stdlib/FreeBSD/alloca.3.patch

   1 --- alloca.3.orig       2010-02-22 12:44:05.000000000 -0800
   2 +++ alloca.3    2010-02-22 12:50:53.000000000 -0800
   3 @@ -34,25 +34,25 @@
   4  .Sh NAME
   5  .Nm alloca
   6  .Nd memory allocator
   7 -.Sh LIBRARY
   8 -.Lb libc
   9  .Sh SYNOPSIS
  10 +.In alloca.h
  11 +or
  12 +.br
  13  .In stdlib.h
  14  .Ft void *
  15  .Fn alloca "size_t size"
  16  .Sh DESCRIPTION
  17  The
  18  .Fn alloca
  19 -function
  20 +macro
  21  allocates
  22  .Fa size
  23  bytes of space in the stack frame of the caller.
  24  This temporary space is automatically freed on
  25  return.
  26  .Sh RETURN VALUES
  27 -The
  28  .Fn alloca
  29 -function returns a pointer to the beginning of the allocated space.
  30 +returns a pointer to the beginning of the allocated space.
  31  .Sh SEE ALSO
  32  .Xr brk 2 ,
  33  .Xr calloc 3 ,
  34 @@ -60,24 +60,20 @@ function returns a pointer to the beginn
  35  .Xr malloc 3 ,
  36  .Xr realloc 3
  37  .Sh HISTORY
  38 -The
  39  .Fn alloca
  40 -function appeared in
  41 +appeared in
  42  .At 32v .
  43  .\" .Bx ?? .
  44  .\" The function appeared in 32v, pwb and pwb.2 and in 3bsd 4bsd
  45  .\" The first man page (or link to a man page that I can find at the
  46  .\" moment is 4.3...
  47  .Sh BUGS
  48 -The
  49  .Fn alloca
  50 -function
  51  is machine and compiler dependent;
  52  its use is discouraged.
  53  .Pp
  54 -The
  55  .Fn alloca
  56 -function is slightly unsafe because it cannot ensure that the pointer
  57 +is slightly unsafe because it cannot ensure that the pointer
  58  returned points to a valid and usable block of memory.
  59  The allocation made may exceed the bounds of the stack, or even go
  60  further into other objects in memory, and
  61 @@ -86,3 +82,8 @@ cannot determine such an error.
  62  Avoid
  63  .Fn alloca
  64  with large unbounded allocations.
  65 +.Pp
  66 +The use of C99 variable-length arrays and
  67 +.Fn alloca
  68 +in the same function will cause the lifetime of alloca's storage to be limited to the block containing the
  69 +.Fn alloca