From 36313f6350b823895c65111fe577083cbc58e088 Mon Sep 17 00:00:00 2001
From: Martin Mares <mj@ucw.cz>
Date: Fri, 24 Nov 2006 00:17:17 +0100
Subject: [PATCH] Added big_alloc() for allocating large, page-aligned buffers.

---
 lib/Makefile   |  3 ++-
 lib/bigalloc.c | 62 ++++++++++++++++++++++++++++++++++++++++++++++++++
 lib/lib.h      |  5 ++++
 3 files changed, 69 insertions(+), 1 deletion(-)
 create mode 100644 lib/bigalloc.c

diff --git a/lib/Makefile b/lib/Makefile
index 15dc0a24..604e61d5 100644
--- a/lib/Makefile
+++ b/lib/Makefile
@@ -7,7 +7,7 @@ PROGS+=$(o)/lib/db-tool
 endif
 
 LIBUCW_MODS= \
-	alloc alloc_str realloc mempool mempool-str mempool-fmt \
+	alloc alloc_str realloc bigalloc mempool mempool-str mempool-fmt \
 	mmap pagecache partmap hashfunc \
 	lists slists simple-lists sorter bitsig \
 	log log-file proctitle \
@@ -80,6 +80,7 @@ $(o)/lib/binheap-test: $(o)/lib/binheap-test.o $(LIBUCW)
 $(o)/lib/lizard-test: $(o)/lib/lizard-test.o $(LIBUCW)
 $(o)/lib/kmp-test: $(o)/lib/kmp-test.o $(LIBUCW) $(LIBCHARSET)
 $(o)/lib/ipaccess-test: $(o)/lib/ipaccess-test.o $(LIBUCW)
+$(o)/lib/bigalloc-test: $(o)/lib/bigalloc-test.o $(LIBUCW)
 
 TESTS+=$(addprefix $(o)/lib/,regex.test unicode-utf8.test hash-test.test mempool.test stkstring.test slists.test kmp-test.test bbuf.test)
 $(o)/lib/regex.test: $(o)/lib/regex-t
diff --git a/lib/bigalloc.c b/lib/bigalloc.c
new file mode 100644
index 00000000..b4589c4a
--- /dev/null
+++ b/lib/bigalloc.c
@@ -0,0 +1,62 @@
+/*
+ *	UCW Library -- Allocation of Large Aligned Buffers
+ *
+ *	(c) 2006 Martin Mares <mj@ucw.cz>
+ *
+ *	This software may be freely distributed and used according to the terms
+ *	of the GNU Lesser General Public License.
+ */
+
+#include "lib/lib.h"
+
+#include <sys/mman.h>
+#include <sys/user.h>
+
+static unsigned int
+big_round(unsigned int len)
+{
+  return ALIGN_TO(len, PAGE_SIZE);
+}
+
+void *
+big_alloc(unsigned int len)
+{
+  len = big_round(len);
+#ifdef CONFIG_DEBUG
+  len += 2*PAGE_SIZE;
+#endif
+  byte *p = mmap(NULL, len, PROT_READ | PROT_WRITE, MAP_PRIVATE | MAP_ANON, -1, 0);
+  if (p == (byte*) MAP_FAILED)
+    die("Cannot mmap %d bytes of memory: %m", len);
+#ifdef CONFIG_DEBUG
+  mprotect(p, PAGE_SIZE, PROT_NONE);
+  mprotect(p+len-PAGE_SIZE, PAGE_SIZE, PROT_NONE);
+  p += PAGE_SIZE;
+#endif
+  return p;
+}
+
+void
+big_free(void *start, unsigned int len)
+{
+  byte *p = start;
+  ASSERT(!((addr_int_t) p & (PAGE_SIZE-1)));
+  len = big_round(len);
+#ifdef CONFIG_DEBUG
+  p -= PAGE_SIZE;
+  len += 2*PAGE_SIZE;
+#endif
+  munmap(p, len);
+}
+
+#ifdef TEST
+
+int main(void)
+{
+  byte *p = big_alloc(123456);
+  // p[-1] = 1;
+  big_free(p, 123456);
+  return 0;
+}
+
+#endif
diff --git a/lib/lib.h b/lib/lib.h
index 43135c6c..21fe4773 100644
--- a/lib/lib.h
+++ b/lib/lib.h
@@ -271,4 +271,9 @@ void unhandle_signal(int signum, struct sigaction *oldact);
 
 byte *str_unesc(byte *dest, byte *src);
 
+/* bigalloc.c */
+
+void *big_alloc(unsigned int len);
+void big_free(void *start, unsigned int len);
+
 #endif
-- 
2.39.5