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test_c_api.cc
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test_c_api.cc
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/*
* 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
*
* https://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 <dlfcn.h>
#include <stdint.h>
#include <string.h>
#include <sys/mman.h>
#include <unistd.h>
#include "bcc_elf.h"
#include "bcc_perf_map.h"
#include "bcc_proc.h"
#include "bcc_syms.h"
#include "vendor/tinyformat.hpp"
#include "catch.hpp"
using namespace std;
TEST_CASE("shared object resolution", "[c_api]") {
const char *libm = bcc_procutils_which_so("m", 0);
REQUIRE(libm);
REQUIRE(libm[0] == '/');
REQUIRE(string(libm).find("libm.so") != string::npos);
}
TEST_CASE("shared object resolution using loaded libraries", "[c_api]") {
const char *libelf = bcc_procutils_which_so("elf", getpid());
REQUIRE(libelf);
REQUIRE(libelf[0] == '/');
REQUIRE(string(libelf).find("libelf") != string::npos);
}
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("resolve symbol name in external library", "[c_api]") {
struct bcc_symbol sym;
REQUIRE(bcc_resolve_symname("c", "malloc", 0x0, 0, &sym) == 0);
REQUIRE(string(sym.module).find("libc.so") != string::npos);
REQUIRE(sym.module[0] == '/');
REQUIRE(sym.offset != 0);
}
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(), &sym) == 0);
REQUIRE(string(sym.module).find("libbcc.so") != string::npos);
REQUIRE(sym.module[0] == '/');
REQUIRE(sym.offset != 0);
}
extern "C" int _a_test_function(const char *a_string) {
int i;
for (i = 0; a_string[i]; ++i)
;
return i;
}
TEST_CASE("resolve symbol addresses for a given PID", "[c_api]") {
struct bcc_symbol sym;
void *resolver = bcc_symcache_new(getpid());
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);
REQUIRE(string("strtok") == sym.name);
}
}
#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 child_func(void *arg) {
unsigned long long map_addr = (unsigned long long)arg;
string path = perf_map_path(getpid());
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);
sleep(5);
unlink(path.c_str());
return 0;
}
static pid_t spawn_child(void *map_addr, bool own_pidns) {
int flags = 0;
if (own_pidns)
flags |= CLONE_NEWPID;
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);
REQUIRE(child > 0);
void *resolver = bcc_symcache_new(child);
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);
REQUIRE(child > 0);
void *resolver = bcc_symcache_new(child);
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);
}
munmap(map_addr, map_sz);
}