mirror of
https://gitlab.isc.org/isc-projects/bind9
synced 2025-08-22 10:10:06 +00:00
b058f99cb8
removed references in code comments, doc/dev documentation, etc, to isc_task, isc_timer_reset(), and isc_timertype_inactive. also removed a coccinelle patch related to isc_timer_reset() that was no longer needed.
70 lines
2.1 KiB
Plaintext
70 lines
2.1 KiB
Plaintext
<!--
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Copyright (C) Internet Systems Consortium, Inc. ("ISC")
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SPDX-License-Identifier: MPL-2.0
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This Source Code Form is subject to the terms of the Mozilla Public
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License, v. 2.0. If a copy of the MPL was not distributed with this
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file, you can obtain one at https://mozilla.org/MPL/2.0/.
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See the COPYRIGHT file distributed with this work for additional
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information regarding copyright ownership.
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-->
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Result Codes
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The use of global variables or a GetLastError() function to return results
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doesn't work well in a multithreaded application. The global variable has
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obvious problems, as does a global GetLastError(). A per-object GetLastError()
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seems more promising, e.g.
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sometype_t s;
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sometype_dosomething(s, buffer);
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if (sometype_error(s)) {
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/* ... */
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}
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If 's' is shared however this approach doesn't work unless the locking is
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done by the caller, e.g.
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sometype_lock();
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sometype_dosomething(s, buffer);
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if (sometype_error(s)) {
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/* ... */
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}
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sometype_unlock();
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Those ISC and DNS libraries which have locks almost universally put the
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locking inside of the called routines, since it's more convenient for
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the calling programmer, makes for a cleaner API, and puts the burden
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of locking on the library programmer, who should know best what the
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locking needs of the routine are.
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Because of this locking style the ISC and DNS libraries typically provide
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result information as the return value of the function. E.g.
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isc_result_t result;
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result = isc_stdio_open(filename, 0644, &fp);
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Note that an explicit result type is used, instead of mixing the error result
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type with the normal result type. E.g. the C library routine getc() can
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return a character or EOF, but the BIND 9 style keeps the types of the
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function's return values separate.
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char c;
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result = isc_io_getc(stream, &c);
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if (result == ISC_R_SUCCESS) {
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/* Do something with 'c'. */
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} else if (result == ISC_R_EOF) {
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/* EOF. */
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} else {
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/* Some other error. */
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}
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Functions which cannot fail (assuming the caller has provided valid
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arguments) need not return a result type. For example, dns_name_issubdomain()
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returns an bool, because it cannot fail.
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