@matheusbsbs / matheus-bagliano / commits / cf7ee48190

agent: advertise OS name via agent capability

As some issues that can happen with a Git client can be operating system specific, it can be useful for a server to know which OS a client is using. In the same way it can be useful for a client to know which OS a server is using. Our current agent capability is in the form of "package/version" (e.g., "git/1.8.3.1"). Let's extend it to include the operating system name (os) i.e in the form "package/version-os" (e.g., "git/1.8.3.1-Linux"). Including OS details in the agent capability simplifies implementation, maintains backward compatibility, avoids introducing a new capability, encourages adoption across Git-compatible software, and enhances debugging by providing complete environment information without affecting functionality. The operating system name is retrieved using the 'sysname' field of the `uname(2)` system call or its equivalent. However, there are differences between `uname(1)` (command-line utility) and `uname(2)` (system call) outputs on Windows. These discrepancies complicate testing on Windows platforms. For example: - `uname(1)` output: MINGW64_NT-10.0-20348.3.4.10-87d57229.x86_64\ .2024-02-14.20:17.UTC.x86_64 - `uname(2)` output: Windows.10.0.20348 On Windows, uname(2) is not actually system-supplied but is instead already faked up by Git itself. We could have overcome the test issue on Windows by implementing a new `uname` subcommand in `test-tool` using uname(2), but except uname(2), which would be tested against itself, there would be nothing platform specific, so it's just simpler to disable the tests on Windows. Mentored-by: Christian Couder <chriscool@tuxfamily.org> Signed-off-by: Usman Akinyemi <usmanakinyemi202@gmail.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>

Usman Akinyemi committed Feb 15, 2025 at 21:20 UTC cf7ee481902df64b26ac8b1741eca861a8d2f7cc

6 files changed +62 -6

Documentation/gitprotocol-v2.txt

+7 -3

@@ -184,9 +184,13 @@ form `agent=X`) to notify the client that the server is running version

184 the `agent` capability with a value `Y` (in the form `agent=Y`) in its

185 request to the server (but it MUST NOT do so if the server did not

186 advertise the agent capability). The `X` and `Y` strings may contain any

187 -printable ASCII characters except space (i.e., the byte range 32 < x <

188 -127), and are typically of the form "package/version" (e.g.,

189 -"git/1.8.3.1"). The agent strings are purely informative for statistics

187 +printable ASCII characters except space (i.e., the byte range 33 <= x <=

188 +126), and are typically of the form "package/version-os" (e.g.,

189 +"git/1.8.3.1-Linux") where `os` is the operating system name (e.g.,

190 +"Linux"). `X` and `Y` can be configured using the GIT_USER_AGENT

191 +environment variable and it takes priority. The `os` is

192 +retrieved using the 'sysname' field of the `uname(2)` system call

193 +or its equivalent. The agent strings are purely informative for statistics

194 and debugging purposes, and MUST NOT be used to programmatically assume

195 the presence or absence of particular features.

196

connect.c

+1 -1

@@ -625,7 +625,7 @@ const char *parse_feature_value(const char *feature_list, const char *feature, s

625 *offset = found + len - orig_start;

626 return value;

627 }

628 - /* feature with a value (e.g., "agent=git/1.2.3") */

628 + /* feature with a value (e.g., "agent=git/1.2.3-Linux") */

629 else if (*value == '=') {

630 size_t end;

631

t/t5701-git-serve.sh

+15 -1

@@ -8,13 +8,19 @@ export GIT_TEST_DEFAULT_INITIAL_BRANCH_NAME

8 . ./test-lib.sh

10 test_expect_success 'setup to generate files with expected content' '

11 - printf "agent=git/%s\n" "$(git version | cut -d" " -f3)" >agent_capability &&

11 + printf "agent=git/%s" "$(git version | cut -d" " -f3)" >agent_capability &&

13 test_oid_cache <<-EOF &&

14 wrong_algo sha1:sha256

15 wrong_algo sha256:sha1

16 EOF

18 + if test_have_prereq WINDOWS

19 + then

20 + printf "agent=FAKE\n" >agent_capability

21 + else

22 + printf -- "-%s\n" $(uname -s | test_redact_non_printables) >>agent_capability

