From patchwork Thu Mar 17 19:31:51 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Florian Weimer X-Patchwork-Id: 52084 Return-Path: X-Original-To: patchwork@sourceware.org Delivered-To: patchwork@sourceware.org Received: from server2.sourceware.org (localhost [IPv6:::1]) by sourceware.org (Postfix) with ESMTP id 419A5386EC38 for ; Thu, 17 Mar 2022 19:48:34 +0000 (GMT) DKIM-Filter: OpenDKIM Filter v2.11.0 sourceware.org 419A5386EC38 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=sourceware.org; s=default; t=1647546514; bh=z4IP2WavyM3xLBuOqxkBwYtpJlAVal3hSJHVk17I3fM=; h=To:Subject:In-Reply-To:References:Date:List-Id:List-Unsubscribe: List-Archive:List-Post:List-Help:List-Subscribe:From:Reply-To: From; b=RWgPctvxIsLKdmzhYPfpYNPzBcApWa4YLszA9Nbfy5ix1Uj7kFeS854a3u+yGRLU5 m0PI15MdNFFZB7nnROdJaeMLBnHnlNYDAueKsp6kFBkNvVMzh8oGglRc8H+COWMD6x XAQ4ny50UnUqoFuzVJM/ImfE/SfZ1D4CBSB0ijqw= X-Original-To: libc-alpha@sourceware.org Delivered-To: libc-alpha@sourceware.org Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.129.124]) by sourceware.org (Postfix) with ESMTPS id 638FE386EC15 for ; Thu, 17 Mar 2022 19:31:57 +0000 (GMT) DMARC-Filter: OpenDMARC Filter v1.4.1 sourceware.org 638FE386EC15 Received: from mimecast-mx02.redhat.com (mx3-rdu2.redhat.com [66.187.233.73]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id us-mta-479-p7I8Z07jPxOLPcj3jMiP5w-1; Thu, 17 Mar 2022 15:31:54 -0400 X-MC-Unique: p7I8Z07jPxOLPcj3jMiP5w-1 Received: from smtp.corp.redhat.com (int-mx03.intmail.prod.int.rdu2.redhat.com [10.11.54.3]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx02.redhat.com (Postfix) with ESMTPS id 2AFDB299E75A for ; Thu, 17 Mar 2022 19:31:54 +0000 (UTC) Received: from oldenburg.str.redhat.com (unknown [10.39.192.88]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 51AC4112C085 for ; Thu, 17 Mar 2022 19:31:53 +0000 (UTC) To: libc-alpha@sourceware.org Subject: [PATCH 23/26] libio: Convert __vasprintf_internal to buffers In-Reply-To: References: X-From-Line: 579c56a84cb717b842cc3194c91ca53cf1db15f6 Mon Sep 17 00:00:00 2001 Message-Id: <579c56a84cb717b842cc3194c91ca53cf1db15f6.1647544751.git.fweimer@redhat.com> Date: Thu, 17 Mar 2022 20:31:51 +0100 User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/27.2 (gnu/linux) MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.78 on 10.11.54.3 X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com X-Spam-Status: No, score=-11.8 required=5.0 tests=BAYES_00, DKIMWL_WL_HIGH, DKIM_SIGNED, DKIM_VALID, DKIM_VALID_AU, DKIM_VALID_EF, GIT_PATCH_0, RCVD_IN_DNSWL_NONE, RCVD_IN_MSPIKE_H4, RCVD_IN_MSPIKE_WL, SPF_HELO_NONE, SPF_NONE, TXREP, T_SCC_BODY_TEXT_LINE autolearn=ham autolearn_force=no version=3.4.4 X-Spam-Checker-Version: SpamAssassin 3.4.4 (2020-01-24) on server2.sourceware.org X-BeenThere: libc-alpha@sourceware.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Libc-alpha mailing list List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-Patchwork-Original-From: Florian Weimer via Libc-alpha From: Florian Weimer Reply-To: Florian Weimer Errors-To: libc-alpha-bounces+patchwork=sourceware.org@sourceware.org Sender: "Libc-alpha" The buffer resizing algorithm is slightly different. The initial buffer is on the stack, and small buffers are directly allocated on the heap using the exact required size. The overhead of the