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authorRahat Mahmood <rahat@google.com>2019-08-29 14:31:44 -0700
committergVisor bot <gvisor-bot@google.com>2019-08-29 14:37:47 -0700
commitf74affe2035ba038674a0b958d8a31348fba15bc (patch)
tree5ff0f360367dafd11cfc9eb50664b6ec0bff335b /test
parent863e11ac4d6a49787cd5e5f6fe1cd771d0ceb100 (diff)
Handle new representation of abstract UDS paths.
When abstract unix domain socket paths are displayed in /proc/net/unix, Linux historically emitted null bytes as padding at the end of the path. Newer versions of Linux (v4.9, e7947ea770d0de434d38a0f823e660d3fd4bebb5) display these as '@' characters. Update proc_net_unix test to handle both version of the padding. PiperOrigin-RevId: 266230200
Diffstat (limited to 'test')
-rw-r--r--test/syscalls/linux/proc_net_unix.cc54
1 files changed, 36 insertions, 18 deletions
diff --git a/test/syscalls/linux/proc_net_unix.cc b/test/syscalls/linux/proc_net_unix.cc
index 9b9be66ff..83dbd1364 100644
--- a/test/syscalls/linux/proc_net_unix.cc
+++ b/test/syscalls/linux/proc_net_unix.cc
@@ -56,19 +56,44 @@ struct UnixEntry {
std::string path;
};
+// Abstract socket paths can have either trailing null bytes or '@'s as padding
+// at the end, depending on the linux version. This function strips any such
+// padding.
+void StripAbstractPathPadding(std::string* s) {
+ const char pad_char = s->back();
+ if (pad_char != '\0' && pad_char != '@') {
+ return;
+ }
+
+ const auto last_pos = s->find_last_not_of(pad_char);
+ if (last_pos != std::string::npos) {
+ s->resize(last_pos + 1);
+ }
+}
+
+// Precondition: addr must be a unix socket address (i.e. sockaddr_un) and
+// addr->sun_path must be null-terminated. This is always the case if addr comes
+// from Linux:
+//
+// Per man unix(7):
+//
+// "When the address of a pathname socket is returned (by [getsockname(2)]), its
+// length is
+//
+// offsetof(struct sockaddr_un, sun_path) + strlen(sun_path) + 1
+//
+// and sun_path contains the null-terminated pathname."
std::string ExtractPath(const struct sockaddr* addr) {
const char* path =
reinterpret_cast<const struct sockaddr_un*>(addr)->sun_path;
// Note: sockaddr_un.sun_path is an embedded character array of length
// UNIX_PATH_MAX, so we can always safely dereference the first 2 bytes below.
//
- // The kernel also enforces that the path is always null terminated.
+ // We also rely on the path being null-terminated.
if (path[0] == 0) {
- // Abstract socket paths are null padded to the end of the struct
- // sockaddr. However, these null bytes may or may not show up in
- // /proc/net/unix depending on the kernel version. Truncate after the first
- // null byte (by treating path as a c-string).
- return StrCat("@", &path[1]);
+ std::string abstract_path = StrCat("@", &path[1]);
+ StripAbstractPathPadding(&abstract_path);
+ return abstract_path;
}
return std::string(path);
}
@@ -96,14 +121,6 @@ PosixErrorOr<std::vector<UnixEntry>> ProcNetUnixEntries() {
continue;
}
- // Abstract socket paths can have trailing null bytes in them depending on
- // the linux version. Strip off everything after a null byte, including the
- // null byte.
- std::size_t null_pos = line.find('\0');
- if (null_pos != std::string::npos) {
- line.erase(null_pos);
- }
-
// Parse a single entry from /proc/net/unix.
//
// Sample file:
@@ -151,6 +168,7 @@ PosixErrorOr<std::vector<UnixEntry>> ProcNetUnixEntries() {
entry.path = "";
if (fields.size() > 1) {
entry.path = fields[1];
+ StripAbstractPathPadding(&entry.path);
}
entries.push_back(entry);
@@ -200,8 +218,8 @@ TEST(ProcNetUnix, FilesystemBindAcceptConnect) {
std::string path1 = ExtractPath(sockets->first_addr());
std::string path2 = ExtractPath(sockets->second_addr());
- std::cout << StreamFormat("Server socket address: %s\n", path1);
- std::cout << StreamFormat("Client socket address: %s\n", path2);
+ std::cerr << StreamFormat("Server socket address (path1): %s\n", path1);
+ std::cerr << StreamFormat("Client socket address (path2): %s\n", path2);
std::vector<UnixEntry> entries =
ASSERT_NO_ERRNO_AND_VALUE(ProcNetUnixEntries());
@@ -224,8 +242,8 @@ TEST(ProcNetUnix, AbstractBindAcceptConnect) {
std::string path1 = ExtractPath(sockets->first_addr());
std::string path2 = ExtractPath(sockets->second_addr());
- std::cout << StreamFormat("Server socket address: '%s'\n", path1);
- std::cout << StreamFormat("Client socket address: '%s'\n", path2);
+ std::cerr << StreamFormat("Server socket address (path1): '%s'\n", path1);
+ std::cerr << StreamFormat("Client socket address (path2): '%s'\n", path2);
std::vector<UnixEntry> entries =
ASSERT_NO_ERRNO_AND_VALUE(ProcNetUnixEntries());