gen/FreeBSD/scandir.3

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  28 .\"     @(#)scandir.3   8.1 (Berkeley) 6/4/93
  29 .\" $FreeBSD: src/lib/libc/gen/scandir.3,v 1.9 2007/01/09 00:27:55 imp Exp $
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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\\*(lpconst struct dirent *\\*(rp" "int \\*(lp*compar\\*(rp\\*(lpconst struct dirent **, const struct dirent **\\*(rp"
  46 .Ft int
  47 .Fn alphasort "const struct dirent **d1" "const struct dirent **d2"
  48 #ifdef UNIFDEF_BLOCKS
  49 .Ft int
  50 .Fn scandir_b "const char *dirname" "struct dirent ***namelist" "int \\*(lp^select\\*(rp\\*(lpconst struct dirent *\\*(rp" "int \\*(lp^compar\\*(rp\\*(lpconst struct dirent **, const struct dirent **\\*(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 (even if the number of entries is 0).
  66 .Pp
  67 The
  68 .Fa select
  69 argument is a pointer to a user supplied subroutine which is called by
  70 .Fn scandir
  71 to select which entries are to be included in the array.
  72 The select routine is passed a
  73 pointer to a directory entry and should return a non-zero
  74 value if the directory entry is to be included in the array.
  75 If
  76 .Fa select
  77 is null, then all the directory entries will be included.
  78 .Pp
  79 The
  80 .Fa compar
  81 argument is a pointer to a user supplied subroutine which is passed to
  82 .Xr qsort 3
  83 to sort the completed array.
  84 If this pointer is null, the array is not sorted.
  85 .Pp
  86 The
  87 .Fn alphasort
  88 function
  89 is a routine which can be used for the
  90 .Fa compar
  91 argument to sort the array alphabetically.
  92 .Pp
  93 The memory allocated for the array can be deallocated with
  94 .Xr free 3 ,
  95 by freeing each pointer in the array and then the array itself.
  96 #ifdef UNIFDEF_BLOCKS
  97 .Pp
  98 The
  99 .Fn scandir_b
 100 function works the same way as the
 101 .Fn scandir
 102 function, except that
 103 .Fa select
 104 and
 105 .Fa compar
 106 are blocks instead of subroutines.
 107 #endif
 108 .Sh DIAGNOSTICS
 109 Returns \-1 if the directory cannot be opened for reading or if
 110 .Xr malloc 3
 111 cannot allocate enough memory to hold all the data structures.
 112 .Sh SEE ALSO
 113 .Xr directory 3 ,
 114 .Xr malloc 3 ,
 115 .Xr qsort 3 ,
 116 .Xr dir 5
 117 .Sh HISTORY
 118 The
 119 .Fn scandir
 120 and
 121 .Fn alphasort
 122 functions appeared in
 123 .Bx 4.2 .
 124 #ifdef UNIFDEF_BLOCKS
 125 The
 126 .Fn scandir_b
 127 function appeared in Mac OS X 10.6.
 128 #endif