Introduce new tinyprint() api

libc/calls/calls.h

@@ -229,6 +229,7 @@ int unveil(const char *, const char *);
 long ptrace(int, ...);
 ssize_t copyfd(int, int, size_t);
 ssize_t readansi(int, char *, size_t);
+ssize_t tinyprint(int, const char *, ...) nullterminated();
 #endif
 
 COSMOPOLITAN_C_END_

libc/calls/tinyprint.c

@@ -0,0 +1,68 @@
+/*-*- 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 2023 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"
+
+static bool tinyflush(int fd, char *buf, size_t n, ssize_t *toto) {
+  ssize_t rc;
+  if ((rc = write(fd, buf, n)) != -1) {
+    *toto += rc;
+    return false;
+  } else {
+    if (!*toto) {
+      --*toto;
+    }
+    return true;
+  }
+}
+
+/**
+ * Writes strings to file descriptor, e.g.
+ *
+ *     tinyprint(1, "hello", " ", "world", "\n", NULL);
+ *
+ * This function is intended so that small command line programs (e.g.
+ * build utilities) can print succinct error messages automatically to
+ * standard io without linking too much binary footprint.
+ *
+ * @param fd is file descriptor
+ * @param s is NUL-terminated string, or NULL
+ * @return bytes written on success, or -1 w/ errno
+ */
+ssize_t tinyprint(int fd, const char *s, ...) {
+  int c;
+  size_t n;
+  va_list va;
+  ssize_t toto;
+  char buf[512];
+  va_start(va, s);
+  for (toto = n = 0; s; s = va_arg(va, const char *)) {
+    while ((c = *s++)) {
+      buf[n++] = c;
+      if (n == sizeof(buf)) {
+        if (tinyflush(fd, buf, n, &toto)) {
+          return toto;
+        }
+        n = 0;
+      }
+    }
+  }
+  va_end(va);
+  tinyflush(fd, buf, n, &toto);
+  return toto;
+}