Replace popen('uname -ap') with uname() syscall in bvar kernel_version

src/bvar/default_variables.cpp

@@ -20,6 +20,7 @@
 #include <unistd.h>                        // getpagesize
 #include <sys/types.h>
 #include <sys/resource.h>                  // getrusage
+#include <sys/utsname.h>                   // uname
 #include <dirent.h>                        // dirent
 #include <iomanip>                         // setw
 #include <stdio.h>
@@ -617,11 +618,26 @@ static void get_cmdline(std::ostream& os, void*) {
 struct ReadVersion {
     std::string content;
     ReadVersion() {
-        std::ostringstream oss;
-        if (butil::read_command_output(oss, "uname -ap") != 0) {
+        struct utsname buf;
+        if (uname(&buf) != 0) {
             LOG(ERROR) << "Fail to read kernel version";
             return;
         }
+#if defined(__APPLE__) && (defined(__aarch64__) || defined(__arm64__))
+        const char* processor = "arm";
+#elif defined(__APPLE__) && defined(__x86_64__)
+        const char* processor = "i386";
+#else
+        const char* processor = buf.machine;
+#endif
+        std::ostringstream oss;
+        oss << buf.sysname << ' ' << buf.nodename << ' '
+            << buf.release << ' ' << buf.version << ' '
+            << buf.machine << ' ' << processor;
+#if !defined(__APPLE__)
+        oss << " GNU/Linux";
+#endif
+        oss << '\n';
         content.append(oss.str());
     }
 };

test/bvar_variable_unittest.cpp

@@ -19,7 +19,8 @@
 
 #include <pthread.h>                                // pthread_*
 #include <unistd.h>                                 // usleep
-
+#include <sys/utsname.h>                            // uname
+#include <string.h>                                 // strlen
 #include <cstddef>
 #include <memory>
 #include <thread>
@@ -462,6 +463,48 @@ TEST_F(VariableTest, dtor_waits_for_inflight_describe) {
 
     ASSERT_TRUE(destructed.load());
 }
+
+TEST_F(VariableTest, uname_returns_valid_kernel_info) {
+    struct utsname buf;
+    ASSERT_EQ(0, uname(&buf));
+
+    // Each field should be non-empty
+    ASSERT_GT(strlen(buf.sysname), 0u);
+    ASSERT_GT(strlen(buf.nodename), 0u);
+    ASSERT_GT(strlen(buf.release), 0u);
+    ASSERT_GT(strlen(buf.version), 0u);
+    ASSERT_GT(strlen(buf.machine), 0u);
+
+    // Build the string the same way ReadVersion does in default_variables.cpp
+#if defined(__APPLE__) && (defined(__aarch64__) || defined(__arm64__))
+    const char* processor = "arm";
+#elif defined(__APPLE__) && defined(__x86_64__)
+    const char* processor = "i386";
+#else
+    const char* processor = buf.machine;
+#endif
+    std::ostringstream oss;
+    oss << buf.sysname << ' ' << buf.nodename << ' '
+        << buf.release << ' ' << buf.version << ' '
+        << buf.machine << ' ' << processor;
+#if !defined(__APPLE__)
+    oss << " GNU/Linux";
+#endif
+    oss << '\n';
+    std::string content = oss.str();
+
+    // The result should contain all key fields
+    ASSERT_NE(content.find(buf.sysname), std::string::npos);
+    ASSERT_NE(content.find(buf.release), std::string::npos);
+    ASSERT_NE(content.find(buf.machine), std::string::npos);
+
+    // On Linux, sysname should be "Linux"; on macOS, "Darwin"
+#if defined(__linux__)
+    ASSERT_STREQ(buf.sysname, "Linux");
+#elif defined(__APPLE__)
+    ASSERT_STREQ(buf.sysname, "Darwin");
+#endif
+}
 } // namespace
 
 int main(int argc, char** argv) {