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Diffstat (limited to 'Documentation/gitattributes.txt')
| -rw-r--r-- | Documentation/gitattributes.txt | 243 |
1 files changed, 233 insertions, 10 deletions
diff --git a/Documentation/gitattributes.txt b/Documentation/gitattributes.txt index 7aff940202..30687de81a 100644 --- a/Documentation/gitattributes.txt +++ b/Documentation/gitattributes.txt @@ -21,9 +21,11 @@ Each line in `gitattributes` file is of form: pattern attr1 attr2 ... That is, a pattern followed by an attributes list, -separated by whitespaces. When the pattern matches the -path in question, the attributes listed on the line are given to -the path. +separated by whitespaces. Leading and trailing whitespaces are +ignored. Lines that begin with '#' are ignored. Patterns +that begin with a double quote are quoted in C style. +When the pattern matches the path in question, the attributes +listed on the line are given to the path. Each attribute can be in one of these states for a given path: @@ -86,7 +88,7 @@ is either not set or empty, $HOME/.config/git/attributes is used instead. Attributes for all users on a system should be placed in the `$(prefix)/etc/gitattributes` file. -Sometimes you would need to override an setting of an attribute +Sometimes you would need to override a setting of an attribute for a path to `Unspecified` state. This can be done by listing the name of the attribute prefixed with an exclamation point `!`. @@ -149,7 +151,10 @@ unspecified. This attribute sets a specific line-ending style to be used in the working directory. It enables end-of-line conversion without any -content checks, effectively setting the `text` attribute. +content checks, effectively setting the `text` attribute. Note that +setting this attribute on paths which are in the index with CRLF line +endings may make the paths to be considered dirty. Adding the path to +the index again will normalize the line endings in the index. Set to string value "crlf":: @@ -227,11 +232,8 @@ From a clean working directory: ------------------------------------------------- $ echo "* text=auto" >.gitattributes -$ rm .git/index # Remove the index to force Git to -$ git reset # re-scan the working directory +$ git add --renormalize . $ git status # Show files that will be normalized -$ git add -u -$ git add .gitattributes $ git commit -m "Introduce end-of-line normalization" ------------------------------------------------- @@ -293,7 +295,15 @@ checkout, when the `smudge` command is specified, the command is fed the blob object from its standard input, and its standard output is used to update the worktree file. Similarly, the `clean` command is used to convert the contents of worktree file -upon checkin. +upon checkin. By default these commands process only a single +blob and terminate. If a long running `process` filter is used +in place of `clean` and/or `smudge` filters, then Git can process +all blobs with a single filter command invocation for the entire +life of a single Git command, for example `git add --all`. If a +long running `process` filter is configured then it always takes +precedence over a configured single blob filter. See section +below for the description of the protocol used to communicate with +a `process` filter. One use of the content filtering is to massage the content into a shape that is more convenient for the platform, filesystem, and the user to use. @@ -317,6 +327,9 @@ You can declare that a filter turns a content that by itself is unusable into a usable content by setting the filter.<driver>.required configuration variable to `true`. +Note: Whenever the clean filter is changed, the repo should be renormalized: +$ git add --renormalize . + For example, in .gitattributes, you would assign the `filter` attribute for paths. @@ -373,6 +386,216 @@ not exist, or may have different contents. So, smudge and clean commands should not try to access the file on disk, but only act as filters on the content provided to them on standard input. +Long Running Filter Process +^^^^^^^^^^^^^^^^^^^^^^^^^^^ + +If the filter command (a string value) is defined via +`filter.<driver>.process` then Git can process all blobs with a +single filter invocation for the entire life of a single Git +command. This is achieved by using a packet format (pkt-line, +see technical/protocol-common.txt) based protocol over standard +input and standard output as follows. All packets, except for the +"*CONTENT" packets and the "0000" flush packet, are considered +text and therefore are terminated by a LF. + +Git starts the filter when it encounters the first file +that needs to be cleaned or smudged. After the filter started +Git sends a welcome message ("git-filter-client"), a list of supported +protocol version numbers, and a flush packet. Git expects to read a welcome +response message ("git-filter-server"), exactly one protocol version number +from the previously sent list, and a flush packet. All further +communication will be based on the selected version. The remaining +protocol description below documents "version=2". Please note that +"version=42" in the example below does not exist and is only there +to illustrate how the protocol would look like with more than one +version. + +After the version negotiation Git sends a list of all capabilities that +it supports and a flush packet. Git expects to read a list of desired +capabilities, which must be a subset of the supported capabilities list, +and a flush packet as response: +------------------------ +packet: git> git-filter-client +packet: git> version=2 +packet: git> version=42 +packet: git> 0000 +packet: git< git-filter-server +packet: git< version=2 +packet: git< 0000 +packet: git> capability=clean +packet: git> capability=smudge +packet: git> capability=not-yet-invented +packet: git> 0000 +packet: git< capability=clean +packet: git< capability=smudge +packet: git< 0000 +------------------------ +Supported filter capabilities in version 2 are "clean", "smudge", +and "delay". + +Afterwards Git sends a list of "key=value" pairs terminated with +a flush packet. The list will contain at least the filter command +(based on the supported capabilities) and the pathname of the file +to filter relative to the repository root. Right after the flush packet +Git sends the content