additional copy is compensated by the lowered setup cost for buffers compared to libio streams. --- include/printf_buffer.h | 4 + libio/vasprintf.c | 141 ++++++++++++++++++++--------- stdio-common/printf_buffer_flush.c | 4 + 3 files changed, 104 insertions(+), 45 deletions(-) diff --git a/include/printf_buffer.h b/include/printf_buffer.h index c938cb6085..0f3543d9b9 100644 --- a/include/printf_buffer.h +++ b/include/printf_buffer.h @@ -48,6 +48,7 @@ enum __printf_buffer_mode __printf_buffer_mode_snprintf, __printf_buffer_mode_sprintf_chk, __printf_buffer_mode_to_file, + __printf_buffer_mode_asprintf, __printf_buffer_mode_strfmon, __printf_buffer_mode_fp, /* For __printf_fp_l_buffer. */ __printf_buffer_mode_fp_to_wide, /* For __wprintf_fp_l_buffer. */ @@ -301,6 +302,9 @@ void __printf_buffer_flush_snprintf (struct __printf_buffer_snprintf *) struct __printf_buffer_to_file; void __printf_buffer_flush_to_file (struct __printf_buffer_to_file *) attribute_hidden; +struct __printf_buffer_asprintf; +void __printf_buffer_flush_asprintf (struct __printf_buffer_asprintf *) + attribute_hidden; struct __printf_buffer_fp; void __printf_buffer_flush_fp (struct __printf_buffer_fp *) attribute_hidden; diff --git a/libio/vasprintf.c b/libio/vasprintf.c index 4430a266c6..f4ff7ec98b 100644 --- a/libio/vasprintf.c +++ b/libio/vasprintf.c @@ -24,64 +24,115 @@ This exception applies to code released by its copyright holders in files containing the exception. */ -#include +#include +#include +#include +#include +#include +#include #include -#include +#include +#include + +struct __printf_buffer_asprintf +{ + /* base.write_base points either to a heap-allocated buffer, or to + the direct array below. */ + struct __printf_buffer base; + + /* Initial allocation. 200 should be large enough to copy almost + all asprintf usages with just a single (final, correctly sized) + heap allocation. */ + char direct[200]; +}; + +void +__printf_buffer_flush_asprintf (struct __printf_buffer_asprintf *buf) +{ + size_t current_pos = buf->base.write_ptr - buf->base.write_base; + if (current_pos >= INT_MAX) + { + /* The result is not representable. No need to continue. */ + __set_errno (EOVERFLOW); + __printf_buffer_mark_failed (&buf->base); + return; + } + + size_t current_size = buf->base.write_end - buf->base.write_base; + /* Implement an exponentiatial sizing policy. Keep the size + congruent 8 (mod 16), to account for the footer in glibc + malloc. */ + size_t new_size = ((current_size + current_size / 2) & -15) | 8; + char *new_buffer; + if (buf->base.write_base == buf->direct) + { + new_buffer = malloc (new_size); + if (new_buffer == NULL) + { + __printf_buffer_mark_failed (&buf->base); + return; + } + memcpy (new_buffer, buf->direct, current_pos); + } + else + { + new_buffer = realloc (buf->base.write_base, new_size); + if (new_buffer == NULL) + { + __printf_buffer_mark_failed (&buf->base); + return; + } + } + + /* Set up the new write area. */ + buf->base.write_base = new_buffer; + buf->base.write_ptr = new_buffer + current_pos; + buf->base.write_end = new_buffer + new_size; +} + int __vasprintf_internal (char **result_ptr, const char *format, va_list args, unsigned int mode_flags) { - /* Initial size of the buffer to be used. Will be doubled each time an - overflow occurs. */ - const size_t init_string_size = 