[PATCH v2 6/6] version: introduce osversion.command config for os-version output

From

Usman Akinyemi <usmanakinyemi202@gmail.com>

Date

Jan 17, 2025, 10:46 UTC

Message-ID

<20250117104639.65608-7-usmanakinyemi202@gmail.com>

In-Reply-To

<20250117104639.65608-1-usmanakinyemi202@gmail.com>

Helped-by: Randall S. Becker <rsbecker@nexbridge.com>
Mentored-by: Christian Couder <chriscool@tuxfamily.org>
Signed-off-by: Usman Akinyemi <usmanakinyemi202@gmail.com>
---
 Documentation/config/transfer.txt | 11 ++++++-
 Documentation/gitprotocol-v2.txt  | 25 ++++++++-------
 t/t5555-http-smart-common.sh      | 28 +++++++++++++++++
 t/t5701-git-serve.sh              | 29 ++++++++++++++++++
 version.c                         | 51 ++++++++++++++++++++++++++++++-
 5 files changed, 129 insertions(+), 15 deletions(-)

diff --git a/Documentation/config/transfer.txt b/Documentation/config/transfer.txt
index c368a893bd..c9f38c5796 100644
--- a/Documentation/config/transfer.txt
+++ b/Documentation/config/transfer.txt
@@ -131,4 +131,13 @@ transfer.advertiseOSVersion::
 	servers. It makes clients and servers send to each other a string
 	representing the operating system name, like "Linux" or "Windows".
 	This string is retrieved from the `sysname` field of the struct returned
-	by the uname(2) system call. Defaults to true.
+	by the uname(2) system call. If the `osVersion.command` is set, the
+	output of the command specified will be the string exchanged by the clients
+	and the servers. Defaults to true.
+
+osVersion.command::
+	If this variable is set, the specified command will be run and the output
+	will be used as the value `X` for `os-version` capability (in the form
+	`os-version=X`). `osVersion.command` is only used if `transfer.advertiseOSVersion`
+	is true. Refer to the linkgit:git-config[1] documentation to learn more about
+	`transfer.advertiseOSVersion` config option.
diff --git a/Documentation/gitprotocol-v2.txt b/Documentation/gitprotocol-v2.txt
index a332b55e4c..93a2e97ec0 100644
--- a/Documentation/gitprotocol-v2.txt
+++ b/Documentation/gitprotocol-v2.txt
@@ -193,20 +193,19 @@ the presence or absence of particular features.
 os-version
 ~~~~~~~~~~
 
-In the same way as the `agent` capability above, the server can
-advertise the `os-version` capability to notify the client the
-kind of operating system it is running on. The client may optionally
-send its own `os-version` capability, to notify the server the kind of
-operating system it is also running on in its request to the server
-(but it MUST NOT do so if the server did not advertise the os-version
-capability). The value of this capability may consist of ASCII printable
+In the same way as the `agent` capability above, the server can advertise
+the `os-version` capability to notify the client the kind of operating system
+it is running on. The client may optionally send its own `os-version` capability,
+to notify the server the kind of operating system it is also running on in its
+request to the server (but it MUST NOT do so if the server did not advertise the
+os-version capability). The value of this capability may consist of ASCII printable
 characters(from 33 to 126 inclusive) and are typically made from the result of
-`uname -s`(OS name e.g Linux). The os-version capability can be disabled
-entirely by setting the `transfer.advertiseOSVersion` config option
-to `false`. The `os-version` strings are purely informative for
-statistics and debugging purposes, and MUST NOT be used to
-programmatically assume the presence or absence of particular
-features.
+`uname -s`(OS name e.g Linux). If the `osVersion.command` is set, the value of this
+capability are made from the ouput of the command specified. The os-version capability
+can be disabled entirely by setting the `transfer.advertiseOSVersion` config option
+to `false`. The `os-version` strings are purely informative for statistics and
+debugging purposes, and MUST NOT be used to programmatically assume the presence or
+absence of particular features.
 
 ls-refs
 ~~~~~~~
diff --git a/t/t5555-http-smart-common.sh b/t/t5555-http-smart-common.sh
index 6f357a005a..1a3df3d090 100755
--- a/t/t5555-http-smart-common.sh
+++ b/t/t5555-http-smart-common.sh
@@ -150,6 +150,34 @@ test_expect_success 'git upload-pack --advertise-refs: v2' '
 	test_cmp actual expect
 '
 
