diff options
| -rw-r--r-- | lib/pure/memfiles.nim | 26 |
1 files changed, 21 insertions, 5 deletions
diff --git a/lib/pure/memfiles.nim b/lib/pure/memfiles.nim index 810223d72..d1a006eee 100644 --- a/lib/pure/memfiles.nim +++ b/lib/pure/memfiles.nim @@ -42,9 +42,10 @@ type wasOpened*: bool ## **Caution**: Windows specific public field. else: handle*: cint ## **Caution**: Posix specific public field. + flags: cint ## **Caution**: Platform specific private field. proc mapMem*(m: var MemFile, mode: FileMode = fmRead, - mappedSize = -1, offset = 0): pointer = + mappedSize = -1, offset = 0, mapFlags = cint(-1)): pointer = ## returns a pointer to a mapped portion of MemFile `m` ## ## ``mappedSize`` of ``-1`` maps to the whole file, and @@ -65,11 +66,17 @@ proc mapMem*(m: var MemFile, mode: FileMode = fmRead, raiseOSError(osLastError()) else: assert mappedSize > 0 + + m.flags = if mapFlags == cint(-1): MAP_SHARED else: mapFlags + #Ensure exactly one of MAP_PRIVATE cr MAP_SHARED is set + if int(m.flags and MAP_PRIVATE) == 0: + m.flags = m.flags or MAP_SHARED + result = mmap( nil, mappedSize, if readonly: PROT_READ else: PROT_READ or PROT_WRITE, - if readonly: (MAP_PRIVATE or MAP_POPULATE) else: (MAP_SHARED or MAP_POPULATE), + m.flags, m.handle, offset) if result == cast[pointer](MAP_FAILED): raiseOSError(osLastError()) @@ -90,7 +97,7 @@ proc unmapMem*(f: var MemFile, p: pointer, size: int) = proc open*(filename: string, mode: FileMode = fmRead, mappedSize = -1, offset = 0, newFileSize = -1, - allowRemap = false): MemFile = + allowRemap = false, mapFlags = cint(-1)): MemFile = ## opens a memory mapped file. If this fails, ``OSError`` is raised. ## ## ``newFileSize`` can only be set if the file does not exist and is opened @@ -105,6 +112,10 @@ proc open*(filename: string, mode: FileMode = fmRead, ## ``allowRemap`` only needs to be true if you want to call ``mapMem`` on ## the resulting MemFile; else file handles are not kept open. ## + ## ``mapFlags`` allows callers to override default choices for memory mapping + ## flags with a bitwise mask of a variety of likely platform-specific flags + ## which may be ignored or even cause `open` to fail if misspecified. + ## ## Example: ## ## .. code-block:: nim @@ -245,11 +256,16 @@ proc open*(filename: string, mode: FileMode = fmRead, else: fail(osLastError(), "error getting file size") + result.flags = if mapFlags == cint(-1): MAP_SHARED else: mapFlags + #Ensure exactly one of MAP_PRIVATE cr MAP_SHARED is set + if int(result.flags and MAP_PRIVATE) == 0: + result.flags = result.flags or MAP_SHARED + result.mem = mmap( nil, result.size, if readonly: PROT_READ else: PROT_READ or PROT_WRITE, - if readonly: (MAP_PRIVATE or MAP_POPULATE) else: (MAP_SHARED or MAP_POPULATE), + result.flags, result.handle, offset) @@ -305,7 +321,7 @@ when defined(posix) or defined(nimdoc): if munmap(f.mem, f.size) != 0: raiseOSError(osLastError()) let newAddr = mmap(nil, newFileSize, PROT_READ or PROT_WRITE, - MAP_SHARED or MAP_POPULATE, f.handle, 0) + f.flags, f.handle, 0) if newAddr == cast[pointer](MAP_FAILED): raiseOSError(osLastError()) f.mem = newAddr |