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Usando la funzione "Stat()" nativa di Gambas

Le modalità di utilizzo della funzione di Gambas "Stat()" è descritta nella seguente pagina.

Usando la funzione "stat()" di C

Per utilizzare la funzione "stat()" di C, bisognerà richiamare la funzione "__xstat()". in quanto, per consentire alla Struttura struct stat di variare senza cambiare numero di versione della libreria condivisa .so, il gruppo di funzioni 'stat' sono traslate nelle chiamate alle funzioni 'xstat', 'fxstat', 'lxstat', alle quali è necessario passare come primo argomento il numero-versione che designa la struttura dei dati e i bit utilizzati. Dunque, in fase di linking la chiamata a "stat()" viene convertita in "__xstat()".

Il codice Gambas potrà essere il seguente:

Library "libc:6"

Public Struct STATUS_File
  st_dev As Long
  st_ino As Long
  st_nlink As Long
  st_mode As Integer
  st_uid As Integer
  st_gid As Long
  st_rdev As Long
  st_size As Long
  st_blksize As Long
  st_blocks As Long
  st_atime As Long
  __unused1 As Integer
  st_mtime As Long
  __unused2 As Long
  st_mtime_nsec As Long 
  st_ctime As Long
  __glibc_reserved[3] As Long
End Struct

Private Const _STAT_VER_LINUX as Integer = 1

' int __xstat (int __ver, const char *__filename, struct stat *__stat_buf)
' Get file attributes for FILE and put them in BUF.
Private Extern __xstat(ver As Integer, s As String, st As STATUS_File) As Integer

' tm* localtime( const time_t *time )
' Converts given time since epoch as time_t value into calendar time, expressed in local time.
Private Extern localtime(tm As Pointer) As Pointer

' char* asctime( const tm* time_ptr )
' Converts given calendar time tm to a textual representation.
Private Extern asctime(time_ptr As Pointer) As String


Public Sub Main()

 Dim stS As New STATUS_File
 Dim i As Integer
 Dim at, mt, ct As Long
 Dim s As String = "/percorso/del/file"

 i = __xstat(_STAT_VER_LINUX, s, stS)
 If i <> 0 Then Error.Raise("Errore alla funzione '__xstat()' !")
 
 Print "File controllato: "; s
 Print

 With stS
   Print .st_dev
   Print .st_ino
   Print .st_nlink
   Print .st_mode
   Print .st_uid
   Print .st_gid
   Print .st_rdev
   Print .st_size; " byte"
   Print .st_blksize
   Print .st_blocks
   at = .st_atime
   mt = .st_mtime
   ct = .st_ctime
 End With
 
 Print asctime(localtime(VarPtr(at)))
 Print asctime(localtime(VarPtr(mt)))
 Print asctime(localtime(VarPtr(ct)))

End

Usando la funzione "stat()" di C mediante una libreria esterna ad hoc

La funzione esterna "stat()" di C potrà essere utilizzata anche mediante una libreria esterna condivisa .so, da noi realizzata, nella quale verrà posta la funzione.
Il codice Gambas, contenente anche una procedura per generare il file sorgente in linguaggio C della libreria esterna condivisa, nonché la libreria medesima .so, sarà il seguente:

Library "libc:6"

Public Struct STATUS_File
  st_dev As Long
  st_ino As Long
  st_nlink As Long
  st_mode As Integer
  st_uid As Integer
  st_gid As Long
  st_rdev As Long
  st_size As Long
  st_blksize As Long
  st_blocks As Long
  st_atime As Long
  unused1 As Integer
  st_mtime As Long
  unused2 As Long
  st_ctime As Long
  __glibc_reserved[3] As Long
End Struct

' tm* localtime( const time_t *time )
' Converts given time since epoch as time_t value into calendar time, expressed in local time.
Private Extern localtime(tm As Pointer) As Pointer

' char* asctime( const tm* time_ptr )
' Converts given calendar time tm to a textual representation.
Private Extern asctime(time_ptr As Pointer) As String

Private Extern Chiama_stat(nomefile As String, stFile As STATUS_File) As Integer In "/tmp/libadhoc"


Public Sub Main()

 Dim i As Integer
 Dim stS As New STATUS_File
 Dim at, mt, ct As Long
 Dim s As String = "/percorso/del/file"

 CreaSo()

 i = Chiama_stat(s, stS)
 If i <> 0 Then Error.Raise("Errore nella chiamata della funzione 'Chiama_stat()' !")
  
 Print "File controllato: "; s
 Print

 With stS
   Print .st_dev
   Print .st_ino
   Print .st_nlink
   Print .st_mode
   Print .st_uid
   Print .st_gid
   Print .st_rdev
   Print .st_size; " byte"
   Print .st_blksize
   Print .st_blocks
   at = .st_atime
   mt = .st_mtime
   ct = .st_ctime
 End With

 Print asctime(localtime(VarPtr(at)))
 Print asctime(localtime(VarPtr(mt)))
 Print asctime(localtime(VarPtr(ct)))

End


Private Procedure CreaSo()

' Scrive e salva il file sorgente in C della libreria condivisa ad hoc:
 File.Save("/tmp/libadhoc.c", "#include <sys/stat.h>" &
                              "\n\nstruct stat status;" &
                              "\n\nint Chiama_stat(const char *s, struct stat *st) {" &
                              "\nint r;" &
                              "\nr = stat(s, &status);" &
                              "\n*st = status;" &
                              "\nreturn r;" &
                              "\n}")

' Genera la libreria condivisa .so ad hoc:
 Shell "gcc -o /tmp/libadhoc.so /tmp/libadhoc.c -shared -fPIC" Wait

End