Add mmap64()

This adds mmap64() to bionic so that it is possible to have
large offset passed to kernel. However, the syscall mechanism
only passes 32-bit number to kernel. So effectively, the
largest offset that can be passed is about 43 bits (since
offset is signed, and the number passed to kernel is number
of pages (page size == 4K => 12 bits)).

Change-Id: Ib54f4e9b54acb6ef8b0324f3b89c9bc810b07281
Signed-off-by: Andrew Boie <andrew.p.boie@intel.com>

2 files changed, 7 insertions, 2 deletions

diff --git a/libc/bionic/mmap.cpp b/libc/bionic/mmap.cpp
index febc459fa..75bea588f 100644
--- a/libc/bionic/mmap.cpp
+++ b/libc/bionic/mmap.cpp
@@ -37,13 +37,13 @@ extern "C" void*  __mmap2(void*, size_t, int, int, int, size_t);
 
 #define MMAP2_SHIFT 12 // 2**12 == 4096
 
-void* mmap(void* addr, size_t size, int prot, int flags, int fd, off_t offset) {
+void* mmap64(void* addr, size_t size, int prot, int flags, int fd, off64_t offset) {
   if (offset & ((1UL << MMAP2_SHIFT)-1)) {
     errno = EINVAL;
     return MAP_FAILED;
   }
 
-  size_t unsigned_offset = static_cast<size_t>(offset); // To avoid sign extension.
+  uint64_t unsigned_offset = static_cast<uint64_t>(offset); // To avoid sign extension.
   void* result = __mmap2(addr, size, prot, flags, fd, unsigned_offset >> MMAP2_SHIFT);
 
   if (result != MAP_FAILED && (flags & (MAP_PRIVATE | MAP_ANONYMOUS)) != 0) {
@@ -53,3 +53,7 @@ void* mmap(void* addr, size_t size, int prot, int flags, int fd, off_t offset) {
 
   return result;
 }
+
+void* mmap(void* addr, size_t size, int prot, int flags, int fd, off_t offset) {
+  return mmap64(addr, size, prot, flags, fd, static_cast<off64_t>(offset));
+}
diff --git a/libc/include/sys/mman.h b/libc/include/sys/mman.h
index 7a3297430..7c5f8d774 100644
--- a/libc/include/sys/mman.h
+++ b/libc/include/sys/mman.h
@@ -45,6 +45,7 @@ __BEGIN_DECLS
 #define MREMAP_FIXED    2
 
 extern void*  mmap(void *, size_t, int, int, int, off_t);
+extern void*  mmap64(void *, size_t, int, int, int, off64_t);
 extern int    munmap(void *, size_t);
 extern int    msync(const void *, size_t, int);
 extern int    mprotect(const void *, size_t, int);