cleanup(userspace/libscap): avoid the usage of non-portable (glibc specific) __gnu_cxx::stdio_filebuf

[FedeDP]

What type of PR is this?

/kind cleanup

Any specific area of the project related to this PR?

/area libscap-engine-gvisor

Does this PR require a change in the driver versions?

What this PR does / why we need it:

Using the glibc specific __gnu_cxx::stdio_filebuf breaks while trying to build Falco/libs with zig compiler (see falcosecurity/falco#3307).
In this specific case, we can make use of POSIX standard popen.

Which issue(s) this PR fixes:

Fixes #

Special notes for your reviewer:

There are a couple more usages of __gnu_cxx::stdio_filebuf; both are inside libsinsp_e2e tests framework, but we don't really need to build libs tests when we build Falco (with zig) therefore i am skipping them for now.

Does this PR introduce a user-facing change?:

NONE

[poiana]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: FedeDP

The full list of commands accepted by this bot can be found here.

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Needs approval from an approver in each of these files:

• OWNERS [FedeDP]

Approvers can indicate their approval by writing /approve in a comment
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[FedeDP]

/milestone 0.19.0

[github-actions]

Perf diff from master - unit tests

     6.18%     +1.08%  [.] sinsp::next
     6.93%     -0.93%  [.] sinsp_evt::get_type
     1.41%     +0.77%  [.] std::_Hashtable<long, std::pair<long const, std::shared_ptr<sinsp_threadinfo> >, std::allocator<std::pair<long const, std::shared_ptr<sinsp_threadinfo> > >, std::__detail::_Select1st, std::equal_to<long>, std::hash<long>, std::__detail::_Mod_range_hashing, std::__detail::_Default_ranged_hash, std::__detail::_Prime_rehash_policy, std::__detail::_Hashtable_traits<false, false, true> >::_M_find_before_node
     4.76%     +0.74%  [.] next
    10.65%     +0.66%  [.] sinsp_parser::reset
     2.71%     -0.56%  [.] scap_event_decode_params
     0.55%     +0.51%  [.] scap_next
     0.71%     -0.45%  [.] copy_and_sanitize_path
     3.84%     +0.43%  [.] sinsp_parser::process_event
     1.52%     -0.43%  [.] sinsp_evt::get_ts

Heap diff from master - unit tests

peak heap memory consumption: 0B
peak RSS (including heaptrack overhead): 0B
total memory leaked: 0B

Heap diff from master - scap file

peak heap memory consumption: 0B
peak RSS (including heaptrack overhead): 0B
total memory leaked: 0B

Benchmarks diff from master

Comparing gbench_data.json to /root/actions-runner/_work/libs/libs/build/gbench_data.json
Benchmark                                                         Time             CPU      Time Old      Time New       CPU Old       CPU New
----------------------------------------------------------------------------------------------------------------------------------------------
BM_sinsp_split_mean                                            +0.0116         +0.0116           150           152           150           152
BM_sinsp_split_median                                          +0.0128         +0.0128           150           152           150           152
BM_sinsp_split_stddev                                          +0.3996         +0.3992             1             1             1             1
BM_sinsp_split_cv                                              +0.3836         +0.3832             0             0             0             0
BM_sinsp_concatenate_paths_relative_path_mean                  -0.0263         -0.0263            48            47            48            47
BM_sinsp_concatenate_paths_relative_path_median                -0.0411         -0.0411            48            46            48            46
BM_sinsp_concatenate_paths_relative_path_stddev                -0.0635         -0.0636             1             1             1             1
BM_sinsp_concatenate_paths_relative_path_cv                    -0.0382         -0.0383             0             0             0             0
BM_sinsp_concatenate_paths_empty_path_mean                     +0.0086         +0.0086            17            17            17            17
BM_sinsp_concatenate_paths_empty_path_median                   +0.0044         +0.0044            17            17            17            17
BM_sinsp_concatenate_paths_empty_path_stddev                   +0.3166         +0.3161             0             0             0             0
BM_sinsp_concatenate_paths_empty_path_cv                       +0.3055         +0.3049             0             0             0             0
BM_sinsp_concatenate_paths_absolute_path_mean                  -0.0095         -0.0095            51            50            51            50
BM_sinsp_concatenate_paths_absolute_path_median                -0.0098         -0.0098            51            50            51            50
BM_sinsp_concatenate_paths_absolute_path_stddev                +0.4263         +0.4274             0             0             0             0
BM_sinsp_concatenate_paths_absolute_path_cv                    +0.4400         +0.4411             0             0             0             0
BM_sinsp_split_container_image_mean                            -0.0367         -0.0367           356           343           356           343
BM_sinsp_split_container_image_median                          -0.0386         -0.0386           356           342           356           342
BM_sinsp_split_container_image_stddev                          -0.0971         -0.0979             2             2             2             2
BM_sinsp_split_container_image_cv                              -0.0627         -0.0636             0             0             0             0

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 73.58%. Comparing base (215db2d) to head (24b3164).
Report is 24 commits behind head on master.

