Merge pull request #17020 from seandewar/vim-8.1.2342

vim-patch:8.1.{2342,2343,2356,2357},8.2.0233: `rand` and `srand`

5 files changed, 247 insertions, 0 deletions

diff --git a/runtime/doc/builtin.txt b/runtime/doc/builtin.txt
index 4153c1c9d8..327b8dc4d9 100644
--- a/runtime/doc/builtin.txt
+++ b/runtime/doc/builtin.txt
@@ -325,6 +325,7 @@ pumvisible()			Number	whether popup menu is visible
 pyeval({expr})			any	evaluate |Python| expression
 py3eval({expr})			any	evaluate |python3| expression
 pyxeval({expr})			any	evaluate |python_x| expression
+rand([{expr}])			Number	get pseudo-random number
 range({expr} [, {max} [, {stride}]])
 				List	items from {expr} to {max}
 readdir({dir} [, {expr}])	List	file names in {dir} selected by {expr}
@@ -441,6 +442,7 @@ spellsuggest({word} [, {max} [, {capital}]])
 split({expr} [, {pat} [, {keepempty}]])
 				List	make |List| from {pat} separated {expr}
 sqrt({expr})			Float	square root of {expr}
+srand([{expr}])			List	get seed for |rand()|
 stdioopen({dict})		Number	open stdio in a headless instance.
 stdpath({what})			String/List  returns the standard path(s) for {what}
 str2float({expr} [, {quoted}])	Float	convert String to Float
@@ -5530,6 +5532,23 @@ range({expr} [, {max} [, {stride}]])				*range()*
 		Can also be used as a |method|: >
 			GetExpr()->range()
 <
+rand([{expr}])						*rand()*
+		Return a pseudo-random Number generated with an xoshiro128**
+		algorithm using seed {expr}.  The returned number is 32 bits,
+		also on 64 bits systems, for consistency.
+		{expr} can be initialized by |srand()| and will be updated by
+		rand().  If {expr} is omitted, an internal seed value is used
+		and updated.
+
+		Examples: >
+			:echo rand()
+			:let seed = srand()
+			:echo rand(seed)
+			:echo rand(seed) % 16  " random number 0 - 15
+<
+		Can also be used as a |method|: >
+			seed->rand()
+<
 							*readdir()*
 readdir({directory} [, {expr}])
 		Return a list with file and directory names in {directory}.
@@ -7178,6 +7197,23 @@ sqrt({expr})						*sqrt()*
 		Can also be used as a |method|: >
 			Compute()->sqrt()
 
+srand([{expr}])						*srand()*
+		Initialize seed used by |rand()|:
+		- If {expr} is not given, seed values are initialized by
+		  reading from /dev/urandom, if possible, or using time(NULL)
+		  a.k.a. epoch time otherwise; this only has second accuracy.
+		- If {expr} is given it must be a Number.  It is used to
+		  initialize the seed values.  This is useful for testing or
+		  when a predictable sequence is intended.
+
+		Examples: >
+			:let seed = srand()
+			:let seed = srand(userinput)
+			:echo rand(seed)
+<
+		Can also be used as a |method|: >
+			userinput->srand()
+
 stdioopen({opts})			 *stdioopen()*
 		With |--headless| this opens stdin and stdout as a |channel|.
 		May be called only once. See |channel-stdio|. stderr is not
diff --git a/runtime/doc/vim_diff.txt b/runtime/doc/vim_diff.txt
index 7e61eac404..11849632c5 100644
--- a/runtime/doc/vim_diff.txt
+++ b/runtime/doc/vim_diff.txt
@@ -574,6 +574,7 @@ Test functions:
   test_scrollbar()
   test_setmouse()
   test_settime()
+  test_srand_seed()
 
