diff options
Diffstat (limited to '')
-rw-r--r-- | src/c-ares/ares_library_init.3 | 111 |
1 files changed, 111 insertions, 0 deletions
diff --git a/src/c-ares/ares_library_init.3 b/src/c-ares/ares_library_init.3 new file mode 100644 index 00000000..4734f926 --- /dev/null +++ b/src/c-ares/ares_library_init.3 @@ -0,0 +1,111 @@ +.\" +.\" Copyright 1998 by the Massachusetts Institute of Technology. +.\" Copyright (C) 2004-2009 by Daniel Stenberg +.\" +.\" Permission to use, copy, modify, and distribute this +.\" software and its documentation for any purpose and without +.\" fee is hereby granted, provided that the above copyright +.\" notice appear in all copies and that both that copyright +.\" notice and this permission notice appear in supporting +.\" documentation, and that the name of M.I.T. not be used in +.\" advertising or publicity pertaining to distribution of the +.\" software without specific, written prior permission. +.\" M.I.T. makes no representations about the suitability of +.\" this software for any purpose. It is provided "as is" +.\" without express or implied warranty. +.\" +.TH ARES_LIBRARY_INIT 3 "19 May 2009" +.SH NAME +ares_library_init \- c-ares library initialization +.SH SYNOPSIS +.nf +#include <ares.h> + +int ares_library_init(int \fIflags\fP) + +int ares_library_init_mem(int \fIflags\fP, + void *(*\fIamalloc\fP)(size_t), + void (*\fIafree\fP)(void *ptr), + void (*\fIarealloc\fP)(void *ptr, size_t size)) +.fi +.SH DESCRIPTION +.PP +The +.B ares_library_init +function performs initializations internally required by the c-ares +library that must take place before any other function provided by +c-ares can be used in a program. +.PP +This function must be called at least once within the life of a program, +before the program actually executes any other c-ares library function. +Initializations done by this function remain effective until a number of +calls to \fIares_library_cleanup(3)\fP equal to the number of calls to +this function are performed. +.PP +Successive calls to this function do nothing further, only the first +call done when c-ares is in an uninitialized state is actually +effective. +.PP +The +.I flags +parameter is a bit pattern that tells c-ares exactly which features +should be initialized, as described below. Set the desired bits by +ORing the values together. In normal operation you should specify +\fIARES_LIB_INIT_ALL\fP. Don't use any other value unless you are +familiar with it and trying to control some internal c-ares feature. +.PP +The +.B ares_library_init_mem +function allows the caller to provide memory management functions that the +c-ares library will be use instead of \fImalloc(3)\fP, \fIfree(3)\fP and +\fIrealloc(3)\fP. +.PP +.B This function is not thread safe. +You have to call it once the program has started, but this call must be done +before the program starts any other thread. This is required to avoid +potential race conditions in library initialization, and also due to the fact +that \fIares_library_init(3)\fP might call functions from other libraries that +are thread unsafe, and could conflict with any other thread that is already +using these other libraries. +.PP +Win32/64 application DLLs shall not call \fIares_library_init(3)\fP from the +DllMain function. Doing so will produce deadlocks and other problems. +.SH FLAGS +.TP 5 +.B ARES_LIB_INIT_ALL +Initialize everything possible. This sets all known bits. +.TP +.B ARES_LIB_INIT_WIN32 +Initialize Win32/64 specific libraries. +.TP +.B ARES_LIB_INIT_NONE +Initialize nothing extra. This sets no bit. +.SH RETURN VALUE +Upon successful completion, ares_library_init() will return 0. Otherwise, a +non-zero error number will be returned to indicate the error. Except for +\fIares_strerror(3)\fP, you shall not call any other c-ares function upon +\fIares_library_init(3)\fP failure. +.SH AVAILABILITY +This function was first introduced in c-ares version 1.7.0 along with the +definition of preprocessor symbol \fICARES_HAVE_ARES_LIBRARY_INIT\fP as an +indication of the availability of this function. Its recursive behavior, +which requires a matching number of calls to \fIares_library_cleanup()\fP +in order to deinitialize the library, is present since c-ares version +1.10.0. Earlier versions would deinitialize the library on the first call +to \fIares_library_cleanup()\fP. +.PP +Since the introduction of this function it is absolutely mandatory to +call it for any Win32/64 program using c-ares. +.PP +Non-Win32/64 systems can still use c-ares version 1.7.0 without calling +\fIares_library_init(3)\fP due to the fact that \fIcurrently\fP it is nearly +a do-nothing function on non-Win32/64 platforms at this point. +.SH SEE ALSO +.BR ares_library_cleanup(3), +.BR ares_strerror(3) +.SH AUTHOR +Yang Tse +.PP +Copyright 1998 by the Massachusetts Institute of Technology. +.br +Copyright (C) 2004-2009 by Daniel Stenberg. |