propagate from branch 'net.randombit.botan' (head 294e2082ce9231d6165276e2f2a4153a0116aca3)

            to branch 'net.randombit.botan.c++0x' (head 0b695fad10f924601e07b009fcd781191fafcb28)

2 files changed, 22 insertions, 12 deletions

diff --git a/src/alloc/alloc_mmap/mmap_mem.cpp b/src/alloc/alloc_mmap/mmap_mem.cpp
index 4a7019ae7..a2059a6ea 100644
--- a/src/alloc/alloc_mmap/mmap_mem.cpp
+++ b/src/alloc/alloc_mmap/mmap_mem.cpp
@@ -6,6 +6,7 @@
 */
 
 #include <botan/internal/mmap_mem.h>
+#include <vector>
 #include <cstring>
 
 #include <sys/types.h>
@@ -44,29 +45,38 @@ void* MemoryMapping_Allocator::alloc_block(u32bit n)
       {
       public:
          int get_fd() const { return fd; }
-         const std::string path() const { return filepath; }
 
          TemporaryFile(const std::string& base)
             {
-            const std::string path = base + "XXXXXX";
+            const std::string mkstemp_template = base + "XXXXXX";
 
-            filepath = new char[path.length() + 1];
-            std::strcpy(filepath, path.c_str());
+            std::vector<char> filepath(mkstemp_template.begin(),
+                                       mkstemp_template.end());
+            filepath.push_back(0); // add terminating NULL
 
             mode_t old_umask = ::umask(077);
-            fd = ::mkstemp(filepath);
+            fd = ::mkstemp(&filepath[0]);
             ::umask(old_umask);
+
+            if(fd == -1)
+               throw MemoryMapping_Failed("Temporary file allocation failed");
+
+            if(::unlink(&filepath[0]) != 0)
+               throw MemoryMapping_Failed("Could not unlink temporary file");
             }
 
          ~TemporaryFile()
             {
-            delete[] filepath;
+            /*
+            * We can safely close here, because post-mmap the file
+            * will continue to exist until the mmap is unmapped from
+            * our address space upon deallocation.
+            */
             if(fd != -1 && ::close(fd) == -1)
                throw MemoryMapping_Failed("Could not close file");
             }
       private:
          int fd;
-         char* filepath;
       };
 
    TemporaryFile file("/tmp/botan_");
@@ -74,9 +84,6 @@ void* MemoryMapping_Allocator::alloc_block(u32bit n)
    if(file.get_fd() == -1)
       throw MemoryMapping_Failed("Could not create file");
 
-   if(::unlink(file.path().c_str()))
-      throw MemoryMapping_Failed("Could not unlink file '" + file.path() + "'");
-
    if(::lseek(file.get_fd(), n-1, SEEK_SET) < 0)
       throw MemoryMapping_Failed("Could not seek file");
 
diff --git a/src/alloc/alloc_mmap/mmap_mem.h b/src/alloc/alloc_mmap/mmap_mem.h
index 14caf5db1..890658ebc 100644
--- a/src/alloc/alloc_mmap/mmap_mem.h
+++ b/src/alloc/alloc_mmap/mmap_mem.h
@@ -12,8 +12,11 @@
 
 namespace Botan {
 
-/*
-* Memory Mapping Allocator
+/**
+* Allocator that uses memory maps backed by disk. We zeroize the map
+* upon deallocation. If swap occurs, the VM will swap to the shared
+* file backing rather than to a swap device, which means we know where
+* it is and can zap it later.
 */
 class MemoryMapping_Allocator : public Pooling_Allocator
    {