tests/cc/test_c_api.cc - platform/external/bcc - Git at Google

 /*
  * Copyright (c) 2016 GitHub, Inc.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
  * You may obtain a copy of the License at
  *
  * http://www.apache.org/licenses/LICENSE-2.0
  *
  * Unless required by applicable law or agreed to in writing, software
  * distributed under the License is distributed on an "AS IS" BASIS,
  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  * See the License for the specific language governing permissions and
  * limitations under the License.
  */
 #include <fcntl.h>
 #include <dlfcn.h>
 #include <stdint.h>
 #include <string.h>
 #include <link.h>
 #include <sys/mman.h>
 #include <sys/mount.h>
 #include <sys/stat.h>
 #include <sys/types.h>
 #include <sys/wait.h>
 #include <unistd.h>

 #include "bcc_elf.h"
 #include "bcc_perf_map.h"
 #include "bcc_proc.h"
 #include "bcc_syms.h"
 #include "common.h"
 #include "vendor/tinyformat.hpp"

 #include "catch.hpp"

 using namespace std;

 static pid_t spawn_child(void *, bool, bool, int (*)(void *));

 TEST_CASE("language detection", "[c_api]") {
   const char *c = bcc_procutils_language(getpid());
   REQUIRE(c);
   REQUIRE(string(c).compare("c") == 0);
 }

 TEST_CASE("shared object resolution", "[c_api]") {
   char *libm = bcc_procutils_which_so("m", 0);
   REQUIRE(libm);
   REQUIRE(libm[0] == '/');
   REQUIRE(string(libm).find("libm.so") != string::npos);
   free(libm);
 }

 TEST_CASE("shared object resolution using loaded libraries", "[c_api]") {
   char *libelf = bcc_procutils_which_so("elf", getpid());
   REQUIRE(libelf);
   REQUIRE(libelf[0] == '/');
   REQUIRE(string(libelf).find("libelf") != string::npos);
   free(libelf);
 }

 TEST_CASE("binary resolution with `which`", "[c_api]") {
   char *ld = bcc_procutils_which("ld");
   REQUIRE(ld);
   REQUIRE(ld[0] == '/');
   free(ld);
 }

 static void _test_ksym(const char *sym, uint64_t addr, void *_) {
   if (!strcmp(sym, "startup_64"))
     REQUIRE(addr != 0x0ull);
 }

 TEST_CASE("list all kernel symbols", "[c_api]") {
   if (geteuid() != 0)
     return;
   bcc_procutils_each_ksym(_test_ksym, NULL);
 }

 TEST_CASE("file-backed mapping identification") {
   CHECK(bcc_mapping_is_file_backed("/bin/ls") == 1);
   CHECK(bcc_mapping_is_file_backed("") == 0);
   CHECK(bcc_mapping_is_file_backed("//anon") == 0);
   CHECK(bcc_mapping_is_file_backed("/dev/zero") == 0);
   CHECK(bcc_mapping_is_file_backed("/anon_hugepage") == 0);
   CHECK(bcc_mapping_is_file_backed("/anon_hugepage (deleted)") == 0);
   CHECK(bcc_mapping_is_file_backed("[stack") == 0);
   CHECK(bcc_mapping_is_file_backed("/SYSV") == 0);
   CHECK(bcc_mapping_is_file_backed("[heap]") == 0);
 }

 TEST_CASE("resolve symbol name in external library", "[c_api]") {
   struct bcc_symbol sym;

   REQUIRE(bcc_resolve_symname("c", "malloc", 0x0, 0, nullptr, &sym) == 0);
   REQUIRE(string(sym.module).find("libc.so") != string::npos);
   REQUIRE(sym.module[0] == '/');
   REQUIRE(sym.offset != 0);
   bcc_procutils_free(sym.module);
 }

 TEST_CASE("resolve symbol name in external library using loaded libraries", "[c_api]") {
   struct bcc_symbol sym;