split in zero or more pkt-line packets and a +flush packet to terminate content. Please note, that the filter +must not send any response before it received the content and the +final flush packet. Also note that the "value" of a "key=value" pair +can contain the "=" character whereas the key would never contain +that character. +------------------------ +packet: git> command=smudge +packet: git> pathname=path/testfile.dat +packet: git> 0000 +packet: git> CONTENT +packet: git> 0000 +------------------------ + +The filter is expected to respond with a list of "key=value" pairs +terminated with a flush packet. If the filter does not experience +problems then the list must contain a "success" status. Right after +these packets the filter is expected to send the content in zero +or more pkt-line packets and a flush packet at the end. Finally, a +second list of "key=value" pairs terminated with a flush packet +is expected. The filter can change the status in the second list +or keep the status as is with an empty list. Please note that the +empty list must be terminated with a flush packet regardless. + +------------------------ +packet: git< status=success +packet: git< 0000 +packet: git< SMUDGED_CONTENT +packet: git< 0000 +packet: git< 0000 # empty list, keep "status=success" unchanged! +------------------------ + +If the result content is empty then the filter is expected to respond +with a "success" status and a flush packet to signal the empty content. +------------------------ +packet: git< status=success +packet: git< 0000 +packet: git< 0000 # empty content! +packet: git< 0000 # empty list, keep "status=success" unchanged! +------------------------ + +In case the filter cannot or does not want to process the content, +it is expected to respond with an "error" status. +------------------------ +packet: git< status=error +packet: git< 0000 +------------------------ + +If the filter experiences an error during processing, then it can +send the status "error" after the content was (partially or +completely) sent. +------------------------ +packet: git< status=success +packet: git< 0000 +packet: git< HALF_WRITTEN_ERRONEOUS_CONTENT +packet: git< 0000 +packet: git< status=error +packet: git< 0000 +------------------------ + +In case the filter cannot or does not want to process the content +as well as any future content for the lifetime of the Git process, +then it is expected to respond with an "abort" status at any point +in the protocol. +------------------------ +packet: git< status=abort +packet: git< 0000 +------------------------ + +Git neither stops nor restarts the filter process in case the +"error"/"abort" status is set. However, Git sets its exit code +according to the `filter.<driver>.required` flag, mimicking the +behavior of the `filter.<driver>.clean` / `filter.<driver>.smudge` +mechanism. + +If the filter dies during the communication or does not adhere to +the protocol then Git will stop the filter process and restart it +with the next file that needs to be processed. Depending on the +`filter.<driver>.required` flag Git will interpret that as error. + +After the filter has processed a command it is expected to wait for +a "key=value" list containing the next command. Git will close +the command pipe on exit. The filter is expected to detect EOF +and exit gracefully on its own. Git will wait until the filter +process has stopped. + +Delay +^^^^^ + +If the filter supports the "delay" capability, then Git can send the +flag "can-delay" after the filter command and pathname. This flag +denotes that the filter can delay filtering the current blob (e.g. to +compensate network latencies) by responding with no content but with +the status "delayed" and a flush packet. +------------------------ +packet: git> command=smudge +packet: git> pathname=path/testfile.dat +packet: git> can-delay=1 +packet: git> 0000 +packet: git> CONTENT +packet: git> 0000 +packet: git< status=delayed +packet: git< 0000 +------------------------ + +If the filter supports the "delay" capability then it must support the +"list_available_blobs" command. If Git sends this command, then the +filter is expected to return a list of pathnames representing blobs +that have been delayed earlier and are now available. +The list must be terminated with a flush packet followed +by a "success" status that is also terminated with a flush packet. If +no blobs for the delayed paths are available, yet, then the filter is +expected to block the response until at least one blob becomes +available. The filter can tell Git that it has no more delayed blobs +by sending an empty list. As soon as the filter responds with an empty +list, Git stops asking. All blobs that Git has not received at this +point are considered missing and will result in an error. + +------------------------ +packet: git> command=list_available_blobs +packet: git> 0000 +packet: git< pathname=path/testfile.dat +packet: git< pathname=path/otherfile.dat +packet: git< 0000 +packet: git< status=success +packet: git< 0000 +------------------------ + +After Git received the pathnames, it will request the corresponding +blobs again. These requests contain a pathname and an empty content +section. The filter is expected to respond with the smudged content +in the usual way as explained above. +------------------------ +packet: git> command=smudge +packet: git> pathname=path/testfile.dat +packet: git> 0000 +packet: git> 0000 # empty content! +packet: git< status=success +packet: git< 0000 +packet: git< SMUDGED_CONTENT +packet: git< 0000 +packet: git< 0000 # empty list, keep "status=success" unchanged! +------------------------ + +Example +^^^^^^^ + +A long running filter demo implementation can be found in +`contrib/long-running-filter/example.pl` located in the Git +core repository. If you develop your own long running filter +process then the `GIT_TRACE_PACKET` environment variables can be +very helpful for debugging (see linkgit:git[1]). + +Please note that you cannot use an existing `filter.<driver>.clean` +or `filter.<driver>.smudge` command with `filter.<driver>.process` +because the former two use a different inter process communication +protocol than the latter one. + + Interaction between checkin/checkout attributes ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ |