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1 /*
2  * Copyright (C) 2017 The Android Open Source Project
3  *
4  * Licensed under the Apache License, Version 2.0 (the "License");
5  * you may not use this file except in compliance with the License.
6  * You may obtain a copy of the License at
7  *
8  *      http://www.apache.org/licenses/LICENSE-2.0
9  *
10  * Unless required by applicable law or agreed to in writing, software
11  * distributed under the License is distributed on an "AS IS" BASIS,
12  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13  * See the License for the specific language governing permissions and
14  * limitations under the License.
15  */
16 
17 #include <spawn.h>
18 
19 #include <errno.h>
20 #include <fcntl.h>
21 #include <gtest/gtest.h>
22 
23 #include "SignalUtils.h"
24 #include "utils.h"
25 
26 #include <android-base/file.h>
27 #include <android-base/strings.h>
28 
29 // Old versions of glibc didn't have POSIX_SPAWN_SETSID.
30 #if __GLIBC__
31 # if !defined(POSIX_SPAWN_SETSID)
32 #  define POSIX_SPAWN_SETSID 0
33 # endif
34 #endif
35 
TEST(spawn,posix_spawnattr_init_posix_spawnattr_destroy)36 TEST(spawn, posix_spawnattr_init_posix_spawnattr_destroy) {
37   posix_spawnattr_t sa;
38   ASSERT_EQ(0, posix_spawnattr_init(&sa));
39   ASSERT_EQ(0, posix_spawnattr_destroy(&sa));
40 }
41 
TEST(spawn,posix_spawnattr_setflags_EINVAL)42 TEST(spawn, posix_spawnattr_setflags_EINVAL) {
43   posix_spawnattr_t sa;
44   ASSERT_EQ(0, posix_spawnattr_init(&sa));
45   ASSERT_EQ(EINVAL, posix_spawnattr_setflags(&sa, ~0));
46   ASSERT_EQ(0, posix_spawnattr_destroy(&sa));
47 }
48 
TEST(spawn,posix_spawnattr_setflags_posix_spawnattr_getflags)49 TEST(spawn, posix_spawnattr_setflags_posix_spawnattr_getflags) {
50   posix_spawnattr_t sa;
51   ASSERT_EQ(0, posix_spawnattr_init(&sa));
52 
53   ASSERT_EQ(0, posix_spawnattr_setflags(&sa, POSIX_SPAWN_RESETIDS));
54   short flags;
55   ASSERT_EQ(0, posix_spawnattr_getflags(&sa, &flags));
56   ASSERT_EQ(POSIX_SPAWN_RESETIDS, flags);
57 
58   constexpr short all_flags = POSIX_SPAWN_RESETIDS | POSIX_SPAWN_SETPGROUP | POSIX_SPAWN_SETSIGDEF |
59                               POSIX_SPAWN_SETSIGMASK | POSIX_SPAWN_SETSCHEDPARAM |
60                               POSIX_SPAWN_SETSCHEDULER | POSIX_SPAWN_USEVFORK | POSIX_SPAWN_SETSID;
61   ASSERT_EQ(0, posix_spawnattr_setflags(&sa, all_flags));
62   ASSERT_EQ(0, posix_spawnattr_getflags(&sa, &flags));
63   ASSERT_EQ(all_flags, flags);
64 
65   ASSERT_EQ(0, posix_spawnattr_destroy(&sa));
66 }
67 
TEST(spawn,posix_spawnattr_setpgroup_posix_spawnattr_getpgroup)68 TEST(spawn, posix_spawnattr_setpgroup_posix_spawnattr_getpgroup) {
69   posix_spawnattr_t sa;
70   ASSERT_EQ(0, posix_spawnattr_init(&sa));
71 
72   ASSERT_EQ(0, posix_spawnattr_setpgroup(&sa, 123));
73   pid_t g;
74   ASSERT_EQ(0, posix_spawnattr_getpgroup(&sa, &g));
75   ASSERT_EQ(123, g);
76 
77   ASSERT_EQ(0, posix_spawnattr_destroy(&sa));
78 }
79 
TEST(spawn,posix_spawnattr_setsigmask_posix_spawnattr_getsigmask)80 TEST(spawn, posix_spawnattr_setsigmask_posix_spawnattr_getsigmask) {
