Improve memory safety

This commit makes numerous refinements to cosmopolitan memory handling.

The default stack size has been reduced from 2mb to 128kb. A new macro
is now provided so you can easily reconfigure the stack size to be any
value you want. Work around the breaking change by adding to your main:

    STATIC_STACK_SIZE(0x00200000);  // 2mb stack

If you're not sure how much stack you need, then you can use:

    STATIC_YOINK("stack_usage_logging");

After which you can `sort -nr o/$MODE/stack.log`. Based on the unit test
suite, nothing in the Cosmopolitan repository (except for Python) needs
a stack size greater than 30kb. There are also new macros for detecting
the size and address of the stack at runtime, e.g. GetStackAddr(). We
also now support sigaltstack() so if you want to see nice looking crash
reports whenever a stack overflow happens, you can put this in main():

    ShowCrashReports();

Under `make MODE=dbg` and `make MODE=asan` the unit testing framework
will now automatically print backtraces of memory allocations when
things like memory leaks happen. Bugs are now fixed in ASAN global
variable overrun detection. The memtrack and asan runtimes also handle
edge cases now. The new tools helped to identify a few memory leaks,
which are fixed by this change.

This change should fix an issue reported in #288 with ARG_MAX limits.
Fixing this doubled the performance of MKDEPS.COM and AR.COM yet again.

libc/log/libfatal.internal.h

@@ -5,42 +5,94 @@
 #include "libc/nexgen32e/bsr.h"
 #include "libc/nt/process.h"
 #include "libc/nt/runtime.h"
+#include "libc/runtime/runtime.h"
 #include "libc/sysv/consts/nr.h"
 #if !(__ASSEMBLER__ + __LINKER__ + 0)
 COSMOPOLITAN_C_START_
 
 extern char __fatalbuf[];
 
+void __printf(const char *, ...);
+
+forceinline void __sysv_exit(long rc) {
+  asm volatile("call\t__syscall__"
+               : /* no outputs */
+               : "a"(__NR_exit_group), "D"(rc)
+               : "memory", "cc");
+}
+
+forceinline int __sysv_close(long fd) {
+  long ax;
+  asm volatile("call\t__syscall__"
+               : "=a"(ax)
+               : "0"(__NR_close), "D"(fd)
+               : "rdx", "memory", "cc");
+  return ax;
+}
+
+forceinline int __sysv_open(const char *path, long flags, long mode) {
+  long ax, dx;
+  asm volatile("call\t__syscall__"
+               : "=a"(ax), "=d"(dx)
+               : "0"(__NR_open), "D"(path), "S"(flags), "1"(mode)
+               : "memory", "cc");
+  return ax;
+}
+
+forceinline long __sysv_read(long fd, void *data, unsigned long size) {
+  long ax, dx;
+  asm volatile("call\t__syscall__"
+               : "=a"(ax), "=d"(dx)
+               : "0"(__NR_read), "D"(fd), "S"(data), "1"(size)
+               : "memory", "cc");
+  return ax;
+}
+
+forceinline long __sysv_write(long fd, const void *data, unsigned long size) {
+  long ax, dx;
+  asm volatile("call\t__syscall__"
+               : "=a"(ax), "=d"(dx)
+               : "0"(__NR_write), "D"(fd), "S"(data), "1"(size)
+               : "memory", "cc");
+  return ax;
+}
+
+forceinline long __sysv_mprotect(void *addr, size_t size, long prot) {
+  long ax, dx;
+  asm volatile("call\t__syscall__"
+               : "=a"(ax), "=d"(dx)
+               : "0"(__NR_mprotect), "D"(addr), "S"(size), "1"(prot)
+               : "memory", "cc");
+  return ax;
+}
+
+forceinline int __sysv_getpid(void) {
+  long ax;
+  asm volatile("call\t__syscall__"
+               : "=a"(ax)
+               : "0"(__NR_getpid)
+               : "rdx", "memory", "cc");
+  return ax;
+}
+
 forceinline int __getpid(void) {
-  int rc;
   if (!IsWindows()) {
-    asm volatile("call\t__syscall__"
-                 : "=a"(rc)
-                 : "0"(__NR_getpid)
-                 : "rcx", "r11", "memory");
-    return rc;
+    return __sysv_getpid();
   } else {
     return GetCurrentProcessId();
   }
 }
 
