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   36: .\" Author: Archie Cobbs <archie@freebsd.org>
   37: .\"
   38: .\" $Id: string_fp.3,v 1.1.1.1 2012/02/21 23:25:53 misho Exp $
   39: .\"
   40: .Dd April 22, 2002
   41: .Dt STRING_FP 3
   42: .Os
   43: .Sh NAME
   44: .Nm string_buf_input ,
   45: .Nm string_buf_output ,
   46: .Nm string_buf_content ,
   47: .Nm string_buf_length
   48: .Nd string buffer streams
   49: .Sh LIBRARY
   50: PDEL Library (libpdel, \-lpdel)
   51: .Sh SYNOPSIS
   52: .In sys/types.h
   53: .In stdio.h
   54: .In pdel/io/string_fp.h
   55: .Ft "FILE *"
   56: .Fn string_buf_input "const void *buf" " size_t len" "int copy"
   57: .Ft "FILE *"
   58: .Fn string_buf_output "const void *mtype"
   59: .Ft "char *"
   60: .Fn string_buf_content "FILE *fp" "int reset"
   61: .Ft "int"
   62: .Fn string_buf_length "FILE *fp"
   63: .Sh DESCRIPTION
   64: These functions allow string buffers to be read and written as streams.
   65: .Pp
   66: .Fn string_buf_input
   67: creates a read-only stream that reads from the buffer pointed to by
   68: .Fa buf
   69: having length
   70: .Fa len .
   71: If
   72: .Fa copy
   73: is non-zero, the contents of the buffer are copied and therefore
   74: .Fa buf
   75: doesn't need to remain valid while the stream is open.
   76: Otherwise, the data pointed to by
   77: .Fa buf
   78: is not copied and must remain valid while the stream is open.
   79: .Xr fclose 3
   80: should be used to close the stream.
   81: .Pp
   82: .Fn string_buf_output
   83: creates a write-only stream that writes into an internal buffer that
   84: grows dynamically.
   85: .Xr fclose 3
   86: should be used to close the stream; this also frees the internal buffer.
   87: The current buffer length is returned by
   88: .Fn string_buf_length .
   89: .Pp
   90: .Fn string_buf_content
   91: returns the contents of the internal buffer.
   92: As with
   93: .Fn string_buf_length ,
   94: the
   95: .Fa fp
   96: argument must be a stream created by
   97: .Fn string_buf_output .
   98: If
   99: .Fa reset
  100: is zero, then the internal buffer remains valid and the returned pointer
  101: should be treated as read-only and not be freed; it also becomes invalid
  102: with the next operation on the stream.
  103: If
  104: .Fa reset
  105: is non-zero, the current buffer contents are "detached" and returned by
  106: .Fn string_buf_content ,
  107: and a new, empty internal buffer is created; in this case, the caller is
  108: responsible for eventually freeing the returned buffer,
  109: which is allocated with
  110: .Xr typed_mem 3
  111: type
  112: .Fa mtype ,
  113: and its contents remain valid until then.
  114: .Pp
  115: In either case, the data returned by
  116: .Fn string_buf_content
  117: is guaranteed to have one additional '\\0' byte appended.
  118: Therefore, it is always safe to treat this pointer as a normal C string.
  119: However, any '\\0' bytes previously written to the stream will cause
  120: this string to appear truncated.
  121: .Sh RETURN VALUES
  122: .Fn string_buf_input ,
  123: .Fn string_buf_output ,
  124: and
  125: .Fn string_buf_content
  126: return
  127: .Dv NULL
  128: to indicate an error, with
  129: .Va errno
  130: set appropriately.
  131: .Pp
  132: Even if 
  133: .Fn string_buf_content
  134: returns
  135: .Dv NULL ,
  136: the stream will still need to be closed.
  137: .Sh IMPLEMENTATION NOTES
  138: .Fn string_buf_content
  139: and
  140: .Fn string_buf_length
  141: attempt to verify that the supplied stream was indeed created by
  142: .Fn string_buf_output .
  143: If they detect otherwise, an immediate assertion failure is generated.
  144: .Sh SEE ALSO
  145: .Xr base64 3 ,
  146: .Xr filter 3 ,
  147: .Xr fopen 3 ,
  148: .Xr libpdel 3 ,
  149: .Xr typed_mem 3
  150: .Sh HISTORY
  151: The PDEL library was developed at Packet Design, LLC.
  152: .Dv "http://www.packetdesign.com/"
  153: .Sh AUTHORS
  154: .An Archie Cobbs Aq archie@freebsd.org