From 1ea7255f8b0661cdfabbd13f8f443f81665a07e0 Mon Sep 17 00:00:00 2001
From: Paul Eggert <eggert@cs.ucla.edu>
Date: Sat, 3 Aug 2024 22:59:12 -0700
Subject: [PATCH] shuf: avoid integer overflow on huge inputs

* gl/lib/randperm.c: Include <stdckdint.h>.
(randperm_bound): Return SIZE_MAX if the multiplication overflows.
Do not overflow when converting bit count to byte count.

Reference:https://github.com/coreutils/coreutils/commit/1ea7255f8b0661cdfabbd13f8f443f81665a07e0
Conflict:change gl/lib/randperm.c to lib/randperm.c; Adaptation to INT_MULTIPLY_WRAPV() and floor_lg()

---
 lib/randperm.c | 10 ++++++----
 1 file changed, 6 insertions(+), 4 deletions(-)

diff --git a/lib/randperm.c b/lib/randperm.c
index c01c296..7517884 100644
--- a/lib/randperm.c
+++ b/lib/randperm.c
@@ -53,13 +53,15 @@ randperm_bound (size_t h, size_t n)
 {
   /* Upper bound on number of bits needed to generate the first number
      of the permutation.  */
-  uintmax_t lg_n = floor_lg (n) + 1;
+  unsigned int lg_n = floor_lg (n) + 1;
 
-  /* Upper bound on number of bits needed to generated the first H elements.  */
-  uintmax_t ar = lg_n * h;
+  /* Upper bound on number of bits needed to generate the first H elements. */
+  uintmax_t ar;
+  if (INT_MULTIPLY_WRAPV (lg_n, h, &ar))
+    return SIZE_MAX;
 
   /* Convert the bit count to a byte count.  */
-  size_t bound = (ar + CHAR_BIT - 1) / CHAR_BIT;
+  size_t bound = ar / CHAR_BIT + (ar % CHAR_BIT != 0);
 
   return bound;
 }
-- 
2.43.0