-forceinline ssize_t __write(const void *data, size_t size) {
+forceinline ssize_t __write(const void *p, size_t n) {
   char cf;
   ssize_t rc;
   uint32_t wrote;
   if (!IsWindows()) {
-    asm volatile("call\t__syscall__"
-                 : "=@ccc"(cf), "=a"(rc)
-                 : "1"(__NR_write), "D"(2), "S"(data), "d"(size)
-                 : "rcx", "r11", "memory");
-    if (cf && IsBsd()) rc = -rc;
-    return rc;
+    return __sysv_write(2, p, n);
+  } else if (WriteFile(GetStdHandle(kNtStdErrorHandle), p, n, &wrote, 0)) {
+    return wrote;
   } else {
-    if (WriteFile(GetStdHandle(kNtStdErrorHandle), data, size, &wrote, 0)) {
-      return wrote;
-    } else {
-      return -1;
-    }
+    return -GetLastError();
   }
 }
 
@@ -54,6 +106,12 @@ forceinline ssize_t __write_str(const char *s) {
   return __write(s, __strlen(s));
 }
 
+forceinline int __strcmp(const char *l, const char *r) {
+  size_t i = 0;
+  while (l[i] == r[i] && r[i]) ++i;
+  return (l[i] & 255) - (r[i] & 255);
+}
+
 forceinline char *__stpcpy(char *d, const char *s) {
   size_t i;
   for (i = 0;; ++i) {
@@ -63,6 +121,13 @@ forceinline char *__stpcpy(char *d, const char *s) {
   }
 }
 
+forceinline void *__repstosb(void *di, char al, size_t cx) {
+  asm("rep stosb"
+      : "=D"(di), "=c"(cx), "=m"(*(char(*)[cx])di)
+      : "0"(di), "1"(cx), "a"(al));
+  return di;
+}
+
 forceinline void *__repmovsb(void *di, void *si, size_t cx) {
   asm("rep movsb"
       : "=D"(di), "=S"(si), "=c"(cx), "=m"(*(char(*)[cx])di)
@@ -112,7 +177,64 @@ forceinline char *__hexcpy(char p[hasatleast 17], uint64_t x) {
   return __fixcpy(p, x, ROUNDUP(x ? bsrl(x) + 1 : 1, 4));
 }
 
-void __printf(const char *, ...);
+forceinline const void *__memchr(const void *s, unsigned char c, size_t n) {
+  size_t i;
+  for (i = 0; i < n; ++i) {
+    if (((const unsigned char *)s)[i] == c) {
+      return (const unsigned char *)s + i;
+    }
+  }
+  return 0;
+}
+
+forceinline char *__strstr(const char *haystack, const char *needle) {
+  size_t i;
+  for (;;) {
+    for (i = 0;; ++i) {
+      if (!needle[i]) return (/*unconst*/ char *)haystack;
+      if (!haystack[i]) break;
+      if (needle[i] != haystack[i]) break;
+    }
+    if (!*haystack++) break;
+  }
+  return 0;
+}
+
+forceinline char *__getenv(char **p, const char *s) {
+  size_t i, j;
+  if (p) {
+    for (i = 0; p[i]; ++i) {
+      for (j = 0;; ++j) {
+        if (!s[j]) {
+          if (p[i][j] == '=') {
+            return p[i] + j + 1;
+          }
+          break;
+        }
+        if (s[j] != p[i][j]) {
+          break;
+        }
+      }
+    }
+  }
+  return 0;
+}
+
+forceinline unsigned long __atoul(const char *p) {
+  int c;
+  unsigned long x = 0;
+  while ('0' <= (c = *p++) && c <= '9') x *= 10, x += c - '0';
+  return x;
+}
+
+forceinline long __atol(const char *p) {
+  int s = *p;
+  unsigned long x;
+  if (s == '-' || s == '+') ++p;
+  x = __atoul(p);
+  if (s == '-') x = -x;
+  return x;
+}
 
 COSMOPOLITAN_C_END_
 #endif /* !(__ASSEMBLER__ + __LINKER__ + 0) */