   REQUIRE(bcc_resolve_symname("bcc", "bcc_procutils_which", 0x0, getpid(), nullptr, &sym) == 0);
   REQUIRE(string(sym.module).find("libbcc.so") != string::npos);
   REQUIRE(sym.module[0] == '/');
   REQUIRE(sym.offset != 0);
   bcc_procutils_free(sym.module);
 }

 extern "C" int _a_test_function(const char *a_string) {
   int i;
   for (i = 0; a_string[i]; ++i)
     ;
   return i;
 }

 static int setup_tmp_mnts(void) {
   // Disconnect this mount namespace from its parent
   if (mount(NULL, "/", NULL, MS_REC|MS_PRIVATE, NULL) < 0) {
     fprintf(stderr, "unable to mark / PRIVATE: %s\n", strerror(errno));
     return -1;
   }
   // create a new tmpfs mounted on /tmp
   if (mount("tmpfs", "/tmp", "tmpfs", 0, NULL) < 0) {
     fprintf(stderr, "unable to mount /tmp in mntns: %s\n", strerror(errno));
     return -1;
   }

   return 0;
 }

 static int mntns_func(void *arg) {
   int in_fd, out_fd;
   char buf[4096];
   char libpath[1024];
   ssize_t rb;
   void *dlhdl;
   struct link_map *lm;

   if (setup_tmp_mnts() < 0) {
     return -1;
   }

   // Find libz.so.1, if it's installed
   dlhdl = dlopen("libz.so.1", RTLD_LAZY);
   if (dlhdl == NULL) {
     fprintf(stderr, "Unable to dlopen libz.so.1: %s\n", dlerror());
     return -1;
   }

   if (dlinfo(dlhdl, RTLD_DI_LINKMAP, &lm) < 0) {
     fprintf(stderr, "Unable to find origin of libz.so.1: %s\n", dlerror());
     return -1;
   }

   strncpy(libpath, lm->l_name, 1024);
   dlclose(dlhdl);
   dlhdl = NULL;

   // Copy a shared library from shared mntns to private /tmp
   snprintf(buf, 4096, "%s", libpath);
   in_fd = open(buf, O_RDONLY);
   if (in_fd < 0) {
     fprintf(stderr, "Unable to open %s: %s\n", buf, strerror(errno));
     return -1;
   }

   out_fd = open("/tmp/libz.so.1", O_RDWR|O_CREAT|O_EXCL,
       S_IRWXU|S_IRGRP|S_IXGRP|S_IROTH|S_IXOTH);
   if (out_fd < 0) {
     fprintf(stderr, "Unable to open /tmp/libz.so.1: %s\n", strerror(errno));
     return -1;
   }
   memset(buf, 0, sizeof (buf));
   while ((rb = read(in_fd, buf, sizeof (buf))) > 0) {
     if (write(out_fd, buf, rb) < 0) {
       fprintf(stderr, "Write error: %s\n", strerror(errno));
       return -1;
     }
   }
   close(in_fd);
   close(out_fd);

   dlhdl = dlopen("/tmp/libz.so.1", RTLD_NOW);
   if (dlhdl == NULL) {
     fprintf(stderr, "dlopen error: %s\n", dlerror());
     return -1;
   }

   sleep(5);
   dlclose(dlhdl);

   return 0;
 }

 extern int cmd_scanf(const char *cmd, const char *fmt, ...);

 TEST_CASE("resolve symbol addresses for a given PID", "[c_api]") {
   struct bcc_symbol sym;
   void *resolver = bcc_symcache_new(getpid(), nullptr);

   REQUIRE(resolver);

   SECTION("resolve in our own binary memory space") {
     REQUIRE(bcc_symcache_resolve(resolver, (uint64_t)&_a_test_function, &sym) ==
             0);

     char *this_exe = realpath("/proc/self/exe", NULL);
     REQUIRE(string(this_exe) == sym.module);
     free(this_exe);