 TUI:
 			  *t_xx* *termcap-options* *t_AB* *t_Sb* *t_vb* *t_SI*
diff --git a/src/nvim/eval.lua b/src/nvim/eval.lua
index 18967b80f2..ef2b8a0cc0 100644
--- a/src/nvim/eval.lua
+++ b/src/nvim/eval.lua
@@ -273,6 +273,7 @@ return {
     pyeval={args=1, base=1, func="f_py3eval"},
     pyxeval={args=1, base=1, func="f_py3eval"},
     perleval={args=1, base=1},
+    rand={args={0, 1}, base=1},
     range={args={1, 3}, base=1},
     readdir={args={1, 2}, base=1},
     readfile={args={1, 3}, base=1},
@@ -348,6 +349,7 @@ return {
     spellsuggest={args={1, 3}, base=1},
     split={args={1, 3}, base=1},
     sqrt={args=1, base=1, func="float_op_wrapper", data="&sqrt"},
+    srand={args={0, 1}, base=1},
     stdpath={args=1},
     str2float={args=1, base=1},
     str2list={args={1, 2}, base=1},
diff --git a/src/nvim/eval/funcs.c b/src/nvim/eval/funcs.c
index 50030f2994..b96ff50787 100644
--- a/src/nvim/eval/funcs.c
+++ b/src/nvim/eval/funcs.c
@@ -22,6 +22,7 @@
 #include "nvim/eval/encode.h"
 #include "nvim/eval/executor.h"
 #include "nvim/eval/funcs.h"
+#include "nvim/eval/typval.h"
 #include "nvim/eval/userfunc.h"
 #include "nvim/ex_cmds2.h"
 #include "nvim/ex_docmd.h"
@@ -6978,6 +6979,162 @@ static void f_py3eval(typval_T *argvars, typval_T *rettv, FunPtr fptr)
   script_host_eval("python3", argvars, rettv);
 }
 
