Update copyright year

… my Emacs previously used tabs+spaces for Scheme,
which is genuinely horrific. >o<

README.md

@@ -0,0 +1,73 @@
+# xattr
+## Interface for extended filesystem attributes
+
+[Extended attributes](https://en.wikipedia.org/wiki/Extended_attributes) are a special type of file attribute that lets you associate key-value pairs with a file without actually modifying the file's contents. Commonly used for program settings, tagging, and file metadata (i.e., storing a file's author with a key like “author.name”) xattrs can be used for used for pretty much anything you can dream up. They're mega-cool and useful.
+
+This is a simple interface for accessing them within [Chicken Scheme](https://call-cc.org/), a friendly Scheme.
+
+
+## API
+### get-xattr
+`get-xattr path attr`
+
+Returns the string-value of a file's extended attribute.  
+If the file has no such attribute, #f is returned. In other cases (e.g., the file doesn't exist, permission not available, no filesystem support), exceptions are raised.
+
+### set-xattr
+`set-xattr path attr value`
+
+Sets the string-value of a file's extended attribute.  
+The set value is returned, if successful.
+
+### remove-xattr
+`remove-xattr path attr`
+
+Removes an extended attribute from a file.  
+The value of the removed attribute is returned, if successful.
+
+### list-xattrs
+`list-xattrs path`
+
+Returns a list of the file's extended attribute names.
+
+
+## Examples
+```
+(import xattr (chicken io) (chicken file))
+;; Create the test file
+(call-with-output-file "testing.txt"
+                       (lambda (out-port) (write-line "Just a test!" out-port)))
+
+(set-xattr "testing.txt" "user.dublincore.author" "Migdal E. F. Lemmings")
+(set-xattr "testing.txt" "user.dublincore.title" "A Treatise on Almonds")
+
+(get-xattr "testing.txt" "user.dublincore.author")
+;; Returns "Migdal E. F. Lemmings"
+
+(list-xattrs "testing.txt")
+;; Returns '("user.dublincore.author" "user.dublincore.title")
+
+(remove-xattr "testing.txt" "user.dublincore.title")
+;; Returns "A Treatise on Almonds"
+
+(list-xattrs "testing.txt")
+;; Now returns '("user.dublincore.author")
+```
+
+
+## On GNU/Linux
+Currently, this egg only supports LiGNUx, a platform that has a particularity: The name of each attribute must contain a “namespace,” separated from the actual name by a period. For example, with the attribute named `user.xdg.origin.url`, the namespace is `user` and the name is `xdg.origin.url`. In most cases, you won't stray from the `user` namespace.  
+
+Don't forget to prepend “user.” to your attribute names!
+
+A handy list of somewhat-standard extended attributes is hosted on FreeDesktop's website, [here](https://www.freedesktop.org/wiki/CommonExtendedAttributes/).
+
+
+## Requirements
+This egg requires `srfi-1` and `srfi-12`.
+
+
+## Meta
+**Author:** Jaidyn Ann <jadedctrl@posteo.at>  
+**License:** GPLv3  
+**Source:** https://github.com/jadedctrl/xattr, https://notabug.org/jadedctrl/xattr

xattr.egg

@@ -1,9 +1,7 @@
 ;; -*- Scheme -*-
 ((synopsis "Access to extended attributes")
  (author "Jaidyn Ann")
- (category net)
+ (category io)
  (license "GPLv3")
-
+ (dependencies srfi-1)
  (components (extension xattr)))
-;;						(csc-options "-O3" "-d1" "-X" "bind" "-s" "-k" "-emit-link-file" "xattr.link" "-o" "xattr_ext.o"))
-;;			 (c-object xattr_ext)))

xattr.scm

@@ -1,5 +1,5 @@
 ;;
-;; Copyright 2022, Jaidyn Levesque <jadedctrl@posteo.at>
+;; Copyright 2024, Jaidyn Levesque <jadedctrl@posteo.at>
 ;;
 ;; This program is free software: you can redistribute it and/or
 ;; modify it under the terms of the GNU General Public License as
@@ -16,176 +16,181 @@
 ;;
 
 (module xattr
-  (get-xattr set-xattr remove-xattr list-xattr)
+    (get-xattr set-xattr remove-xattr list-xattrs)
 
-(import (chicken base) (chicken memory) srfi-1 scheme (chicken foreign) srfi-12)
+  (import scheme
-
+          (chicken base) (chicken condition) (chicken foreign) (chicken memory)
-(foreign-declare "#include \"xattr_ext.c\"")
+          srfi-1)
 
 
-;; The direct foreign binding for `get_xattr`
+  (foreign-declare "#include \"xattr_ext.c\"")
-(define get-xattr-foreign
-  (foreign-lambda c-string* "get_xattr" c-string c-string (c-pointer int)))
 
