Make improvements

- Get threads working on NetBSD
- Get threads working on OpenBSD
- Fix Emacs config for Emacs v28
- Improve --strace logging of sigset_t
- Improve --strace logging of struct stat
- Improve memory safety of DescribeThing functions
- Refactor auto stack allocation into LIBC_RUNTIME
- Introduce shell.com example which works on Windows
- Refactor __strace_thing into DescribeThing functions
- Document the CHECK macros and improve them in NDEBUG mode
- Rewrite MAP_STACK so it uses FreeBSD behavior across platforms
- Deprecate and discourage the use of MAP_GROWSDOWN (it's weird)

examples/shell.c

@@ -0,0 +1,172 @@
+#if 0
+/*─────────────────────────────────────────────────────────────────╗
+│ To the extent possible under law, Justine Tunney has waived      │
+│ all copyright and related or neighboring rights to this file,    │
+│ as it is written in the following disclaimers:                   │
+│   • http://unlicense.org/                                        │
+│   • http://creativecommons.org/publicdomain/zero/1.0/            │
+╚─────────────────────────────────────────────────────────────────*/
+#endif
+#include "libc/calls/calls.h"
+#include "libc/calls/sigbits.h"
+#include "libc/calls/struct/sigaction.h"
+#include "libc/calls/struct/sigset.h"
+#include "libc/fmt/fmt.h"
+#include "libc/fmt/itoa.h"
+#include "libc/log/internal.h"
+#include "libc/macros.internal.h"
+#include "libc/runtime/internal.h"
+#include "libc/runtime/runtime.h"
+#include "libc/stdio/stdio.h"
+#include "libc/str/str.h"
+#include "libc/sysv/consts/dt.h"
+#include "libc/sysv/consts/sig.h"
+#include "libc/x/x.h"
+#include "third_party/linenoise/linenoise.h"
+
+/**
+ * @fileoverview Shell that works on Windows.
+ *
+ * This doesn't have script language features like UNBOURNE.COM but it
+ * works on Windows and, unlike CMD.EXE, actually has CTRL-P and CTRL-R
+ * which alone make it so much better.
+ *
+ * One day we'll have UNBOURNE.COM working on Windows but the code isn't
+ * very maintainable sadly.
+ */
+
+static void AddUniqueCompletion(linenoiseCompletions *c, char *s) {
+  size_t i;
+  if (!s) return;
+  for (i = 0; i < c->len; ++i) {
+    if (!strcmp(s, c->cvec[i])) {
+      return;
+    }
+  }
+  c->cvec = realloc(c->cvec, ++c->len * sizeof(*c->cvec));
+  c->cvec[c->len - 1] = s;
+}
+
+static void CompleteFilename(const char *p, const char *q, const char *b,
+                             linenoiseCompletions *c) {
+  DIR *d;
+  char *buf;
+  const char *g;
+  struct dirent *e;
+  if ((buf = malloc(512))) {
+    if ((g = memrchr(p, '/', q - p))) {
+      *(char *)mempcpy(buf, p, MIN(g - p, 511)) = 0;
+      p = ++g;
+    } else {
+      strcpy(buf, ".");
+    }
+    if ((d = opendir(buf))) {
+      while ((e = readdir(d))) {
+        if (!strcmp(e->d_name, ".")) continue;
+        if (!strcmp(e->d_name, "..")) continue;
+        if (!strncmp(e->d_name, p, q - p)) {
+          snprintf(buf, 512, "%.*s%s%s", p - b, b, e->d_name,
+                   e->d_type == DT_DIR ? "/" : "");
+          AddUniqueCompletion(c, strdup(buf));
+        }
+      }
+      closedir(d);
+    }
+    free(buf);
+  }
+}
+
+static void ShellCompletion(const char *p, linenoiseCompletions *c) {
+  bool slashed;
+  const char *q, *b;
+  for (slashed = false, b = p, q = (p += strlen(p)); p > b; --p) {
+    if (p[-1] == '/' && p[-1] == '\\') slashed = true;
+    if (!isalnum(p[-1]) &&
+        (p[-1] != '.' && p[-1] != '_' && p[-1] != '-' && p[-1] != '+' &&
+         p[-1] != '[' && p[-1] != '/' && p[-1] != '\\')) {
+      break;
+    }
+  }
+  CompleteFilename(p, q, b, c);
+}
+
+static char *ShellHint(const char *p, const char **ansi1, const char **ansi2) {
+  char *h = 0;
+  linenoiseCompletions c = {0};
+  ShellCompletion(p, &c);
+  if (c.len == 1) {
+    h = strdup(c.cvec[0] + strlen(p));
+  }
+  linenoiseFreeCompletions(&c);
+  return h;
+}
+
+int main(int argc, char *argv[]) {
+  int n, ws, pid;
+  char *prog, path[PATH_MAX];
+  sigset_t chldmask, savemask;
+  struct sigaction ignore, saveint, savequit;
+  char *p, *line, **args, *arg, *start, *state, prompt[64];
+  linenoiseSetFreeHintsCallback(free);
+  linenoiseSetHintsCallback(ShellHint);
+  linenoiseSetCompletionCallback(ShellCompletion);
+  stpcpy(prompt, "$ ");
+  while ((line = linenoiseWithHistory(prompt, "cmd"))) {
+    n = 0;
+    start = line;
+    args = xcalloc(1, sizeof(*args));
+    while ((arg = strtok_r(start, " \t\r\n", &state))) {
+      args = xrealloc(args, (++n + 1) * sizeof(*args));
+      args[n - 1] = arg;
+      args[n - 0] = 0;
+      start = 0;
+    }
+    if (n > 0) {
+      if ((prog = commandv(args[0], path, sizeof(path)))) {
+        ignore.sa_flags = 0;
+        ignore.sa_handler = SIG_IGN;
+        sigemptyset(&ignore.sa_mask);
+        sigaction(SIGINT, &ignore, &saveint);
+        sigaction(SIGQUIT, &ignore, &savequit);
+        sigemptyset(&chldmask);
+        sigaddset(&chldmask, SIGCHLD);
+        sigprocmask(SIG_BLOCK, &chldmask, &savemask);
+
+        if (!fork()) {
+          sigaction(SIGINT, &saveint, 0);
+          sigaction(SIGQUIT, &savequit, 0);
+          sigprocmask(SIG_SETMASK, &savemask, 0);
+          execv(prog, args);
+          _Exit(127);
+        }
+
+        wait(&ws);
+        p = prompt;
+        if (WIFEXITED(ws)) {
+          if (WEXITSTATUS(ws)) {
+            if (!__nocolor) p = stpcpy(p, "\e[1;31m");
+            p = stpcpy(p, "rc=");
+            p = FormatInt32(p, WEXITSTATUS(ws));
+            if (!__nocolor) p = stpcpy(p, "\e[0m");
+            *p++ = ' ';
+          }
+        } else {
+          if (!__nocolor) p = stpcpy(p, "\e[1;31m");
+          p = stpcpy(p, "rc=");
+          p = stpcpy(p, strsignal(WTERMSIG(ws)));
+          if (!__nocolor) p = stpcpy(p, "\e[0m");
+          *p++ = ' ';
+        }
+        p = stpcpy(p, "$ ");
+
+        sigaction(SIGINT, &saveint, 0);
+        sigaction(SIGQUIT, &savequit, 0);
+        sigprocmask(SIG_SETMASK, &savemask, 0);
+      } else {
+        fprintf(stderr, "%s: %s: command not found\n", argv[0], args[0]);
+      }
+    }
+    free(line);
+    free(args);
+  }
+}