Update copyright dates with scripts/update-copyrights.

[thirdparty/glibc.git] / misc / hsearch_r.c

diff --git a/misc/hsearch_r.c b/misc/hsearch_r.c
index 398f0b6dd9dcced1848c89d8eebf79ae26dc2b85..c75619b3e18390080e369ba64a0fa151be8f1489 100644 (file)
--- a/misc/hsearch_r.c
+++ b/misc/hsearch_r.c
@@ -1,4 +1,4 @@
-/* Copyright (C) 1993, 1995, 1996, 1997, 2002 Free Software Foundation, Inc.
+/* Copyright (C) 1993-2019 Free Software Foundation, Inc.
    This file is part of the GNU C Library.
    Contributed by Ulrich Drepper <drepper@gnu.ai.mit.edu>, 1993.
 
@@ -13,15 +13,15 @@
    Lesser General Public License for more details.
 
    You should have received a copy of the GNU Lesser General Public
-   License along with the GNU C Library; if not, write to the Free
-   Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
-   02111-1307 USA.  */
+   License along with the GNU C Library; if not, see
+   <http://www.gnu.org/licenses/>.  */
 
 #include <errno.h>
 #include <malloc.h>
 #include <string.h>
-
+#include <stdint.h>
 #include <search.h>
+#include <limits.h>
 
 /* [Aho,Sethi,Ullman] Compilers: Principles, Techniques and Tools, 1986
    [Knuth]            The Art of Computer Programming, part 3 (6.4)  */
@@ -47,15 +47,12 @@ static int
 isprime (unsigned int number)
 {
   /* no even number will be passed */
-  unsigned int div = 3;
-
-  while (div * div < number && number % div != 0)
-    div += 2;
-
-  return number % div != 0;
+  for (unsigned int div = 3; div <= number / div; div += 2)
+    if (number % div == 0)
+      return 0;
+  return 1;
 }
 
-
 /* Before using the hash table we must allocate memory for it.
    Test for an existing table are done. We allocate one element
    more as the found prime number says. This is done for more effective
@@ -63,9 +60,7 @@ isprime (unsigned int number)
    The contents of the table is zeroed, especially the field used
    becomes zero.  */
 int
-hcreate_r (nel, htab)
-     size_t nel;
-     struct hsearch_data *htab;
+__hcreate_r (size_t nel, struct hsearch_data *htab)
 {
   /* Test for correct arguments.  */
   if (htab == NULL)
@@ -78,10 +73,23 @@ hcreate_r (nel, htab)
   if (htab->table != NULL)
     return 0;
 
-  /* Change nel to the first prime number not smaller as nel. */
-  nel |= 1;      /* make odd */
-  while (!isprime (nel))
-    nel += 2;
+  /* We need a size of at least 3.  Otherwise the hash functions we
+     use will not work.  */
+  if (nel < 3)
+    nel = 3;
+
+  /* Change nel to the first prime number in the range [nel, UINT_MAX - 2],
+     The '- 2' means 'nel += 2' cannot overflow.  */
+  for (nel |= 1; ; nel += 2)
+    {
+      if (UINT_MAX - 2 < nel)
+       {
+         __set_errno (ENOMEM);
+         return 0;
+       }
+      if (isprime (nel))
+       break;
+    }
 
   htab->size = nel;
   htab->filled = 0;
@@ -94,14 +102,14 @@ hcreate_r (nel, htab)
   /* everything went alright */
   return 1;
 }
-libc_hidden_def (hcreate_r)
+libc_hidden_def (__hcreate_r)
+weak_alias (__hcreate_r, hcreate_r)
 
 
 /* After using the hash table it has to be destroyed. The used memory can
    be freed and the local static variable can be marked as not used.  */
 void
-hdestroy_r (htab)
-     struct hsearch_data *htab;
+__hdestroy_r (struct hsearch_data *htab)
 {
   /* Test for correct arguments.  */
   if (htab == NULL)
@@ -110,14 +118,14 @@ hdestroy_r (htab)
       return;
     }
 
-  if (htab->table != NULL)
-    /* free used memory */
-    free (htab->table);
+  /* Free used memory.  */
+  free (htab->table);
 
   /* the sign for an existing table is an value != NULL in htable */
   htab->table = NULL;
 }
-libc_hidden_def (hdestroy_r)
+libc_hidden_def (__hdestroy_r)
+weak_alias (__hdestroy_r, hdestroy_r)
 
 
 /* This is the search function. It uses double hashing with open addressing.
@@ -134,11 +142,8 @@ libc_hidden_def (hdestroy_r)
    equality of the stored and the parameter value. This helps to prevent
    unnecessary expensive calls of strcmp.  */
 int
-hsearch_r (item, action, retval, htab)
-     ENTRY item;
-     ACTION action;
-     ENTRY **retval;
-     struct hsearch_data *htab;
+__hsearch_r (ENTRY item, ACTION action, ENTRY **retval,
+            struct hsearch_data *htab)
 {
   unsigned int hval;
   unsigned int count;
@@ -153,20 +158,15 @@ hsearch_r (item, action, retval, htab)
       hval <<= 4;
       hval += item.key[count];
     }
-
-  /* First hash function: simply take the modul but prevent zero. */
-  hval %= htab->size;
   if (hval == 0)
     ++hval;
 
-  /* The first index tried. */
-  idx = hval;
+  /* First hash function: simply take the modul but prevent zero. */
+  idx = hval % htab->size + 1;
 
   if (htab->table[idx].used)
     {
       /* Further action might be required according to the action value. */
-      unsigned hval2;
-
       if (htab->table[idx].used == hval
          && strcmp (item.key, htab->table[idx].entry.key) == 0)
        {
@@ -175,7 +175,8 @@ hsearch_r (item, action, retval, htab)
        }
 
       /* Second hash function, as suggested in [Knuth] */
-      hval2 = 1 + hval % (htab->size - 2);
+      unsigned int hval2 = 1 + hval % (htab->size - 2);
+      unsigned int first_idx = idx;
 
       do
        {
@@ -187,7 +188,7 @@ hsearch_r (item, action, retval, htab)
            idx -= hval2;
 
          /* If we visited all entries leave the loop unsuccessfully.  */
-         if (idx == hval)
+         if (idx == first_idx)
            break;
 
             /* If entry is found use it. */
@@ -206,7 +207,7 @@ hsearch_r (item, action, retval, htab)
     {
       /* If table is full and another entry should be entered return
         with error.  */
-      if (action == ENTER && htab->filled == htab->size)
+      if (htab->filled == htab->size)
        {
          __set_errno (ENOMEM);
          *retval = NULL;
@@ -226,4 +227,5 @@ hsearch_r (item, action, retval, htab)
   *retval = NULL;
   return 0;
 }
-libc_hidden_def (hsearch_r)
+libc_hidden_def (__hsearch_r)
+weak_alias (__hsearch_r, hsearch_r)