 
-;; Wrapper around get-xattr-foreign, which throws exceptions and such.
+  ;; The direct foreign binding for `get_xattr`
-(define (get-xattr path attr)
+  (define get-xattr-foreign
-  (let-location ([error-code int])
+    (foreign-lambda c-string* "get_xattr" c-string c-string (c-pointer int)))
-    (let ([attr-value (get-xattr-foreign path attr (location error-code))]
-		  [exception (or (getxattr-exception error-code)
-						 (stat-exception error-code))])
-	  (if exception
-		  (signal exception)
-		  attr-value))))
 
 
-;; The direct foreign binding for `list_xattr`
+  ;; Wrapper around get-xattr-foreign, which throws exceptions and such.
-(define list-xattr-foreign
+  (define (get-xattr path attr)
-  (foreign-lambda (c-pointer char) "list_xattr" c-string (c-pointer ssize_t) (c-pointer int)))
+    (let-location ([error-code int])
+      (let ([attr-value (get-xattr-foreign path attr (location error-code))]
+            [exception (or (getxattr-exception error-code)
+                           (stat-exception error-code))])
+        (if exception
+            (signal exception)
+            attr-value))))
 
 
-;; Wrapper around list-xattr-foreign, which throws exceptions and such.
+  ;; The direct foreign binding for `list_xattr`
-(define (list-xattr path)
+  (define list-xattrs-foreign
-  (let-location ([error-code int]
+    (foreign-lambda (c-pointer char) "list_xattr" c-string (c-pointer ssize_t) (c-pointer int)))
-				 [length ssize_t])
-    (let ([list-pointer (list-xattr-foreign path (location length) (location error-code))]
-		  [exception (or (getxattr-exception error-code)
-						 (stat-exception error-code))])
-	  (if exception
-		  (signal exception)
-		  ;; listxattr offers a const char* \0-delimited list of strings
-		  (pointer->delimited-string-list list-pointer length 0)))))
 
 
-;; The direct foreign binding for `set_xattr`
+  ;; Wrapper around list-xattrs-foreign, which throws exceptions and such.
-(define set-xattr-foreign
+  (define (list-xattrs path)
-  (foreign-lambda int "set_xattr" c-string c-string c-string (c-pointer int)))
+    (let-location ([error-code int]
+                   [length ssize_t])
+      (let ([list-pointer (list-xattrs-foreign path (location length) (location error-code))]
+            [exception (or (getxattr-exception error-code)
+                           (stat-exception error-code))])
+        (if exception
+            (signal exception)
+            ;; listxattr offers a const char* \0-delimited list of strings
+            (pointer->delimited-string-list list-pointer length 0)))))
 
 
-;; Wrapper around set-xattr-foreign, throwing exceptions and all that jazz
+  ;; The direct foreign binding for `set_xattr`
-(define (set-xattr path attr value)
+  (define set-xattr-foreign
-  (let-location ([error-code int])
+    (foreign-lambda int "set_xattr" c-string c-string c-string (c-pointer int)))
-    (let ([return-code (set-xattr-foreign path attr value (location error-code))]
-		  [exception (or (setxattr-exception error-code)
-						 (getxattr-exception error-code)
-						 (stat-exception error-code))])
-	  (if exception
-		  (signal exception)
-		  value))))
 
 
-;; The direct foreign binding for `remove_xattr`
+  ;; Wrapper around set-xattr-foreign, throwing exceptions and all that jazz
-(define remove-xattr-foreign
+  (define (set-xattr path attr value)
-  (foreign-lambda int "remove_xattr" c-string c-string))
+    (let-location ([error-code int])
+      (let ([return-code (set-xattr-foreign path attr value (location error-code))]
+            [exception (or (setxattr-exception error-code)
+                           (getxattr-exception error-code)
+                           (stat-exception error-code))])
+        (if exception
+            (signal exception)
+            value))))
 
 
-;; Wrapper around remove-xattr-foreign, blah blah
+  ;; The direct foreign binding for `remove_xattr`
-(define (remove-xattr path attr)
+  (define remove-xattr-foreign
-  (let* ([error-code (remove-xattr-foreign path attr)]
+    (foreign-lambda int "remove_xattr" c-string c-string))
-		 [exception (or (getxattr-exception error-code)
-						(stat-exception error-code))])
-	(if exception
-		(signal exception)
-		attr)))
 
 
-;; TODO: These exception functions should be constructed with a macro and a simple
+  ;; Wrapper around remove-xattr-foreign, blah blah
-;; list, like `((c-constant symbol error-message) ("E2BIG" 'e2big "The attribute value was too big."))
+  (define (remove-xattr path attr)
-;; Unfortunately, it looks like chicken's macros work a good bit differently from CLs?
+    (let* ([value (get-xattr path attr)]
-;; orr I'm losing my mind
+           [error-code (remove-xattr-foreign path attr)]
+           [exception (or (getxattr-exception error-code)
+                          (stat-exception error-code))])
+      (if exception
+          (signal exception)
+          value)))
 