     REQUIRE(string("_a_test_function") == sym.name);
   }

   SECTION("resolve in libbcc.so") {
     void *libbcc = dlopen("libbcc.so", RTLD_LAZY | RTLD_NOLOAD);
     REQUIRE(libbcc);

     void *libbcc_fptr = dlsym(libbcc, "bcc_resolve_symname");
     REQUIRE(libbcc_fptr);

     REQUIRE(bcc_symcache_resolve(resolver, (uint64_t)libbcc_fptr, &sym) == 0);
     REQUIRE(string(sym.module).find("libbcc.so") != string::npos);
     REQUIRE(string("bcc_resolve_symname") == sym.name);
   }

   SECTION("resolve in libc") {
     void *libc_fptr = dlsym(NULL, "strtok");
     REQUIRE(libc_fptr);

     REQUIRE(bcc_symcache_resolve(resolver, (uint64_t)libc_fptr, &sym) == 0);
     REQUIRE(sym.module);
     REQUIRE(sym.module[0] == '/');
     REQUIRE(string(sym.module).find("libc") != string::npos);

     // In some cases, a symbol may have multiple aliases. Since
     // bcc_symcache_resolve() returns only the first alias of a
     // symbol, this may not always be "strtok" even if it points
     // to the same address.
     bool sym_match = (string("strtok") == sym.name);
     if (!sym_match) {
       uint64_t exp_addr, sym_addr;
       char cmd[256];
       const char *cmdfmt = "nm %s | grep \" %s$\" | cut -f 1 -d \" \"";

       // Find address of symbol by the expected name
       sprintf(cmd, cmdfmt, sym.module, "strtok");
       REQUIRE(cmd_scanf(cmd, "%lx", &exp_addr) == 0);

       // Find address of symbol by the name that was
       // returned by bcc_symcache_resolve()
       sprintf(cmd, cmdfmt, sym.module, sym.name);
       REQUIRE(cmd_scanf(cmd, "%lx", &sym_addr) == 0);

       // If both addresses match, they are definitely
       // aliases of the same symbol
       sym_match = (exp_addr == sym_addr);
     }

     REQUIRE(sym_match);
   }

   SECTION("resolve in separate mount namespace") {
     pid_t child;
     uint64_t addr = 0;

     child = spawn_child(0, true, true, mntns_func);
     REQUIRE(child > 0);

     void *resolver = bcc_symcache_new(child, nullptr);
     REQUIRE(resolver);

     REQUIRE(bcc_symcache_resolve_name(resolver, "/tmp/libz.so.1", "zlibVersion",
         &addr) == 0);
     REQUIRE(addr != 0);
   }
 }

 #define STACK_SIZE (1024 * 1024)
 static char child_stack[STACK_SIZE];

 static string perf_map_path(pid_t pid) {
   return tfm::format("/tmp/perf-%d.map", pid);
 }

 static int make_perf_map_file(string &path, unsigned long long map_addr) {
   FILE *file = fopen(path.c_str(), "w");
   if (file == NULL) {
     return -1;
   }
   fprintf(file, "%llx 10 dummy_fn\n", map_addr);
   fprintf(file, "%llx 10 right_next_door_fn\n", map_addr + 0x10);
   fclose(file);

   return 0;
 }

 static int perf_map_func(void *arg) {
   string path = perf_map_path(getpid());
   if (make_perf_map_file(path, (unsigned long long)arg) < 0)
     return -1;

   sleep(5);

   unlink(path.c_str());
   return 0;
 }

 static int perf_map_func_mntns(void *arg) {
   string path = perf_map_path(getpid());

   if (setup_tmp_mnts() < 0) {
     return -1;
   }

   if (make_perf_map_file(path, (unsigned long long)arg) < 0)
     return -1;

   sleep(5);

   unlink(path.c_str());
   return 0;
 }

 static int perf_map_func_noop(void *arg) {
   if (setup_tmp_mnts() < 0) {
     return -1;
   }

   sleep(5);

   return 0;
 }

 static pid_t spawn_child(void *map_addr, bool own_pidns, bool own_mntns,
     int (*child_func)(void *)) {
   int flags = SIGCHLD;
   if (own_pidns)
     flags |= CLONE_NEWPID;
   if (own_mntns)
     flags |= CLONE_NEWNS;

