;;; Ikarus Scheme -- A compiler for R6RS Scheme.
;;; Copyright (C) 2006,2007,2008  Abdulaziz Ghuloum
;;; 
;;; This program is free software: you can redistribute it and/or modify
;;; it under the terms of the GNU General Public License version 3 as
;;; published by the Free Software Foundation.
;;; 
;;; This program is distributed in the hope that it will be useful, but
;;; WITHOUT ANY WARRANTY; without even the implied warranty of
;;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
;;; General Public License for more details.
;;; 
;;; You should have received a copy of the GNU General Public License
;;; along with this program.  If not, see <http://www.gnu.org/licenses/>.


(library (ikarus.posix)

  (export 
    posix-fork fork waitpid system file-exists? delete-file
    nanosleep getenv setenv unsetenv env environ split-file-name
    file-ctime file-mtime file-real-path current-directory
    file-regular? file-directory? file-readable? file-writable?
    file-executable? file-size rename-file file-symbolic-link?
    make-symbolic-link make-hard-link directory-list make-directory
    make-directory* delete-directory change-mode kill strerror
    wstatus-pid wstatus-exit-status wstatus-received-signal)

  (import 
    (rnrs bytevectors)
    (except (ikarus)
      nanosleep posix-fork fork waitpid system file-exists?
      delete-file getenv setenv unsetenv env environ split-file-name
      file-ctime file-mtime file-real-path current-directory
      file-regular? file-directory? file-readable? file-writable?
      file-executable? file-size rename-file file-symbolic-link?
      make-symbolic-link make-hard-link directory-list
      make-directory make-directory* delete-directory change-mode
      kill strerror wstatus-pid wstatus-exit-status
      wstatus-received-signal))

  (define posix-fork
    (lambda ()
      (foreign-call "ikrt_fork")))

  (define fork
    (lambda (parent-proc child-proc)
      (let ([pid (posix-fork)])
        (cond
          [(fx= pid 0) (child-proc)]
          [(fx< pid 0) (raise/strerror 'fork pid)]
          [else (parent-proc pid)]))))
  
  (module (signal-code->signal-name signal-name->signal-code)
    
    (define signal-names-al
      ;; From ikarus-process.c
      '((1 . SIGABRT) 
        (2 . SIGALRM)
        (3 . SIGBUS)
        (4 . SIGCHLD)                   
        (5 . SIGCONT) 
        (6 . SIGFPE)
        (7 . SIGHUP)
        (8 . SIGILL)
        (9 . SIGINT)
        (10 . SIGKILL)
        (11 . SIGPIPE)
        (12 . SIGQUIT)
        (13 . SIGSEGV)
        (14 . SIGSTOP)
        (15 . SIGTERM)
        (16 . SIGTSTP)
        (17 . SIGTTIN)
        (18 . SIGTTOU)
        (19 . SIGUSR1)
        (20 . SIGUSR2)
        (21 . SIGPOLL)
        (22 . SIGPROF)
        (23 . SIGSYS)
        (24 . SIGTRAP)
        (25 . SIGURG)
        (26 . SIGVTALRM)
        (27 . SIGXCPU)
        (28 . SIGXFSZ)))
    
    (define signal-code->signal-name
      (lambda (sigcode)        
        (cond
          [(assv sigcode signal-names-al) => cdr]
          [else sigcode])))
    
    (define signal-name->signal-code
      (lambda (signame)        
        (cond
          [(find (lambda (p) (eqv? (cdr p) signame)) signal-names-al) => car]
          [else #f])))
  )
  
  (define kill
    (lambda (pid signame)
      (define who 'kill)
      (unless (fixnum? pid) (die who "not a fixnum" pid))
      (unless (symbol? signame) (die who "not a symbol" signame))
      (let ([r (foreign-call "ikrt_kill" pid
                 (or (signal-name->signal-code signame)
                     (die who "invalid signal name" signame)))])
        (when (fx< r 0)
          (error who (strerror r) pid signame)))))

  (define-struct wstatus (pid exit-status received-signal))

