From fdda28cfe40701deb71632faa403cde86695d737 Mon Sep 17 00:00:00 2001 From: Jeremy Boynes Date: Sat, 9 Sep 2023 08:19:28 +0100 Subject: [PATCH] Remove deprecation diagnostic supppression for dtostrf --- api/deprecated-avr-comp/avr/dtostrf.c.impl | 3 --- test/src/dtostrf.cpp | 27 ++++++++++++++++++---- 2 files changed, 23 insertions(+), 7 deletions(-) diff --git a/api/deprecated-avr-comp/avr/dtostrf.c.impl b/api/deprecated-avr-comp/avr/dtostrf.c.impl index f410886c..96987a8f 100644 --- a/api/deprecated-avr-comp/avr/dtostrf.c.impl +++ b/api/deprecated-avr-comp/avr/dtostrf.c.impl @@ -29,12 +29,9 @@ char *dtostrf (double val, signed char width, unsigned char prec, char *sout) { asm(".global _printf_float"); -#pragma GCC diagnostic push -#pragma GCC diagnostic ignored "-Wdeprecated-declarations" char fmt[20]; sprintf(fmt, "%%%d.%df", width, prec); sprintf(sout, fmt, val); return sout; -#pragma GCC diagnostic pop } diff --git a/test/src/dtostrf.cpp b/test/src/dtostrf.cpp index 0700debb..afa90213 100644 --- a/test/src/dtostrf.cpp +++ b/test/src/dtostrf.cpp @@ -6,9 +6,8 @@ * INCLUDE **************************************************************************************/ -#include - -#include +#include +#include /************************************************************************************** * FUNCTION IMPLEMENTATION @@ -17,8 +16,28 @@ #ifdef __cplusplus extern "C" { #endif +/* + * A fundamental issue with dtostrf is the risk of buffer overflow as the size of the + * output buffer is not passed in. Previous implementation relied on sprintf which has + * the same issue and has now been deprecated, leading to compilation warnings that are + * considered fatal. Here, we use snprintf to avoid those warnings, with a limit + * set large enough for the longest buffer used by the String class. The risk + * of buffer overflow remains when a smaller buffer is passed in. + * + * TODO Refactor String not to rely on this function. + */ +char *dtostrf (double val, signed char width, unsigned char prec, char *sout) { + + // From String.h - DOUBLE_BUF_SIZE is the largest it could use + static size_t const FLT_MAX_DECIMAL_PLACES = 10; + static size_t const DBL_MAX_DECIMAL_PLACES = FLT_MAX_DECIMAL_PLACES; + static size_t const DOUBLE_BUF_SIZE = DBL_MAX_10_EXP + DBL_MAX_DECIMAL_PLACES + 1 /* '-' */ + 1 /* '.' */ + 1 /* '\0' */; -#include + char fmt[20]; + snprintf(fmt, sizeof(fmt), "%%%d.%df", width, prec); + snprintf(sout, DOUBLE_BUF_SIZE, fmt, val); + return sout; +} #ifdef __cplusplus } // extern "C" pFad - Phonifier reborn

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