t5564: use a short path for the SOCKS proxy socket

From: Johannes Schindelin <[email protected]>

The SOCKS proxy test introduced in 0ca365c2ed4 (http: do not ignore proxy path, 2024-08-02) creates a Unix domain socket in $TRASH_DIRECTORY. When the trash directory path is long (e.g. when running from a deeply nested worktree), the socket path can exceed the 108-character limit for struct sockaddr_un.sun_path on Linux, causing the test to fail with "Path length ... is longer than maximum supported length (108)".

Move the socket to $TMPDIR (defaulting to /tmp) where the path is short, following the same approach used in t7528 for the SSH agent socket in b7fb2194b96 (t7528: work around ETOOMANY in OpenSSH 10.1 and newer, 2025-10-23).

---
t5564: use a short path for the SOCKS proxy socket

When trying to run the entire test suite in a slightly deeper path than usual, I was surprised to see that this test failed due to our old friend, the 108 character limit of Unix sockets.

Published-As: https://github.com/gitgitgadget/git/releases/tag/pr-2100%2Fdscho%2Favoid-too-long-unix-socket-path-in-socks-proxy-test-v1
Fetch-It-Via: git fetch https://github.com/gitgitgadget/git pr-2100/dscho/avoid-too-long-unix-socket-path-in-socks-proxy-test-v1
Pull-Request: https://github.com/gitgitgadget/git/pull/2100

 t/t5564-http-proxy.sh | 10 ++++++++--
 1 file changed, 8 insertions(+), 2 deletions(-)

index 3bcbdef409..cb7ede4ca4 100755
@@ -50,14 +50,19 @@ start_socks() {
 
 # The %30 tests that the correct amount of percent-encoding is applied to the
 # proxy string passed to curl.
+# Use a short path for the socket to avoid exceeding the 108-character
+# Unix domain socket limit when the trash directory path is long.
+SOCKS_SOCK="${TMPDIR:-/tmp}/git-test-socks-%30.sock"
+
 test_lazy_prereq SOCKS_PROXY '
 	test_have_prereq PERL &&
-	start_socks "$TRASH_DIRECTORY/%30.sock"
+	start_socks "$SOCKS_SOCK"
 '
 
 test_atexit '
 	test ! -e "$TRASH_DIRECTORY/socks.pid" ||
 	kill "$(cat "$TRASH_DIRECTORY/socks.pid")"
+	rm -f "$SOCKS_SOCK"
 '
 
 # The below tests morally ought to be gated on a prerequisite that Git is

@@ -70,7 +75,8 @@ old_libcurl_error() {
 
 test_expect_success SOCKS_PROXY 'clone via Unix socket' '
 	test_when_finished "rm -rf clone" &&
-	test_config_global http.proxy "socks4://localhost$PWD/%2530.sock" && {
+	socks_proxy_url="socks4://localhost$(echo "$SOCKS_SOCK" | sed "s/%/%25/g")" &&
+	test_config_global http.proxy "$socks_proxy_url" && {
 		{
 			GIT_TRACE_CURL=$PWD/trace \
 			GIT_TRACE_CURL_COMPONENTS=socks \

base-commit: 94f057755b7941b321fd11fec1b2e3ca5313a4e0

gitgitgadget

OK. We try to work around this with a chdir in our own socket code, but I guess we're not using it here:

1. The socket is created by our socks4-proxy.pl script, which just feeds it to perl's IO::Socket::UNIX. And it looks like it recognizes the long path and complains. We could fix that, but...

2. The reading side is implemented by libcurl, not by us. And it seems to similarly detect and complain. We _could_ work around that with a chdir, but it would be quite nasty, as we'd have to do it before every curl call. So that's probably off the table.

And so we are stuck with either using a relative path, or a known-small one.

OK, there we went with the known-small solution, since openssh made it easy to do so. I think that is OK here, but...

     (e.g., a --stress run).

From: Johannes Schindelin <[email protected]>

The SOCKS proxy test introduced in 0ca365c2ed4 (http: do not ignore proxy path, 2024-08-02) creates a Unix domain socket in $TRASH_DIRECTORY. When the trash directory path is long (e.g. when running from a deeply nested worktree), the socket path can exceed the 108-character limit for struct sockaddr_un.sun_path on Linux, causing the test to fail with "Path length ... is longer than maximum supported length (108)".

We cannot work around this using the chdir trick our own socket code employs, because both sides of the connection are outside our control:
the socket is created by socks4-proxy.pl via Perl's IO::Socket::UNIX, and the client side is libcurl.

Use mktemp -d to create a unique temporary directory with a short path, and place the socket inside it. This avoids collisions between concurrent test runs (e.g. --stress) and tmpdir-race vulnerabilities that a static /tmp path would be susceptible to.

