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Merge pull request #1182 from boydgreenfield/devel

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Clarify newFileSize & mappedSize params in memfiles.open() docs
This commit is contained in:
Varriount 2014-05-21 18:17:48 -04:00
commit b54f66eeff
1 changed files with 20 additions and 4 deletions
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24
lib/pure/memfiles.nim
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@ -74,9 +74,22 @@ proc unmapMem*(f: var TMemFile, p: pointer, size: int) =
proc open*(filename: string, mode: TFileMode = fmRead, proc open*(filename: string, mode: TFileMode = fmRead,
mappedSize = -1, offset = 0, newFileSize = -1): TMemFile = mappedSize = -1, offset = 0, newFileSize = -1): TMemFile =
## opens a memory mapped file. If this fails, ``EOS`` is raised. ## opens a memory mapped file. If this fails, ``EOS`` is raised.
## `newFileSize` can only be set if the file is not opened with ``fmRead`` ## `newFileSize` can only be set if the file does not exist and is opened
## access. `mappedSize` and `offset` can be used to map only a slice of ## with write access (e.g., with fmReadWrite). `mappedSize` and `offset`
## the file. ## can be used to map only a slice of the file. Example:
##
## .. code-block:: nimrod
## var
## mm, mm_full, mm_half: TMemFile
##
## mm = memfiles.open("/tmp/test.mmap", mode = fmWrite, newFileSize = 1024) # Create a new file
## mm.close()
##
## # Read the whole file, would fail if newFileSize was set
## mm_full = memfiles.open("/tmp/test.mmap", mode = fmReadWrite, mappedSize = -1)
##
## # Read the first 512 bytes
## mm_half = memfiles.open("/tmp/test.mmap", mode = fmReadWrite, mappedSize = 512)
# The file can be resized only when write mode is used: # The file can be resized only when write mode is used:
assert newFileSize == -1 or mode != fmRead assert newFileSize == -1 or mode != fmRead
@ -165,8 +178,11 @@ proc open*(filename: string, mode: TFileMode = fmRead,
if newFileSize != -1: if newFileSize != -1:
flags = flags or O_CREAT or O_TRUNC flags = flags or O_CREAT or O_TRUNC
var permissions_mode = S_IRUSR or S_IWUSR
result.handle = open(filename, flags, permissions_mode)
else:
result.handle = open(filename, flags) result.handle = open(filename, flags)
if result.handle == -1: if result.handle == -1:
# XXX: errno is supposed to be set here # XXX: errno is supposed to be set here
# Is there an exception that wraps it? # Is there an exception that wraps it?