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Diffstat (limited to 'Documentation/git-fast-import.txt')
| -rw-r--r-- | Documentation/git-fast-import.txt | 268 |
1 files changed, 227 insertions, 41 deletions
diff --git a/Documentation/git-fast-import.txt b/Documentation/git-fast-import.txt index 19082b04eb..2620d28b4b 100644 --- a/Documentation/git-fast-import.txt +++ b/Documentation/git-fast-import.txt @@ -8,6 +8,7 @@ git-fast-import - Backend for fast Git data importers SYNOPSIS -------- +[verse] frontend | 'git fast-import' [options] DESCRIPTION @@ -78,8 +79,12 @@ OPTIONS set of marks. If a mark is defined to different values, the last file wins. +--import-marks-if-exists=<file>:: + Like --import-marks but instead of erroring out, silently + skips the file if it does not exist. + --relative-marks:: - After specifying --relative-marks= the paths specified + After specifying --relative-marks the paths specified with --import-marks= and --export-marks= are relative to an internal directory in the current repository. In git-fast-import this means that the paths are relative @@ -89,9 +94,21 @@ OPTIONS --no-relative-marks:: Negates a previous --relative-marks. Allows for combining relative and non-relative marks by interweaving - --(no-)-relative-marks= with the --(import|export)-marks= + --(no-)-relative-marks with the --(import|export)-marks= options. +--cat-blob-fd=<fd>:: + Write responses to `cat-blob` and `ls` queries to the + file descriptor <fd> instead of `stdout`. Allows `progress` + output intended for the end-user to be separated from other + output. + +--done:: + Require a `done` command at the end of the stream. + This option might be useful for detecting errors that + cause the frontend to terminate before it has started to + write a stream. + --export-pack-edges=<file>:: After creating a packfile, print a line of data to <file> listing the filename of the packfile and the last @@ -187,7 +204,8 @@ especially when a higher level language such as Perl, Python or Ruby is being used. fast-import is very strict about its input. Where we say SP below we mean -*exactly* one space. Likewise LF means one (and only one) linefeed. +*exactly* one space. Likewise LF means one (and only one) linefeed +and HT one (and only one) horizontal tab. Supplying additional whitespace characters will cause unexpected results, such as branch names or file names with leading or trailing spaces in their name, or early termination of fast-import when it encounters @@ -320,6 +338,21 @@ and control the current import process. More detailed discussion standard output. This command is optional and is not needed to perform an import. +`done`:: + Marks the end of the stream. This command is optional + unless the `done` feature was requested using the + `--done` command line option or `feature done` command. + +`cat-blob`:: + Causes fast-import to print a blob in 'cat-file --batch' + format to the file descriptor set with `--cat-blob-fd` or + `stdout` if unspecified. + +`ls`:: + Causes fast-import to print a line describing a directory + entry in 'ls-tree' format to the file descriptor set with + `--cat-blob-fd` or `stdout` if unspecified. + `feature`:: Require that fast-import supports the specified feature, or abort if it does not. @@ -393,8 +426,8 @@ Here `<name>` is the person's display name (for example (``cm@example.com''). `LT` and `GT` are the literal less-than (\x3c) and greater-than (\x3e) symbols. These are required to delimit the email address from the other fields in the line. Note that -`<name>` is free-form and may contain any sequence of bytes, except -`LT` and `LF`. It is typically UTF-8 encoded. +`<name>` and `<email>` are free-form and may contain any sequence +of bytes, except `LT`, `GT` and `LF`. `<name>` is typically UTF-8 encoded. The time of the change is specified by `<when>` using the date format that was selected by the \--date-format=<fmt> command line option. @@ -439,16 +472,16 @@ Marks must be declared (via `mark`) before they can be used. * A complete 40 byte or abbreviated commit SHA-1 in hex. * Any valid Git SHA-1 expression that resolves to a commit. See - ``SPECIFYING REVISIONS'' in linkgit:git-rev-parse[1] for details. + ``SPECIFYING REVISIONS'' in linkgit:gitrevisions[7] for details. The special case of restarting an incremental import from the current branch value should be written as: ---- from refs/heads/branch^0 ---- -The `{caret}0` suffix is necessary as fast-import does not permit a branch to +The `^0` suffix is necessary as fast-import does not permit a branch to start from itself, and the branch is created in memory before the -`from` command is even read from the input. Adding `{caret}0` will force +`from` command is even read from the input. Adding `^0` will force fast-import to resolve the commit through Git's revision parsing library, rather than its internal