[llvm-commits] CVS: llvm/lib/System/Unix/MappedFile.cpp

[Reid Spencer]

Changes in directory llvm/lib/System/Unix:

MappedFile.cpp added (r1.1)
---
Log message:

First version of the MappedFile abstraction for operating system idependent
mapping of files. This first version uses mmap where its available. The
class needs to implement an alternate mechanism based on malloc'd memory
and file reading/writing for platforms without virtual memory.


---
Diffs of the changes:  (+138 -0)

Index: llvm/lib/System/Unix/MappedFile.cpp
diff -c /dev/null llvm/lib/System/Unix/MappedFile.cpp:1.1
*** /dev/null	Mon Oct  4 06:08:42 2004
--- llvm/lib/System/Unix/MappedFile.cpp	Mon Oct  4 06:08:32 2004
***************
*** 0 ****
--- 1,138 ----
+ //===- Unix/MappedFile.cpp - Unix MappedFile Implementation -----*- C++ -*-===//
+ // 
+ //                     The LLVM Compiler Infrastructure
+ //
+ // This file was developed by Reid Spencer and is distributed under the 
+ // University of Illinois Open Source License. See LICENSE.TXT for details.
+ // 
+ //===----------------------------------------------------------------------===//
+ //
+ // This file provides the generic Unix implementation of the MappedFile concept.
+ //
+ //===----------------------------------------------------------------------===//
+ 
+ //===----------------------------------------------------------------------===//
+ //=== WARNING: Implementation here must contain only generic UNIX code that
+ //===          is guaranteed to work on *all* UNIX variants.
+ //===----------------------------------------------------------------------===//
+ 
+ #include "llvm/System/Process.h"
+ #include "Unix.h"
+ #include <sys/fcntl.h>
+ #include <sys/mman.h>
+ 
+ namespace llvm {
+ using namespace sys;
+ 
+ struct sys::MappedFileInfo {
+   int fd_;
+   struct stat sbuf_;
+ };
+ 
+ void MappedFile::initialize() {
+   if (path_.exists()) {
+     info_ = new MappedFileInfo;
+     int mode = 0;
+     if (options_&READ_ACCESS) 
+       if (options_&WRITE_ACCESS)
+         mode = O_RDWR;
+       else
+         mode = O_RDONLY;
+     else if (options_&WRITE_ACCESS)
+       mode = O_WRONLY;
+     info_->fd_ = ::open(path_.c_str(),mode);
+     if (info_->fd_ < 0) {
+       delete info_;
+       info_ = 0;
+       ThrowErrno(std::string("Can't open file: ") + path_.get());
+     }
+     struct stat sbuf;
+     if(::fstat(info_->fd_, &info_->sbuf_) < 0) {
+       ::close(info_->fd_);
+       delete info_;
+       info_ = 0;
+       ThrowErrno(std::string("Can't stat file: ") + path_.get());
+     }
+   }
+ }
+ 
+ void MappedFile::terminate() {
+   assert(info_ && "MappedFile not initialized");
+   if (info_->fd_ >= 0)
+     ::close(info_->fd_);
+   delete info_;
+   info_ = 0;
+ }
+ 
+ void MappedFile::unmap() {
+   assert(info_ && "MappedFile not initialized");
+   if (isMapped()) {
+     if (options_ & WRITE_ACCESS)
+       ::msync(base_, info_->sbuf_.st_size, MS_SYNC);
+     ::munmap(base_, info_->sbuf_.st_size);
+   }
+ }
+ 
+ void* MappedFile::map() {
+   if (!isMapped()) {
+     int prot = PROT_NONE;
+     int flags = MAP_FILE;
+     if (options_ == 0) {
+       prot = PROT_READ;
+       flags = MAP_PRIVATE;
+     } else {
+       if (options_ & READ_ACCESS)
+         prot |= PROT_READ;
+       if (options_ & WRITE_ACCESS)
+         prot |= PROT_WRITE;
+       if (options_ & EXEC_ACCESS)
+         prot |= PROT_EXEC;
+       if (options_ & SHARED_MAPPING)
+         flags |= MAP_SHARED;
+       else
+         flags |= MAP_PRIVATE;
+     }
+     size_t map_size = ((info_->sbuf_.st_size / Process::GetPageSize())+1) *
+       Process::GetPageSize();
+ 
+     base_ = ::mmap(0, map_size, prot, flags, info_->fd_, 0);
+     if (base_ == MAP_FAILED)
+       ThrowErrno(std::string("Can't map file:") + path_.get());
+   }
+   return base_;
+ }
+ 
+ size_t MappedFile::size() {
+   assert(info_ && "MappedFile not initialized");
+   return info_->sbuf_.st_size;
+ }
+ 
+ void MappedFile::size(size_t new_size) {
+   assert(info_ && "MappedFile not initialized");
+ 
+   // Take the mapping out of memory
+   this->unmap();
+ 
+   // Adjust the current size to a page boundary
+   size_t cur_size = ((info_->sbuf_.st_size / Process::GetPageSize())+1) *
+     Process::GetPageSize();
+ 
+   // Adjust the new_size to a page boundary
+   new_size = ((new_size / Process::GetPageSize())+1) *
+     Process::GetPageSize();
+ 
+   // If the file needs to be extended
+   if (new_size > cur_size) {
+     // Ensure we can allocate at least the idodes necessary to handle the
+     // file size requested. 
+     ::lseek(info_->fd_, new_size, SEEK_SET);
+     ::write(info_->fd_, "\0", 1);
+   }
+ 
+   // Seek to current end of file. 
+   this->map();
+ }
+ 
+ }
+ 
+ // vim: sw=2 smartindent smarttab tw=80 autoindent expandtab