As the description of the "progress" option in git-fast-import.1
hints, there is no convenient way to immediately access the blobs
written to a new repository through fast-import. Until a checkpoint
has been started and finishes writing the pack index, any new blobs
will not be accessible using standard git tools.
So introduce another way: a "cat-blob" command introduced in the
command stream requests for fast-import to print a blob to stdout
or a file descriptor specified by the argument --cat-blob-fd.
The output uses the same format as "git cat-file --batch".
Cc: Shawn O. Pearce <spearce@xxxxxxxxxxx>
Cc: Ramkumar Ramachandra <artagnon@xxxxxxxxx>
Helped-by: Sverre Rabbelier <srabbelier@xxxxxxxxx>
Based-on-patch-by: Jonathan Nieder <jrnieder@xxxxxxxxx>
Signed-off-by: David Barr <david.barr@xxxxxxxxxxxx>
---
Documentation/git-fast-import.txt | 34 ++++++++++++++
fast-import.c | 92 +++++++++++++++++++++++++++++++++++++
2 files changed, 126 insertions(+), 0 deletions(-)
diff --git a/Documentation/git-fast-import.txt b/Documentation/git-fast-import.txt
index 966ba4f..42a100b 100644
--- a/Documentation/git-fast-import.txt
+++ b/Documentation/git-fast-import.txt
@@ -92,6 +92,17 @@ OPTIONS
--(no-)-relative-marks= with the --(import|export)-marks=
options.
+--cat-blob-fd=<fd>::
+ Specify the file descriptor that will be written to
+ when the `cat-blob` command is encountered in the stream.
+ The default behaviour is to write to `stdout`.
++
+The described objects are not necessarily accessible
+using standard git plumbing tools until a little while
+after the next checkpoint. To request access to the
+blobs before then, use `cat-blob` lines in the command
+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
@@ -320,6 +331,11 @@ and control the current import process. More detailed discussion
standard output. This command is optional and is not needed
to perform an import.
+`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.
+
`feature`::
Require that fast-import supports the specified feature, or
abort if it does not.
@@ -876,6 +892,23 @@ 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.
+`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 a little quicker than by the
+method suggested by the description of the `progress` option.
+
+....
+ 'cat-blob' SP <dataref> LF
+....
+
+The `<dataref>` can be either a mark reference (`:<idnum>`)
+set previously, or a full 40-byte SHA-1 of any Git blob,
+preexisting or ready to be written.
+
`feature`
~~~~~~~~~
Require that fast-import supports the specified feature, or abort if
@@ -896,6 +929,7 @@ The following features are currently supported:
* date-format
* import-marks
* export-marks
+* cat-blob
* relative-marks
* no-relative-marks
* force
diff --git a/fast-import.c b/fast-import.c
index 2317b0f..ea3e529 100644
--- a/fast-import.c
+++ b/fast-import.c
@@ -55,6 +55,8 @@ Format of STDIN stream:
('from' sp committish lf)?
lf?;
+ cat_blob ::= 'cat-blob' sp (hexsha1 | idnum) lf;
+
checkpoint ::= 'checkpoint' lf
lf?;
@@ -361,6 +363,9 @@ static uintmax_t next_mark;
static struct strbuf new_data = STRBUF_INIT;
static int seen_data_command;
+/* Where to write output of cat-blob commands */
+static int cat_blob_fd = 1;
+
static void parse_argv(void);
static void write_branch_report(FILE *rpt, struct branch *b)
@@ -2680,6 +2685,77 @@ static void parse_reset_branch(void)
unread_command_buf = 1;
}
+static void cat_blob_write(const char *buf, unsigned long size)
+{
+ if (write_in_full(cat_blob_fd, buf, size) != size)
+ die_errno("Write to frontend failed");
+}
+
+static void cat_blob(struct object_entry *oe, unsigned char sha1[20])
+{
+ struct strbuf line = STRBUF_INIT;
+ unsigned long size;
+ enum object_type type = 0;
+ char *buf;
+
+ if (oe && oe->pack_id != MAX_PACK_ID) {
+ type = oe->type;
+ buf = gfi_unpack_entry(oe, &size);
+ } else {
+ buf = read_sha1_file(sha1, &type, &size);
+ }
+ if (!buf)
+ die("Can't read object %s", sha1_to_hex(sha1));
+
+ /*
+ * Output based on batch_one_object() from cat-file.c.