Additional details and impacted files

@@           Coverage Diff           @@
##           master    #2037   +/-   ##
=======================================
  Coverage   73.57%   73.58%           
=======================================
  Files         253      253           
  Lines       31860    31867    +7     
  Branches     5640     5641    +1     
=======================================
+ Hits        23442    23450    +8     
+ Misses       8407     8392   -15     
- Partials       11       25   +14     

Flag	Coverage Δ
libsinsp	73.58% <ø> (+<0.01%)	⬆️

Flags with carried forward coverage won't be shown. Click here to find out more.

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.

[github-actions]

X64 kernel testing matrix

KERNEL	CMAKE-CONFIGURE	KMOD BUILD	KMOD SCAP-OPEN	BPF-PROBE BUILD	BPF-PROBE SCAP-OPEN	MODERN-BPF SCAP-OPEN
amazonlinux2-4.19	🟢	🟢	🟢	🟢	🟢	🟡
amazonlinux2-5.10	🟢	🟢	🟢	🟢	🟢	🟢
amazonlinux2-5.15	🟢	🟢	🟢	🟢	🟢	🟢
amazonlinux2-5.4	🟢	🟢	🟢	🟢	🟢	🟡
amazonlinux2022-5.15	🟢	🟢	🟢	🟢	🟢	🟢
amazonlinux2023-6.1	🟢	🟢	🟢	🟢	🟢	🟢
archlinux-6.0	🟢	🟢	🟢	🟢	🟢	🟢
archlinux-6.7	🟢	🟢	🟢	🟢	🟢	🟢
centos-3.10	🟢	🟢	🟢	🟡	🟡	🟡
centos-4.18	🟢	🟢	🟢	🟢	🟢	🟢
centos-5.14	🟢	🟢	🟢	🟢	🟢	🟢
fedora-5.17	🟢	🟢	🟢	🟢	🟢	🟢
fedora-5.8	🟢	🟢	🟢	🟢	🟢	🟢
fedora-6.2	🟢	🟢	🟢	🟢	🟢	🟢
oraclelinux-3.10	🟢	🟢	🟢	🟡	🟡	🟡
oraclelinux-4.14	🟢	🟢	🟢	🟢	🟢	🟡
oraclelinux-5.15	🟢	🟢	🟢	🟢	🟢	🟢
oraclelinux-5.4	🟢	🟢	🟢	🟢	🟢	🟡
ubuntu-4.15	🟢	🟢	🟢	🟢	🟢	🟡
ubuntu-5.8	🟢	🟢	🟢	🟢	🟢	🟡
ubuntu-6.5	🟢	🟢	🟢	🟢	🟢	🟢

ARM64 kernel testing matrix

KERNEL	CMAKE-CONFIGURE	KMOD BUILD	KMOD SCAP-OPEN	BPF-PROBE BUILD	BPF-PROBE SCAP-OPEN	MODERN-BPF SCAP-OPEN
amazonlinux2-5.4	🟢	🟢	🟢	🟢	🟢	🟡
amazonlinux2022-5.15	🟢	🟢	🟢	🟢	🟢	🟢
fedora-6.2	🟢	🟢	🟢	🟢	🟢	🟢
oraclelinux-4.14	🟢	🟢	🟢	🟡	🟡	🟡
oraclelinux-5.15	🟢	🟢	🟢	🟢	🟢	🟢
ubuntu-6.5	🟢	🟢	🟢	🟢	🟢	🟢

[FedeDP]

@LucaGuerra tested with this small test file:

#include <sys/wait.h>
#include <ext/stdio_filebuf.h>
#include <iostream>
#include <fstream>
#include <unistd.h>
#include <string>
#include <vector>

struct result {
   int error = 0;
   std::vector<std::string> output;
};

// Old method
result runsc(char *argv[])
{
	result res;
	int pipefds[2];

	int ret = pipe(pipefds);
	if(ret)
	{
		return res;
	}

	pid_t pid = vfork();
	if(pid > 0)
	{
		int status;

		close(pipefds[1]);
		wait(&status);
		if(!WIFEXITED(status) || WEXITSTATUS(status) != 0)
		{
			res.error = status;
			return res;
		}