81   posix_spawnattr_t sa;
82   ASSERT_EQ(0, posix_spawnattr_init(&sa));
83 
84   sigset_t sigs;
85   ASSERT_EQ(0, posix_spawnattr_getsigmask(&sa, &sigs));
86   ASSERT_FALSE(sigismember(&sigs, SIGALRM));
87 
88   sigset_t just_SIGALRM;
89   sigemptyset(&just_SIGALRM);
90   sigaddset(&just_SIGALRM, SIGALRM);
91   ASSERT_EQ(0, posix_spawnattr_setsigmask(&sa, &just_SIGALRM));
92 
93   ASSERT_EQ(0, posix_spawnattr_getsigmask(&sa, &sigs));
94   ASSERT_TRUE(sigismember(&sigs, SIGALRM));
95 
96   ASSERT_EQ(0, posix_spawnattr_destroy(&sa));
97 }
98 
TEST(spawn,posix_spawnattr_setsigmask64_posix_spawnattr_getsigmask64)99 TEST(spawn, posix_spawnattr_setsigmask64_posix_spawnattr_getsigmask64) {
100   posix_spawnattr_t sa;
101   ASSERT_EQ(0, posix_spawnattr_init(&sa));
102 
103   sigset64_t sigs;
104   ASSERT_EQ(0, posix_spawnattr_getsigmask64(&sa, &sigs));
105   ASSERT_FALSE(sigismember64(&sigs, SIGRTMIN));
106 
107   sigset64_t just_SIGRTMIN;
108   sigemptyset64(&just_SIGRTMIN);
109   sigaddset64(&just_SIGRTMIN, SIGRTMIN);
110   ASSERT_EQ(0, posix_spawnattr_setsigmask64(&sa, &just_SIGRTMIN));
111 
112   ASSERT_EQ(0, posix_spawnattr_getsigmask64(&sa, &sigs));
113   ASSERT_TRUE(sigismember64(&sigs, SIGRTMIN));
114 
115   ASSERT_EQ(0, posix_spawnattr_destroy(&sa));
116 }
117 
TEST(spawn,posix_spawnattr_setsigdefault_posix_spawnattr_getsigdefault)118 TEST(spawn, posix_spawnattr_setsigdefault_posix_spawnattr_getsigdefault) {
119   posix_spawnattr_t sa;
120   ASSERT_EQ(0, posix_spawnattr_init(&sa));
121 
122   sigset_t sigs;
123   ASSERT_EQ(0, posix_spawnattr_getsigdefault(&sa, &sigs));
124   ASSERT_FALSE(sigismember(&sigs, SIGALRM));
125 
126   sigset_t just_SIGALRM;
127   sigemptyset(&just_SIGALRM);
128   sigaddset(&just_SIGALRM, SIGALRM);
129   ASSERT_EQ(0, posix_spawnattr_setsigdefault(&sa, &just_SIGALRM));
130 
131   ASSERT_EQ(0, posix_spawnattr_getsigdefault(&sa, &sigs));
132   ASSERT_TRUE(sigismember(&sigs, SIGALRM));
133 
134   ASSERT_EQ(0, posix_spawnattr_destroy(&sa));
135 }
136 
TEST(spawn,posix_spawnattr_setsigdefault64_posix_spawnattr_getsigdefault64)137 TEST(spawn, posix_spawnattr_setsigdefault64_posix_spawnattr_getsigdefault64) {
138   posix_spawnattr_t sa;
139   ASSERT_EQ(0, posix_spawnattr_init(&sa));
140 
141   sigset64_t sigs;
142   ASSERT_EQ(0, posix_spawnattr_getsigdefault64(&sa, &sigs));
143   ASSERT_FALSE(sigismember64(&sigs, SIGRTMIN));
144 
145   sigset64_t just_SIGRTMIN;
146   sigemptyset64(&just_SIGRTMIN);
147   sigaddset64(&just_SIGRTMIN, SIGRTMIN);
148   ASSERT_EQ(0, posix_spawnattr_setsigdefault64(&sa, &just_SIGRTMIN));
149 
150   ASSERT_EQ(0, posix_spawnattr_getsigdefault64(&sa, &sigs));
151   ASSERT_TRUE(sigismember64(&sigs, SIGRTMIN));
152 
153   ASSERT_EQ(0, posix_spawnattr_destroy(&sa));
154 }
155 
TEST(spawn,posix_spawnattr_setsschedparam_posix_spawnattr_getsschedparam)156 TEST(spawn, posix_spawnattr_setsschedparam_posix_spawnattr_getsschedparam) {
157   posix_spawnattr_t sa;
158   ASSERT_EQ(0, posix_spawnattr_init(&sa));
159 
160   sched_param sp;
