cleanup(userspace/libscap): avoid the usage of non-portable (glibc sp…

…ecific) `__gnu_cxx::stdio_filebuf`.

Signed-off-by: Federico Di Pierro <[email protected]>

userspace/libscap/engine/gvisor/runsc.cpp

@@ -16,10 +16,6 @@ limitations under the License.
 */
 
 #include <unistd.h>
-#include <sys/wait.h>
-#include <ext/stdio_filebuf.h>
-#include <iostream>
-#include <fstream>
 #include <string>
 
 #include <libscap/engine/gvisor/gvisor.h>
@@ -31,43 +27,39 @@ namespace runsc {
 result runsc(char *argv[])
 {
 	result res;
-	int pipefds[2];
 
-	int ret = pipe(pipefds);
-	if(ret)
+	std::string full_command;
+	int i = 0;
+	while (true)
 	{
-		return res;
+		if (argv[i] == nullptr)
+		{
+			break;
+		}
+		full_command.append(argv[i]);
+		full_command.append(" ");
+		i++;
 	}
-
-	pid_t pid = vfork();
-	if(pid > 0)
+	FILE *cmd_out = popen(full_command.c_str(), "r");
+	if (cmd_out == nullptr)
 	{
-		int status;
-
-		close(pipefds[1]);
-		wait(&status);
-		if(!WIFEXITED(status) || WEXITSTATUS(status) != 0)
+		res.error = -errno;
+	}
+	else
+	{
+		char *out = nullptr;
+		size_t len = 0;
+		while (getline(&out, &len, cmd_out) >= 0)
 		{
-			res.error = status;
-			return res;
+			res.output.emplace_back(out);
 		}
-
-		__gnu_cxx::stdio_filebuf<char> filebuf(pipefds[0], std::ios::in);
-		std::string line;
-		std::istream is(&filebuf);
-
-		while(std::getline(is, line))
+		free(out);
+		int status = pclose(cmd_out);
+		if(!WIFEXITED(status) || WEXITSTATUS(status) != 0)
 		{
-			res.output.emplace_back(std::string(line));
+		      res.error = status;
 		}
 	}
-	else
-	{
-		close(pipefds[0]);
-		dup2(pipefds[1], STDOUT_FILENO);
-		execvp("runsc", argv);
-		exit(1);
-	}
 
 	return res;
 }
@@ -77,7 +69,7 @@ result version()
 	const char *argv[] = {
 		"runsc",
 		"--version",
-		NULL
+		nullptr
 	};
 
 	return runsc((char **)argv);
@@ -93,7 +85,7 @@ result list(const std::string &root_path)
 		"--root",
 		root_path.c_str(),
 		"list",
-		NULL
+		nullptr
 	};
 
 	res = runsc((char **)argv);
@@ -127,7 +119,7 @@ result trace_create(const std::string &root_path, const std::string &trace_sessi
 		"--config",
 		trace_session_path.c_str(),
 		sandbox_id.c_str(),
-		NULL
+		nullptr
 	};
 
 	return runsc((char **)argv);
@@ -144,7 +136,7 @@ result trace_delete(const std::string &root_path, const std::string &session_nam
 		"--name",
 		session_name.c_str(),
 		sandbox_id.c_str(),
-		NULL
+		nullptr
 	};
 
 	return runsc((char **)argv);
@@ -159,7 +151,7 @@ result trace_procfs(const std::string &root_path, const std::string &sandbox_id)
 		"trace",
 		"procfs",
 		sandbox_id.c_str(),
-		NULL,
+		nullptr,
 	};
 
 	return runsc((char **)argv);