   pid_t child = clone(child_func,
       /* stack grows down */ child_stack + STACK_SIZE, flags, (void*)map_addr);
   if (child < 0)
     return -1;

   sleep(1); // let the child get set up
   return child;
 }

 TEST_CASE("resolve symbols using /tmp/perf-pid.map", "[c_api]") {
   const int map_sz = 4096;
   void *map_addr = mmap(NULL, map_sz, PROT_READ | PROT_EXEC,
     MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
   REQUIRE(map_addr != MAP_FAILED);

   struct bcc_symbol sym;
   pid_t child = -1;

   SECTION("same namespace") {
     child = spawn_child(map_addr, /* own_pidns */ false, false, perf_map_func);
     REQUIRE(child > 0);

     void *resolver = bcc_symcache_new(child, nullptr);
     REQUIRE(resolver);

     REQUIRE(bcc_symcache_resolve(resolver, (unsigned long long)map_addr,
         &sym) == 0);
     REQUIRE(sym.module);
     REQUIRE(string(sym.module) == perf_map_path(child));
     REQUIRE(string("dummy_fn") == sym.name);

     REQUIRE(bcc_symcache_resolve(resolver, (unsigned long long)map_addr + 0x10,
         &sym) == 0);
     REQUIRE(sym.module);
     REQUIRE(string(sym.module) == perf_map_path(child));
     REQUIRE(string("right_next_door_fn") == sym.name);
   }

   SECTION("separate namespace") {
     child = spawn_child(map_addr, /* own_pidns */ true, false, perf_map_func);
     REQUIRE(child > 0);

     void *resolver = bcc_symcache_new(child, nullptr);
     REQUIRE(resolver);

     REQUIRE(bcc_symcache_resolve(resolver, (unsigned long long)map_addr,
         &sym) == 0);
     REQUIRE(sym.module);
     // child is PID 1 in its namespace
     REQUIRE(string(sym.module) == perf_map_path(1));
     REQUIRE(string("dummy_fn") == sym.name);
     unlink("/tmp/perf-1.map");
   }

   SECTION("separate pid and mount namespace") {
     child = spawn_child(map_addr, /* own_pidns */ true, true,
         perf_map_func_mntns);
     REQUIRE(child > 0);

     void *resolver = bcc_symcache_new(child, nullptr);
     REQUIRE(resolver);

     REQUIRE(bcc_symcache_resolve(resolver, (unsigned long long)map_addr,
         &sym) == 0);
     REQUIRE(sym.module);
     // child is PID 1 in its namespace
     REQUIRE(string(sym.module) == perf_map_path(1));
     REQUIRE(string("dummy_fn") == sym.name);
   }

   SECTION("separate pid and mount namespace, perf-map in host") {
     child = spawn_child(map_addr, /* own_pidns */ true, true,
         perf_map_func_noop);
     REQUIRE(child > 0);

     string path = perf_map_path(child);
     REQUIRE(make_perf_map_file(path, (unsigned long long)map_addr) == 0);

     void *resolver = bcc_symcache_new(child, nullptr);
     REQUIRE(resolver);

     REQUIRE(bcc_symcache_resolve(resolver, (unsigned long long)map_addr,
         &sym) == 0);
     REQUIRE(sym.module);
     // child is PID 1 in its namespace
     REQUIRE(string(sym.module) == perf_map_path(child));
     REQUIRE(string("dummy_fn") == sym.name);

