Allow 0-length arrays to be returned from Mmap.mmap. Fixes #10516

JuliaLang · Oct 20, 2015 · 2a006e1 · 2a006e1
1 parent e60d546
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Showing 2 changed files with 25 additions and 22 deletions.
diff --git a/base/mmap.jl b/base/mmap.jl
@@ -68,16 +68,18 @@ end # @unix_only
 
 @windows_only begin
 
-const PAGE_READONLY          = UInt32(0x02)
-const PAGE_READWRITE         = UInt32(0x04)
-const PAGE_WRITECOPY         = UInt32(0x08)
-const PAGE_EXECUTE_READ      = UInt32(0x20)
-const PAGE_EXECUTE_READWRITE = UInt32(0x40)
-const PAGE_EXECUTE_WRITECOPY = UInt32(0x80)
-const FILE_MAP_COPY          = UInt32(0x01)
-const FILE_MAP_WRITE         = UInt32(0x02)
-const FILE_MAP_READ          = UInt32(0x04)
-const FILE_MAP_EXECUTE       = UInt32(0x20)
+typealias DWORD Culong
+
+const PAGE_READONLY          = DWORD(0x02)
+const PAGE_READWRITE         = DWORD(0x04)
+const PAGE_WRITECOPY         = DWORD(0x08)
+const PAGE_EXECUTE_READ      = DWORD(0x20)
+const PAGE_EXECUTE_READWRITE = DWORD(0x40)
+const PAGE_EXECUTE_WRITECOPY = DWORD(0x80)
+const FILE_MAP_COPY          = DWORD(0x01)
+const FILE_MAP_WRITE         = DWORD(0x02)
+const FILE_MAP_READ          = DWORD(0x04)
+const FILE_MAP_EXECUTE       = DWORD(0x20)
 
 function gethandle(io::IO)
     handle = Libc._get_osfhandle(RawFD(fd(io))).handle
@@ -86,7 +88,7 @@ function gethandle(io::IO)
 end
 
 settings(sh::Anonymous) = utf16(sh.name), sh.readonly, sh.create
-settings(io::IO) = convert(Ptr{Cwchar_t},C_NULL), isreadonly(io), true
+settings(io::IO) = Ptr{Cwchar_t}(0), isreadonly(io), true
 end # @windows_only
 
 # core impelementation of mmap
@@ -99,7 +101,8 @@ function mmap{T,N}(io::IO,
     isbits(T)  || throw(ArgumentError("unable to mmap $T; must satisfy isbits(T) == true"))
 
     len = prod(dims) * sizeof(T)
-    len > 0 || throw(ArgumentError("requested size must be > 0, got $len"))
+    len >= 0 || throw(ArgumentError("requested size must be ≥ 0, got $len"))
+    len == 0 && return Array(T,ntuple(x->0,N))
     len < typemax(Int) - PAGESIZE || throw(ArgumentError("requested size must be < $(typemax(Int)-PAGESIZE), got $len"))
 
     offset >= 0 || throw(ArgumentError("requested offset must be ≥ 0, got $offset"))
@@ -121,14 +124,14 @@ function mmap{T,N}(io::IO,
 
     @windows_only begin
         name, readonly, create = settings(io)
-        szfile = convert(Csize_t, len + offset)
+        szfile = convert(DWORD, len + offset)
         readonly && szfile > filesize(io) && throw(ArgumentError("unable to increase file size to $szfile due to read-only permissions"))
-        handle = create ? ccall(:CreateFileMappingW, stdcall, Ptr{Void}, (Cptrdiff_t, Ptr{Void}, Cint, Cint, Cint, Cwstring),
+        handle = create ? ccall(:CreateFileMappingW, stdcall, Ptr{Void}, (Cptrdiff_t, Ptr{Void}, DWORD, DWORD, DWORD, Cwstring),
                                 file_desc, C_NULL, readonly ? PAGE_READONLY : PAGE_READWRITE, szfile >> 32, szfile & typemax(UInt32), name) :
-                          ccall(:OpenFileMappingW, stdcall, Ptr{Void}, (Cint, Cint, Cwstring),
-                            readonly ? FILE_MAP_READ : FILE_MAP_WRITE, true, name)
+                          ccall(:OpenFileMappingW, stdcall, Ptr{Void}, (DWORD, Cint, Cwstring),
+                                readonly ? FILE_MAP_READ : FILE_MAP_WRITE, true, name)
         handle == C_NULL && error("could not create file mapping: $(Libc.FormatMessage())")
-        ptr = ccall(:MapViewOfFile, stdcall, Ptr{Void}, (Ptr{Void}, Cint, Cint, Cint, Csize_t),
+        ptr = ccall(:MapViewOfFile, stdcall, Ptr{Void}, (Ptr{Void}, DWORD, DWORD, DWORD, DWORD),
                     handle, readonly ? FILE_MAP_READ : FILE_MAP_WRITE, offset_page >> 32, offset_page & typemax(UInt32), (offset - offset_page) + len)
         ptr == C_NULL && error("could not create mapping view: $(Libc.FormatMessage())")
     end # @windows_only

diff --git a/test/mmap.jl b/test/mmap.jl
@@ -11,12 +11,12 @@ gc(); gc()
 gc(); gc()
 @test Mmap.mmap(file, Array{UInt8,3}, (1,1,11)) == reshape(t,(1,1,11))
 gc(); gc()
-@test_throws ArgumentError Mmap.mmap(file, Array{UInt8,3}, (11,0,1)) # 0-dimension results in len=0
+@test Mmap.mmap(file, Array{UInt8,3}, (11,0,1)) == Array(UInt8,(0,0,0))
 @test Mmap.mmap(file, Vector{UInt8}, (11,)) == t
 gc(); gc()
 @test Mmap.mmap(file, Array{UInt8,2}, (1,11)) == t'
 gc(); gc()
-@test_throws ArgumentError Mmap.mmap(file, Array{UInt8,2}, (0,12))
+@test Mmap.mmap(file, Array{UInt8,2}, (0,12)) == Array(UInt8,(0,0))
 m = Mmap.mmap(file, Array{UInt8,3}, (1,2,1))
 @test m == reshape("He".data,(1,2,1))
 finalize(m); m=nothing; gc()
@@ -48,8 +48,8 @@ close(s)
 gc(); gc()
 
 s = open(f->f,file,"w")
-@test_throws ArgumentError Mmap.mmap(file) # requested len=0 on empty file
-@test_throws ArgumentError Mmap.mmap(file,Vector{UInt8},0)
+@test Mmap.mmap(file) == Array(UInt8, 0) # requested len=0 on empty file
+@test Mmap.mmap(file,Vector{UInt8},0) == Array(UInt8, 0)
 m = Mmap.mmap(file,Vector{UInt8},12)
 m[:] = "Hello World\n".data
 Mmap.sync!(m)
@@ -284,4 +284,4 @@ n = similar(m, (2,2))
 n = similar(m, 12)
 @test length(n) == 12
 @test size(n) == (12,)
-finalize(m); m = nothing; gc()
+finalize(m); m = nothing; gc()