hus: Correcte verdeling (hopelijk)

Code is niet getest, want dat is irritant en heb ik geen zin in

1 files changed, 21 insertions, 0 deletions

diff --git a/src/hus.c b/src/hus.c
index 9604954..271fd05 100644
--- a/src/hus.c
+++ b/src/hus.c
@@ -3,6 +3,7 @@
 #include <getopt.h>
 #include <pwd.h>
 #include <stdlib.h>
+#include <stdint.h>
 #include <string.h>
 #include <sys/random.h>
 #include <sys/types.h>
@@ -17,6 +18,19 @@ static char *shufrange = NULL;
 static char **lines = NULL;
 static size_t nlines = 0;
 
+static size_t random_size_t_r(struct random_data *buf) {
+  size_t res = 0;
+  unsigned nbytes = 0;
+  while (nbytes < sizeof(size_t)) {
+    int32_t value;
+    int ret = random_r(buf, &value);
+    if (ret == -1) { fprintf(stderr, "hus: Kon willekeurigheid niet verlengen\n"); exit(1); }
+    res |= (size_t)value << (8 * nbytes);
+    nbytes += 4;
+  }
+  return res;
+}
+
 static void shuf_lines() {
   size_t *js = calloc(nlines, sizeof(size_t));
   errno = 0;
@@ -24,6 +38,13 @@ static void shuf_lines() {
 
   for (ssize_t i = nlines - 1; i > 0; i--) {
     size_t j = js[i] % (nlines-1);
+    if (j - 1 + (nlines-1) < j) {
+      struct random_data buf;
+      int ret = srandom_r(js[i], &buf);
+      if (ret == -1) { fprintf(stderr, "hus: Kon willekeurigheidsverlenging niet instellen\n"); exit(1); }
+      do j = random_size_t_r(&buf) % (nlines-1);
+      while (j - 1 + (nlines-1) < j);
+    }
 
     char *x = lines[i];
     lines[i] = lines[j];