Introduce a new type, PtrdiffT. Replace lots of uses of OffT (all those

that are memory offsets) with PtrdiffT;  OffT should only be used for file
sizes and offsets.

Change Off64T from a ULong to a Long, as it should be.  Replace some uses
of ULong in the address space manager with Off64T to match.

Also add a comment explaining the meanings of the basic types like Addr,
OffT, SizeT, etc.

Also fix the prototype for VG_(pread) -- the last arg is an OffT, not an
Int.



git-svn-id: svn://svn.valgrind.org/valgrind/trunk@8959 a5019735-40e9-0310-863c-91ae7b9d1cf9

6 files changed, 37 insertions, 19 deletions

diff --git a/include/pub_tool_aspacemgr.h b/include/pub_tool_aspacemgr.h
index 6144d270e..118655126 100644
--- a/include/pub_tool_aspacemgr.h
+++ b/include/pub_tool_aspacemgr.h
@@ -101,7 +101,7 @@ typedef
       /* Associated file (SkFile{C,V} only) */
       ULong   dev;
       ULong   ino;
-      ULong   offset;
+      Off64T  offset;
       UInt    mode;
       Int     fnIdx;    // file name table index, if name is known
       /* Permissions (SkAnon{C,V}, SkFile{C,V} only) */
diff --git a/include/pub_tool_basics.h b/include/pub_tool_basics.h
index 3292f00b9..d91bb81f3 100644
--- a/include/pub_tool_basics.h
+++ b/include/pub_tool_basics.h
@@ -62,22 +62,40 @@
 
 // By choosing the right types, we can get these right for 32-bit and 64-bit
 // platforms without having to do any conditional compilation or anything.
+// POSIX references:
+// - http://www.opengroup.org/onlinepubs/009695399/basedefs/sys/types.h.html
+// - http://www.opengroup.org/onlinepubs/009695399/basedefs/stddef.h.html
 // 
 // Size in bits on:                          32-bit archs   64-bit archs
 //                                           ------------   ------------
 typedef unsigned long          UWord;     // 32             64
+typedef   signed long           Word;     // 32             64
 
-typedef signed long            Word;      // 32             64
-
+// Addr is for holding an address.  AddrH was intended to be "Addr on the
+// host", for the notional case where host word size != guest word size.
+// But since the assumption that host arch == guest arch has become so
+// deeply wired in, it's a pretty pointless distinction now.
 typedef UWord                  Addr;      // 32             64
 typedef UWord                  AddrH;     // 32             64
 
+// Our equivalents of POSIX 'size_t' and 'ssize_t':
+// - size_t is an "unsigned integer type of the result of the sizeof operator".
+// - ssize_t is "used for a count of bytes or an error indication".
 typedef UWord                  SizeT;     // 32             64
 typedef  Word                 SSizeT;     // 32             64
 
-typedef  Word                   OffT;     // 32             64
-
-typedef ULong                 Off64T;     // 64             64
+// Our equivalent of POSIX 'ptrdiff_t':
+// - ptrdiff_t is a "signed integer type of the result of subtracting two
+//   pointers".
+// We use it for memory offsets, eg. the offset into a memory block.
+typedef  Word                 PtrdiffT;   // 32             64
+
+// Our equivalent of POSIX 'off_t':
+// - off_t is "used for file sizes".
+// At one point we were using it for memory offsets, but PtrdiffT should be
+// used in those cases.
+typedef Word                   OffT;      // 32             64
+typedef Long                 Off64T;      // 64             64
 
 #if !defined(NULL)
 #  define NULL ((void*)0)
diff --git a/include/pub_tool_debuginfo.h b/include/pub_tool_debuginfo.h
index 30725d542..baf998147 100644
--- a/include/pub_tool_debuginfo.h
+++ b/include/pub_tool_debuginfo.h
@@ -80,7 +80,7 @@ extern Bool VG_(get_fnname_if_entry) ( Addr a, Char* fnname, Int n_fnname );
    from the symbol start is put into *offset. */
 extern Bool VG_(get_datasym_and_offset)( Addr data_addr,
                                          /*OUT*/Char* dname, Int n_dname,
-                                         /*OUT*/OffT* offset );
+                                         /*OUT*/PtrdiffT* offset );
 