+test_expect_success 'git upload-pack --advertise-refs: v2 with osVersion.command config set' '
+	test_config osVersion.command "uname -srvm" &&
+	printf "agent=FAKE" >agent_and_long_osversion &&
+
+	if test_have_prereq !WINDOWS
+	then
+		printf "\nos-version=%s\n" $(uname -srvm | test_redact_non_printables) >>agent_and_long_osversion
+	fi &&
+
+	cat >expect <<-EOF &&
+	version 2
+	$(cat agent_and_long_osversion)
+	ls-refs=unborn
+	fetch=shallow wait-for-done
+	server-option
+	object-format=$(test_oid algo)
+	0000
+	EOF
+
+	GIT_PROTOCOL=version=2 \
+	GIT_USER_AGENT=FAKE \
+	git upload-pack --advertise-refs . >out 2>err &&
+
+	test-tool pkt-line unpack <out >actual &&
+	test_must_be_empty err &&
+	test_cmp actual expect
+'
+
 test_expect_success 'git receive-pack --advertise-refs: v2' '
 	# There is no v2 yet for receive-pack, implicit v0
 	cat >expect <<-EOF &&
diff --git a/t/t5701-git-serve.sh b/t/t5701-git-serve.sh
index 8a783b3924..1395ac4eba 100755
--- a/t/t5701-git-serve.sh
+++ b/t/t5701-git-serve.sh
@@ -53,6 +53,35 @@ test_expect_success 'test capability advertisement' '
 	test_cmp expect actual
 '
 
+test_expect_success 'test capability advertisement with osVersion.command config set' '
+	test_config osVersion.command "uname -srvm" &&
+	printf "agent=git/$(git version | cut -d" " -f3)" >agent_and_long_osversion &&
+
+	if test_have_prereq !WINDOWS
+	then
+		printf "\nos-version=%s\n" $(uname -srvm | test_redact_non_printables) >>agent_and_long_osversion
+	fi &&
+
+	test_oid_cache <<-EOF &&
+	wrong_algo sha1:sha256
+	wrong_algo sha256:sha1
+	EOF
+	cat >expect_long.base <<-EOF &&
+	version 2
+	$(cat agent_and_long_osversion)
+	ls-refs=unborn
+	fetch=shallow wait-for-done
+	server-option
+	object-format=$(test_oid algo)
+	EOF
+	cat expect_long.base expect.trailer >expect &&
+
+	GIT_TEST_SIDEBAND_ALL=0 test-tool serve-v2 \
+		--advertise-capabilities >out &&
+	test-tool pkt-line unpack <out >actual &&
+	test_cmp expect actual
+'
+
 test_expect_success 'stateless-rpc flag does not list capabilities' '
 	# Empty request
 	test-tool pkt-line pack >in <<-EOF &&
diff --git a/version.c b/version.c
index ea334c3e9c..2aa55e56b5 100644
--- a/version.c
+++ b/version.c
@@ -1,9 +1,13 @@
+#define USE_THE_REPOSITORY_VARIABLE
+
 #include "git-compat-util.h"
 #include "version.h"
 #include "version-def.h"
 #include "strbuf.h"
 #include "gettext.h"
 #include "config.h"
+#include "run-command.h"
+#include "alias.h"
 
 const char git_version_string[] = GIT_VERSION;
 const char git_built_from_commit_string[] = GIT_BUILT_FROM_COMMIT;
@@ -71,6 +75,50 @@ int get_uname_info(struct strbuf *buf, unsigned int full)
 	return 0;
 }
 
+/*
+ * Return -1 if unable to retrieve the osversion.command config or
+ * if the command is malformed; otherwise, return 0 if successful.
+ */
+static int fill_os_version_command(struct child_process *cmd)
+{
+	const char *os_version_command;
+	const char **argv;
+	char *os_version_copy;
+	int n;
+
+	if (git_config_get_string_tmp("osversion.command", &os_version_command))
+		return -1;
+
+	os_version_copy = xstrdup(os_version_command);
+	n = split_cmdline(os_version_copy, &argv);
+
+	if (n < 0) {
+		warning(_("malformed osVersion.command config option: %s"),
+			_(split_cmdline_strerror(n)));
+		free(os_version_copy);
+		return -1;
+	}
+
+	for (int i = 0; i < n; i++)
+		strvec_push(&cmd->args, argv[i]);
+	free(os_version_copy);
+	free(argv);
+
+	return 0;
+}
+
+static int capture_os_version(struct strbuf *buf)
+{
+	struct child_process cmd = CHILD_PROCESS_INIT;
+
+	if (fill_os_version_command(&cmd))
+		return -1;
+	if (capture_command(&cmd, buf, 0))
+		return -1;
+
+	return 0;
+}
+
 const char *os_version(void)
 {
 	static const char *os = NULL;
@@ -78,7 +126,8 @@ const char *os_version(void)
 	if (!os) {
 		struct strbuf buf = STRBUF_INIT;
 
-		get_uname_info(&buf, 0);
+		if (capture_os_version(&buf))
+			get_uname_info(&buf, 0);
 		os = strbuf_detach(&buf, NULL);
 	}
 

-- 
2.48.0