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From: Stuart Prescott <stuart@debian.org>
Date: Sun, 21 Dec 2025 16:22:50 +1100
Subject: Fix handling of str/bytes through ctypes
libNeXus uses bytes for all the c_char types not Python strings. The
encoding/decoding interface is defined as the call into the CDLL, that
is everything in Python code is in strings, except for the immediate
call into the CDLL. Encoding to bytes / decoding from bytes is done
via a specified encoding, defaulting to UTF-8.
---
nxs/napi.py | 71 ++++++++++++++++++++++++++++++++++++++++++-------------------
1 file changed, 49 insertions(+), 22 deletions(-)
diff --git a/nxs/napi.py b/nxs/napi.py
index 7d9acbf..afdd6e4 100755
--- a/nxs/napi.py
+++ b/nxs/napi.py
@@ -310,7 +310,7 @@ class NeXus(object):
# ==== File ====
nxlib.nxiopen_.restype = c_int
nxlib.nxiopen_.argtypes = [c_char_p, c_int, c_void_pp]
- def __init__(self, filename, mode='r'):
+ def __init__(self, filename, mode='r', encoding='UTF-8'):
"""
Open the NeXus file returning a handle.
@@ -336,17 +336,19 @@ class NeXus(object):
if mode not in _nxopen_mode.values():
raise ValueError("Invalid open mode %s" % str(mode))
- self.filename, self.mode = filename, mode
+ self.encoding = encoding
+ self.filename = self._str2bytes(filename)
+ self.mode = mode
self.handle = c_void_p(None)
self._path = []
self._indata = False
- status = nxlib.nxiopen_(filename,mode,_ref(self.handle))
+ status = nxlib.nxiopen_(self.filename,mode,_ref(self.handle))
if status == ERROR:
if mode in [ACC_READ, ACC_RDWR]:
op = 'open'
else:
op = 'create'
- raise NeXusError("Could not %s %s" % (op,filename))
+ raise NeXusError("Could not %s %s" % (op,self.filename))
self.isopen = True
def _getpath(self):
@@ -360,6 +362,16 @@ class NeXus(object):
longpath = property(_getlongpath, doc="Unix-style path including " \
+ "nxclass to the node")
+ def _str2bytes(self, s):
+ if isinstance(s, str):
+ s = s.encode(self.encoding)
+ return s
+
+ def _bytes2str(self, b):
+ if isinstance(b, bytes):
+ b = b.decode(self.encoding)
+ return b
+
def __del__(self):
"""
Be sure to close the file before deleting the last reference.
@@ -438,7 +450,7 @@ class NeXus(object):
Corresponds to NXsetnumberformat(&handle,type,format)
"""
type = _nxtype_code[type]
- status = nxlib.nxisetnumberformat_(self.handle,type,format)
+ status = nxlib.nxisetnumberformat_(self.handle,type,self._str2bytes(format))
if status == ERROR:
raise ValueError("Could not set %s to %s in %s" %
(type, format, self.filename))
@@ -455,7 +467,8 @@ class NeXus(object):
Corresponds to NXmakegroup(handle, name, nxclass)
"""
# print("makegroup", self._loc(), name, nxclass)
- status = nxlib.nximakegroup_(self.handle, name, nxclass)
+ status = nxlib.nximakegroup_(self.handle, self._str2bytes(name),
+ self._str2bytes(nxclass))
if status == ERROR:
raise NeXusError("Could not create %s:%s in %s" %
(nxclass, name, self._loc()))
@@ -476,7 +489,7 @@ class NeXus(object):
Corresponds to NXopenpath(handle, path)
"""
- self._openpath(path, opendata=True)
+ self._openpath(self._str2bytes(path), opendata=True)
def _openpath(self, path, opendata=True):
"""helper function: open relative path and maybe data"""
@@ -579,7 +592,7 @@ class NeXus(object):
Corresponds to NXopengrouppath(handle, path)
"""
- self._openpath(path,opendata=False)
+ self._openpath(self._str2bytes(path),opendata=False)
nxlib.nxiopengroup_.restype = c_int
nxlib.nxiopengroup_.argtypes = [c_void_p, c_char_p, c_char_p]
@@ -595,7 +608,8 @@ class NeXus(object):
# print("opengroup", self._loc(), name, nxclass)
if nxclass is None:
nxclass = self.__getnxclass(name)
- status = nxlib.nxiopengroup_(self.handle, name, nxclass)
+ status = nxlib.nxiopengroup_(self.handle, self._str2bytes(name),
+ self._str2bytes(nxclass))
if status == ERROR:
raise ValueError("Could not open %s:%s in %s" %
(nxclass, name, self._loc()))
@@ -639,6 +653,8 @@ class NeXus(object):
nxclass = ctypes.create_string_buffer(MAXNAMELEN)
n = c_int(0)
status = nxlib.nxigetgroupinfo_(self.handle,_ref(n),path,nxclass)
+ path = self._bytes2str(path)
+ nxclass = self._bytes2str(nxclass)
if status == ERROR:
raise ValueError("Could not get group info: %s" % (self._loc()))