 /* Try to form some description of data_addr by looking at the DWARF3
    debug info we have.  This considers all global variables, and all
@@ -113,11 +113,11 @@ extern Char* VG_(describe_IP)(Addr eip, Char* buf, Int n_buf);
 
 typedef
    struct {
-      OffT  base;     /* offset from sp or fp */
-      SizeT szB;      /* size in bytes */
-      Bool  spRel;    /* True => sp-rel, False => fp-rel */
-      Bool  isVec;    /* does block have an array type, or not? */
-      HChar name[16]; /* first 15 chars of name (asciiz) */
+      PtrdiffT base;       /* offset from sp or fp */
+      SizeT    szB;        /* size in bytes */
+      Bool     spRel;      /* True => sp-rel, False => fp-rel */
+      Bool     isVec;      /* does block have an array type, or not? */
+      HChar    name[16];   /* first 15 chars of name (asciiz) */
    }
    StackBlock;
 
@@ -167,7 +167,7 @@ extern       Addr     VG_(seginfo_get_gotplt_avma)( const DebugInfo *di );
 extern       SizeT    VG_(seginfo_get_gotplt_size)( const DebugInfo *di );
 extern const UChar*   VG_(seginfo_soname)       ( const DebugInfo *di );
 extern const UChar*   VG_(seginfo_filename)     ( const DebugInfo *di );
-extern       ULong    VG_(seginfo_get_text_bias)( const DebugInfo *di );
+extern       PtrdiffT VG_(seginfo_get_text_bias)( const DebugInfo *di );
 
 /* Function for traversing the seginfo list.  When called with NULL it
    returns the first element; otherwise it returns the given element's
diff --git a/include/pub_tool_machine.h b/include/pub_tool_machine.h
index ae9669c05..fc86bf960 100644
--- a/include/pub_tool_machine.h
+++ b/include/pub_tool_machine.h
@@ -90,10 +90,10 @@ extern void VG_(set_IP) ( ThreadId tid, Addr ip );
 void
 VG_(get_shadow_regs_area) ( ThreadId tid, 
                             /*DST*/UChar* dst,
-                            /*SRC*/Int shadowNo, OffT offset, SizeT size );
+                            /*SRC*/Int shadowNo, PtrdiffT offset, SizeT size );
 void
 VG_(set_shadow_regs_area) ( ThreadId tid, 
-                            /*DST*/Int shadowNo, OffT offset, SizeT size,
+                            /*DST*/Int shadowNo, PtrdiffT offset, SizeT size,
                             /*SRC*/const UChar* src );
 
 // Sets the shadow values for the syscall return value register(s).
diff --git a/include/pub_tool_oset.h b/include/pub_tool_oset.h
index 1573136fa..c496523fb 100644
--- a/include/pub_tool_oset.h
+++ b/include/pub_tool_oset.h
@@ -183,7 +183,7 @@ extern Bool  VG_(OSetWord_Next)         ( OSet* os, /*OUT*/UWord* val );
 //   a deallocation function (such as VG_(free)()) directly will likely
 //   lead to assertions in Valgrind's allocator.
 
-extern OSet* VG_(OSetGen_Create)    ( OffT keyOff, OSetCmp_t cmp,
+extern OSet* VG_(OSetGen_Create)    ( PtrdiffT keyOff, OSetCmp_t cmp,
                                       OSetAlloc_t alloc, HChar* ec,
                                       OSetFree_t free );
 extern void  VG_(OSetGen_Destroy)   ( OSet* os );
diff --git a/include/pub_tool_tooliface.h b/include/pub_tool_tooliface.h
index 210df361a..8194706c8 100644
--- a/include/pub_tool_tooliface.h
+++ b/include/pub_tool_tooliface.h
@@ -567,15 +567,15 @@ void VG_(track_post_mem_write)     (void(*f)(CorePart part, ThreadId tid,
 /* Register events.  Use VG_(set_shadow_state_area)() to set the shadow regs
    for these events.  */
 void VG_(track_pre_reg_read)  (void(*f)(CorePart part, ThreadId tid,
-                                        Char* s, OffT guest_state_offset,
+                                        Char* s, PtrdiffT guest_state_offset,
                                         SizeT size));
 void VG_(track_post_reg_write)(void(*f)(CorePart part, ThreadId tid,
-                                        OffT guest_state_offset,
+                                        PtrdiffT guest_state_offset,
                                         SizeT size));
 
 /* This one is called for malloc() et al if they are replaced by a tool. */
 void VG_(track_post_reg_write_clientcall_return)(
-      void(*f)(ThreadId tid, OffT guest_state_offset, SizeT size, Addr f));
+      void(*f)(ThreadId tid, PtrdiffT guest_state_offset, SizeT size, Addr f));
 
 
 /* Scheduler events (not exhaustive) */