H5Awrite for strings has premature null termination

[LTLA]

library(rhdf5)
tmp <- tempfile(fileext=".h5")
fhandle <- H5Fcreate(tmp, "H5F_ACC_TRUNC")
ghandle <- H5Gcreate(fhandle, "whee")

tid <- H5Tcopy("H5T_C_S1")
H5Tset_strpad(tid, strpad = "NULLPAD")
H5Tset_size(tid, 5L) # size of 5 bytes

ahandle <- H5Acreate(ghandle, "name", dtype_id=tid, h5space=H5Screate("H5S_SCALAR"))
H5Awrite(ahandle, "Aaron") # string of length 5

H5Aclose(ahandle)
H5Gclose(ghandle)
H5Fclose(fhandle)

One would expect my name to fit inside the attribute, but alas:

h5readAttributes(tmp, "whee")
## $name
## [1] "Aaro"

This seems to be caused by

rhdf5/src/H5A.c

Line 457 in cb102ba

for (j=0; (j < LENGTH(STRING_ELT(_buf,i))) & (j < (stsize-1)); j++) {

where the loop stops prematurely because of the j < (stsize-1) condition. The fix is probably quite simple; just make this j < stsize instead, which would cause the entire string to be written.

Incidentally, datasets do the right thing, so I don't see why attributes have this weird behavior.

library(rhdf5)
tmp <- tempfile(fileext=".h5")
fhandle <- H5Fcreate(tmp, "H5F_ACC_TRUNC")

tid <- H5Tcopy("H5T_C_S1")
H5Tset_strpad(tid, strpad = "NULLPAD")
H5Tset_size(tid, 5L) # size of 5 bytes

dhandle <- H5Dcreate(fhandle, "name", dtype_id=tid, h5space=H5Screate("H5S_SCALAR"))
H5Dwrite(dhandle, "Aaron") # string of length 5

H5Dclose(dhandle)
H5Fclose(fhandle)

h5read(tmp, "name")
## [1] "Aaron"

Session information

R Under development (unstable) (2023-11-10 r85507)
Platform: x86_64-pc-linux-gnu
Running under: Ubuntu 20.04.6 LTS

Matrix products: default
BLAS:   /home/luna/Software/R/trunk/lib/libRblas.so 
LAPACK: /home/luna/Software/R/trunk/lib/libRlapack.so;  LAPACK version 3.11.0

locale:
 [1] LC_CTYPE=en_US.UTF-8       LC_NUMERIC=C              
 [3] LC_TIME=en_US.UTF-8        LC_COLLATE=en_US.UTF-8    
 [5] LC_MONETARY=en_US.UTF-8    LC_MESSAGES=en_US.UTF-8   
 [7] LC_PAPER=en_US.UTF-8       LC_NAME=C                 
 [9] LC_ADDRESS=C               LC_TELEPHONE=C            
[11] LC_MEASUREMENT=en_US.UTF-8 LC_IDENTIFICATION=C       

time zone: America/Los_Angeles
tzcode source: system (glibc)

attached base packages:
[1] stats     graphics  grDevices utils     datasets  methods   base     

other attached packages:
[1] rhdf5_2.47.0

loaded via a namespace (and not attached):
[1] compiler_4.4.0      rhdf5filters_1.15.1 Rhdf5lib_1.25.0