161   ASSERT_EQ(0, posix_spawnattr_getschedparam(&sa, &sp));
162   ASSERT_EQ(0, sp.sched_priority);
163 
164   sched_param sp123 = { .sched_priority = 123 };
165   ASSERT_EQ(0, posix_spawnattr_setschedparam(&sa, &sp123));
166 
167   ASSERT_EQ(0, posix_spawnattr_getschedparam(&sa, &sp));
168   ASSERT_EQ(123, sp.sched_priority);
169 
170   ASSERT_EQ(0, posix_spawnattr_destroy(&sa));
171 }
172 
TEST(spawn,posix_spawnattr_setschedpolicy_posix_spawnattr_getschedpolicy)173 TEST(spawn, posix_spawnattr_setschedpolicy_posix_spawnattr_getschedpolicy) {
174   posix_spawnattr_t sa;
175   ASSERT_EQ(0, posix_spawnattr_init(&sa));
176 
177   int p;
178   ASSERT_EQ(0, posix_spawnattr_getschedpolicy(&sa, &p));
179   ASSERT_EQ(0, p);
180 
181   ASSERT_EQ(0, posix_spawnattr_setschedpolicy(&sa, SCHED_FIFO));
182 
183   ASSERT_EQ(0, posix_spawnattr_getschedpolicy(&sa, &p));
184   ASSERT_EQ(SCHED_FIFO, p);
185 
186   ASSERT_EQ(0, posix_spawnattr_destroy(&sa));
187 }
188 
TEST(spawn,posix_spawn)189 TEST(spawn, posix_spawn) {
190   ExecTestHelper eth;
191   eth.SetArgs({BIN_DIR "true", nullptr});
192   pid_t pid;
193   ASSERT_EQ(0, posix_spawn(&pid, eth.GetArg0(), nullptr, nullptr, eth.GetArgs(), nullptr));
194   AssertChildExited(pid, 0);
195 }
196 
TEST(spawn,posix_spawn_not_found)197 TEST(spawn, posix_spawn_not_found) {
198   ExecTestHelper eth;
199   eth.SetArgs({"true", nullptr});
200   pid_t pid;
201   ASSERT_EQ(0, posix_spawn(&pid, eth.GetArg0(), nullptr, nullptr, eth.GetArgs(), nullptr));
202   AssertChildExited(pid, 127);
203 }
204 
TEST(spawn,posix_spawnp)205 TEST(spawn, posix_spawnp) {
206   ExecTestHelper eth;
207   eth.SetArgs({"true", nullptr});
208   pid_t pid;
209   ASSERT_EQ(0, posix_spawnp(&pid, eth.GetArg0(), nullptr, nullptr, eth.GetArgs(), nullptr));
210   AssertChildExited(pid, 0);
211 }
212 
TEST(spawn,posix_spawnp_not_found)213 TEST(spawn, posix_spawnp_not_found) {
214   ExecTestHelper eth;
215   eth.SetArgs({"does-not-exist", nullptr});
216   pid_t pid;
217   ASSERT_EQ(0, posix_spawnp(&pid, eth.GetArg0(), nullptr, nullptr, eth.GetArgs(), nullptr));
218   AssertChildExited(pid, 127);
219 }
220 
TEST(spawn,posix_spawn_environment)221 TEST(spawn, posix_spawn_environment) {
222   ExecTestHelper eth;
223   eth.SetArgs({"sh", "-c", "exit $posix_spawn_environment_test", nullptr});
224   eth.SetEnv({"posix_spawn_environment_test=66", nullptr});
225   pid_t pid;
226   ASSERT_EQ(0, posix_spawnp(&pid, eth.GetArg0(), nullptr, nullptr, eth.GetArgs(), eth.GetEnv()));
227   AssertChildExited(pid, 66);
228 }
229 
TEST(spawn,posix_spawn_file_actions)230 TEST(spawn, posix_spawn_file_actions) {
231   int fds[2];
232   ASSERT_NE(-1, pipe(fds));
233 
234   posix_spawn_file_actions_t fa;
235   ASSERT_EQ(0, posix_spawn_file_actions_init(&fa));
236 
237   ASSERT_EQ(0, posix_spawn_file_actions_addclose(&fa, fds[0]));
238   ASSERT_EQ(0, posix_spawn_file_actions_adddup2(&fa, fds[1], 1));
239   ASSERT_EQ(0, posix_spawn_file_actions_addclose(&fa, fds[1]));
240   // Check that close(2) failures are ignored by closing the same fd again.