branch table, thereby loading in the existing value of the branch. @@ -482,9 +515,11 @@ External data format:: 'M' SP <mode> SP <dataref> SP <path> LF .... + -Here `<dataref>` can be either a mark reference (`:<idnum>`) +Here usually `<dataref>` must be either a mark reference (`:<idnum>`) set by a prior `blob` command, or a full 40-byte SHA-1 of an -existing Git blob object. +existing Git blob object. If `<mode>` is `040000`` then +`<dataref>` must be the full 40-byte SHA-1 of an existing +Git tree object or a mark reference set with `--import-marks`. Inline data format:: The data content for the file has not been supplied yet. @@ -509,6 +544,8 @@ in octal. Git only supports the following modes: * `160000`: A gitlink, SHA-1 of the object refers to a commit in another repository. Git links can only be specified by SHA or through a commit mark. They are used to implement submodules. +* `040000`: A subdirectory. Subdirectories can only be specified by + SHA or through a tree mark set with `--import-marks`. In both formats `<path>` is the complete path of the file to be added (if not already existing) or modified (if already existing). @@ -528,6 +565,8 @@ The value of `<path>` must be in canonical form. That is it must not: * contain the special component `.` or `..` (e.g. `foo/./bar` and `foo/../bar` are invalid). +The root of the tree can be represented by an empty string as `<path>`. + It is recommended that `<path>` always be encoded using UTF-8. `filedelete` @@ -622,9 +661,14 @@ paths for a commit are encouraged to do so. `notemodify` ^^^^^^^^^^^^ -Included in a `commit` command to add a new note (annotating a given -commit) or change the content of an existing note. This command has -two different means of specifying the content of the note. +Included in a `commit` `<notes_ref>` command to add a new note +annotating a `<committish>` or change this annotation contents. +Internally it is similar to filemodify 100644 on `<committish>` +path (maybe split into subdirectories). It's not advised to +use any other commands to write to the `<notes_ref>` tree except +`filedeleteall` to delete all existing notes in this tree. +This command has two different means of specifying the content +of the note. External data format:: The data content for the note was already supplied by a prior @@ -872,34 +916,138 @@ Placing a `progress` command immediately after a `checkpoint` will inform the reader when the `checkpoint` has been completed and it can safely access the refs that fast-import updated. -`feature` -~~~~~~~~~ -Require that fast-import supports the specified feature, or abort if -it does not. +`cat-blob` +~~~~~~~~~~ +Causes fast-import to print a blob to a file descriptor previously +arranged with the `--cat-blob-fd` argument. The command otherwise +has no impact on the current import; its main purpose is to +retrieve blobs that may be in fast-import's memory but not +accessible from the target repository. .... - 'feature' SP <feature> LF + 'cat-blob' SP <dataref> LF .... -The <feature> part of the command may be any string matching -^[a-zA-Z][a-zA-Z-]*$ and should be understood by fast-import. +The `<dataref>` can be either a mark reference (`:<idnum>`) +set previously or a full 40-byte SHA-1 of a Git blob, preexisting or +ready to be written. + +Output uses the same format as `git cat-file --batch`: + +==== + <sha1> SP 'blob' SP <size> LF + <contents> LF +==== -Feature work identical as their option counterparts with the -exception of the import-marks feature, see below. +This command can be used anywhere in the stream that comments are +accepted. In particular, the `cat-blob` command can be used in the +middle of a commit but not in the middle of a `data` command. -The following features are currently supported: +See ``Responses To Commands'' below for details about how to read +this output safely. -* date-format -* import-marks -* export-marks -* relative-marks -* no-relative-marks -* force +`ls` +~~~~ +Prints information about the object at a path to a file descriptor +previously arranged with the `--cat-blob-fd` argument. This allows +printing a blob from the active commit (with `cat-blob`) or copying a +blob or tree from a previous commit for use in the current one (with +`filemodify`). + +The `ls` command can be used anywhere in the stream that comments are +accepted, including the middle of a commit. + +Reading from the active commit:: + This form can only be used in the middle of a `commit`. + The path names a directory entry within fast-import's + active commit. The path must be quoted in this case. ++ +.... + 'ls' SP <path> LF +.... + +Reading from a named tree:: + The `<dataref>` can be a mark reference (`:<idnum>`) or the + full 40-byte SHA-1 of a Git tag, commit, or tree object, + preexisting or waiting to be written. + The path is relative to the top level of the tree + named by `<dataref>`. ++ +.... + 'ls' SP <dataref> SP <path> LF +.... + +See `filemodify` above for a detailed description of `<path>`. + +Output uses the same format as `git ls-tree <tree> -- <path>`: + +==== + <mode> SP ('blob' | 'tree' | 'commit') SP <dataref> HT <path> LF +==== + +The <dataref> represents the blob, tree, or commit object at <path> +and can be used in later 'cat-blob', 'filemodify', or 'ls' commands. + +If there is no file or subtree at that path, 'git fast-import' will +instead report + +==== + missing SP <path> LF +==== + +See ``Responses To Commands'' below for details about how to read +this output safely. + +`feature` +~~~~~~~~~ +Require that fast-import supports the specified feature, or abort if +it does not. -The import-marks behaves differently from when it is specified as -commandline option in that only one "feature import-marks" is allowed -per stream. Also, any --import-marks= specified on the commandline -will override those from the stream (if any). +.... + 'feature' SP <feature> ('=' <argument>)? LF +.... + +The <feature> part of the command may be any one of the following: + +date-format:: +export-marks:: +relative-marks:: +no-relative-marks:: +force:: + Act as though the corresponding command-line option with + a leading '--' was passed on the command line + (see OPTIONS, above). + +import-marks:: +import-marks-if-exists:: + Like --import-marks except in two respects: first, only one + "feature import-marks" or "feature import-marks-if-exists" + command is allowed per stream; second, an --import-marks= + or --import-marks-if-exists command-line option overrides + any of these "feature" commands in the stream; third, + "feature import-marks-if-exists" like a corresponding + command-line option silently skips a nonexistent file. + +cat-blob:: +ls:: + Require that the backend support the 'cat-blob' or 'ls' command. + Versions of fast-import not supporting the specified command + will exit with a message indicating so. + This lets the import error out early with a clear message, + rather than wasting time on the early part of an import + before the unsupported command is detected. + +notes:: + Require that the backend support the 'notemodify' (N) + subcommand to the 'commit' command. + Versions of fast-import not supporting notes will exit + with a message indicating so. + +done:: + Error out if the stream ends without a 'done' command. + Without this feature, errors causing the frontend to end + abruptly at a convenient point in the stream can go + undetected. `option` ~~~~~~~~ @@ -926,8 +1074,47 @@ not be passed as option: * date-format * import-marks * export-marks +* cat-blob-fd * force +`done` +~~~~~~ +If the `done` feature is not in use, treated as if EOF was read. +This can be used to tell fast-import to finish early. + +If the `--done` command line option or `feature done` command is +in use, the `done` command is mandatory and marks the end of the +stream. + +Responses To Commands +--------------------- +New objects written by fast-import are not available immediately. +Most fast-import commands have no visible effect until the next +checkpoint (or completion). The frontend can send commands to +fill fast-import's input pipe without worrying about how quickly +they will take effect, which improves performance by simplifying +scheduling. + +For some frontends, though, it is useful to be able to read back +data from the current repository as it is being updated (for +example when the source material describes objects in terms of +patches to be applied to previously imported objects). This can +be accomplished by connecting the frontend and fast-import via +bidirectional pipes: + +==== + mkfifo fast-import-output + frontend <fast-import-output | + git fast-import >fast-import-output +==== + +A frontend set up this way can use `progress`, `ls`, and `cat-blob` +commands to read information from the import in progress. + +To avoid deadlock, such frontends must completely consume any +pending output from `progress`, `ls`, and `cat-blob` before +performing writes to fast-import that might block. + Crash Reports ------------- If fast-import is supplied invalid input it will terminate with a @@ -1226,14 +1413,13 @@ and lazy loading of subtrees, allows fast-import to efficiently import projects with 2,000+ branches and 45,114+ files in a very limited memory footprint (less than 2.7 MiB per active branch). - -Author ------- -Written by Shawn O. Pearce <spearce@spearce.org>. - -Documentation --------------- -Documentation by Shawn O. Pearce <spearce@spearce.org>. +Signals +------- +Sending *SIGUSR1* to the 'git fast-import' process ends the current +packfile early, simulating a `checkpoint` command. The impatient +operator can use this facility to peek at the objects and refs from an +import in progress, at the cost of some added running time and worse +compression. GIT --- |