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#
#
# Nim's Runtime Library
# (c) Copyright 2012 Andreas Rumpf
#
# See the file "copying.txt", included in this
# distribution, for details about the copyright.
#
## This module implements the ability to access symbols from shared
## libraries. On POSIX this uses the `dlsym` mechanism, on
## Windows `LoadLibrary`.
##
## Examples
## ========
##
## Loading a simple C function
## ---------------------------
##
## The following example demonstrates loading a function called `greet`
## from a library that is determined at runtime based upon a language choice.
## If the library fails to load or the function `greet` is not found,
## it quits with a failure error code.
##
runnableExamples:
type
GreetFunction = proc (): cstring {.gcsafe, stdcall.}
proc loadGreet(lang: string) =
let lib =
case lang
of "french":
loadLib("french.dll")
else:
loadLib("english.dll")
assert lib != nil, "Error loading library"
let greet = cast[GreetFunction](lib.symAddr("greet"))
assert greet != nil, "Error loading 'greet' function from library"
echo greet()
unloadLib(lib)
import std/strutils
type
LibHandle* = pointer ## A handle to a dynamically loaded library.
proc loadLib*(path: string, globalSymbols = false): LibHandle {.gcsafe.}
## Loads a library from `path`. Returns nil if the library could not
## be loaded.
proc loadLib*(): LibHandle {.gcsafe.}
## Gets the handle from the current executable. Returns nil if the
## library could not be loaded.
proc unloadLib*(lib: LibHandle) {.gcsafe.}
## Unloads the library `lib`.
proc raiseInvalidLibrary*(name: cstring) {.noinline, noreturn.} =
## Raises a `LibraryError` exception.
raise newException(LibraryError, "could not find symbol: " & $name)
proc symAddr*(lib: LibHandle, name: cstring): pointer {.gcsafe.}
## Retrieves the address of a procedure/variable from `lib`. Returns nil
## if the symbol could not be found.
proc checkedSymAddr*(lib: LibHandle, name: cstring): pointer =
## Retrieves the address of a procedure/variable from `lib`. Raises
## `LibraryError` if the symbol could not be found.
result = symAddr(lib, name)
if result == nil: raiseInvalidLibrary(name)
proc libCandidates*(s: string, dest: var seq[string]) =
## Given a library name pattern `s`, write possible library names to `dest`.
var le = strutils.find(s, '(')
var ri = strutils.find(s, ')', le+1)
if le >= 0 and ri > le:
var prefix = substr(s, 0, le - 1)
var suffix = substr(s, ri + 1)
for middle in split(substr(s, le + 1, ri - 1), '|'):
libCandidates(prefix & middle & suffix, dest)
else:
add(dest, s)
proc loadLibPattern*(pattern: string, globalSymbols = false): LibHandle =
## Loads a library with name matching `pattern`, similar to what the `dynlib`
## pragma does. Returns nil if the library could not be loaded.
##
## .. warning:: this proc uses the GC and so cannot be used to load the GC.
var candidates = newSeq[string]()
libCandidates(pattern, candidates)
for c in candidates:
result = loadLib(c, globalSymbols)
if not result.isNil: break
when defined(posix) and not defined(nintendoswitch):
#
# =========================================================================
# This is an implementation based on the dlfcn interface.
# The dlfcn interface is available in Linux, SunOS, Solaris, IRIX, FreeBSD,
# NetBSD, AIX 4.2, HPUX 11, and probably most other Unix flavors, at least
# as an emulation layer on top of native functions.
# =========================================================================
#
import std/posix
proc loadLib(path: string, globalSymbols = false): LibHandle =
let flags =
if globalSymbols: RTLD_NOW or RTLD_GLOBAL
else: RTLD_NOW
dlopen(path, flags)
proc loadLib(): LibHandle = dlopen(nil, RTLD_NOW)
proc unloadLib(lib: LibHandle) = discard dlclose(lib)
proc symAddr(lib: LibHandle, name: cstring): pointer = dlsym(lib, name)
elif defined(nintendoswitch):
#
# =========================================================================
# Nintendo switch DevkitPro sdk does not have these. Raise an error if called.
# =========================================================================
#
proc dlclose(lib: LibHandle) =
raise newException(OSError, "dlclose not implemented on Nintendo Switch!")
proc dlopen(path: cstring, mode: int): LibHandle =
raise newException(OSError, "dlopen not implemented on Nintendo Switch!")
proc dlsym(lib: LibHandle, name: cstring): pointer =
raise newException(OSError, "dlsym not implemented on Nintendo Switch!")
proc loadLib(path: string, global_symbols = false): LibHandle =
raise newException(OSError, "loadLib not implemented on Nintendo Switch!")
proc loadLib(): LibHandle =
raise newException(OSError, "loadLib not implemented on Nintendo Switch!")
proc unloadLib(lib: LibHandle) =
raise newException(OSError, "unloadLib not implemented on Nintendo Switch!")
proc symAddr(lib: LibHandle, name: cstring): pointer =
raise newException(OSError, "symAddr not implemented on Nintendo Switch!")
elif defined(genode):
#
# =========================================================================
# Not implemented for Genode without POSIX. Raise an error if called.
# =========================================================================
#
template raiseErr(prc: string) =
raise newException(OSError, prc & " not implemented, compile with POSIX support")
proc dlclose(lib: LibHandle) =
raiseErr(OSError, "dlclose")
proc dlopen(path: cstring, mode: int): LibHandle =
raiseErr(OSError, "dlopen")
proc dlsym(lib: LibHandle, name: cstring): pointer =
raiseErr(OSError, "dlsym")
proc loadLib(path: string, global_symbols = false): LibHandle =
raiseErr(OSError, "loadLib")
proc loadLib(): LibHandle =
raiseErr(OSError, "loadLib")
proc unloadLib(lib: LibHandle) =
raiseErr(OSError, "unloadLib")
proc symAddr(lib: LibHandle, name: cstring): pointer =
raiseErr(OSError, "symAddr")
elif defined(windows) or defined(dos):
#
# =======================================================================
# Native Windows Implementation
# =======================================================================
#
type
HMODULE {.importc: "HMODULE".} = pointer
FARPROC {.importc: "FARPROC".} = pointer
proc FreeLibrary(lib: HMODULE) {.importc, header: "<windows.h>", stdcall.}
proc winLoadLibrary(path: cstring): HMODULE {.
importc: "LoadLibraryA", header: "<windows.h>", stdcall.}
proc getProcAddress(lib: HMODULE, name: cstring): FARPROC {.
importc: "GetProcAddress", header: "<windows.h>", stdcall.}
proc loadLib(path: string, globalSymbols = false): LibHandle =
result = cast[LibHandle](winLoadLibrary(path))
proc loadLib(): LibHandle =
result = cast[LibHandle](winLoadLibrary(nil))
proc unloadLib(lib: LibHandle) = FreeLibrary(cast[HMODULE](lib))
proc symAddr(lib: LibHandle, name: cstring): pointer =
result = cast[pointer](getProcAddress(cast[HMODULE](lib), name))
else:
{.error: "no implementation for dynlib".}
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