23 + fi &&

24 cat >expect.base <<-EOF &&

25 version 2

26 $(cat agent_capability)

@@ -31,6 +37,10 @@ test_expect_success 'setup to generate files with expected content' '

37 test_expect_success 'test capability advertisement' '

38 cat expect.base expect.trailer >expect &&

40 + if test_have_prereq WINDOWS

41 + then

42 + GIT_USER_AGENT=FAKE && export GIT_USER_AGENT

43 + fi &&

44 GIT_TEST_SIDEBAND_ALL=0 test-tool serve-v2 \

45 --advertise-capabilities >out &&

46 test-tool pkt-line unpack <out >actual &&

@@ -361,6 +371,10 @@ test_expect_success 'test capability advertisement with uploadpack.advertiseBund

371 expect.extra \

372 expect.trailer >expect &&

373

374 + if test_have_prereq WINDOWS

375 + then

376 + GIT_USER_AGENT=FAKE && export GIT_USER_AGENT

377 + fi &&

378 GIT_TEST_SIDEBAND_ALL=0 test-tool serve-v2 \

379 --advertise-capabilities >out &&

380 test-tool pkt-line unpack <out >actual &&

t/test-lib-functions.sh

@@ -2007,3 +2007,11 @@ test_trailing_hash () {

2007 test-tool hexdump |

2008 sed "s/ //g"

2009 }

2010 +

2011 +# Trim and replace each character with ascii code below 32 or above

2012 +# 127 (included) using a dot '.' character.

2013 +# Octal intervals \001-\040 and \177-\377

2014 +# correspond to decimal intervals 1-32 and 127-255

2015 +test_redact_non_printables () {

2016 + tr -d "\n\r" | tr "[\001-\040][\177-\377]" "."

2017 +}

version.c

+28 -1

@@ -1,8 +1,9 @@

1 +#define USE_THE_REPOSITORY_VARIABLE

2 +

3 #include "git-compat-util.h"

4 #include "version.h"

5 #include "version-def.h"

6 #include "strbuf.h"

5 -#include "sane-ctype.h"

7 #include "gettext.h"

9 const char git_version_string[] = GIT_VERSION;

@@ -34,6 +35,27 @@ const char *git_user_agent(void)

35 return agent;

36 }

38 +/*

39 + Retrieve, sanitize and cache operating system info for subsequent

40 + calls. Return a pointer to the sanitized operating system info

41 + string.

42 +*/

43 +static const char *os_info(void)

44 +{

45 + static const char *os = NULL;

46 +

47 + if (!os) {

48 + struct strbuf buf = STRBUF_INIT;

49 +

50 + get_uname_info(&buf, 0);

51 + /* Sanitize the os information immediately */

52 + redact_non_printables(&buf);

53 + os = strbuf_detach(&buf, NULL);

54 + }

55 +

56 + return os;

57 +}

58 +

59 const char *git_user_agent_sanitized(void)

60 {

61 static const char *agent = NULL;

@@ -42,6 +64,11 @@ const char *git_user_agent_sanitized(void)

64 struct strbuf buf = STRBUF_INIT;

66 strbuf_addstr(&buf, git_user_agent());

67 +

68 + if (!getenv("GIT_USER_AGENT")) {

69 + strbuf_addch(&buf, '-');

70 + strbuf_addstr(&buf, os_info());

71 + }

72 redact_non_printables(&buf);

73 agent = strbuf_detach(&buf, NULL);

74 }

version.h

@@ -1,6 +1,8 @@

1 #ifndef VERSION_H

2 #define VERSION_H

4 +struct repository;

5 +

6 extern const char git_version_string[];

7 extern const char git_built_from_commit_string[];

@@ -14,4 +16,5 @@ const char *git_user_agent_sanitized(void);

16 */

17 int get_uname_info(struct strbuf *buf, unsigned int full);

19 +

20 #endif /* VERSION_H */