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[PATCH v2 2/6] remote-curl: add 'get' capability

From
Derrick Stolee via GitGitGadget <gitgitgadget@gmail.com>
Date
Jun 29, 2022, 20:40 UTC
Message-ID
<0a2cf60437f781588ae8dd77963901e4e9014959.1656535245.git.gitgitgadget@gmail.com>
In-Reply-To
<pull.1248.v2.git.1656535245.gitgitgadget@gmail.com>
From: Derrick Stolee <derrickstolee@github.com>

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@github.com>
---
 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;
 
 	/*
 	 * 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
Previous: Derrick Stolee via GitGitGadgetNext: Josh Steadmon
Message 28 of 64 in “bundle URIs: design doc and initial git fetch --bundle-uri implementation”
  1. 0/6 bundle URIs: design doc and initial git fetch --bundle-uri implementationDerrick Stolee via GitGitGadget, Jun 6, 2022
  2. 6/6 fetch: add 'refs/bundle/' to log.excludeDecorationDerrick Stolee via GitGitGadget, Jun 6, 2022
  3. 4/6 fetch: add --bundle-uri optionDerrick Stolee via GitGitGadget, Jun 6, 2022
  4. 5/6 bundle-uri: add support for http(s):// and file://Derrick Stolee via GitGitGadget, Jun 6, 2022
  5. 3/6 bundle-uri: create basic file-copy logicDerrick Stolee via GitGitGadget, Jun 6, 2022
  6. 1/6 docs: document bundle URI standardDerrick Stolee via GitGitGadget, Jun 6, 2022
  7. Junio C HamanoJun 6, 2022
  8. Derrick StoleeJun 8, 2022
  9. Junio C HamanoJun 8, 2022
  10. Junio C HamanoJun 8, 2022
  11. Junio C HamanoJun 8, 2022
  12. Derrick StoleeJun 8, 2022
  13. Junio C HamanoJun 7, 2022
  14. Derrick StoleeJun 8, 2022
  15. Junio C HamanoJun 8, 2022
  16. Derrick StoleeJun 9, 2022
  17. Junio C HamanoJun 9, 2022
  18. Ævar Arnfjörð BjarmasonJun 9, 2022
  19. Derrick StoleeJun 9, 2022
  20. Junio C HamanoJun 9, 2022
  21. Derrick StoleeJun 21, 2022
  22. Junio C HamanoJun 21, 2022
  23. Derrick StoleeJun 21, 2022
  24. Junio C HamanoJun 21, 2022
  25. 2/6 remote-curl: add 'get' capabilityDerrick Stolee via GitGitGadget, Jun 6, 2022
  26. Junio C HamanoJul 21, 2022
  27. 0/6 bundle URIs: design doc and initial git fetch --bundle-uri implementationDerrick Stolee via GitGitGadget, Jun 29, 2022
  28. 2/6 remote-curl: add 'get' capabilityDerrick Stolee via GitGitGadget, Jun 29, 2022
  29. Josh SteadmonJul 21, 2022
  30. 3/6 bundle-uri: create basic file-copy logicDerrick Stolee via GitGitGadget, Jun 29, 2022
  31. Josh SteadmonJul 21, 2022
  32. Derrick StoleeJul 22, 2022
  33. 1/6 docs: document bundle URI standardDerrick Stolee via GitGitGadget, Jun 29, 2022
  34. SZEDER GáborJul 18, 2022
  35. Matthew John CheethamJul 21, 2022
  36. Derrick StoleeJul 22, 2022
  37. Derrick StoleeJul 22, 2022
  38. Josh SteadmonJul 21, 2022
  39. Derrick StoleeJul 22, 2022
  40. Derrick StoleeJul 22, 2022
  41. 4/6 fetch: add --bundle-uri optionDerrick Stolee via GitGitGadget, Jun 29, 2022
  42. 5/6 bundle-uri: add support for http(s):// and file://Derrick Stolee via GitGitGadget, Jun 29, 2022
  43. 6/6 fetch: add 'refs/bundle/' to log.excludeDecorationDerrick Stolee via GitGitGadget, Jun 29, 2022
  44. Josh SteadmonJul 21, 2022
  45. Derrick StoleeJul 22, 2022
  46. Josh SteadmonJul 21, 2022
  47. Junio C HamanoJul 21, 2022
  48. 0/2 bundle URIs: design doc and initial git fetch --bundle-uri implementationDerrick Stolee via GitGitGadget, Jul 25, 2022
  49. 2/2 bundle-uri: add example bundle organizationDerrick Stolee via GitGitGadget, Jul 25, 2022
  50. Matthew John CheethamAug 4, 2022
  51. Derrick StoleeAug 4, 2022
  52. Ævar Arnfjörð BjarmasonAug 4, 2022
  53. Derrick StoleeAug 5, 2022
  54. 1/2 docs: document bundle URI standardDerrick Stolee via GitGitGadget, Jul 25, 2022
  55. 1/2 docs: document bundle URI standardtenglong.tl, Jul 28, 2022
  56. Derrick StoleeAug 1, 2022
  57. Josh SteadmonJul 25, 2022
  58. 0/2 bundle URIs: design docDerrick Stolee via GitGitGadget, Aug 9, 2022
  59. 1/2 docs: document bundle URI standardDerrick Stolee via GitGitGadget, Aug 9, 2022
  60. Philip OakleyOct 4, 2022
  61. 2/2 bundle-uri: add example bundle organizationDerrick Stolee via GitGitGadget, Aug 9, 2022
  62. Phillip WoodAug 9, 2022
  63. Derrick StoleeAug 9, 2022
  64. Phillip WoodAug 11, 2022

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