 
-;; Return the exception associated with an error-code as per getxattr(2), if it exists
+  ;; TODO: These exception functions should be constructed with a macro and a simple
-(define (getxattr-exception error-code)
+  ;; list, like `((c-constant symbol error-message) ("E2BIG" 'e2big "The attribute value was too big."))
-  (cond
-   [(eq? error-code (foreign-value "E2BIG" int))
-	(build-exception 'e2big "The attribute value was too big.")]
-   [(eq? error-code (foreign-value "ENOTSUP" int))
-	(build-exception 'enotsup "Extended attributes are disabled or unavailable on this filesystem.")]
-   [(eq? error-code (foreign-value "ERANGE" int))
-	(build-exception 'erange "The xattr module's buffer was too small for the attribute value. Whoops <w<\"")]
-   [#t
-	#f]))
 
 
-;; Return the exception associated with a setxattr(2) error-code, if it exists.
+  ;; Return the exception associated with an error-code as per getxattr(2), if it exists
-(define (setxattr-exception error-code)
+  (define (getxattr-exception error-code)
-  (cond
+    (cond
-   [(eq? error-code (foreign-value "EDQUOT" int))
+     [(eq? error-code (foreign-value "E2BIG" int))
-	(build-exception 'edquot "Setting this attribute would violate disk quota.")]
+      (build-exception 'e2big "The attribute value was too big.")]
-   [(eq? error-code (foreign-value "ENOSPC" int))
+     [(eq? error-code (foreign-value "ENOTSUP" int))
-	(build-exception 'enospc "There is insufficient space to store the extended attribute.")]
+      (build-exception 'enotsup "Extended attributes are disabled or unavailable on this filesystem.")]
-   [(eq? error-code (foreign-value "EPERM" int))
+     [(eq? error-code (foreign-value "ERANGE" int))
-	(build-exception 'eperm "The file is immutable or append-only.")]
+      (build-exception 'erange "The xattr module's buffer was too small for the attribute value. Whoops <w<\"")]
-   [(eq? error-code (foreign-value "ERANGE" int))
+     [#t
-	(build-exception 'erange "Either the attribute name or value exceeds the filesystem's limit.")]
+      #f]))
-   [#t
-	#f]))
 
 
-;; Return the exception associated with an error-code as per stat(2), if applicable
+  ;; Return the exception associated with a setxattr(2) error-code, if it exists.
-(define (stat-exception error-code)
+  (define (setxattr-exception error-code)
-  (cond
+    (cond
-   [(eq? error-code (foreign-value "EACCES" int))
+     [(eq? error-code (foreign-value "EDQUOT" int))
-	(build-exception 'file "Search permission denied for a parent directory.")]
+      (build-exception 'edquot "Setting this attribute would violate disk quota.")]
-   [(eq? error-code (foreign-value "EBADF" int))
+     [(eq? error-code (foreign-value "ENOSPC" int))
-	(build-exception 'file "The file-descriptor is bad. Wait, wha…?")]
+      (build-exception 'enospc "There is insufficient space to store the extended attribute.")]
-   [(eq? error-code (foreign-value "EFAULT" int))
+     [(eq? error-code (foreign-value "EPERM" int))
-	(build-exception 'file "The address is bad. OK.")]
+      (build-exception 'eperm "The file is immutable or append-only.")]
-   [(eq? error-code (foreign-value "EINVAL" int))
+     [(eq? error-code (foreign-value "ERANGE" int))
-	(build-exception 'file "Invalid fstatat flag.")]
+      (build-exception 'erange "Either the attribute name or value exceeds the filesystem's limit.")]
-   [(eq? error-code (foreign-value "ELOOP" int))
+     [#t
-	(build-exception 'file "Too many symbolic links in recursion.")]
+      #f]))
-   [(eq? error-code (foreign-value "ENAMETOOLONG" int))
-	(build-exception 'file "The given pathname is too long.")]
-   [(eq? error-code (foreign-value "ENOENT" int))
-	(build-exception 'file "This file doesn't exist, or there is a dangling symlink.")]
-   [(eq? error-code (foreign-value "ENOMEM" int))
-	(build-exception 'file "Out of memory.")]
-   [(eq? error-code (foreign-value "ENOTDIR" int))
-	(build-exception 'file "Component of path isn't a proper directory.")]
-   [(eq? error-code (foreign-value "EOVERFLOW" int))
-	(build-exception 'file "An overflow has occured.")]
-   [#t
-	#f]))
 