# print("getgroupinfo", self._loc(), nxclass.value, name.value, n.value)
@@ -692,7 +708,7 @@ class NeXus(object):
# if nxclass == 'SDS':
# dtype = _pytype_code(storage.value)
# print("nextentry", nxclass.value, name.value, storage.value)
- return name.value,nxclass.value
+ return self._bytes2str(name.value), self._bytes2str(nxclass.value)
def getentries(self):
"""
@@ -848,7 +864,7 @@ class NeXus(object):
if self._indata:
status = ERROR
else:
- status = nxlib.nxiopendata_(self.handle, name)
+ status = nxlib.nxiopendata_(self.handle, self._str2bytes(name))
if status == ERROR:
raise ValueError("Could not open data %s: %s" % (name, self._loc()))
self._path.append((name,"SDS"))
@@ -893,7 +909,7 @@ class NeXus(object):
# print("makedata", self._loc(), name, shape, dtype)
storage = _nxtype_code[str(dtype)]
shape = numpy.asarray(shape,'int64')
- status = nxlib.nximakedata64_(self.handle,name,storage,len(shape),
+ status = nxlib.nximakedata64_(self.handle,self._str2bytes(name),storage,len(shape),
shape.ctypes.data_as(c_int64_p))
if status == ERROR:
raise ValueError("Could not create data %s: %s" %
@@ -927,7 +943,9 @@ class NeXus(object):
chunks[-1] = shape[-1]
else:
chunks = numpy.array(chunks,'int64')
- status = nxlib.nxicompmakedata64_(self.handle,name,storage,len(dims),
+ status = nxlib.nxicompmakedata64_(self.handle,
+ self._str2bytes(name),
+ storage,len(dims),
dims.ctypes.data_as(c_int64_p),
_compression_code[mode],
chunks.ctypes.data_as(c_int64_p))
@@ -1092,7 +1110,7 @@ class NeXus(object):
raise NeXusError("Could not get next attr: %s" % (self._loc()))
dtype = _pytype_code[storage.value]
# print("getnextattr", name.value, length.value, dtype)
- return name.value, length.value, dtype
+ return self._bytes2str(name.value), length.value, dtype
# TODO: Resolve discrepency between NeXus API documentation and
# TODO: apparent behaviour for getattr/putattr length.
@@ -1111,7 +1129,8 @@ class NeXus(object):
storage = c_int(_nxtype_code[str(dtype)])
# print("getattr", self._loc(), name, length, size, dtype)
size = c_int(size)
- status = nxlib.nxigetattr_(self.handle,name,pdata,_ref(size),_ref(storage))
+ status = nxlib.nxigetattr_(self.handle,self._str2bytes(name),
+ pdata,_ref(size),_ref(storage))
if status == ERROR:
raise ValueError("Could not read attr %s: %s" % (name, self._loc()))
# print("getattr", self._loc(), name, datafn())
@@ -1163,7 +1182,8 @@ class NeXus(object):
# Perform the call
storage = c_int(_nxtype_code[dtype])
- status = nxlib.nxiputattr_(self.handle,name,data,length,storage)
+ status = nxlib.nxiputattr_(self.handle,self._str2bytes(name),
+ data,length,storage)
if status == ERROR:
raise NeXusError("Could not write attr %s: %s" %
(name, self._loc()))
@@ -1258,7 +1278,8 @@ class NeXus(object):
Corresponds to NXmakenamedlink(handle,name,&ID)
"""
- status = nxlib.nximakenamedlink_(self.handle,name,_ref(ID))
+ status = nxlib.nximakenamedlink_(self.handle,self._str2bytes(name),
+ _ref(ID))
if status == ERROR:
raise NeXusError("Could not make link %s: %s" % (name, self._loc()))
@@ -1333,7 +1354,7 @@ class NeXus(object):
status = nxlib.nxiinquirefile_(self.handle,filename,maxnamelen)
if status == ERROR:
raise NeXusError("Could not determine filename: %s" % (self._loc()))
- return filename.value
+ return self._bytes2str(filename.value)
nxlib.nxilinkexternal_.restype = c_int
nxlib.nxilinkexternal_.argtyps = [c_void_p, c_char_p,
@@ -1347,7 +1368,10 @@ class NeXus(object):
Corresponds to NXisexternalgroup(&handle,name,nxclass,file,len)
"""
- status = nxlib.nxilinkexternal_(self.handle,name,nxclass,url)
+ status = nxlib.nxilinkexternal_(self.handle,
+ self._str2bytes(name),
+ self._str2bytes(nxclass),
+ self._str2bytes(url))
if status == ERROR:
raise NeXusError("Could not link %s to %s: %s" %
(name, url, self._loc()))
@@ -1363,12 +1387,15 @@ class NeXus(object):
Corresponds to NXisexternalgroup(&handle,name,nxclass,file,len)
"""
url = ctypes.create_string_buffer(maxnamelen)
- status = nxlib.nxiisexternalgroup_(self.handle,name,nxclass,
- url,maxnamelen)
+ status = nxlib.nxiisexternalgroup_(self.handle,
+ self._str2bytes(name),
+ self._str2bytes(nxclass),
+ url,
+ maxnamelen)
if status == ERROR:
return None
else:
- return url.value
+ return self._bytes2str(url.value)
# ==== Utility functions ====
def _loc(self):
|
