fast-import: add a get-mark command
It is sometimes useful for importers to be able to read the SHA-1 corresponding to a mark that they have created via fast-import. For example, they might want to embed the SHA-1 into the commit message of a later commit. Or it might be useful for internal bookkeeping uses, or for logging. Add a "get-mark" command to "git fast-import" that allows the importer to ask for the value of a mark that has been created earlier. Signed-off-by: Michael Haggerty <mhagger@alum.mit.edu> Signed-off-by: Junio C Hamano <gitster@pobox.com>
Michael Haggerty committed
Jul 1, 2015 at 17:05 UTC
28c7b1f7b7b70013c2f380c2d720d0c918d3d83a
3 files changed
+75
-10
Documentation/git-fast-import.txt
+33
-6
@@ -54,7 +54,7 @@ Options for Frontends
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~~~~~~~~~~~~~~~~~~~~~
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--cat-blob-fd=<fd>::
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- Write responses to `cat-blob` and `ls` queries to the
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+ Write responses to `get-mark`, `cat-blob`, and `ls` queries to the
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file descriptor <fd> instead of `stdout`. Allows `progress`
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output intended for the end-user to be separated from other
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output.
@@ -350,6 +350,11 @@ and control the current import process. More detailed discussion
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unless the `done` feature was requested using the
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`--done` command-line option or `feature done` command.
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+`get-mark`::
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+ Causes fast-import to print the SHA-1 corresponding to a mark
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+ to the file descriptor set with `--cat-blob-fd`, or `stdout` if
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+ unspecified.
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+
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`cat-blob`::
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Causes fast-import to print a blob in 'cat-file --batch'
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format to the file descriptor set with `--cat-blob-fd` or
@@ -930,6 +935,25 @@ Placing a `progress` command immediately after a `checkpoint` will
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inform the reader when the `checkpoint` has been completed and it
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can safely access the refs that fast-import updated.
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+`get-mark`
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+~~~~~~~~~~
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+Causes fast-import to print the SHA-1 corresponding to a mark to
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+stdout or to the file descriptor previously arranged with the
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+`--cat-blob-fd` argument. The command otherwise has no impact on the
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+current import; its purpose is to retrieve SHA-1s that later commits
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+might want to refer to in their commit messages.
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+
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+....
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+ 'get-mark' SP ':' <idnum> LF
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+....
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+
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+This command can be used anywhere in the stream that comments are
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+accepted. In particular, the `get-mark` command can be used in the
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+middle of a commit but not in the middle of a `data` command.
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+
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+See ``Responses To Commands'' below for details about how to read
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+this output safely.
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+
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`cat-blob`
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~~~~~~~~~~
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Causes fast-import to print a blob to a file descriptor previously
@@ -1000,7 +1024,8 @@ Output uses the same format as `git ls-tree <tree> -- <path>`:
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====
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The <dataref> represents the blob, tree, or commit object at <path>
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-and can be used in later 'cat-blob', 'filemodify', or 'ls' commands.
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+and can be used in later 'get-mark', 'cat-blob', 'filemodify', or
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+'ls' commands.
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If there is no file or subtree at that path, 'git fast-import' will
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instead report
@@ -1042,9 +1067,11 @@ import-marks-if-exists::
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"feature import-marks-if-exists" like a corresponding
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command-line option silently skips a nonexistent file.
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+get-mark::
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cat-blob::
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ls::
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- Require that the backend support the 'cat-blob' or 'ls' command.
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+ Require that the backend support the 'get-mark', 'cat-blob',
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+ or 'ls' command respectively.
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Versions of fast-import not supporting the specified command
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will exit with a message indicating so.
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This lets the import error out early with a clear message,
@@ -1124,11 +1151,11 @@ bidirectional pipes:
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git fast-import >fast-import-output
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====
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-A frontend set up this way can use `progress`, `ls`, and `cat-blob`
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-commands to read information from the import in progress.
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+A frontend set up this way can use `progress`, `get-mark`, `ls`, and
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+`cat-blob` commands to read information from the import in progress.