  (define waitpid
    ;; If block? is #f and waitpid() would have blocked,
    ;; or if want-error? is #f and there was an error,
    ;; the value returned is #f
    (case-lambda
      [() (waitpid -1 #t #t)]
      [(pid) (waitpid pid #t #t)]
      [(pid block?) (waitpid pid block? #t)]
      [(pid block? want-error?)
       (define who 'waitpid)
       (unless (fixnum? pid) (die who "not a fixnum" pid))
       (unless (boolean? block?) (die who "not a boolean" block?))
       (let ([r (foreign-call "ikrt_waitpid" (make-wstatus #f #f #f) pid block?)])
         (cond 
           [(wstatus? r)
            (set-wstatus-received-signal! r
              (signal-code->signal-name 
                (wstatus-received-signal r)))
            r]
           [(and want-error? (not (eqv? r 0)))
            (error who (strerror r) pid)]
           [else #f]))]))

  (define system
    (lambda (x)
      (unless (string? x)
        (die 'system "not a string" x))
      (let ([rv (foreign-call "ik_system"
                  (string->utf8 x))])
        (if (fx< rv 0)
            (raise/strerror 'system rv)
            rv))))
  
  (define stat
    (lambda (path follow who)
      (unless (string? path)
        (die who "not a string" path))
      (let ([r (foreign-call "ikrt_stat" (string->utf8 path) follow)])
        (case r
          [(0) 'unknown]
          [(1) 'regular]
          [(2) 'directory]
          [(3) 'symlink]
          [(-45) #f]  ;; from ikarus-errno.c: ENOENT -- path does not exist
          [(-57) #f]  ;; from ikarus-errno.c: ENOTDIR -- path does not exist
          [else (raise/strerror who r path)]))))

  (define (split-file-name str)
    (define who 'split-file-name)
    (define path-sep #\/)
    (define (find-last c str)
      (let f ([i (string-length str)])
        (if (fx=? i 0)
            #f
            (let ([i (fx- i 1)])
              (if (char=? (string-ref str i) c)
                  i
                  (f i))))))
    (unless (string? str) (die who "not a string" str))
    (cond
      [(find-last path-sep str) =>
       (lambda (i) 
         (values
           (substring str 0 i)
           (let ([i (fx+ i 1)])
             (substring str i (string-length str) ))))]
      [else (values "" str)]))

  (define access
    (lambda (path how who)
      (unless (string? path)
        (die who "not a string" path))
      (let ([r (foreign-call "ikrt_access" (string->utf8 path) how)])
        (unless (boolean? r) (raise/strerror who r path))
        r)))

  (define file-exists?
    (case-lambda 
      [(path) (file-exists? path #t)]
      [(path follow)
       (and (stat path follow 'file-exists?) #t)]))
  
  (define file-regular?
    (case-lambda
      [(path) (file-regular? path #t)]
      [(path follow)
       (eq? 'regular (stat path follow 'file-regular?))]))
  
  (define file-directory?
    (case-lambda
      [(path) (file-directory? path #t)]
      [(path follow)
       (eq? 'directory (stat path follow 'file-directory?))]))
  
  (define file-symbolic-link?
    (lambda (path)
      (eq? 'symlink (stat path #f 'file-symbolic-link?))))

  (define file-readable?
    (lambda (path)
      (access path 1 'file-readable?)))
  
  (define file-writable?
    (lambda (path)
      (access path 2 'file-writable?)))

  (define file-executable?
    (lambda (path)
      (access path 4 'file-executable?)))

  (define file-size
    (lambda (path)
      (define who 'file-size)
      (unless (string? path)
        (die who "filename is not a string" path))
      (let* ([v (foreign-call "ikrt_file_size" (string->utf8 path))])
        (if (>= v 0)
            v
            (raise/strerror who v path)))))

  (define delete-file
    (lambda (x)
      (define who 'delete-file)
      (unless (string? x)
        (die who "filename is not a string" x))
      (let ([v (foreign-call "ikrt_delete_file"
                 (string->utf8 x))])
        (unless (eq? v #t)
          (raise/strerror who v x)))))
  
  (define rename-file
    (lambda (src dst)
      (define who 'rename-file)
      (unless (string? src)
        (die who "source file name is not a string" src))
      (unless (string? dst)
        (die who "destination file name is not a string" dst))
      (let ([v (foreign-call "ikrt_rename_file"
                             (string->utf8 src)
                             (string->utf8 dst))])
        (unless (eq? v #t)
          (raise/strerror who v src)))))

  (define directory-list
    (lambda (path)
      (define who 'directory-list)
      (unless (string? path)
        (die who "not a string" path))
      (let ([r (foreign-call "ikrt_directory_list" (string->utf8 path))])
        (if (fixnum? r)
            (raise/strerror who r path)
            (map utf8->string (reverse r))))))
  