 
-;; Creates a generic exception with given symbol and message
+  ;; Return the exception associated with an error-code as per stat(2), if applicable
-(define (build-exception symbol message)
+  (define (stat-exception error-code)
-  (signal (make-property-condition 'exn 'location symbol 'message message)))
+    (cond
+     [(eq? error-code (foreign-value "EACCES" int))
+      (build-exception 'file "Search permission denied for a parent directory.")]
+     [(eq? error-code (foreign-value "EBADF" int))
+      (build-exception 'file "The file-descriptor is bad. Wait, wha…?")]
+     [(eq? error-code (foreign-value "EFAULT" int))
+      (build-exception 'file "The address is bad. OK.")]
+     [(eq? error-code (foreign-value "EINVAL" int))
+      (build-exception 'file "Invalid fstatat flag.")]
+     [(eq? error-code (foreign-value "ELOOP" int))
+      (build-exception 'file "Too many symbolic links in recursion.")]
+     [(eq? error-code (foreign-value "ENAMETOOLONG" int))
+      (build-exception 'file "The given pathname is too long.")]
+     [(eq? error-code (foreign-value "ENOENT" int))
+      (build-exception 'file "This file doesn't exist, or there is a dangling symlink.")]
+     [(eq? error-code (foreign-value "ENOMEM" int))
+      (build-exception 'file "Out of memory.")]
+     [(eq? error-code (foreign-value "ENOTDIR" int))
+      (build-exception 'file "Component of path isn't a proper directory.")]
+     [(eq? error-code (foreign-value "EOVERFLOW" int))
+      (build-exception 'file "An overflow has occured.")]
+     [#t
+      #f]))
 
 
-;; Some C functions offer up a string-list that isn't a two-dimensional array, but a
+  ;; Creates a generic exception with given symbol and message
-;; one-dimensional array with given length and strings separated by a given delimeter.
+  (define (build-exception symbol message)
-;; This takes that sort of pointer and gives you a nice list of strings.
+    (signal (make-property-condition 'exn 'location symbol 'message message)))
-(define (pointer->delimited-string-list pointer length delimiter)
-  (let* ([is-zero (lambda (num) (eq? num 0))]
-		[map-to-char (lambda (a) (map integer->char a))]
-		[byte-list (drop-right (pointer->integers pointer length) 1)])
-	(map list->string
-		 (map map-to-char
-			  (split-list is-zero byte-list)))))
 
 
-;; Takes a pointer and returns a list of bytes of a given length
+  ;; Some C functions offer up a string-list that isn't a two-dimensional array, but a
-(define (pointer->integers pointer length)
+  ;; one-dimensional array with given length and strings separated by a given delimeter.
-  (let ([byte (pointer-s8-ref pointer)])
+  ;; This takes that sort of pointer and gives you a nice list of strings.
-	(if (eq? length 0)
+  (define (pointer->delimited-string-list pointer length delimiter)
-		byte
+    (let* ([is-zero (lambda (num) (eq? num 0))]
-		(append (list byte)
+           [map-to-char (lambda (a) (map integer->char a))]
-				(pointer->integers (pointer+ pointer 1) (- length 1))))))
+           [pointer-ints (pointer->integers pointer length)]
+           [byte-list (when (list? pointer-ints)
+                        (drop-right pointer-ints 1))])
+      (if (and (list? byte-list)
+               (not (null-list? byte-list)))
+        (map list->string
+              (map map-to-char
+                   (split-list is-zero byte-list)))
+        '())))
 
 
-;; Split a list into sublists, with items passing `test` being the delimiters
+  ;; Takes a pointer and returns a list of bytes of a given length
-(define (split-list test list)
+  (define (pointer->integers pointer length)
-  (let ([before (take-while (compose not test) list)]
+    (let ([byte (pointer-s8-ref pointer)])
-		[after (drop-while (compose not test) list)])
+      (if (eq? length 0)
-	(cond
+          byte
-	 [(or (null-list? after) (null-list? (cdr after)))
+          (append (list byte)
-	  `(,before)]
+                  (pointer->integers (pointer+ pointer 1) (- length 1))))))
-	 [(null-list? before)
-	  (split-list test (cdr after))]
-	 [#t
-	  (append `(,before) (split-list test (cdr after)))])))
 
-)
+
+  ;; Split a list into sublists, with items passing `test` being the delimiters
+  (define (split-list test list)
+    (let ([before (take-while (compose not test) list)]
+          [after (drop-while (compose not test) list)])
+      (cond
+       [(or (null-list? after) (null-list? (cdr after)))
+        `(,before)]
+       [(null-list? before)
+        (split-list test (cdr after))]
+       [#t
+        (append `(,before) (split-list test (cdr after)))]))))