+static void init_srand(uint32_t *const x)
+  FUNC_ATTR_NONNULL_ALL
+{
+#ifndef MSWIN
+  static int dev_urandom_state = NOTDONE;  // FAIL or OK once tried
+
+  if (dev_urandom_state != FAIL) {
+    const int fd = os_open("/dev/urandom", O_RDONLY, 0);
+    struct {
+      union {
+        uint32_t number;
+        char bytes[sizeof(uint32_t)];
+      } contents;
+    } buf;
+
+    // Attempt reading /dev/urandom.
+    if (fd == -1) {
+      dev_urandom_state = FAIL;
+    } else {
+      buf.contents.number = 0;
+      if (read(fd, buf.contents.bytes, sizeof(uint32_t)) != sizeof(uint32_t)) {
+        dev_urandom_state = FAIL;
+      } else {
+        dev_urandom_state = OK;
+        *x = buf.contents.number;
+      }
+      os_close(fd);
+    }
+  }
+  if (dev_urandom_state != OK) {
+    // Reading /dev/urandom doesn't work, fall back to time().
+#endif
+    *x = time(NULL);
+#ifndef MSWIN
+  }
+#endif
+}
+
+static inline uint32_t splitmix32(uint32_t *const x)
+  FUNC_ATTR_NONNULL_ALL FUNC_ATTR_ALWAYS_INLINE
+{
+  uint32_t z = (*x += 0x9e3779b9);
+  z = (z ^ (z >> 16)) * 0x85ebca6b;
+  z = (z ^ (z >> 13)) * 0xc2b2ae35;
+  return z ^ (z >> 16);
+}
+
+static inline uint32_t shuffle_xoshiro128starstar(uint32_t *const x, uint32_t *const y,
+                                                  uint32_t *const z, uint32_t *const w)
+  FUNC_ATTR_NONNULL_ALL FUNC_ATTR_ALWAYS_INLINE
+{
+#define ROTL(x, k) ((x << k) | (x >> (32 - k)))
+  const uint32_t result = ROTL(*y * 5, 7) * 9;
+  const uint32_t t = *y << 9;
+  *z ^= *x;
+  *w ^= *y;
+  *y ^= *z;
+  *x ^= *w;
+  *z ^= t;
+  *w = ROTL(*w, 11);
+#undef ROTL
+  return result;
+}
+
+/// "rand()" function
+static void f_rand(typval_T *argvars, typval_T *rettv, FunPtr fptr)
+{
+  uint32_t result;
+
+  if (argvars[0].v_type == VAR_UNKNOWN) {
+    static uint32_t gx, gy, gz, gw;
+    static bool initialized = false;
+
+    // When no argument is given use the global seed list.
+    if (!initialized) {
+      // Initialize the global seed list.
+      uint32_t x;
+      init_srand(&x);
+
+      gx = splitmix32(&x);
+      gy = splitmix32(&x);
+      gz = splitmix32(&x);
+      gw = splitmix32(&x);
+      initialized = true;
+    }
+
+    result = shuffle_xoshiro128starstar(&gx, &gy, &gz, &gw);
+  } else if (argvars[0].v_type == VAR_LIST) {
+    list_T *const l = argvars[0].vval.v_list;
+    if (tv_list_len(l) != 4) {
+      goto theend;
+    }
+
+    typval_T *const tvx = TV_LIST_ITEM_TV(tv_list_find(l, 0L));
+    typval_T *const tvy = TV_LIST_ITEM_TV(tv_list_find(l, 1L));
+    typval_T *const tvz = TV_LIST_ITEM_TV(tv_list_find(l, 2L));
+    typval_T *const tvw = TV_LIST_ITEM_TV(tv_list_find(l, 3L));
+    if (tvx->v_type != VAR_NUMBER) {
+      goto theend;
+    }
+    if (tvy->v_type != VAR_NUMBER) {
+      goto theend;
+    }
+    if (tvz->v_type != VAR_NUMBER) {
+      goto theend;
+    }
+    if (tvw->v_type != VAR_NUMBER) {
+      goto theend;
+    }
+    uint32_t x = tvx->vval.v_number;
+    uint32_t y = tvy->vval.v_number;
+    uint32_t z = tvz->vval.v_number;
+    uint32_t w = tvw->vval.v_number;
+
+    result = shuffle_xoshiro128starstar(&x, &y, &z, &w);
+
+    tvx->vval.v_number = (varnumber_T)x;
+    tvy->vval.v_number = (varnumber_T)y;
+    tvz->vval.v_number = (varnumber_T)z;
+    tvw->vval.v_number = (varnumber_T)w;
+  } else {
+    goto theend;
+  }
+
+  rettv->v_type = VAR_NUMBER;
+  rettv->vval.v_number = (varnumber_T)result;
+  return;
+
+theend:
+  semsg(_(e_invarg2), tv_get_string(&argvars[0]));
+  rettv->v_type = VAR_NUMBER;
+  rettv->vval.v_number = -1;
+}
+
+/// "srand()" function
+static void f_srand(typval_T *argvars, typval_T *rettv, FunPtr fptr)
+{
+  uint32_t x = 0;
+
+  tv_list_alloc_ret(rettv, 4);
+  if (argvars[0].v_type == VAR_UNKNOWN) {
+    init_srand(&x);
+  } else {
+    bool error = false;
+    x = tv_get_number_chk(&argvars[0], &error);
+    if (error) {
+      return;
+    }
+  }
+
+  tv_list_append_number(rettv->vval.v_list, (varnumber_T)splitmix32(&x));
+  tv_list_append_number(rettv->vval.v_list, (varnumber_T)splitmix32(&x));
+  tv_list_append_number(rettv->vval.v_list, (varnumber_T)splitmix32(&x));
+  tv_list_append_number(rettv->vval.v_list, (varnumber_T)splitmix32(&x));
+}
+
 /// "perleval()" function
 static void f_perleval(typval_T *argvars, typval_T *rettv, FunPtr fptr)
 {
diff --git a/src/nvim/testdir/test_random.vim b/src/nvim/testdir/test_random.vim
new file mode 100644
index 0000000000..6d3f7dcfd9
--- /dev/null
+++ b/src/nvim/testdir/test_random.vim
@@ -0,0 +1,51 @@
+" Tests for srand() and rand()
+
+func Test_Rand()
+  let r = srand(123456789)
+  call assert_equal([1573771921, 319883699, 2742014374, 1324369493], r)
+  call assert_equal(4284103975, rand(r))
+  call assert_equal(1001954530, rand(r))
+  call assert_equal(2701803082, rand(r))
+  call assert_equal(2658065534, rand(r))
+  call assert_equal(3104308804, rand(r))
+
+  " Nvim does not support test_settime
+  " call test_settime(12341234)
+  let s = srand()
+  if !has('win32') && filereadable('/dev/urandom')
+    " using /dev/urandom
+    call assert_notequal(s, srand())
+  " else
+  "   " using time()
+  "   call assert_equal(s, srand())
+  "   call test_settime(12341235)
+  "   call assert_notequal(s, srand())
+  endif
+
+  " Nvim does not support test_srand_seed
+  " call test_srand_seed(123456789)
+  " call assert_equal(4284103975, rand())
+  " call assert_equal(1001954530, rand())
+  " call test_srand_seed()
+
+  if has('float')
+    call assert_fails('echo srand(1.2)', 'E805:')
+  endif
+  call assert_fails('echo srand([1])', 'E745:')
+  call assert_fails('echo rand("burp")', 'E475:')
+  call assert_fails('echo rand([1, 2, 3])', 'E475:')
+  call assert_fails('echo rand([[1], 2, 3, 4])', 'E475:')
+  call assert_fails('echo rand([1, [2], 3, 4])', 'E475:')
+  call assert_fails('echo rand([1, 2, [3], 4])', 'E475:')
+  call assert_fails('echo rand([1, 2, 3, [4]])', 'E475:')
+
+  " call test_settime(0)
+endfunc
+
+func Test_issue_5587()
+  call rand()
+  call garbagecollect()
+  call rand()
+endfunc
+
+" vim: shiftwidth=2 sts=2 expandtab