gen/scandir.3

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  28 .\"     @(#)scandir.3   8.1 (Berkeley) 6/4/93
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  31 .Dd May 20, 2008
  32 .Dt SCANDIR 3
  33 .Os
  34 .Sh NAME
  35 .Nm scandir ,
  36 #ifdef UNIFDEF_BLOCKS
  37 .Nm scandir_b ,
  38 #endif
  39 .Nm alphasort
  40 .Nd scan a directory
  41 .Sh SYNOPSIS
  42 .In sys/types.h
  43 .In dirent.h
  44 .Ft int
  45 .Fn scandir "const char *dirname" "struct dirent ***namelist" "int \\*(lp*select\\*(rp\\*(lpstruct dirent *\\*(rp" "int \\*(lp*compar\\*(rp\\*(lpconst void *, const void *\\*(rp"
  46 .Ft int
  47 .Fn alphasort "const void *d1" "const void *d2"
  48 #ifdef UNIFDEF_BLOCKS
  49 .Ft int
  50 .Fn scandir_b "const char *dirname" "struct dirent ***namelist" "int \\*(lp^select\\*(rp\\*(lpstruct dirent *\\*(rp" "int \\*(lp^compar\\*(rp\\*(lpconst void *, const void *\\*(rp"
  51 #endif
  52 .Sh DESCRIPTION
  53 The
  54 .Fn scandir
  55 function
  56 reads the directory
  57 .Fa dirname
  58 and builds an array of pointers to directory
  59 entries using
  60 .Xr malloc 3 .
  61 It returns the number of entries in the array.
  62 A pointer to the array of directory entries is stored in the location
  63 referenced by
  64 .Fa namelist .
  65 .Pp
  66 The
  67 .Fa select
  68 argument is a pointer to a user supplied subroutine which is called by
  69 .Fn scandir
  70 to select which entries are to be included in the array.
  71 The select routine is passed a
  72 pointer to a directory entry and should return a non-zero
  73 value if the directory entry is to be included in the array.
  74 If
  75 .Fa select
  76 is null, then all the directory entries will be included.
  77 .Pp
  78 The
  79 .Fa compar
  80 argument is a pointer to a user supplied subroutine which is passed to
  81 .Xr qsort 3
  82 to sort the completed array.
  83 If this pointer is null, the array is not sorted.
  84 Note that from within the
  85 .Fa compar
  86 subroutine, the two arguments are of type
  87 .Ft const struct dirent ** ,
  88 so that a double-dereference is needed to access the fields in the
  89 .Ft dirent
  90 structure.
  91 .Pp
  92 The
  93 .Fn alphasort
  94 function
  95 is a routine which can be used for the
  96 .Fa compar
  97 argument to sort the array alphabetically.
  98 .Pp
  99 The memory allocated for the array can be deallocated with
 100 .Xr free 3 ,
 101 by freeing each pointer in the array and then the array itself.
 102 #ifdef UNIFDEF_BLOCKS
 103 .Pp
 104 The
 105 .Fn scandir_b
 106 function works the same way as the
 107 .Fn scandir
 108 function, except that
 109 .Fa select
 110 and
 111 .Fa compar
 112 are blocks instead of subroutines.
 113 #endif
 114 .Sh DIAGNOSTICS
 115 Returns \-1 if the directory cannot be opened for reading or if
 116 .Xr malloc 3
 117 cannot allocate enough memory to hold all the data structures.
 118 .Sh SEE ALSO
 119 .Xr directory 3 ,
 120 .Xr malloc 3 ,
 121 .Xr qsort 3 ,
 122 .Xr dir 5
 123 .Sh HISTORY
 124 The
 125 .Fn scandir
 126 and
 127 .Fn alphasort
 128 functions appeared in
 129 .Bx 4.2 .
 130 #ifdef UNIFDEF_BLOCKS
 131 The
 132 .Fn scandir_b
 133 function appeared in Mac OS X 10.6.
 134 #endif