100; - char *string; - _IO_strfile sf; - int ret; - size_t needed; - size_t allocated; - /* No need to clear the memory here (unlike for open_memstream) since - we know we will never seek on the stream. */ - string = (char *) malloc (init_string_size); - if (string == NULL) - return -1; -#ifdef _IO_MTSAFE_IO - sf._sbf._f._lock = NULL; -#endif - _IO_no_init (&sf._sbf._f, _IO_USER_LOCK, -1, NULL, NULL); - _IO_JUMPS (&sf._sbf) = &_IO_str_jumps; - _IO_str_init_static_internal (&sf, string, init_string_size, string); - sf._sbf._f._flags &= ~_IO_USER_BUF; - sf._s._allocate_buffer_unused = (_IO_alloc_type) malloc; - sf._s._free_buffer_unused = (_IO_free_type) free; - ret = __vfprintf_internal (&sf._sbf._f, format, args, mode_flags); - if (ret < 0) + struct __printf_buffer_asprintf buf; + __printf_buffer_init (&buf.base, buf.direct, array_length (buf.direct), + __printf_buffer_mode_asprintf); + + __printf_buffer (&buf.base, format, args, mode_flags); + int done = __printf_buffer_done (&buf.base); + if (done < 0) { - free (sf._sbf._f._IO_buf_base); - return ret; + if (buf.base.write_base != buf.direct) + free (buf.base.write_base); + return done; + } + + /* Transfer to the final buffer. */ + char *result; + size_t size = buf.base.write_ptr - buf.base.write_base; + if (buf.base.write_base == buf.direct) + { + result = malloc (size + 1); + if (result == NULL) + return -1; + memcpy (result, buf.direct, size); } - /* Only use realloc if the size we need is of the same (binary) - order of magnitude then the memory we allocated. */ - needed = sf._sbf._f._IO_write_ptr - sf._sbf._f._IO_write_base + 1; - allocated = sf._sbf._f._IO_write_end - sf._sbf._f._IO_write_base; - if ((allocated >> 1) <= needed) - *result_ptr = (char *) realloc (sf._sbf._f._IO_buf_base, needed); else { - *result_ptr = (char *) malloc (needed); - if (*result_ptr != NULL) + result = realloc (buf.base.write_base, size + 1); + if (result == NULL) { - memcpy (*result_ptr, sf._sbf._f._IO_buf_base, needed - 1); - free (sf._sbf._f._IO_buf_base); + free (buf.base.write_base); + return -1; } - else - /* We have no choice, use the buffer we already have. */ - *result_ptr = (char *) realloc (sf._sbf._f._IO_buf_base, needed); } - if (*result_ptr == NULL) - *result_ptr = sf._sbf._f._IO_buf_base; - (*result_ptr)[needed - 1] = '\0'; - return ret; + + /* Add NUL termination. */ + result[size] = '\0'; + *result_ptr = result; + + return done; } int diff --git a/stdio-common/printf_buffer_flush.c b/stdio-common/printf_buffer_flush.c index f44c8b887f..14fe1b2df4 100644 --- a/stdio-common/printf_buffer_flush.c +++ b/stdio-common/printf_buffer_flush.c @@ -27,6 +27,7 @@ #ifndef SHARED # pragma weak __printf_buffer_flush_snprintf # pragma weak __printf_buffer_flush_to_file +# pragma weak __printf_buffer_flush_asprintf # pragma weak __printf_buffer_flush_fp # pragma weak __printf_buffer_flush_fp_to_wide # pragma weak __printf_buffer_flush_fphex_to_wide @@ -49,6 +50,9 @@ __printf_buffer_do_flush (struct __printf_buffer *buf) case __printf_buffer_mode_to_file: __printf_buffer_flush_to_file ((struct __printf_buffer_to_file *) buf); return; + case __printf_buffer_mode_asprintf: + __printf_buffer_flush_asprintf ((struct __printf_buffer_asprintf *) buf); + return; case __printf_buffer_mode_strfmon: __set_errno (E2BIG); __printf_buffer_mark_failed (buf);