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Replace popen('uname -ap') with uname() syscall in bvar kernel_version #3517

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Replace popen('uname -ap') with uname() syscall in bvar kernel_version #3517

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7b6d678
Replace popen('uname -ap') with uname() syscall in bvar kernel_version
Sep 3, 2026
3c83555
Update processor variable assignment for Apple platforms
weim0000 Sep 5, 2026
4877659
update unittest add <string.h>
Sep 5, 2026
4f67f87
update unittest for bvar_variable kernel_version
Sep 5, 2026
432abde
Fix kernel_version to match uname -ap output format across platforms
Sep 5, 2026
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20 changes: 18 additions & 2 deletions src/bvar/default_variables.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -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>
Expand Down Expand Up @@ -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;

@wwbmmm wwbmmm Sep 6, 2026

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The reconstructed output is not byte-equivalent to uname -ap as stated in the PR. On Linux, uname -ap appends the operating-system identifier as the final field, e.g. ... aarch64 GNU/Linux; this new code stops at machine processor and drops that OS field entirely. Additionally, uname(1) omits a field whose value is the literal string "unknown" (common for uname -p), whereas this code always appends processor (here equal to buf.machine, producing a duplicated machine value).

If exact parity with the previous output is required (e.g. for scrapers/keying off the string), either append the proper OS name field (GNU/Linux on Linux; none on macOS) and mirror uname's handling of "unknown", or update the PR description to not claim the output format is preserved. Since these fields are informational this may be acceptable, but the claim and the format should match.

🤖 This reply was automatically generated by brpc-oncall

@weim0000 weim0000 Sep 6, 2026

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'GNU/Linux' has been added here. Please take a look at the following four lines of code

@weim0000 weim0000 Sep 6, 2026

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@wwbmmm Please check the latest code，thanks

#if !defined(__APPLE__)
oss << " GNU/Linux";
#endif
oss << '\n';

@weim0000 weim0000 Sep 6, 2026

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@wwbmmm here

content.append(oss.str());
}
};
Expand Down
45 changes: 44 additions & 1 deletion test/bvar_variable_unittest.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -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>
Expand Down Expand Up @@ -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();
Comment on lines +467 to +494

// 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) {
Expand Down
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