Add torture test for zipos file descriptors

This change hardens the code for opening /zip/ files using the system
call interface. Thread safety and signal safety has been improved for
file descriptors in general. We now document fixed addresses that are
needed for low level allocations.

test/libc/calls/reservefd_test.c

@@ -0,0 +1,135 @@
+/*-*- mode:c;indent-tabs-mode:nil;c-basic-offset:2;tab-width:8;coding:utf-8 -*-│
+│vi: set net ft=c ts=2 sts=2 sw=2 fenc=utf-8                                :vi│
+╞══════════════════════════════════════════════════════════════════════════════╡
+│ Copyright 2022 Justine Alexandra Roberts Tunney                              │
+│                                                                              │
+│ Permission to use, copy, modify, and/or distribute this software for         │
+│ any purpose with or without fee is hereby granted, provided that the         │
+│ above copyright notice and this permission notice appear in all copies.      │
+│                                                                              │
+│ THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL                │
+│ WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED                │
+│ WARRANTIES OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE             │
+│ AUTHOR BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL         │
+│ DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR        │
+│ PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER               │
+│ TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR             │
+│ PERFORMANCE OF THIS SOFTWARE.                                                │
+╚─────────────────────────────────────────────────────────────────────────────*/
+#include "libc/calls/calls.h"
+#include "libc/calls/internal.h"
+#include "libc/calls/state.internal.h"
+#include "libc/calls/struct/itimerval.h"
+#include "libc/calls/struct/rlimit.h"
+#include "libc/calls/struct/sigaction.h"
+#include "libc/errno.h"
+#include "libc/intrin/kprintf.h"
+#include "libc/intrin/spinlock.h"
+#include "libc/macros.internal.h"
+#include "libc/nexgen32e/threaded.h"
+#include "libc/rand/rand.h"
+#include "libc/runtime/stack.h"
+#include "libc/sysv/consts/clone.h"
+#include "libc/sysv/consts/itimer.h"
+#include "libc/sysv/consts/map.h"
+#include "libc/sysv/consts/o.h"
+#include "libc/sysv/consts/prot.h"
+#include "libc/sysv/consts/rlimit.h"
+#include "libc/sysv/consts/sa.h"
+#include "libc/sysv/consts/sig.h"
+#include "libc/testlib/hyperion.h"
+#include "libc/testlib/testlib.h"
+#include "libc/time/time.h"
+
+STATIC_YOINK("zip_uri_support");
+STATIC_YOINK("libc/testlib/hyperion.txt");
+
+#define THREADS 8
+
+void PullSomeZipFilesIntoLinkage(void) {
+  gmtime(0);
+}
+
+char *stack[THREADS];
+char tls[THREADS][64];
+
+TEST(reservefd, testGrowthOfFdsDataStructure) {
+  int i, n;
+  struct rlimit rlim;
+  ASSERT_EQ(g_fds.n, OPEN_MAX);
+  n = 1700;  // pe '2**16/40' → 1638 (likely value of g_fds.n)
+  if (!getrlimit(RLIMIT_NOFILE, &rlim)) n = MIN(n, rlim.rlim_cur - 3);
+  for (i = 0; i < n; ++i) {
+    EXPECT_SYS(0, i + 3, open("/zip/usr/share/zoneinfo/UTC", O_RDONLY));
+  }
+  ASSERT_GT(g_fds.n, OPEN_MAX);
+  for (i = 0; i < n; ++i) {
+    EXPECT_SYS(0, 0, close(i + 3));
+  }
+}
+
+void OnSigAlrm(int sig, siginfo_t *si, ucontext_t *ctx) {
+  int rc, fd;
+  char buf[64];
+  ASSERT_NE(-1, (fd = open("/zip/libc/testlib/hyperion.txt", O_RDONLY)));
+  for (;;) {
+    rc = read(fd, buf, 64);
+    if (rc != -1) {
+      ASSERT_EQ(64, rc);
+      break;
+    } else {
+      ASSERT_EQ(EINTR, errno);
+      errno = 0;
+    }
+  }
+  ASSERT_EQ(0, memcmp(kHyperion, buf, 64));
+  close(fd);  // can eintr which doesn't matter
+}
+
+int Worker(void *p) {
+  char buf[64];
+  int i, rc, fd;
+  for (i = 0; i < 64; ++i) {
+    ASSERT_NE(-1, (fd = open("/zip/libc/testlib/hyperion.txt", O_RDONLY)));
+    usleep(rand64() % 100);
+    for (;;) {
+      rc = read(fd, buf, 64);
+      if (rc != -1) {
+        ASSERT_EQ(64, rc);
+        break;
+      } else {
+        ASSERT_EQ(EINTR, errno);
+        errno = 0;
+      }
+    }
+    ASSERT_EQ(0, memcmp(kHyperion, buf, 64));
+    close(fd);
+  }
+  return 0;
+}
+
+TEST(reservefd, tortureTest) {
+  int i;
+  struct sigaction oldsa;
+  struct itimerval oldit;
+  struct itimerval it = {{0, 10000}, {0, 100}};
+  struct sigaction sa = {.sa_sigaction = OnSigAlrm,
+                         .sa_flags = 0 /* SA_NODEFER */};
+  // ASSERT_SYS(0, 0, sigaction(SIGALRM, &sa, &oldsa));
+  // ASSERT_SYS(0, 0, setitimer(ITIMER_REAL, &it, &oldit));
+  for (i = 0; i < THREADS; ++i) {
+    clone(Worker,
+          (stack[i] = mmap(0, GetStackSize(), PROT_READ | PROT_WRITE,
+                           MAP_STACK | MAP_ANONYMOUS, -1, 0)),
+          GetStackSize(),
+          CLONE_THREAD | CLONE_VM | CLONE_FS | CLONE_FILES | CLONE_SIGHAND |
+              CLONE_CHILD_SETTID | CLONE_CHILD_CLEARTID | CLONE_SETTLS,
+          0, 0, __initialize_tls(tls[i]), sizeof(tls[i]),
+          (int *)(tls[i] + 0x38));
+  }
+  for (i = 0; i < THREADS; ++i) {
+    _spinlock((int *)(tls[i] + 0x38));
+  }
+  // EXPECT_SYS(0, 0, sigaction(SIGALRM, &oldsa, 0));
+  // EXPECT_SYS(0, 0, setitimer(ITIMER_REAL, &oldit, 0));
+}

test/libc/str/test.mk

@@ -45,6 +45,7 @@ TEST_LIBC_STR_DIRECTDEPS =						\
 	LIBC_STR							\
 	LIBC_STUBS							\
 	LIBC_SYSV							\
+	LIBC_SYSV_CALLS							\
 	LIBC_TESTLIB							\
 	LIBC_UNICODE							\
 	LIBC_X								\