Make improvements

- Improved async signal safety of read() particularly for longjmp()
- Started adding cancel cleanup handlers for locks / etc on Windows
- Make /dev/tty work better particularly for uses like `foo | less`
- Eagerly read console input into a linked list, so poll can signal
- Fix some libc definitional bugs, which configure scripts detected

libc/mem/setenv.c

@@ -0,0 +1,51 @@
+/*-*- 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 2020 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/intrin/leaky.internal.h"
+#include "libc/intrin/strace.internal.h"
+#include "libc/mem/internal.h"
+#include "libc/mem/mem.h"
+#include "libc/runtime/runtime.h"
+#include "libc/str/str.h"
+#include "libc/sysv/errfuns.h"
+
+/**
+ * Copies variable to environment.
+ *
+ * @return 0 on success, or -1 w/ errno and environment is unchanged
+ * @raise EINVAL if `name` is empty or contains `'='`
+ * @raise ENOMEM if out of memory
+ * @see putenv(), getenv()
+ * @threadunsafe
+ */
+int setenv(const char *name, const char *value, int overwrite) {
+  int rc;
+  char *s;
+  size_t n, m;
+  if (!name || !*name || !value || strchr(name, '=')) return einval();
+  if ((s = malloc((n = strlen(name)) + 1 + (m = strlen(value)) + 1))) {
+    memcpy(mempcpy(mempcpy(s, name, n), "=", 1), value, m + 1);
+    rc = __putenv(s, overwrite);
+  } else {
+    rc = -1;
+  }
+  STRACE("setenv(%#s, %#s, %hhhd) → %d% m", name, value, overwrite, rc);
+  return rc;
+}
+
+IGNORE_LEAKS(setenv)