A C library for asynchronous DNS requests (grpc依赖)
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.\"
.\" Copyright 1998 by the Massachusetts Institute of Technology.
.\" SPDX-License-Identifier: MIT
.\"
.TH ARES_SAVE_OPTIONS 3 "5 March 2010"
.SH NAME
ares_save_options \- Save configuration values obtained from initialized ares_channel
.SH SYNOPSIS
.nf
#include <ares.h>
`ares_channel` -> `ares_channel_t *`: don't bury the pointer (#595) `ares_channel` is defined as `typedef struct ares_channeldata *ares_channel;`. The problem with this, is it embeds the pointer into the typedef, which means an `ares_channel` can never be declared as `const` as if you write `const ares_channel channel`, that expands to `struct ares_channeldata * const ares_channel` and not `const struct ares_channeldata *channel`. We will now typedef `ares_channel_t` as `typedef struct ares_channeldata ares_channel_t;`, so if you write `const ares_channel_t *channel`, it properly expands to `const struct ares_channeldata *channel`. We are maintaining the old typedef for API compatibility with existing integrations, and due to typedef expansion this should not even cause any compiler warnings for existing code. There are no ABI implications with this change. I could be convinced to keep existing public functions as `ares_channel` if a sufficient argument exists, but internally we really need make this change for modern best practices. This change will allow us to internally use `const ares_channel_t *` where appropriate. Whether or not we decide to change any public interfaces to use `const` may require further discussion on if there might be ABI implications (I don't think so, but I'm also not 100% sure what a compiler internally does with `const` when emitting machine code ... I think more likely ABI implications would occur going the opposite direction). FYI, This PR was done via a combination of sed and clang-format, the only manual code change was the addition of the new typedef, and a couple doc fixes :) Fix By: Brad House (@bradh352)
1 year ago
int ares_save_options(ares_channel_t *\fIchannel\fP,
struct ares_options *\fIoptions\fP, int *\fIoptmask\fP)
.fi
.SH DESCRIPTION
The \fBares_save_options(3)\fP function saves the channel data identified by
.IR channel ,
into the options struct identified by
.IR options ,
and saves the mask of options which are set to the integer
pointer (passed by reference) identified by
.IR optmask .
The resultant options and optmask are then able to be
passed directly to ares_init_options. When the options
are no longer needed, ares_destroy_options should be called
to free any associated memory.
.SH RETURN VALUES
.B ares_save_options(3)
can return any of the following values:
.TP 15
.B ARES_SUCCESS
The channel data was successfully stored
.TP 15
.B ARES_ENOMEM
The memory was exhausted
.TP 15
.B ARES_ENODATA
The channel data identified by
.IR channel
were invalid.
.SH NOTE
Since c-ares 1.6.0 the ares_options struct has been "locked" meaning that it
won't be extended to cover new functions. This function will remain
functioning, but it can only return config data that can be represented in
this config struct, which may no longer be the complete set of config
options. \fBares_dup(3)\fP will not have that restriction.
The ares_options struct can not handle potential IPv6 name servers the
`ares_channel` -> `ares_channel_t *`: don't bury the pointer (#595) `ares_channel` is defined as `typedef struct ares_channeldata *ares_channel;`. The problem with this, is it embeds the pointer into the typedef, which means an `ares_channel` can never be declared as `const` as if you write `const ares_channel channel`, that expands to `struct ares_channeldata * const ares_channel` and not `const struct ares_channeldata *channel`. We will now typedef `ares_channel_t` as `typedef struct ares_channeldata ares_channel_t;`, so if you write `const ares_channel_t *channel`, it properly expands to `const struct ares_channeldata *channel`. We are maintaining the old typedef for API compatibility with existing integrations, and due to typedef expansion this should not even cause any compiler warnings for existing code. There are no ABI implications with this change. I could be convinced to keep existing public functions as `ares_channel` if a sufficient argument exists, but internally we really need make this change for modern best practices. This change will allow us to internally use `const ares_channel_t *` where appropriate. Whether or not we decide to change any public interfaces to use `const` may require further discussion on if there might be ABI implications (I don't think so, but I'm also not 100% sure what a compiler internally does with `const` when emitting machine code ... I think more likely ABI implications would occur going the opposite direction). FYI, This PR was done via a combination of sed and clang-format, the only manual code change was the addition of the new typedef, and a couple doc fixes :) Fix By: Brad House (@bradh352)
1 year ago
ares channel might be configured to use. The \fBares_save_options(3)\fP function
will only return IPv4 servers, if any. In order to retrieve all name servers
`ares_channel` -> `ares_channel_t *`: don't bury the pointer (#595) `ares_channel` is defined as `typedef struct ares_channeldata *ares_channel;`. The problem with this, is it embeds the pointer into the typedef, which means an `ares_channel` can never be declared as `const` as if you write `const ares_channel channel`, that expands to `struct ares_channeldata * const ares_channel` and not `const struct ares_channeldata *channel`. We will now typedef `ares_channel_t` as `typedef struct ares_channeldata ares_channel_t;`, so if you write `const ares_channel_t *channel`, it properly expands to `const struct ares_channeldata *channel`. We are maintaining the old typedef for API compatibility with existing integrations, and due to typedef expansion this should not even cause any compiler warnings for existing code. There are no ABI implications with this change. I could be convinced to keep existing public functions as `ares_channel` if a sufficient argument exists, but internally we really need make this change for modern best practices. This change will allow us to internally use `const ares_channel_t *` where appropriate. Whether or not we decide to change any public interfaces to use `const` may require further discussion on if there might be ABI implications (I don't think so, but I'm also not 100% sure what a compiler internally does with `const` when emitting machine code ... I think more likely ABI implications would occur going the opposite direction). FYI, This PR was done via a combination of sed and clang-format, the only manual code change was the addition of the new typedef, and a couple doc fixes :) Fix By: Brad House (@bradh352)
1 year ago
an ares channel might be using, the \fBares_get_servers(3)\fP function must be
used instead.
.SH SEE ALSO
.BR ares_destroy_options (3),
.BR ares_init_options (3),
.BR ares_get_servers (3),
.BR ares_dup (3)
.SH AVAILABILITY
ares_save_options(3) was added in c-ares 1.4.0