Improve system calls

- Wrap clock_getres()
- Wrap sched_setscheduler()
- Make sleep() api conformant
- Polyfill sleep() using select()
- Improve clock_gettime() polyfill
- Make nanosleep() POSIX conformant
- Slightly improve some DNS functions
- Further strengthen pledge() sandboxing
- Improve rounding of timeval / timespec
- Allow layering of pledge() calls on Linux
- Polyfill sched_yield() using select() on XNU
- Delete more system constants we probably don't need

libc/dns/dns.h

@@ -37,6 +37,15 @@
 #define AI_ADDRCONFIG  0x0400
 #define AI_V4MAPPED    0x0800
 
+#define NI_NUMERICSCOPE 0
+#define NI_NUMERICHOST  1
+#define NI_NUMERICSERV  2
+#define NI_NOFQDN       4
+#define NI_NAMEREQD     8
+#define NI_DGRAM        16
+#define NI_MAXSERV      32
+#define NI_MAXHOST      1025
+
 #if !(__ASSEMBLER__ + __LINKER__ + 0)
 COSMOPOLITAN_C_START_
 

libc/dns/ent.h

@@ -1,11 +1,15 @@
 #ifndef COSMOPOLITAN_LIBC_DNS_ENT_H_
 #define COSMOPOLITAN_LIBC_DNS_ENT_H_
 #include "libc/dns/dns.h"
+
+#define HOST_NOT_FOUND 1
+#define TRY_AGAIN      2
+#define NO_RECOVERY    3
+#define NO_DATA        4
+
 #if !(__ASSEMBLER__ + __LINKER__ + 0)
 COSMOPOLITAN_C_START_
 
-extern int h_errno;
-
 struct netent {
   char *n_name;     /* official network name */
   char **n_aliases; /* alias list */
@@ -35,6 +39,10 @@ struct servent {
   char *s_proto;    /* protocol to use */
 };
 
+extern int h_errno;
+void herror(const char *);
+const char *hstrerror(int);
+
 struct netent *getnetent(void);
 struct netent *getnetbyname(const char *);
 struct netent *getnetbyaddr(uint32_t, int);

libc/dns/h_errno.c

@@ -0,0 +1,24 @@
+/*-*- 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/dns/dns.h"
+
+/**
+ * Error number global for gethostbyname*(), gethostbyaddr*(), etc.
+ */
+int h_errno;

libc/dns/herror.c

@@ -25,12 +25,12 @@
 │ OTHER DEALINGS IN THE SOFTWARE.                                              │
 ╚─────────────────────────────────────────────────────────────────────────────*/
 #include "libc/dns/ent.h"
+#include "libc/stdio/stdio.h"
 
-int h_errno;
-
+/**
+ * Prints `h_errno` description to stderr.
+ * @see perror()
+ */
 void herror(const char *s) {
-}
-
-const char *hstrerror(int err) {
-  return "unknown";
+  fprintf(stderr, "%s%s%s\n", s ? s : "", s ? ": " : "", hstrerror(h_errno));
 }

libc/dns/hstrerror.c

@@ -0,0 +1,37 @@
+/*-*- 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/dns/ent.h"
+
+/**
+ * Turns `h_errno` value into string.
+ */
+const char *hstrerror(int err) {
+  switch (err) {
+    case HOST_NOT_FOUND:
+      return "HOST_NOT_FOUND";
+    case TRY_AGAIN:
+      return "TRY_AGAIN";
+    case NO_RECOVERY:
+      return "NO_RECOVERY";
+    case NO_DATA:
+      return "NO_DATA";
+    default:
+      return "UNKNOWN";
+  }
+}