From 6ca844da053f979d169a6de01167dfa7a02b4696 Mon Sep 17 00:00:00 2001
From: Rob Landley <rob@landley.net>
Date: Fri, 31 Mar 2023 13:55:55 -0500
Subject: [PATCH] Add shuf.

---
 toys/other/shuf.c | 63 +++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 63 insertions(+)
 create mode 100644 toys/other/shuf.c

diff --git a/toys/other/shuf.c b/toys/other/shuf.c
new file mode 100644
index 00000000..fe8230f1
--- /dev/null
+++ b/toys/other/shuf.c
@@ -0,0 +1,63 @@
+/* shuf.c - Output lines in random order.
+ *
+ * Copyright 2023 Rob Landley <rob@landley.net>
+ *
+ * See https://man7.org/linux/man-pages/man1/shuf.1.html
+
+USE_SHUF(NEWTOY(shuf, "zen#<0", TOYFLAG_USR|TOYFLAG_BIN))
+
+config SHUF
+  bool "shuf"
+  default y
+  help
+    usage: shuf [-ze] [-n COUNT] [FILE...]
+
+    Write lines of input to output in random order.
+
+    -z	Input/output lines are NUL terminated.
+    -n	Stop after COUNT many output lines.
+    -e	Echo mode: arguments are inputs to shuffle, not files to read.
+*/
+
+#define FOR_shuf
+#include "toys.h"
+
+GLOBALS(
+  long n;
+
+  char **lines;
+  long count;
+)
+
+static void do_shuf_line(char **pline, long len)
+{
+  if (!pline) return;
+  if (!(TT.count&255))
+    TT.lines = xrealloc(TT.lines, sizeof(void *)*(TT.count+256));
+  TT.lines[TT.count++] = *pline; // TODO: repack?
+  *pline = 0;
+}
+
+static void do_shuf(int fd, char *name)
+{
+  do_lines(fd, '\n'*!FLAG(z), do_shuf_line);
+}
+
+void shuf_main(void)
+{
+  if (FLAG(e)) {
+    TT.lines = toys.optargs;
+    TT.count = toys.optc;
+  } else loopfiles(toys.optargs, do_shuf);
+
+  if (!FLAG(n) || TT.n>TT.count) TT.n = TT.count;
+
+  srandom(millitime());
+  while (TT.n--) {
+    long ll = random()%TT.count;
+    writeall(1, TT.lines[ll], strlen(TT.lines[ll])+FLAG(z));
+    if (!FLAG(e)) free(TT.lines[ll]);
+    else if (!FLAG(z)) writeall(1, "\n", 1);
+    TT.lines[ll] = TT.lines[--TT.count];
+  }
+}
-- 
2.39.2