     unlink(path.c_str());
   }


   munmap(map_addr, map_sz);
 }


 TEST_CASE("get online CPUs", "[c_api]") {
 	std::vector<int> cpus = ebpf::get_online_cpus();
 	int num_cpus = sysconf(_SC_NPROCESSORS_ONLN);
 	REQUIRE(cpus.size() == num_cpus);
 }
	/*
	* Copyright (c) 2016 GitHub, Inc.
	*
	* Licensed under the Apache License, Version 2.0 (the "License");
	* you may not use this file except in compliance with the License.
	* You may obtain a copy of the License at
	*
	* http://www.apache.org/licenses/LICENSE-2.0
	*
	* Unless required by applicable law or agreed to in writing, software
	* distributed under the License is distributed on an "AS IS" BASIS,
	* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
	* See the License for the specific language governing permissions and
	* limitations under the License.
	*/
	#include <fcntl.h>
	#include <dlfcn.h>
	#include <stdint.h>
	#include <string.h>
	#include <link.h>
	#include <sys/mman.h>
	#include <sys/mount.h>
	#include <sys/stat.h>
	#include <sys/types.h>
	#include <sys/wait.h>
	#include <unistd.h>

	#include "bcc_elf.h"
	#include "bcc_perf_map.h"
	#include "bcc_proc.h"
	#include "bcc_syms.h"
	#include "common.h"
	#include "vendor/tinyformat.hpp"

	#include "catch.hpp"

	using namespace std;

	static pid_t spawn_child(void , bool, bool, int ()(void *));

	TEST_CASE("language detection", "[c_api]") {
	const char *c = bcc_procutils_language(getpid());
	REQUIRE(c);
	REQUIRE(string(c).compare("c") == 0);
	}

	TEST_CASE("shared object resolution", "[c_api]") {
	char *libm = bcc_procutils_which_so("m", 0);
	REQUIRE(libm);
	REQUIRE(libm[0] == '/');
	REQUIRE(string(libm).find("libm.so") != string::npos);
	free(libm);
	}

	TEST_CASE("shared object resolution using loaded libraries", "[c_api]") {
	char *libelf = bcc_procutils_which_so("elf", getpid());
	REQUIRE(libelf);
	REQUIRE(libelf[0] == '/');
	REQUIRE(string(libelf).find("libelf") != string::npos);
	free(libelf);
	}

	TEST_CASE("binary resolution with `which`", "[c_api]") {
	char *ld = bcc_procutils_which("ld");
	REQUIRE(ld);
	REQUIRE(ld[0] == '/');
	free(ld);
	}

	static void _test_ksym(const char sym, uint64_t addr, void _) {
	if (!strcmp(sym, "startup_64"))
	REQUIRE(addr != 0x0ull);
	}

	TEST_CASE("list all kernel symbols", "[c_api]") {
	if (geteuid() != 0)
	return;
	bcc_procutils_each_ksym(_test_ksym, NULL);
	}

	TEST_CASE("file-backed mapping identification") {
	CHECK(bcc_mapping_is_file_backed("/bin/ls") == 1);
	CHECK(bcc_mapping_is_file_backed("") == 0);
	CHECK(bcc_mapping_is_file_backed("//anon") == 0);
	CHECK(bcc_mapping_is_file_backed("/dev/zero") == 0);
	CHECK(bcc_mapping_is_file_backed("/anon_hugepage") == 0);
	CHECK(bcc_mapping_is_file_backed("/anon_hugepage (deleted)") == 0);
	CHECK(bcc_mapping_is_file_backed("[stack") == 0);
	CHECK(bcc_mapping_is_file_backed("/SYSV") == 0);
	CHECK(bcc_mapping_is_file_backed("[heap]") == 0);
	}

	TEST_CASE("resolve symbol name in external library", "[c_api]") {
	struct bcc_symbol sym;

	REQUIRE(bcc_resolve_symname("c", "malloc", 0x0, 0, nullptr, &sym) == 0);
	REQUIRE(string(sym.module).find("libc.so") != string::npos);
	REQUIRE(sym.module[0] == '/');
	REQUIRE(sym.offset != 0);
	bcc_procutils_free(sym.module);
	}

	TEST_CASE("resolve symbol name in external library using loaded libraries", "[c_api]") {
	struct bcc_symbol sym;