241   ASSERT_EQ(0, posix_spawn_file_actions_addclose(&fa, fds[1]));
242   ASSERT_EQ(0, posix_spawn_file_actions_addopen(&fa, 56, "/proc/version", O_RDONLY, 0));
243 
244   ExecTestHelper eth;
245   eth.SetArgs({"ls", "-l", "/proc/self/fd", nullptr});
246   pid_t pid;
247   ASSERT_EQ(0, posix_spawnp(&pid, eth.GetArg0(), &fa, nullptr, eth.GetArgs(), eth.GetEnv()));
248   ASSERT_EQ(0, posix_spawn_file_actions_destroy(&fa));
249 
250   ASSERT_EQ(0, close(fds[1]));
251   std::string content;
252   ASSERT_TRUE(android::base::ReadFdToString(fds[0], &content));
253   ASSERT_EQ(0, close(fds[0]));
254 
255   AssertChildExited(pid, 0);
256 
257   // We'll know the dup2 worked if we see any ls(1) output in our pipe.
258   // The open we can check manually...
259   bool open_to_fd_56_worked = false;
260   for (const auto& line : android::base::Split(content, "\n")) {
261     if (line.find(" 56 -> /proc/version") != std::string::npos) open_to_fd_56_worked = true;
262   }
263   ASSERT_TRUE(open_to_fd_56_worked);
264 }
265 
CatFileToString(posix_spawnattr_t * sa,const char * path,std::string * content)266 static void CatFileToString(posix_spawnattr_t* sa, const char* path, std::string* content) {
267   int fds[2];
268   ASSERT_NE(-1, pipe(fds));
269 
270   posix_spawn_file_actions_t fa;
271   ASSERT_EQ(0, posix_spawn_file_actions_init(&fa));
272   ASSERT_EQ(0, posix_spawn_file_actions_addclose(&fa, fds[0]));
273   ASSERT_EQ(0, posix_spawn_file_actions_adddup2(&fa, fds[1], 1));
274   ASSERT_EQ(0, posix_spawn_file_actions_addclose(&fa, fds[1]));
275 
276   ExecTestHelper eth;
277   eth.SetArgs({"cat", path, nullptr});
278   pid_t pid;
279   ASSERT_EQ(0, posix_spawnp(&pid, eth.GetArg0(), &fa, sa, eth.GetArgs(), nullptr));
280   ASSERT_EQ(0, posix_spawn_file_actions_destroy(&fa));
281 
282   ASSERT_EQ(0, close(fds[1]));
283   ASSERT_TRUE(android::base::ReadFdToString(fds[0], content));
284   ASSERT_EQ(0, close(fds[0]));
285   AssertChildExited(pid, 0);
286 }
287 
288 struct ProcStat {
289   pid_t pid;
290   pid_t ppid;
291   pid_t pgrp;
292   pid_t sid;
293 };
294 
GetChildStat(posix_spawnattr_t * sa,ProcStat * ps)295 static void GetChildStat(posix_spawnattr_t* sa, ProcStat* ps) {
296   std::string content;
297   CatFileToString(sa, "/proc/self/stat", &content);
298 
299   ASSERT_EQ(4, sscanf(content.c_str(), "%d (cat) %*c %d %d %d", &ps->pid, &ps->ppid, &ps->pgrp,
300                       &ps->sid));
301 
302   ASSERT_EQ(getpid(), ps->ppid);
303 }
304 
305 struct ProcStatus {
306   uint64_t sigblk;
307   uint64_t sigign;
308 };
309 
GetChildStatus(posix_spawnattr_t * sa,ProcStatus * ps)310 static void GetChildStatus(posix_spawnattr_t* sa, ProcStatus* ps) {
311   std::string content;
312   CatFileToString(sa, "/proc/self/status", &content);
313 
314   bool saw_blk = false;
315   bool saw_ign = false;
316   for (const auto& line : android::base::Split(content, "\n")) {
317     if (sscanf(line.c_str(), "SigBlk: %" SCNx64, &ps->sigblk) == 1) saw_blk = true;