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To avoid deadlock, such frontends must completely consume any
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-pending output from `progress`, `ls`, and `cat-blob` before
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+pending output from `progress`, `ls`, `get-mark`, and `cat-blob` before
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performing writes to fast-import that might block.
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Crash Reports
fast-import.c
+29
-4
@@ -134,16 +134,17 @@ Format of STDIN stream:
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ts ::= # time since the epoch in seconds, ascii base10 notation;
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tz ::= # GIT style timezone;
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- # note: comments, ls and cat requests may appear anywhere
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- # in the input, except within a data command. Any form
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- # of the data command always escapes the related input
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- # from comment processing.
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+ # note: comments, get-mark, ls-tree, and cat-blob requests may
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+ # appear anywhere in the input, except within a data command. Any
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+ # form of the data command always escapes the related input from
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+ # comment processing.
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#
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# In case it is not clear, the '#' that starts the comment
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# must be the first character on that line (an lf
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# preceded it).
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#
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+ get_mark ::= 'get-mark' sp idnum lf;
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cat_blob ::= 'cat-blob' sp (hexsha1 | idnum) lf;
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ls_tree ::= 'ls' sp (hexsha1 | idnum) sp path_str lf;
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@@ -372,6 +373,7 @@ static volatile sig_atomic_t checkpoint_requested;
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static int cat_blob_fd = STDOUT_FILENO;
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static void parse_argv(void);
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+static void parse_get_mark(const char *p);
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static void parse_cat_blob(const char *p);
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static void parse_ls(const char *p, struct branch *b);
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@@ -1907,6 +1909,10 @@ static int read_next_command(void)
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rc->prev->next = rc;
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cmd_tail = rc;
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}
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+ if (skip_prefix(command_buf.buf, "get-mark ", &p)) {
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+ parse_get_mark(p);
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+ continue;
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+ }
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if (skip_prefix(command_buf.buf, "cat-blob ", &p)) {
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parse_cat_blob(p);
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continue;
@@ -2919,6 +2925,23 @@ static void cat_blob(struct object_entry *oe, unsigned char sha1[20])
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free(buf);
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}
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+static void parse_get_mark(const char *p)
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+{
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+ struct object_entry *oe = oe;
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+ char output[42];
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+
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+ /* get-mark SP <object> LF */
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+ if (*p != ':')
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+ die("Not a mark: %s", p);
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+
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+ oe = find_mark(parse_mark_ref_eol(p));
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+ if (!oe)
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+ die("Unknown mark: %s", command_buf.buf);
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+
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+ snprintf(output, sizeof(output), "%s\n", sha1_to_hex(oe->idx.sha1));
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+ cat_blob_write(output, 41);
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+}
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+
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static void parse_cat_blob(const char *p)
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{
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struct object_entry *oe = oe;
@@ -3243,6 +3266,8 @@ static int parse_one_feature(const char *feature, int from_stream)
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option_import_marks(arg, from_stream, 1);
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} else if (skip_prefix(feature, "export-marks=", &arg)) {
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option_export_marks(arg);
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+ } else if (!strcmp(feature, "get-mark")) {
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+ ; /* Don't die - this feature is supported */
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} else if (!strcmp(feature, "cat-blob")) {
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; /* Don't die - this feature is supported */
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} else if (!strcmp(feature, "relative-marks")) {
t/t9300-fast-import.sh
+13
@@ -2339,6 +2339,19 @@ test_expect_success !MINGW 'R: in-stream cat-blob-fd not respected' '
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test_cmp expect actual.1
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'
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+test_expect_success !MINGW 'R: print mark for new blob' '
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+ echo "effluentish" | git hash-object --stdin >expect &&
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+ git fast-import --cat-blob-fd=6 6>actual <<-\EOF &&
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+ blob
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+ mark :1
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+ data <<BLOB_END
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+ effluentish
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+ BLOB_END
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+ get-mark :1
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+ EOF
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+ test_cmp expect actual
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+'
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+
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test_expect_success !MINGW 'R: print new blob' '
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blob=$(echo "yep yep yep" | git hash-object --stdin) &&
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cat >expect <<-EOF &&