Smarter implementation of calloc(3), which uses the fact that mmap(2)

returns zero filled pages; remember to replace this function as well if you
provide your own malloc implementation; ok djm@ deraadt@

2 files changed, 57 insertions, 8 deletions

diff --git a/src/lib/libc/stdlib/Makefile.inc b/src/lib/libc/stdlib/Makefile.inc
index f1708a1111..09db4ce793 100644
--- a/src/lib/libc/stdlib/Makefile.inc
+++ b/src/lib/libc/stdlib/Makefile.inc
@@ -1,10 +1,10 @@
-#       $OpenBSD: Makefile.inc,v 1.38 2008/06/13 21:04:24 landry Exp $
+#       $OpenBSD: Makefile.inc,v 1.39 2008/08/22 17:14:56 otto Exp $
 
 # stdlib sources
 .PATH: ${LIBCSRCDIR}/arch/${MACHINE_ARCH}/stdlib ${LIBCSRCDIR}/stdlib
 
 SRCS+=  a64l.c abort.c atexit.c atoi.c atof.c atol.c atoll.c bsearch.c \
-        calloc.c cfree.c exit.c ecvt.c gcvt.c getenv.c getopt_long.c \
+        cfree.c exit.c ecvt.c gcvt.c getenv.c getopt_long.c \
         getsubopt.c hcreate.c heapsort.c imaxabs.c imaxdiv.c l64a.c llabs.c \
         lldiv.c lsearch.c malloc.c merge.c putenv.c qsort.c radixsort.c rand.c \
         random.c realpath.c setenv.c strtoimax.c strtod.c strtof.c strtol.c \
diff --git a/src/lib/libc/stdlib/malloc.c b/src/lib/libc/stdlib/malloc.c
index 645dc5afc9..d03b831514 100644
--- a/src/lib/libc/stdlib/malloc.c
+++ b/src/lib/libc/stdlib/malloc.c
@@ -1,4 +1,4 @@
-/*      $OpenBSD: malloc.c,v 1.93 2008/08/07 18:41:47 otto Exp $        */
+/*      $OpenBSD: malloc.c,v 1.94 2008/08/22 17:14:57 otto Exp $        */
 /*
  * Copyright (c) 2008 Otto Moerbeek <otto@drijf.net>
  *
@@ -443,7 +443,7 @@ unmap(struct dir_info *d, void *p, size_t sz)
 }
 
 static void *
-map(struct dir_info *d, size_t sz)
+map(struct dir_info *d, size_t sz, int zero_fill)
 {
         size_t psz = PAGEROUND(sz) >> MALLOC_PAGESHIFT;
         struct region_info *r, *big = NULL;
@@ -454,6 +454,7 @@ map(struct dir_info *d, size_t sz)
                 p = MMAP(sz);
                 if (p != MAP_FAILED)
                         malloc_used += sz;
+                /* zero fill not needed */
                 return p;
         }
         offset = getrbyte();
@@ -469,6 +470,8 @@ map(struct dir_info *d, size_t sz)
                                 r->p = NULL;
                                 r->size = 0;
                                 d->free_regions_size -= psz;
+                                if (zero_fill)
+                                        memset(p, 0, sz);
                                 return p;
                         } else if (r->size > psz)
                                 big = r;
@@ -483,6 +486,8 @@ map(struct dir_info *d, size_t sz)
                         madvise(p, sz, MADV_NORMAL);
                 r->size -= psz;
                 d->free_regions_size -= psz;
+                if (zero_fill)
+                        memset(p, 0, sz);
                 return p;
         }
         p = MMAP(sz);
@@ -490,6 +495,7 @@ map(struct dir_info *d, size_t sz)
                 malloc_used += sz;
         if (d->free_regions_size > malloc_cache)
                 wrtwarning("malloc cache");
+        /* zero fill not needed */
         return p;
 }
 
@@ -835,7 +841,7 @@ omalloc_make_chunks(struct dir_info *d, int bits)
         long            i, k;
 
         /* Allocate a new bucket */
-        pp = map(d, MALLOC_PAGESIZE);
+        pp = map(d, MALLOC_PAGESIZE, 0);
         if (pp == MAP_FAILED)
                 return NULL;
 
@@ -1053,7 +1059,7 @@ omalloc(size_t sz, int zero_fill)
                 }
                 sz += malloc_guard;
                 psz = PAGEROUND(sz);
-                p = map(&g_pool, psz);
+                p = map(&g_pool, psz, zero_fill);
                 if (p == MAP_FAILED) {
                         errno = ENOMEM;
                         return NULL;
@@ -1077,8 +1083,6 @@ omalloc(size_t sz, int zero_fill)
                     sz - malloc_guard < MALLOC_PAGESIZE - MALLOC_MINSIZE)
                         p = ((char *)p) + ((MALLOC_PAGESIZE - MALLOC_MINSIZE -
                             (sz - malloc_guard)) & ~(MALLOC_MINSIZE-1));
-                if (zero_fill)
-                        memset(p, 0, sz - malloc_guard);
         } else {
                 /* takes care of SOME_JUNK */
                 p = malloc_bytes(&g_pool, sz);
@@ -1323,3 +1327,48 @@ realloc(void *ptr, size_t size)
         }
         return r;
 }
+
+
+#define MUL_NO_OVERFLOW (1UL << (sizeof(size_t) * 4))
+
+void *
+calloc(size_t nmemb, size_t size)
+{
+        void *r;
+
+        _MALLOC_LOCK();
+        malloc_func = " in calloc():";  
+        if (!g_pool.regions_total) {
+                if (omalloc_init(&g_pool)) {
+                         _MALLOC_UNLOCK();
+                        if (malloc_xmalloc)
+                                wrterror("out of memory");
+                        errno = ENOMEM;
+                        return NULL;
+                }
+        }
+        if ((nmemb >= MUL_NO_OVERFLOW || size >= MUL_NO_OVERFLOW) &&
+            nmemb > 0 && SIZE_MAX / nmemb < size) {
+                 _MALLOC_UNLOCK();
+                if (malloc_xmalloc)
+                        wrterror("out of memory");
+                errno = ENOMEM;
+                return NULL;
+        }
+
+        if (malloc_active++) {
+                malloc_recurse();
+                return NULL;
+        }
+
+        size *= nmemb;
+        r = omalloc(size, 1);
+  
+        malloc_active--;
+        _MALLOC_UNLOCK();
+        if (r == NULL && malloc_xmalloc) {
+                wrterror("out of memory");
+                errno = ENOMEM;
+        }
+        return r;
+}