318     if (sscanf(line.c_str(), "SigIgn: %" SCNx64, &ps->sigign) == 1) saw_ign = true;
319   }
320   ASSERT_TRUE(saw_blk);
321   ASSERT_TRUE(saw_ign);
322 }
323 
TEST(spawn,posix_spawn_POSIX_SPAWN_SETSID_clear)324 TEST(spawn, posix_spawn_POSIX_SPAWN_SETSID_clear) {
325   pid_t parent_sid = getsid(0);
326 
327   posix_spawnattr_t sa;
328   ASSERT_EQ(0, posix_spawnattr_init(&sa));
329   ASSERT_EQ(0, posix_spawnattr_setflags(&sa, 0));
330 
331   ProcStat ps = {};
332   GetChildStat(&sa, &ps);
333   ASSERT_EQ(parent_sid, ps.sid);
334   ASSERT_EQ(0, posix_spawnattr_destroy(&sa));
335 }
336 
TEST(spawn,posix_spawn_POSIX_SPAWN_SETSID_set)337 TEST(spawn, posix_spawn_POSIX_SPAWN_SETSID_set) {
338   pid_t parent_sid = getsid(0);
339 
340   posix_spawnattr_t sa;
341   ASSERT_EQ(0, posix_spawnattr_init(&sa));
342   ASSERT_EQ(0, posix_spawnattr_setflags(&sa, POSIX_SPAWN_SETSID));
343 
344   ProcStat ps = {};
345   GetChildStat(&sa, &ps);
346   ASSERT_NE(parent_sid, ps.sid);
347   ASSERT_EQ(0, posix_spawnattr_destroy(&sa));
348 }
349 
TEST(spawn,posix_spawn_POSIX_SPAWN_SETPGROUP_clear)350 TEST(spawn, posix_spawn_POSIX_SPAWN_SETPGROUP_clear) {
351   pid_t parent_pgrp = getpgrp();
352 
353   posix_spawnattr_t sa;
354   ASSERT_EQ(0, posix_spawnattr_init(&sa));
355   ASSERT_EQ(0, posix_spawnattr_setflags(&sa, 0));
356 
357   ProcStat ps = {};
358   GetChildStat(&sa, &ps);
359   ASSERT_EQ(parent_pgrp, ps.pgrp);
360   ASSERT_EQ(0, posix_spawnattr_destroy(&sa));
361 }
362 
TEST(spawn,posix_spawn_POSIX_SPAWN_SETPGROUP_set)363 TEST(spawn, posix_spawn_POSIX_SPAWN_SETPGROUP_set) {
364   pid_t parent_pgrp = getpgrp();
365 
366   posix_spawnattr_t sa;
367   ASSERT_EQ(0, posix_spawnattr_init(&sa));
368   ASSERT_EQ(0, posix_spawnattr_setpgroup(&sa, 0));
369   ASSERT_EQ(0, posix_spawnattr_setflags(&sa, POSIX_SPAWN_SETPGROUP));
370 
371   ProcStat ps = {};
372   GetChildStat(&sa, &ps);
373   ASSERT_NE(parent_pgrp, ps.pgrp);
374   // Setting pgid 0 means "the same as the caller's pid".
375   ASSERT_EQ(ps.pid, ps.pgrp);
376   ASSERT_EQ(0, posix_spawnattr_destroy(&sa));
377 }
378 
TEST(spawn,posix_spawn_POSIX_SPAWN_SETSIGMASK)379 TEST(spawn, posix_spawn_POSIX_SPAWN_SETSIGMASK) {
380   // Block SIGBUS in the parent...
381   sigset_t just_SIGBUS;
382   sigemptyset(&just_SIGBUS);
383   sigaddset(&just_SIGBUS, SIGBUS);
384   ASSERT_EQ(0, sigprocmask(SIG_BLOCK, &just_SIGBUS, nullptr));
385 
386   posix_spawnattr_t sa;
387   ASSERT_EQ(0, posix_spawnattr_init(&sa));
388 
389   // Ask for only SIGALRM to be blocked in the child...
390   sigset_t just_SIGALRM;
391   sigemptyset(&just_SIGALRM);
392   sigaddset(&just_SIGALRM, SIGALRM);
393   ASSERT_EQ(0, posix_spawnattr_setsigmask(&sa, &just_SIGALRM));
394   ASSERT_EQ(0, posix_spawnattr_setflags(&sa, POSIX_SPAWN_SETSIGMASK));
395 
396   // Check that's what happens...
397   ProcStatus ps = {};
398   GetChildStatus(&sa, &ps);
399 
400   // TIMER_SIGNAL should also be blocked.