  (define ($make-directory path mode who)
    (unless (string? path)
      (die who "not a string" path))
    (unless (fixnum? mode)
      (die who "not a fixnum" mode))
    (let ([r (foreign-call "ikrt_mkdir" (string->utf8 path) mode)])
      (unless (eq? r #t)
        (raise/strerror who r path))))

  (define default-dir-mode #o755) 

  (define make-directory
    (case-lambda 
      [(path) (make-directory path default-dir-mode)]
      [(path mode) ($make-directory path mode 'make-directory)]))

  (module (make-directory*)
    (define who 'make-directory*)
    (define (mkdir* dirname0 mode)
      (unless (string? dirname0)
        (die who "not a string" dirname0))
      (let f ([dirname dirname0])
        (cond
          [(file-exists? dirname)
           (unless (file-directory? dirname)
             (die who 
               (format "path component ~a is not a directory" dirname)
               dirname0))]
          [else
           (let-values ([(base suffix) (split-file-name dirname)])
             (unless (string=? base "") (f base))
             (unless (string=? suffix "") 
               ($make-directory dirname mode who)))])))
    (define make-directory*
      (case-lambda
        [(name) (mkdir* name default-dir-mode)]
        [(name mode) (mkdir* name mode)])))

  (define delete-directory
    (case-lambda
      [(path) (delete-directory path #f)]
      [(path want-error?)
       (define who 'delete-directory)
       (unless (string? path)
         (die who "not a string" path))
       (let ([r (foreign-call "ikrt_rmdir" (string->utf8 path))])
         (if want-error?
             (unless (eq? r #t) (raise/strerror who r path))
             (eq? r #t)))]))
  
  (define change-mode
    (lambda (path mode)
      (define who 'change-mode)
      (unless (string? path)
        (die who "not a string" path))
      (unless (fixnum? mode)
        (die who "not a fixnum" mode))
      (let ([r (foreign-call "ikrt_chmod" (string->utf8 path) mode)])
        (unless (eq? r #t)
          (raise/strerror who r path)))))
  
  (define ($make-link to path who proc)
    (unless (and (string? to) (string? path))
      (die who "not a string" (if (string? to) path to)))
    (let ([r (proc (string->utf8 to) (string->utf8 path))])
      (unless (eq? r #t)
        (raise/strerror who r path))))
  
  (define (make-symbolic-link to path)
    ($make-link to path 'make-symbolic-link
                (lambda (u-to u-path)
                  (foreign-call "ikrt_symlink" u-to u-path))))
  
  (define (make-hard-link to path)
    ($make-link to path 'make-hard-link
                (lambda (u-to u-path)
                  (foreign-call "ikrt_link" u-to u-path))))
  
  (define ($file-time x who proc)
    (unless (string? x) 
      (die who "not a string" x))
    (let ([v (proc (string->utf8 x))])
      (cond
        [(bytevector? v) 
         (let ([n0 (bytevector-u8-ref v 0)]
               [n1 (bytevector-u8-ref v 1)])
           (+ (* (bytevector-uint-ref v 2 (native-endianness) n0)
                 #e1e9)
              (bytevector-uint-ref v (+ 2 n0) (native-endianness) n1)))]
        [else (raise/strerror who v x)])))

  (define (file-ctime x)
    ($file-time x 'file-ctime 
      (lambda (u) (foreign-call "ikrt_file_ctime2" u))))

  (define (file-mtime x)
    ($file-time x 'file-mtime 
      (lambda (u) (foreign-call "ikrt_file_mtime2" u))))

  (define (file-real-path x)
    (define who 'file-real-path)
    (unless (string? x) 
      (die who "not a string" x))
    (let ([v (foreign-call "ikrt_realpath" (string->utf8 x))])
      (cond
        [(bytevector? v) 
         (let ([s (utf8->string v)])
           (when (or (string=? s "")
                     (not (char=? (string-ref s 0) #\/)))
             (error who "unexpected value returned from OS" s x))
           s)]
        [else (raise/strerror who v x)])))

