From: Alex Rousskov <rousskov@measurement-factory.com>
Date: Thu, 14 Apr 2011 20:16:35 +0000 (-0600)
Subject: Use off_t instead of int and size_t for segment sizes
X-Git-Tag: take06~25
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=e08b0f778791043501c04a4a0a4b1dd5c97f8bc6;p=thirdparty%2Fsquid.git

Use off_t instead of int and size_t for segment sizes
to be able to allocated larger than 4GB segments on some platforms.

Double check the newly created segment size using fstat().
---

diff --git a/src/ipc/mem/Segment.cc b/src/ipc/mem/Segment.cc
index 1bd100a525..3c0305fe37 100644
--- a/src/ipc/mem/Segment.cc
+++ b/src/ipc/mem/Segment.cc
@@ -6,7 +6,7 @@
  */
 
 #include "config.h"
-
+#include "base/TextException.h"
 #include "ipc/mem/Segment.h"
 #include "protos.h"
 
@@ -31,7 +31,7 @@ Ipc::Mem::Segment::~Segment() {
 }
 
 void
-Ipc::Mem::Segment::create(const int aSize)
+Ipc::Mem::Segment::create(const off_t aSize)
 {
     assert(aSize > 0);
     assert(theFD < 0);
@@ -48,6 +48,8 @@ Ipc::Mem::Segment::create(const int aSize)
         fatal("Ipc::Mem::Segment::create failed to ftruncate");
     }
 
+    assert(statSize("Ipc::Mem::Segment::create") == aSize); // paranoid
+
     theSize = aSize;
     theReserved = 0;
 
@@ -69,18 +71,7 @@ Ipc::Mem::Segment::open()
         fatal(s.termedBuf());
     }
 
-    {
-        struct stat s;
-        memset(&s, 0, sizeof(s));
-        if (fstat(theFD, &s)) {
-            debugs(54, 5, HERE << "fstat: " << xstrerror());
-        String s = "Ipc::Mem::Segment::open failed to fstat";
-        s.append(theName);
-        fatal(s.termedBuf());
-        }
-
-        theSize = s.st_size;
-    }
+    theSize = statSize("Ipc::Mem::Segment::open");
 
     debugs(54, 3, HERE << "opened " << theName << " segment: " << theSize);
 
@@ -120,13 +111,35 @@ Ipc::Mem::Segment::detach()
 void *
 Ipc::Mem::Segment::reserve(size_t chunkSize)
 {
-    assert(chunkSize <= theSize);
-    assert(theReserved <= theSize - chunkSize);
+    // check for overflows
+    assert(static_cast<off_t>(chunkSize) >= 0);
+    assert(static_cast<off_t>(chunkSize) <= theSize);
+    assert(theReserved <= theSize - static_cast<off_t>(chunkSize));
     void *result = reinterpret_cast<char*>(mem()) + theReserved;
     theReserved += chunkSize;
     return result;
 }
 
+/// determines the size of the underlying "file"
+off_t
+Ipc::Mem::Segment::statSize(const char *context) const
+{
+    Must(theFD >= 0);
+
+    struct stat s;
+    memset(&s, 0, sizeof(s));
+
+    if (fstat(theFD, &s) != 0) {
+        debugs(54, 5, HERE << "fstat: " << xstrerror());
+        String s = context;
+        s.append("failed to fstat(2)");
+        s.append(theName);
+        fatal(s.termedBuf());
+    }
+
+    return s.st_size;
+}
+
 /// Generate name for shared memory segment. Replaces all slashes with dots.
 String
 Ipc::Mem::Segment::GenerateName(const char *id)
diff --git a/src/ipc/mem/Segment.h b/src/ipc/mem/Segment.h
index 807b24fa38..f05481729f 100644
--- a/src/ipc/mem/Segment.h
+++ b/src/ipc/mem/Segment.h
@@ -21,11 +21,11 @@ public:
 
     /// Create a new shared memory segment. Fails if a segment with
     /// the same name already exists.
-    void create(const int aSize);
+    void create(const off_t aSize);
     void open(); ///< Open an existing shared memory segment.
 
     const String &name() { return theName; } ///< shared memory segment name
-    int size() { return theSize; } ///< shared memory segment size
+    off_t size() { return theSize; } ///< shared memory segment size
     void *mem() { return theMem; } ///< pointer to mmapped shared memory segment
     void *reserve(size_t chunkSize); ///< reserve and return the next chunk
     // TODO: convert most mem() calls to reserve()
@@ -33,14 +33,15 @@ public:
 private:
     void attach();
     void detach();
+    off_t statSize(const char *context) const;
 
     static String GenerateName(const char *id);
 
     const String theName; ///< shared memory segment file name
     int theFD; ///< shared memory segment file descriptor
     void *theMem; ///< pointer to mmapped shared memory segment
-    size_t theSize; ///< shared memory segment size
-    size_t theReserved; ///< the total number of reserve()d bytes
+    off_t theSize; ///< shared memory segment size
+    off_t theReserved; ///< the total number of reserve()d bytes
 };
 
 } // namespace Mem