401   uint64_t expected_blocked = 0;
402   SignalSetAdd(&expected_blocked, SIGALRM);
403   SignalSetAdd(&expected_blocked, __SIGRTMIN + 0);
404   EXPECT_EQ(expected_blocked, ps.sigblk);
405 
406   EXPECT_EQ(static_cast<uint64_t>(0), ps.sigign);
407 
408   ASSERT_EQ(0, posix_spawnattr_destroy(&sa));
409 }
410 
TEST(spawn,posix_spawn_POSIX_SPAWN_SETSIGDEF)411 TEST(spawn, posix_spawn_POSIX_SPAWN_SETSIGDEF) {
412   // Ignore SIGALRM and SIGCONT in the parent...
413   ASSERT_NE(SIG_ERR, signal(SIGALRM, SIG_IGN));
414   ASSERT_NE(SIG_ERR, signal(SIGCONT, SIG_IGN));
415 
416   posix_spawnattr_t sa;
417   ASSERT_EQ(0, posix_spawnattr_init(&sa));
418 
419   // Ask for SIGALRM to be defaulted in the child...
420   sigset_t just_SIGALRM;
421   sigemptyset(&just_SIGALRM);
422   sigaddset(&just_SIGALRM, SIGALRM);
423 
424   ASSERT_EQ(0, posix_spawnattr_setsigdefault(&sa, &just_SIGALRM));
425   ASSERT_EQ(0, posix_spawnattr_setflags(&sa, POSIX_SPAWN_SETSIGDEF));
426 
427   // Check that's what happens...
428   ProcStatus ps = {};
429   GetChildStatus(&sa, &ps);
430 
431   // TIMER_SIGNAL should be blocked.
432   uint64_t expected_blocked = 0;
433   SignalSetAdd(&expected_blocked, __SIGRTMIN + 0);
434   EXPECT_EQ(expected_blocked, ps.sigblk);
435 
436   uint64_t expected_ignored = 0;
437   SignalSetAdd(&expected_ignored, SIGCONT);
438   EXPECT_EQ(expected_ignored, ps.sigign);
439 
440   ASSERT_EQ(0, posix_spawnattr_destroy(&sa));
441 }
442 
TEST(spawn,signal_stress)443 TEST(spawn, signal_stress) {
444   // Ensure that posix_spawn doesn't restore the caller's signal mask in the
445   // child without first defaulting any caught signals (http://b/68707996).
446   static pid_t parent = getpid();
447 
448   setpgid(0, 0);
449   signal(SIGRTMIN, SIG_IGN);
450 
451   pid_t pid = fork();
452   ASSERT_NE(-1, pid);
453 
454   if (pid == 0) {
455     for (size_t i = 0; i < 1024; ++i) {
456       kill(0, SIGRTMIN);
457       usleep(10);
458     }
459     _exit(99);
460   }
461 
462   // We test both with and without attributes, because they used to be
463   // different codepaths. We also test with an empty `sigdefault` set.
464   posix_spawnattr_t attr1;
465   posix_spawnattr_init(&attr1);
466 
467   sigset_t empty_mask = {};
468   posix_spawnattr_t attr2;
469   posix_spawnattr_init(&attr2);
470   posix_spawnattr_setflags(&attr2, POSIX_SPAWN_SETSIGDEF);
471   posix_spawnattr_setsigdefault(&attr2, &empty_mask);
472 
473   posix_spawnattr_t* attrs[] = { nullptr, &attr1, &attr2 };
474 
475   // We use a real-time signal because that's a tricky case for LP32
476   // because our sigset_t was too small.
477   ScopedSignalHandler ssh(SIGRTMIN, [](int) { ASSERT_EQ(getpid(), parent); });
478 
479   const size_t pid_count = 128;
480   pid_t spawned_pids[pid_count];
481 
482   ExecTestHelper eth;
483   eth.SetArgs({"true", nullptr});
484   for (size_t i = 0; i < pid_count; ++i) {
485     pid_t spawned_pid;
486     ASSERT_EQ(0, posix_spawn(&spawned_pid, "true", nullptr, attrs[i % 3], eth.GetArgs(), nullptr));
487     spawned_pids[i] = spawned_pid;
488   }
489 
490   for (pid_t spawned_pid : spawned_pids) {
491     ASSERT_EQ(spawned_pid, TEMP_FAILURE_RETRY(waitpid(spawned_pid, nullptr, 0)));
492   }
493 
494   AssertChildExited(pid, 99);
495 }
496