	REQUIRE(bcc_resolve_symname("bcc", "bcc_procutils_which", 0x0, getpid(), nullptr, &sym) == 0);
	REQUIRE(string(sym.module).find("libbcc.so") != string::npos);
	REQUIRE(sym.module[0] == '/');
	REQUIRE(sym.offset != 0);
	bcc_procutils_free(sym.module);
	}

	extern "C" int _a_test_function(const char *a_string) {
	int i;
	for (i = 0; a_string[i]; ++i)
	;
	return i;
	}

	static int setup_tmp_mnts(void) {
	// Disconnect this mount namespace from its parent
	if (mount(NULL, "/", NULL, MS_REC\|MS_PRIVATE, NULL) < 0) {
	fprintf(stderr, "unable to mark / PRIVATE: %s\n", strerror(errno));
	return -1;
	}
	// create a new tmpfs mounted on /tmp
	if (mount("tmpfs", "/tmp", "tmpfs", 0, NULL) < 0) {
	fprintf(stderr, "unable to mount /tmp in mntns: %s\n", strerror(errno));
	return -1;
	}

	return 0;
	}

	static int mntns_func(void *arg) {
	int in_fd, out_fd;
	char buf[4096];
	char libpath[1024];
	ssize_t rb;
	void *dlhdl;
	struct link_map *lm;

	if (setup_tmp_mnts() < 0) {
	return -1;
	}

	// Find libz.so.1, if it's installed
	dlhdl = dlopen("libz.so.1", RTLD_LAZY);
	if (dlhdl == NULL) {
	fprintf(stderr, "Unable to dlopen libz.so.1: %s\n", dlerror());
	return -1;
	}

	if (dlinfo(dlhdl, RTLD_DI_LINKMAP, &lm) < 0) {
	fprintf(stderr, "Unable to find origin of libz.so.1: %s\n", dlerror());
	return -1;
	}

	strncpy(libpath, lm->l_name, 1024);
	dlclose(dlhdl);
	dlhdl = NULL;

	// Copy a shared library from shared mntns to private /tmp
	snprintf(buf, 4096, "%s", libpath);
	in_fd = open(buf, O_RDONLY);
	if (in_fd < 0) {
	fprintf(stderr, "Unable to open %s: %s\n", buf, strerror(errno));
	return -1;
	}

	out_fd = open("/tmp/libz.so.1", O_RDWR\|O_CREAT\|O_EXCL,
	S_IRWXU\|S_IRGRP\|S_IXGRP\|S_IROTH\|S_IXOTH);
	if (out_fd < 0) {
	fprintf(stderr, "Unable to open /tmp/libz.so.1: %s\n", strerror(errno));
	return -1;
	}
	memset(buf, 0, sizeof (buf));
	while ((rb = read(in_fd, buf, sizeof (buf))) > 0) {
	if (write(out_fd, buf, rb) < 0) {
	fprintf(stderr, "Write error: %s\n", strerror(errno));
	return -1;
	}
	}
	close(in_fd);
	close(out_fd);

	dlhdl = dlopen("/tmp/libz.so.1", RTLD_NOW);
	if (dlhdl == NULL) {
	fprintf(stderr, "dlopen error: %s\n", dlerror());
	return -1;
	}

	sleep(5);
	dlclose(dlhdl);

	return 0;
	}

	extern int cmd_scanf(const char cmd, const char fmt, ...);

	TEST_CASE("resolve symbol addresses for a given PID", "[c_api]") {
	struct bcc_symbol sym;
	void *resolver = bcc_symcache_new(getpid(), nullptr);

	REQUIRE(resolver);

	SECTION("resolve in our own binary memory space") {
	REQUIRE(bcc_symcache_resolve(resolver, (uint64_t)&_a_test_function, &sym) ==
	0);

	char *this_exe = realpath("/proc/self/exe", NULL);
	REQUIRE(string(this_exe) == sym.module);
	free(this_exe);

