/master/miscellaneous/git-branch-re-test.py.
Status: All the regexes below are failing to compile. This could indicate there's a problem with my script or incompatible syntaxes.
Let's dissect the various rules and build regex parts from them:
They can include slash /
for hierarchical (directory) grouping, but no slash-separated component can begin with a dot .
or end with the sequence .lock
.
# must not contain /.
(?!.*/\.)
# must not end with .lock
(?<!\.lock)$
They must contain at least one /
. This enforces the presence of a category like heads/, tags/ etc. but the actual names are not restricted. If the --allow-onelevel
option is used, this rule is waived.
.+/.+ # may get more precise later
They cannot have two consecutive dots ..
anywhere.
(?!.*\.\.)
They cannot have ASCII control characters (i.e. bytes whose values are lower than \040
, or \177 DEL
), space, tilde ~
, caret ^
, or colon :
anywhere.
[^\000-\037\177 ~^:]+ # pattern for allowed characters
They cannot have question-mark ?
, asterisk *
, or open bracket [
anywhere. See the --refspec-pattern
option below for an exception to this rule.
[^\000-\037\177 ~^:?*[]+ # new pattern for allowed characters
They cannot begin or end with a slash /
or contain multiple consecutive slashes (see the --normalize
option below for an exception to this rule)
^(?!/)
(?<!/)$
(?!.*//)
They cannot end with a dot .
.
(?<!\.)$
They cannot contain a sequence @{
.
(?!.*@\{)
They cannot contain a \
.
(?!.*\\)
Piecing it all together we arrive at the following monstrosity:
^(?!.*/\.)(?!.*\.\.)(?!/)(?!.*//)(?!.*@\{)(?!.*\\)[^\000-\037\177 ~^:?*[]+/[^\000-\037\177 ~^:?*[]+(?<!\.lock)(?<!/)(?<!\.)$
And if you want to exclude those that start with build-
then just add another lookahead:
^(?!build-)(?!.*/\.)(?!.*\.\.)(?!/)(?!.*//)(?!.*@\{)(?!.*\\)[^\000-\037\177 ~^:?*[]+/[^\000-\037\177 ~^:?*[]+(?<!\.lock)(?<!/)(?<!\.)$
This can be optimized a bit as well by conflating a few things that look for common patterns:
^(?!@$|build-|/|.*([/.]\.|//|@\{|\\))[^\000-\037\177 ~^:?*[]+/[^\000-\037\177 ~^:?*[]+(?<!\.lock|[/.])$