From: Ralph Ronnquist Date: Tue, 18 Apr 2023 13:42:23 +0000 (+1000) Subject: Adding mmap API with test and documentation. X-Git-Url: https://git.rrq.au/?a=commitdiff_plain;h=4d9a34c5fb5811b6498bfa531402ac77c2711aec;p=rrq%2Flsp-utils.git Adding mmap API with test and documentation. --- diff --git a/lsp-dbus-test.lsp b/lsp-dbus-test.lsp index dd71083..94981b5 100644 --- a/lsp-dbus-test.lsp +++ b/lsp-dbus-test.lsp @@ -23,8 +23,7 @@ (Dbus:process-all-pending) (println (setf org.bluez (Dbus "/" "org.bluez"))) -(println (if (:invoke org.bluez - (println (:m ObjectManager "GetManagedObjects()"))) +(println (if (:invoke org.bluez (:m ObjectManager "GetManagedObjects()")) ($it -1 -1 -1) ; Return value )) diff --git a/lsp-misc.a.8.adoc b/lsp-misc.a.8.adoc index 5dd0b04..7f8a5d0 100644 --- a/lsp-misc.a.8.adoc +++ b/lsp-misc.a.8.adoc @@ -28,7 +28,7 @@ packnl _main.lsp_ *-A lsp-misc.a* The *prog1* function is like a *begin* function except that it returns the value of the first term rather than the last. -(die [_N_ [_term_]]):: +(die _N_ [_term_]*):: The *die* function printes to stderr the join of term values as strings with space separation, and if _N_ is a number, then the @@ -93,6 +93,41 @@ the respective naming formats (:%name obj) and (:!name obj value). --> A = (EX 1 4 3) ---- +=== mmap.lsp API + +This newlisp module implements a small FOOP model based memory mapping +API that links in the _libc6_ functions _mmap_, _munmap_, _msync_ and +_lseek_. + +(*MMap* _FD_ _LENGTH_ [_OFFSET_ [_PROT_]]):: + +This function creates a FOOP object that represents the memory mapping +of the given file descriptor. _FD_ may be the pathname string of a +file to memory map or an already opened file descriptor. The MMap +object represents the memory block starting at (:%base) and (%len) +bytes in length where the file is memory mapped. ++ +.Access example (from test.lsp) +[caption=""] +---- +(println (setf X (MMap "mmap.lsp"))) +(println (get-string (:%base X))) +---- ++ +Note that only a plain text file would be accessed with _get-string_. +A binary file would rather be accessed with _unpack_. The memory +mapping provides read-only "random access" to the file content. ++ +To set up read-write acces requires an _OFFSET_ and the _PROT_ +argument 0x3, and writing should be accompanied by _MMap:msync_ calls +so as to synchronize with the backing file. ++ +The FOOP object includes get and set methods for the fields (in +order): _base_, _len_, _prot_, _flags_, _fd_ and _offset_. + +=== test.lsp + +This file is a small test of the MMap memory mapping. == SEE ALSO diff --git a/lsp-misc/mmap.lsp b/lsp-misc/mmap.lsp index 639b1c9..bb3f3be 100644 --- a/lsp-misc/mmap.lsp +++ b/lsp-misc/mmap.lsp @@ -28,19 +28,26 @@ "int" ; int whence ) +(import LIBC "msync" "int" + "void*" ; void *addr + "long" ; size_t length + "int" ; int flags + ) + (constant 'PROT_READ 0x01 + 'PROT_WRITE 0x2 'MAP_SHARED 0x01 'SEEK_END 2 ) ;; Creates a new mapping in the virtual address space of the calling ;; process. -(define (MMap:MMap FD LENGTH (OFFSET 0)) +(define (MMap:MMap FD LENGTH (OFFSET 0) (PROT PROT_READ)) (when (string? FD) (setf FD (open FD "r"))) (let ((D (list (context) nil LENGTH 0 0 FD OFFSET))) (when (< LENGTH) (setf (D 2) (lseek FD 0 SEEK_END))) - (setf (D 1) (mmap 0 (D 2) PROT_READ MAP_SHARED FD OFFSET)) + (setf (D 1) (mmap 0 (D 2) PROT MAP_SHARED FD OFFSET)) D)) (define (Unmap)