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# [description]
# Create a definition file (.def) from a .dll file, using objdump. This
# is used by FindLibR.cmake when building the R package with MSVC.
#
# [usage]
#
# Rscript make-r-def.R something.dll something.def
#
# [references]
# * https://www.cs.colorado.edu/~main/cs1300/doc/mingwfaq.html
args <- commandArgs(trailingOnly = TRUE)
IN_DLL_FILE <- args[[1L]]
OUT_DEF_FILE <- args[[2L]]
DLL_BASE_NAME <- basename(IN_DLL_FILE)
message(sprintf("Creating '%s' from '%s'", OUT_DEF_FILE, IN_DLL_FILE))
# system() will not raise an R exception if the process called
# fails. Wrapping it here to get that behavior.
#
# system() introduces a lot of overhead, at least on Windows,
# so trying processx if it is available
.pipe_shell_command_to_stdout <- function(command, args, out_file) {
has_processx <- suppressMessages({
suppressWarnings({
require("processx") # nolint
})
})
if (has_processx) {
p <- processx::process$new(
command = command
, args = args
, stdout = out_file
, windows_verbatim_args = FALSE
)
invisible(p$wait())
} else {
message(paste0(
"Using system2() to run shell commands. Installing "
, "'processx' with install.packages('processx') might "
, "make this faster."
))
exit_code <- system2(
command = command
, args = shQuote(args)
, stdout = out_file
)
if (exit_code != 0L) {
stop(paste0("Command failed with exit code: ", exit_code))
}
}
return(invisible(NULL))
}
# use objdump to dump all the symbols
OBJDUMP_FILE <- "objdump-out.txt"
.pipe_shell_command_to_stdout(
command = "objdump"
, args = c("-p", IN_DLL_FILE)
, out_file = OBJDUMP_FILE
)
objdump_results <- readLines(OBJDUMP_FILE)
result <- file.remove(OBJDUMP_FILE)
# Only one table in the objdump results matters for our purposes,
# see https://www.cs.colorado.edu/~main/cs1300/doc/mingwfaq.html
start_index <- which(
grepl(
pattern = "[Ordinal/Name Pointer] Table"
, x = objdump_results
, fixed = TRUE
)
)
empty_lines <- which(objdump_results == "")
end_of_table <- empty_lines[empty_lines > start_index][1L]
# Read the contents of the table
exported_symbols <- objdump_results[(start_index + 1L):end_of_table]
exported_symbols <- gsub("\t", "", exported_symbols)
exported_symbols <- gsub(".*\\] ", "", exported_symbols)
exported_symbols <- gsub(" ", "", exported_symbols)
# Write R.def file
writeLines(
text = c(
paste0("LIBRARY \"", DLL_BASE_NAME, "\"")
, "EXPORTS"
, exported_symbols
)
, con = OUT_DEF_FILE
, sep = "\n"
)
message(sprintf("Successfully created '%s'", OUT_DEF_FILE))
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