  (define (getenv key)
    (define who 'getenv)
    (define ($getenv-str key) 
      (define ($getenv-bv key)
        (foreign-call "ikrt_getenv" key))
      (let ([rv ($getenv-bv (string->utf8 key))])
        (and rv (utf8->string rv))))
    (if (string? key)
        ($getenv-str key)
        (die who "key is not a string" key)))

  (define ($setenv key val overwrite)
    (foreign-call "ikrt_setenv" 
       (string->utf8 key) (string->utf8 val) overwrite))

  (define setenv
    (case-lambda
      [(key val overwrite)
       (define who 'setenv)
       (if (string? key)
           (if (string? val)
               (unless ($setenv key val overwrite) 
                 (error who "cannot setenv"))
               (die who "invalid value" val))
           (die who "invalid key" key))]
      [(key val) (setenv key val #t)]))

  (define (unsetenv key)
    (define who 'unsetenv)
    (if (string? key) 
        (foreign-call "ikrt_unsetenv" (string->utf8 key))
        (die who "invalid key" key)))

  (define env
    (let ()
      (define env
        (case-lambda
          [(key) 
           (if (string? key)
               (foreign-call "ikrt_getenv" key)
               (die 'env "the key is not a string" key))]
          [(key val) (env key val #t)]
          [(key val overwrite?)
           (if (string? key)
               (if (string? val)
                   (unless (foreign-call "ikrt_setenv" key val overwrite?)
                     (die 'env "failed" key val))
                   (die 'env "the value is not a string" val))
               (die 'env "the key is not a string" key))]))
      (define busted (lambda args (die 'env "BUG: busted!")))
      busted))


  (define environ
    (lambda ()
      (map 
        (lambda (bv)
          (let ([s (utf8->string bv)])
            (define (loc= s i n)
              (cond
                [(fx= i n) i]
                [(char=? (string-ref s i) #\=) i]
                [else (loc= s (fx+ i 1) n)]))
            (let ([n (string-length s)])
              (let ([i (loc= s 0 n)])
                (cons (substring s 0 i)
                      (if (fx< (fxadd1 i) n)
                          (substring s (fxadd1 i) n)
                          ""))))))
        (foreign-call "ikrt_environ"))))

  (define (nanosleep secs nsecs)
    (import (ikarus system $fx))
    (unless (cond
              [(fixnum? secs) ($fx>= secs 0)]
              [(bignum? secs) (<= 0 secs (- (expt 2 32) 1))]
              [else (die 'nanosleep "not an exact integer" secs)])
      (die 'nanosleep "seconds must be a nonnegative integer <=" secs))
    (unless (cond
              [(fixnum? nsecs) ($fx>= nsecs 0)]
              [(bignum? nsecs) (<= 0 nsecs 999999999)]
              [else (die 'nanosleep "not an exact integer" nsecs)])
      (die 'nanosleep "nanoseconds must be an integer \
                       in the range 0..999999999" nsecs))
    (let ([rv (foreign-call "ikrt_nanosleep" secs nsecs)])
      (unless (eq? rv 0)
        (error 'nanosleep "failed"))))


  (define current-directory
    (case-lambda
      [() 
       (let ([v (foreign-call "ikrt_getcwd")])
         (if (bytevector? v)
             (utf8->string v)
             (raise/strerror 'current-directory v)))]
      [(x) 
       (if (string? x) 
           (let ([rv (foreign-call "ikrt_chdir" (string->utf8 x))])
             (unless (eq? rv #t)
               (raise/strerror 'current-directory rv x)))
           (die 'current-directory "not a string" x))]))
  
  (define raise/strerror 
    (case-lambda
      [(who errno-code) 
       (raise/strerror who errno-code #f)]
      [(who errno-code filename)
       (raise
         (condition
           (make-error)
           (make-who-condition who)
           (make-message-condition (strerror errno-code))
           (if filename 
               (make-i/o-filename-error filename)
               (condition))))]))
  
  (define strerror
    (lambda (errno-code)
      (define who 'strerror)
      (unless (fixnum? errno-code)
        (die who "not a fixnum" errno-code))
      (let ([emsg (foreign-call "ikrt_strerror" errno-code)])
        (if emsg
            (let ([errno-name 
                   (foreign-call "ikrt_errno_code_to_name" errno-code)])
              (assert errno-name)
              (format "~a: ~a" 
                (utf8->string errno-name)
                (utf8->string emsg)))
            (format "Ikarus's ~a: don't know Ikarus errno code ~s" 
              who errno-code)))))

  )