	REQUIRE(string("_a_test_function") == sym.name);
	}

	SECTION("resolve in libbcc.so") {
	void *libbcc = dlopen("libbcc.so", RTLD_LAZY \| RTLD_NOLOAD);
	REQUIRE(libbcc);

	void *libbcc_fptr = dlsym(libbcc, "bcc_resolve_symname");
	REQUIRE(libbcc_fptr);

	REQUIRE(bcc_symcache_resolve(resolver, (uint64_t)libbcc_fptr, &sym) == 0);
	REQUIRE(string(sym.module).find("libbcc.so") != string::npos);
	REQUIRE(string("bcc_resolve_symname") == sym.name);
	}

	SECTION("resolve in libc") {
	void *libc_fptr = dlsym(NULL, "strtok");
	REQUIRE(libc_fptr);

	REQUIRE(bcc_symcache_resolve(resolver, (uint64_t)libc_fptr, &sym) == 0);
	REQUIRE(sym.module);
	REQUIRE(sym.module[0] == '/');
	REQUIRE(string(sym.module).find("libc") != string::npos);

	// In some cases, a symbol may have multiple aliases. Since
	// bcc_symcache_resolve() returns only the first alias of a
	// symbol, this may not always be "strtok" even if it points
	// to the same address.
	bool sym_match = (string("strtok") == sym.name);
	if (!sym_match) {
	uint64_t exp_addr, sym_addr;
	char cmd[256];
	const char *cmdfmt = "nm %s \| grep \" %s$\" \| cut -f 1 -d \" \"";

	// Find address of symbol by the expected name
	sprintf(cmd, cmdfmt, sym.module, "strtok");
	REQUIRE(cmd_scanf(cmd, "%lx", &exp_addr) == 0);

	// Find address of symbol by the name that was
	// returned by bcc_symcache_resolve()
	sprintf(cmd, cmdfmt, sym.module, sym.name);
	REQUIRE(cmd_scanf(cmd, "%lx", &sym_addr) == 0);

	// If both addresses match, they are definitely
	// aliases of the same symbol
	sym_match = (exp_addr == sym_addr);
	}

	REQUIRE(sym_match);
	}

	SECTION("resolve in separate mount namespace") {
	pid_t child;
	uint64_t addr = 0;

	child = spawn_child(0, true, true, mntns_func);
	REQUIRE(child > 0);

	void *resolver = bcc_symcache_new(child, nullptr);
	REQUIRE(resolver);

	REQUIRE(bcc_symcache_resolve_name(resolver, "/tmp/libz.so.1", "zlibVersion",
	&addr) == 0);
	REQUIRE(addr != 0);
	}
	}

	#define STACK_SIZE (1024 * 1024)
	static char child_stack[STACK_SIZE];

	static string perf_map_path(pid_t pid) {
	return tfm::format("/tmp/perf-%d.map", pid);
	}

	static int make_perf_map_file(string &path, unsigned long long map_addr) {
	FILE *file = fopen(path.c_str(), "w");
	if (file == NULL) {
	return -1;
	}
	fprintf(file, "%llx 10 dummy_fn\n", map_addr);
	fprintf(file, "%llx 10 right_next_door_fn\n", map_addr + 0x10);
	fclose(file);

	return 0;
	}

	static int perf_map_func(void *arg) {
	string path = perf_map_path(getpid());
	if (make_perf_map_file(path, (unsigned long long)arg) < 0)
	return -1;

	sleep(5);

	unlink(path.c_str());
	return 0;
	}

	static int perf_map_func_mntns(void *arg) {
	string path = perf_map_path(getpid());

	if (setup_tmp_mnts() < 0) {
	return -1;
	}

	if (make_perf_map_file(path, (unsigned long long)arg) < 0)
	return -1;

	sleep(5);

	unlink(path.c_str());
	return 0;
	}

	static int perf_map_func_noop(void *arg) {
	if (setup_tmp_mnts() < 0) {
	return -1;
	}

	sleep(5);

	return 0;
	}

	static pid_t spawn_child(void *map_addr, bool own_pidns, bool own_mntns,
	int (child_func)(void )) {
	int flags = SIGCHLD;
	if (own_pidns)
	flags \|= CLONE_NEWPID;
	if (own_mntns)
	flags \|= CLONE_NEWNS;