+ */
+ if (type <= 0) {
+ strbuf_reset(&line);
+ strbuf_addf(&line, "%s missing\n", sha1_to_hex(sha1));
+ cat_blob_write(line.buf, line.len);
+ return;
+ } else if (type != OBJ_BLOB) {
+ die("Object %s is a %s but a blob was expected.",
+ sha1_to_hex(sha1), typename(type));
+ }
+ strbuf_reset(&line);
+ strbuf_addf(&line, "%s %s %lu\n", sha1_to_hex(sha1),
+ typename(type), size);
+ cat_blob_write(line.buf, line.len);
+ cat_blob_write(buf, size);
+ cat_blob_write("\n", 1);
+ free(buf);
+}
+
+
+static void parse_cat_blob(void)
+{
+ const char *p;
+ struct object_entry *oe = oe;
+ unsigned char sha1[20];
+
+ /* cat SP <object> */
+ p = command_buf.buf + strlen("cat-blob ");
+ if (*p == ':') {
+ char *x;
+ oe = find_mark(strtoumax(p + 1, &x, 10));
+ if (x == p + 1)
+ die("Invalid mark: %s", command_buf.buf);
+ if (!oe)
+ die("Unknown mark: %s", command_buf.buf);
+ p = x;
+ hashcpy(sha1, oe->idx.sha1);
+ } else {
+ if (get_sha1_hex(p, sha1))
+ die("Invalid SHA1: %s", command_buf.buf);
+ p += 40;
+ oe = find_object(sha1);
+ }
+
+ cat_blob(oe, sha1);
+}
+
static void parse_checkpoint(void)
{
if (object_count) {
@@ -2755,6 +2831,14 @@ static void option_export_marks(const char *marks)
safe_create_leading_directories_const(export_marks_file);
}
+static void option_cat_blob_fd(const char *fd)
+{
+ unsigned long n = strtoul(fd, NULL, 0);
+ if (n > (unsigned long) INT_MAX)
+ die("--cat-blob-fd cannot exceed %d", INT_MAX);
+ cat_blob_fd = (int) n;
+}
+
static void option_export_pack_edges(const char *edges)
{
if (pack_edges)
@@ -2808,6 +2892,8 @@ static int parse_one_feature(const char *feature, int from_stream)
option_import_marks(feature + 13, from_stream);
} else if (!prefixcmp(feature, "export-marks=")) {
option_export_marks(feature + 13);
+ } else if (!prefixcmp(feature, "cat-blob")) {
+ /* Don't die - this feature is supported */
} else if (!prefixcmp(feature, "relative-marks")) {
relative_marks_paths = 1;
} else if (!prefixcmp(feature, "no-relative-marks")) {
@@ -2896,6 +2982,10 @@ static void parse_argv(void)
if (*a != '-' || !strcmp(a, "--"))
break;
+ if (!prefixcmp(a + 2, "cat-blob-fd=")) {
+ option_cat_blob_fd(a + 2 + 12);
+ }
+
if (parse_one_option(a + 2))
continue;
@@ -2953,6 +3043,8 @@ int main(int argc, const char **argv)
parse_new_tag();
else if (!prefixcmp(command_buf.buf, "reset "))
parse_reset_branch();
+ else if (!prefixcmp(command_buf.buf, "cat-blob "))
+ parse_cat_blob();
else if (!strcmp("checkpoint", command_buf.buf))
parse_checkpoint();
else if (!prefixcmp(command_buf.buf, "progress "))
--
1.7.3.32.g634ef
--
To unsubscribe from this list: send the line "unsubscribe git" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html