		__gnu_cxx::stdio_filebuf<char> filebuf(pipefds[0], std::ios::in);
		std::string line;
		std::istream is(&filebuf);

		while(std::getline(is, line))
		{
			res.output.emplace_back(std::string(line));
		}
	}
	else
	{
		close(pipefds[0]);
		dup2(pipefds[1], STDOUT_FILENO);
		execvp("docker", argv);
		exit(1);
	}

	return res;
}

// New method
result runsc_popen(char *argv[])
{
	result res;

	std::string full_command;
	int i = 0;
	while (true)
	{
		if (argv[i] == nullptr)
		{
			break;
		}
		full_command.append(argv[i]);
		full_command.append(" ");
		i++;
	}
	FILE *cmd_out = popen(full_command.c_str(), "r");
	if (cmd_out == nullptr)
	{
		res.error = -errno;
	}
	else
	{
		char *out = nullptr;
		size_t len = 0;
		ssize_t readbytes;
		while ((readbytes = getline(&out, &len, cmd_out)) >= 0)
		{
			if (out[readbytes - 1] == '\n')
				out[readbytes - 1] = '\0';
			res.output.emplace_back(out);
		}
		free(out);
		int status = pclose(cmd_out);
		if(!WIFEXITED(status) || WEXITSTATUS(status) != 0)
		{
		      res.error = status;
		}
	}

	return res;
}

int main()
{
	const char *argv[] = {
		"docker",
		"--version",
		nullptr
	};

	auto res = runsc((char **)argv);
	printf("run with exit code: %d\n", res.error);
	for (const auto &o : res.output) {
	 	printf("%s\n", o.c_str());
	}
	
	auto res_popen = runsc_popen((char **)argv);
	printf("run_popen with exit code: %d\n", res_popen.error);
	for (const auto &o : res_popen.output) {
	 	printf("%s\n", o.c_str());
	}
	return 0;
}

[FedeDP]

New function test:

#include <sys/wait.h>
#include <ext/stdio_filebuf.h>
#include <iostream>
#include <fstream>
#include <unistd.h>
#include <string>
#include <vector>
#include <sstream>
#include <cstring>

struct result {
   int error = 0;
   std::vector<std::string> output;
};

result runsc(char *argv[])
{
	result res;
	int pipefds[2];

	int ret = pipe(pipefds);
	if(ret)
	{
		return res;
	}

	pid_t pid = vfork();
	if(pid > 0)
	{
		int status;

		close(pipefds[1]);
		wait(&status);
		if(!WIFEXITED(status) || WEXITSTATUS(status) != 0)
		{
			res.error = status;
			return res;
		}

		__gnu_cxx::stdio_filebuf<char> filebuf(pipefds[0], std::ios::in);
		std::string line;
		std::istream is(&filebuf);

		while(std::getline(is, line))
		{
			res.output.emplace_back(std::string(line));
		}
	}
	else
	{
		close(pipefds[0]);
		dup2(pipefds[1], STDOUT_FILENO);
		execvp("docker", argv);
		exit(1);
	}

	return res;
}

result runsc_read(char *argv[])
{
	result res;
	int pipefds[2];

	int ret = pipe(pipefds);
	if(ret)
	{
		return res;
	}

	pid_t pid = vfork();
	if(pid > 0)
	{
		int status;

		close(pipefds[1]);
		wait(&status);
		if(!WIFEXITED(status) || WEXITSTATUS(status) != 0)
		{
			res.error = status;
			return res;
		}


		std::string line;

		char buf[512] = {0};
		std::stringstream ss;
		size_t len;

		// Read until EOF
		while ((len = read(pipefds[0], buf, sizeof(buf) - 1)) != 0)
		{
			ss << buf;
			// Be smart: only reset first len bytes
			memset(buf, 0, len);
		}

		while(std::getline(ss, line))
		{
			res.output.emplace_back(line);
		}
	}
	else
	{
		close(pipefds[0]);
		dup2(pipefds[1], STDOUT_FILENO);
		execvp("docker", argv);
		exit(1);
	}

	return res;
}

int main()
{
	const char *argv[] = {
		"docker",
		"--version",
		nullptr
	};

	auto res = runsc((char **)argv);
	printf("run with exit code: %d\n", res.error);
	for (const auto &o : res.output) {
	 	printf("%s\n", o.c_str());
	}
	
	auto res_read = runsc_read((char **)argv);
	printf("run_read with exit code: %d\n", res_read.error);
	for (const auto &o : res_read.output) {
	 	printf("%s\n", o.c_str());
	}
	return 0;
}

[LucaGuerra]

leftover? :D

[FedeDP]

Uh! ops ahha

[FedeDP]

greatest catch ever 🤣