	pid_t child = clone(child_func,
	/* stack grows down / child_stack + STACK_SIZE, flags, (void)map_addr);
	if (child < 0)
	return -1;

	sleep(1); // let the child get set up
	return child;
	}

	TEST_CASE("resolve symbols using /tmp/perf-pid.map", "[c_api]") {
	const int map_sz = 4096;
	void *map_addr = mmap(NULL, map_sz, PROT_READ \| PROT_EXEC,
	MAP_PRIVATE \| MAP_ANONYMOUS, -1, 0);
	REQUIRE(map_addr != MAP_FAILED);

	struct bcc_symbol sym;
	pid_t child = -1;

	SECTION("same namespace") {
	child = spawn_child(map_addr, /* own_pidns */ false, false, perf_map_func);
	REQUIRE(child > 0);

	void *resolver = bcc_symcache_new(child, nullptr);
	REQUIRE(resolver);

	REQUIRE(bcc_symcache_resolve(resolver, (unsigned long long)map_addr,
	&sym) == 0);
	REQUIRE(sym.module);
	REQUIRE(string(sym.module) == perf_map_path(child));
	REQUIRE(string("dummy_fn") == sym.name);

	REQUIRE(bcc_symcache_resolve(resolver, (unsigned long long)map_addr + 0x10,
	&sym) == 0);
	REQUIRE(sym.module);
	REQUIRE(string(sym.module) == perf_map_path(child));
	REQUIRE(string("right_next_door_fn") == sym.name);
	}

	SECTION("separate namespace") {
	child = spawn_child(map_addr, /* own_pidns */ true, false, perf_map_func);
	REQUIRE(child > 0);

	void *resolver = bcc_symcache_new(child, nullptr);
	REQUIRE(resolver);

	REQUIRE(bcc_symcache_resolve(resolver, (unsigned long long)map_addr,
	&sym) == 0);
	REQUIRE(sym.module);
	// child is PID 1 in its namespace
	REQUIRE(string(sym.module) == perf_map_path(1));
	REQUIRE(string("dummy_fn") == sym.name);
	unlink("/tmp/perf-1.map");
	}

	SECTION("separate pid and mount namespace") {
	child = spawn_child(map_addr, /* own_pidns */ true, true,
	perf_map_func_mntns);
	REQUIRE(child > 0);

	void *resolver = bcc_symcache_new(child, nullptr);
	REQUIRE(resolver);

	REQUIRE(bcc_symcache_resolve(resolver, (unsigned long long)map_addr,
	&sym) == 0);
	REQUIRE(sym.module);
	// child is PID 1 in its namespace
	REQUIRE(string(sym.module) == perf_map_path(1));
	REQUIRE(string("dummy_fn") == sym.name);
	}

	SECTION("separate pid and mount namespace, perf-map in host") {
	child = spawn_child(map_addr, /* own_pidns */ true, true,
	perf_map_func_noop);
	REQUIRE(child > 0);

	string path = perf_map_path(child);
	REQUIRE(make_perf_map_file(path, (unsigned long long)map_addr) == 0);

	void *resolver = bcc_symcache_new(child, nullptr);
	REQUIRE(resolver);

	REQUIRE(bcc_symcache_resolve(resolver, (unsigned long long)map_addr,
	&sym) == 0);
	REQUIRE(sym.module);
	// child is PID 1 in its namespace
	REQUIRE(string(sym.module) == perf_map_path(child));
	REQUIRE(string("dummy_fn") == sym.name);

	unlink(path.c_str());
	}



	munmap(map_addr, map_sz);
	}


	TEST_CASE("get online CPUs", "[c_api]") {
	std::vector<int> cpus = ebpf::get_online_cpus();
	int num_cpus = sysconf(_SC_NPROCESSORS_ONLN);
	REQUIRE(cpus.size() == num_cpus);
	}