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@xxxxxxxxxxxx>
---
This is something that we need for an internal GitHub project, but I
think it will also be of general interest.
Documentation/git-fast-import.txt | 39 +++++++++++++++++++++++++++++++++------
fast-import.c | 33 +++++++++++++++++++++++++++++----
t/t9300-fast-import.sh | 13 +++++++++++++
3 files changed, 75 insertions(+), 10 deletions(-)
diff --git a/Documentation/git-fast-import.txt b/Documentation/git-fast-import.txt
index fd32895..66910aa 100644
--- a/Documentation/git-fast-import.txt
+++ b/Documentation/git-fast-import.txt
@@ -54,7 +54,7 @@ Options for Frontends
~~~~~~~~~~~~~~~~~~~~~
--cat-blob-fd=<fd>::
- Write responses to `cat-blob` and `ls` queries to the
+ Write responses to `get-mark`, `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.
@@ -350,6 +350,11 @@ and control the current import process. More detailed discussion
unless the `done` feature was requested using the
`--done` command-line option or `feature done` command.
+`get-mark`::
+ Causes fast-import to print the SHA-1 corresponding to a mark
+ to the file descriptor set with `--cat-blob-fd`, or `stdout` if
+ unspecified.
+
`cat-blob`::
Causes fast-import to print a blob in 'cat-file --batch'
format to the file descriptor set with `--cat-blob-fd` or
@@ -930,6 +935,25 @@ 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.
+`get-mark`
+~~~~~~~~~~
+Causes fast-import to print the SHA-1 corresponding to a mark to
+stdout or to the file descriptor previously arranged with the
+`--cat-blob-fd` argument. The command otherwise has no impact on the
+current import; its purpose is to retrieve SHA-1s that later commits
+might want to refer to in their commit messages.
+
+....
+ 'get-mark' SP ':' <idnum> LF
+....
+
+This command can be used anywhere in the stream that comments are
+accepted. In particular, the `get-mark` command can be used in the
+middle of a commit but not in the middle of a `data` command.
+
+See ``Responses To Commands'' below for details about how to read
+this output safely.
+
`cat-blob`
~~~~~~~~~~
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>`:
====
The <dataref> represents the blob, tree, or commit object at <path>
-and can be used in later 'cat-blob', 'filemodify', or 'ls' commands.
+and can be used in later 'get-mark', 'cat-blob', 'filemodify', or
+'ls' commands.
If there is no file or subtree at that path, 'git fast-import' will
instead report
@@ -1042,9 +1067,11 @@ import-marks-if-exists::
"feature import-marks-if-exists" like a corresponding
command-line option silently skips a nonexistent file.
+get-mark::
cat-blob::
ls::
- Require that the backend support the 'cat-blob' or 'ls' command.
+ Require that the backend support the 'get-mark', 'cat-blob',
+ or 'ls' command respectively.
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,
@@ -1124,11 +1151,11 @@ bidirectional pipes:
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.
+A frontend set up this way can use `progress`, `get-mark`, `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
+pending output from `progress`, `ls`, `get-mark`, and `cat-blob` before
performing writes to fast-import that might block.
Crash Reports
diff --git a/fast-import.c b/fast-import.c
index 6378726..1ba83d6 100644
--- a/fast-import.c
+++ b/fast-import.c
@@ -134,16 +134,17 @@ Format of STDIN stream:
ts ::= # time since the epoch in seconds, ascii base10 notation;
tz ::= # GIT style timezone;
- # note: comments, ls and cat requests may appear anywhere
- # in the input, except within a data command. Any form
- # of the data command always escapes the related input
- # from comment processing.
+ # note: comments, get-mark, ls-tree, and cat-blob requests may
+ # appear anywhere in the input, except within a data command. Any
+ # form of the data command always escapes the related input from
+ # comment processing.
#
# In case it is not clear, the '#' that starts the comment
# must be the first character on that line (an lf
# preceded it).
#
+ get_mark ::= 'get-mark' sp idnum lf;
cat_blob ::= 'cat-blob' sp (hexsha1 | idnum) lf;
ls_tree ::= 'ls' sp (hexsha1 | idnum) sp path_str lf;
@@ -372,6 +373,7 @@ static volatile sig_atomic_t checkpoint_requested;
static int cat_blob_fd = STDOUT_FILENO;
static void parse_argv(void);
+static void parse_get_mark(const char *p);
static void parse_cat_blob(const char *p);
static void parse_ls(const char *p, struct branch *b);
@@ -1907,6 +1909,10 @@ static int read_next_command(void)
rc->prev->next = rc;
cmd_tail = rc;
}
+ if (skip_prefix(command_buf.buf, "get-mark ", &p)) {
+ parse_get_mark(p);
+ continue;
+ }
if (skip_prefix(command_buf.buf, "cat-blob ", &p)) {
parse_cat_blob(p);
continue;
@@ -2919,6 +2925,23 @@ static void cat_blob(struct object_entry *oe, unsigned char sha1[20])
free(buf);
}
+static void parse_get_mark(const char *p)
+{
+ struct object_entry *oe = oe;
+ char output[42];
+
+ /* get-mark SP <object> LF */
+ if (*p != ':')
+ die("Not a mark: %s", p);
+
+ oe = find_mark(parse_mark_ref_eol(p));
+ if (!oe)
+ die("Unknown mark: %s", command_buf.buf);
+
+ snprintf(output, sizeof(output), "%s\n", sha1_to_hex(oe->idx.sha1));
+ cat_blob_write(output, 41);
+}
+
static void parse_cat_blob(const char *p)
{
struct object_entry *oe = oe;
@@ -3240,6 +3263,8 @@ static int parse_one_feature(const char *feature, int from_stream)
option_import_marks(arg, from_stream, 1);
} else if (skip_prefix(feature, "export-marks=", &arg)) {
option_export_marks(arg);
+ } else if (!strcmp(feature, "get-mark")) {
+ ; /* Don't die - this feature is supported */
} else if (!strcmp(feature, "cat-blob")) {
; /* Don't die - this feature is supported */
} else if (!strcmp(feature, "relative-marks")) {
diff --git a/t/t9300-fast-import.sh b/t/t9300-fast-import.sh
index aac126f..9984c48 100755
--- a/t/t9300-fast-import.sh
+++ b/t/t9300-fast-import.sh
@@ -2339,6 +2339,19 @@ test_expect_success !MINGW 'R: in-stream cat-blob-fd not respected' '
test_cmp expect actual.1
'
+test_expect_success !MINGW 'R: print mark for new blob' '
+ echo "effluentish" | git hash-object --stdin >expect &&
+ git fast-import --cat-blob-fd=6 6>actual <<-\EOF &&
+ blob
+ mark :1
+ data <<BLOB_END
+ effluentish
+ BLOB_END
+ get-mark :1
+ EOF
+ test_cmp expect actual
+'
+
test_expect_success !MINGW 'R: print new blob' '
blob=$(echo "yep yep yep" | git hash-object --stdin) &&
cat >expect <<-EOF &&
--
2.1.4
--
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