---
t5564: use a short path for the SOCKS proxy socket

When trying to run the entire test suite in a slightly deeper path than usual, I was surprised to see that this test failed due to our old friend, the 108 character limit of Unix sockets.

Changes since v1:

* Uses mktemp -d now, to handle --stress better (thanks, Jeff!)

Published-As: https://github.com/gitgitgadget/git/releases/tag/pr-2100%2Fdscho%2Favoid-too-long-unix-socket-path-in-socks-proxy-test-v2
Fetch-It-Via: git fetch https://github.com/gitgitgadget/git pr-2100/dscho/avoid-too-long-unix-socket-path-in-socks-proxy-test-v2
Pull-Request: https://github.com/gitgitgadget/git/pull/2100

Range-diff vs v1:

1: 16826e612c ! 1: 256b76a999 t5564: use a short path for the SOCKS proxy socket
@@ Commit message
Linux, causing the test to fail with "Path length ... is longer than maximum supported length (108)".

- Move the socket to $TMPDIR (defaulting to /tmp) where the path
- is short, following the same approach used in t7528 for the SSH
- agent socket in b7fb2194b96 (t7528: work around ETOOMANY in OpenSSH
- 10.1 and newer, 2025-10-23).
+ We cannot work around this using the chdir trick our own socket code
+ employs, because both sides of the connection are outside our control:
+ the socket is created by socks4-proxy.pl via Perl's IO::Socket::UNIX,
+ and the client side is libcurl.

+ Use mktemp -d to create a unique temporary directory with a short
+ path, and place the socket inside it. This avoids collisions between
+ concurrent test runs (e.g. --stress) and tmpdir-race vulnerabilities
+ that a static /tmp path would be susceptible to.
+
+ Helped-by: Jeff King <[email protected]>

@@ t/t5564-http-proxy.sh: start_socks() {
# proxy string passed to curl.
+# Use a short path for the socket to avoid exceeding the 108-character +# Unix domain socket limit when the trash directory path is long.
-+SOCKS_SOCK="${TMPDIR:-/tmp}/git-test-socks-%30.sock" ++SOCKS_TMPDIR=$(mktemp -d) ++SOCKS_SOCK="$SOCKS_TMPDIR/%30.sock"
+
test_lazy_prereq SOCKS_PROXY '
test_have_prereq PERL &&
@@ t/t5564-http-proxy.sh: start_socks() {
test_atexit '
test ! -e "$TRASH_DIRECTORY/socks.pid" ||
kill "$(cat "$TRASH_DIRECTORY/socks.pid")"
-+ rm -f "$SOCKS_SOCK"
++ rm -rf "$SOCKS_TMPDIR"
'

# The below tests morally ought to be gated on a prerequisite that Git is

 t/t5564-http-proxy.sh | 11 +++++++++--
 1 file changed, 9 insertions(+), 2 deletions(-)

index 3bcbdef409..b4d95b12ca 100755
@@ -50,14 +50,20 @@ start_socks() {
 
 # The %30 tests that the correct amount of percent-encoding is applied to the
 # proxy string passed to curl.
+# Use a short path for the socket to avoid exceeding the 108-character
+# Unix domain socket limit when the trash directory path is long.
+SOCKS_TMPDIR=$(mktemp -d)
+SOCKS_SOCK="$SOCKS_TMPDIR/%30.sock"
+
 test_lazy_prereq SOCKS_PROXY '
 	test_have_prereq PERL &&
-	start_socks "$TRASH_DIRECTORY/%30.sock"
+	start_socks "$SOCKS_SOCK"
 '
 
 test_atexit '
 	test ! -e "$TRASH_DIRECTORY/socks.pid" ||
 	kill "$(cat "$TRASH_DIRECTORY/socks.pid")"
+	rm -rf "$SOCKS_TMPDIR"
 '
 
 # The below tests morally ought to be gated on a prerequisite that Git is

@@ -70,7 +76,8 @@ old_libcurl_error() {
 
 test_expect_success SOCKS_PROXY 'clone via Unix socket' '
 	test_when_finished "rm -rf clone" &&
-	test_config_global http.proxy "socks4://localhost$PWD/%2530.sock" && {
+	socks_proxy_url="socks4://localhost$(echo "$SOCKS_SOCK" | sed "s/%/%25/g")" &&
+	test_config_global http.proxy "$socks_proxy_url" && {
 		{
 			GIT_TRACE_CURL=$PWD/trace \
 			GIT_TRACE_CURL_COMPONENTS=socks \

base-commit: 94f057755b7941b321fd11fec1b2e3ca5313a4e0

gitgitgadget

Thanks, this looks great to me (and thank you for fleshing out the explanation in the commit message, too).

-Peff