On 2022.06.29 20:40, Derrick Stolee via GitGitGadget wrote:
> From: Derrick Stolee <derrickstolee@xxxxxxxxxx>
>
> A future change will want a way to download a file over HTTP(S) using
> the simplest of download mechanisms. We do not want to assume that the
> server on the other side understands anything about the Git protocol but
> could be a simple static web server.
>
> Create the new 'get' capability for the remote helpers which advertises
> that the 'get' command is avalable. A caller can send a line containing
> 'get <url> <path>' to download the file at <url> into the file at
> <path>.
>
> Signed-off-by: Derrick Stolee <derrickstolee@xxxxxxxxxx>
> ---
> Documentation/gitremote-helpers.txt | 9 +++++++
> remote-curl.c | 33 +++++++++++++++++++++++++
> t/t5557-http-get.sh | 37 +++++++++++++++++++++++++++++
> transport-helper.c | 5 +++-
> 4 files changed, 83 insertions(+), 1 deletion(-)
> create mode 100755 t/t5557-http-get.sh
>
> diff --git a/Documentation/gitremote-helpers.txt b/Documentation/gitremote-helpers.txt
> index 6f1e269ae43..ed8da428c98 100644
> --- a/Documentation/gitremote-helpers.txt
> +++ b/Documentation/gitremote-helpers.txt
> @@ -168,6 +168,9 @@ Supported commands: 'list', 'import'.
> Can guarantee that when a clone is requested, the received
> pack is self contained and is connected.
>
> +'get'::
> + Can use the 'get' command to download a file from a given URI.
> +
> If a helper advertises 'connect', Git will use it if possible and
> fall back to another capability if the helper requests so when
> connecting (see the 'connect' command under COMMANDS).
> @@ -418,6 +421,12 @@ Supported if the helper has the "connect" capability.
> +
> Supported if the helper has the "stateless-connect" capability.
>
> +'get' <uri> <path>::
> + Downloads the file from the given `<uri>` to the given `<path>`. If
> + `<path>.temp` exists, then Git assumes that the `.temp` file is a
> + partial download from a previous attempt and will resume the
> + download from that position.
> +
> If a fatal error occurs, the program writes the error message to
> stderr and exits. The caller should expect that a suitable error
> message has been printed if the child closes the connection without
> diff --git a/remote-curl.c b/remote-curl.c
> index 67f178b1120..f005419f872 100644
> --- a/remote-curl.c
> +++ b/remote-curl.c
> @@ -1276,6 +1276,34 @@ static void parse_fetch(struct strbuf *buf)
> strbuf_reset(buf);
> }
>
> +static void parse_get(struct strbuf *buf)
> +{
> + struct http_get_options opts = { 0 };
> + struct strbuf url = STRBUF_INIT;
> + struct strbuf path = STRBUF_INIT;
> + const char *p, *space;
> +
> + if (!skip_prefix(buf->buf, "get ", &p))
> + die(_("http transport does not support %s"), buf->buf);
> +
> + space = strchr(p, ' ');
> +
> + if (!space)
> + die(_("protocol error: expected '<url> <path>', missing space"));
> +
> + strbuf_add(&url, p, space - p);
> + strbuf_addstr(&path, space + 1);
> +
> + if (http_get_file(url.buf, path.buf, &opts))
> + die(_("failed to download file at URL '%s'"), url.buf);
> +
> + strbuf_release(&url);
> + strbuf_release(&path);
> + printf("\n");
> + fflush(stdout);
> + strbuf_reset(buf);
> +}
> +
> static int push_dav(int nr_spec, const char **specs)
> {
> struct child_process child = CHILD_PROCESS_INIT;
> @@ -1549,9 +1577,14 @@ int cmd_main(int argc, const char **argv)
> printf("unsupported\n");
> fflush(stdout);
>
> + } else if (skip_prefix(buf.buf, "get ", &arg)) {
> + parse_get(&buf);
> + fflush(stdout);
> +
> } else if (!strcmp(buf.buf, "capabilities")) {
> printf("stateless-connect\n");
> printf("fetch\n");
> + printf("get\n");
> printf("option\n");
> printf("push\n");
> printf("check-connectivity\n");
> diff --git a/t/t5557-http-get.sh b/t/t5557-http-get.sh
> new file mode 100755
> index 00000000000..1fd4ded3eb1
> --- /dev/null
> +++ b/t/t5557-http-get.sh
> @@ -0,0 +1,37 @@
> +#!/bin/sh
> +
> +test_description='test downloading a file by URL'
> +
> +. ./test-lib.sh
> +
> +. "$TEST_DIRECTORY"/lib-httpd.sh
> +start_httpd
> +
> +test_expect_success 'get by URL: 404' '
> + url="$HTTPD_URL/none.txt" &&
> + cat >input <<-EOF &&
> + capabilities
> + get $url file1
> + EOF
> +
> + test_must_fail git remote-http $url $url <input 2>err &&
> + test_path_is_missing file1 &&
> + grep "failed to download file at URL" err &&
> + rm file1.temp
> +'
> +
> +test_expect_success 'get by URL: 200' '
> + echo data >"$HTTPD_DOCUMENT_ROOT_PATH/exists.txt" &&
> +
> + url="$HTTPD_URL/exists.txt" &&
> + cat >input <<-EOF &&
> + capabilities
> + get $url file2
> +
> + EOF
> +
> + GIT_TRACE2_PERF=1 git remote-http $url $url <input &&
> + test_cmp "$HTTPD_DOCUMENT_ROOT_PATH/exists.txt" file2
> +'
> +
> +test_done
> diff --git a/transport-helper.c b/transport-helper.c
> index b4dbbabb0c2..dfbeaebe40c 100644
> --- a/transport-helper.c
> +++ b/transport-helper.c
> @@ -33,7 +33,8 @@ struct helper_data {
> check_connectivity : 1,
> no_disconnect_req : 1,
> no_private_update : 1,
> - object_format : 1;
> + object_format : 1,
> + get : 1;
This new `get` field is set in the hunk below, but it never seems to be
accessed, even in later patches in this series.
>
> /*
> * As an optimization, the transport code may invoke fetch before
> @@ -210,6 +211,8 @@ static struct child_process *get_helper(struct transport *transport)
> data->no_private_update = 1;
> } else if (starts_with(capname, "object-format")) {
> data->object_format = 1;
> + } else if (!strcmp(capname, "get")) {
> + data->get = 1;
> } else if (mandatory) {
> die(_("unknown mandatory capability %s; this remote "
> "helper probably needs newer version of Git"),
> --
> gitgitgadget
>
