Make more fixes and improvements

- Remove PAGESIZE constant
- Fix realloc() documentation
- Fix ttyname_r() error reporting
- Make forking more reliable on Windows
- Make execvp() a few microseconds faster
- Make system() a few microseconds faster
- Tighten up the socket-related magic numbers
- Loosen restrictions on mmap() offset alignment
- Improve GetProgramExecutableName() with getenv("_")
- Use mkstemp() as basis for mktemp(), tmpfile(), tmpfd()
- Fix flakes in pthread_cancel_test, unix_test, fork_test
- Fix recently introduced futex stack overflow regression
- Let sockets be passed as stdio to subprocesses on Windows
- Improve security of bind() on Windows w/ SO_EXCLUSIVEADDRUSE

test/libc/runtime/fork_test.c

@@ -16,15 +16,19 @@
 │ TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR             │
 │ PERFORMANCE OF THIS SOFTWARE.                                                │
 ╚─────────────────────────────────────────────────────────────────────────────*/
+#include "libc/atomic.h"
 #include "libc/calls/calls.h"
 #include "libc/calls/struct/sigaction.h"
+#include "libc/calls/struct/sigset.h"
 #include "libc/calls/struct/timespec.h"
 #include "libc/dce.h"
+#include "libc/errno.h"
 #include "libc/intrin/kprintf.h"
 #include "libc/log/check.h"
 #include "libc/macros.internal.h"
 #include "libc/nexgen32e/rdtsc.h"
 #include "libc/runtime/runtime.h"
+#include "libc/str/str.h"
 #include "libc/sysv/consts/map.h"
 #include "libc/sysv/consts/msync.h"
 #include "libc/sysv/consts/prot.h"
@@ -38,6 +42,7 @@ TEST(fork, testPipes) {
   int a, b;
   int ws, pid;
   int pipefds[2];
+  alarm(5);
   ASSERT_NE(-1, pipe(pipefds));
   ASSERT_NE(-1, (pid = fork()));
   if (!pid) {
@@ -52,9 +57,11 @@ TEST(fork, testPipes) {
   EXPECT_NE(-1, close(pipefds[0]));
   EXPECT_NE(-1, waitpid(pid, &ws, 0));
   EXPECT_EQ(31337, b);
+  alarm(0);
 }
 
 TEST(fork, testSharedMemory) {
+  alarm(5);
   int ws, pid;
   int stackvar;
   int *sharedvar;
@@ -86,6 +93,7 @@ TEST(fork, testSharedMemory) {
   EXPECT_EQ(1, *privatevar);
   EXPECT_NE(-1, munmap(sharedvar, FRAMESIZE));
   EXPECT_NE(-1, munmap(privatevar, FRAMESIZE));
+  alarm(0);
 }
 
 static volatile bool gotsigusr1;
@@ -109,6 +117,7 @@ TEST(fork, childToChild) {
   signal(SIGUSR1, OnSigusr1);
   signal(SIGUSR2, OnSigusr2);
   sigemptyset(&mask);
+  sigaddset(&mask, SIGUSR1);
   sigaddset(&mask, SIGUSR2);
   sigprocmask(SIG_BLOCK, &mask, &oldmask);
   ASSERT_NE(-1, (child1 = fork()));
@@ -117,28 +126,27 @@ TEST(fork, childToChild) {
     sigsuspend(0);
     _Exit(!gotsigusr1);
   }
-  sigdelset(&mask, SIGUSR2);
-  sigsuspend(&mask);
+  sigsuspend(0);
   ASSERT_NE(-1, (child2 = fork()));
   if (!child2) {
     kill(child1, SIGUSR1);
     _Exit(0);
   }
   ASSERT_NE(-1, wait(&ws));
-  EXPECT_TRUE(WIFEXITED(ws));
-  EXPECT_EQ(0, WEXITSTATUS(ws));
+  EXPECT_EQ(0, ws);
   ASSERT_NE(-1, wait(&ws));
-  EXPECT_TRUE(WIFEXITED(ws));
-  EXPECT_EQ(0, WEXITSTATUS(ws));
+  EXPECT_EQ(0, ws);
   sigprocmask(SIG_SETMASK, &oldmask, 0);
 }
 
 TEST(fork, preservesTlsMemory) {
+  alarm(5);
   int pid;
   __get_tls()->tib_errno = 31337;
   SPAWN(fork);
   ASSERT_EQ(31337, __get_tls()->tib_errno);
   EXITS(0);
+  alarm(0);
 }
 
 void ForkInSerial(void) {