Prevent crash with /proc path canonicalization

The filesystem::canonical does not work very well with /proc paths,
explictly ignoring those paths from filesystem::canonical for now.

src/utils.cpp

@@ -924,8 +924,17 @@ uint32_t kernel_version(int attempt)
 
 std::string abs_path(const std::string &rel_path)
 {
-  auto p = std_filesystem::path(rel_path);
-  return std_filesystem::canonical(std_filesystem::absolute(p)).string();
+  // filesystem::canonical does not work very well with /proc paths
+  // failing during canonicalization. See iovisor:bpftrace#1595
+  if (rel_path.rfind("/proc", 0) != 0)
+  {
+    auto p = std_filesystem::path(rel_path);
+    return std_filesystem::canonical(std_filesystem::absolute(p)).string();
+  }
+  else
+  {
+    return rel_path;
+  }
 }
 
 } // namespace bpftrace

tests/utils.cpp

@@ -131,6 +131,12 @@ TEST(utils, parse_exponent)
   EXPECT_EQ(parse_exponent((const char*)"2a9"), 2ULL);
 }
 
+TEST(utils, abs_path)
+{
+  EXPECT_NO_THROW(
+      abs_path(std::string("/proc/1/root/usr/local/bin/usdt_test.so")));
+}
+
 } // namespace utils
 } // namespace test
 } // namespace bpftrace