commit 8f0b29961eb4b9965f22bbcabdc0aa0354c19a4a Merge: e5deb2bbc 0e0cf4abd Author: Nick Mathewson <nickm@torproject.org> Date: Wed May 29 09:43:20 2019 -0400 Merge branch 'ticket30561_029' into ticket30561_035 changes/bug30561 | 6 ++++++ src/lib/string/printf.c | 16 +++++++++++++--- 2 files changed, 19 insertions(+), 3 deletions(-) diff --cc src/lib/string/printf.c index 415d4ac4a,000000000..a5cb71ce0 mode 100644,000000..100644 --- a/src/lib/string/printf.c +++ b/src/lib/string/printf.c @@@ -1,157 -1,0 +1,167 @@@ +/* Copyright (c) 2003-2004, Roger Dingledine + * Copyright (c) 2004-2006, Roger Dingledine, Nick Mathewson. + * Copyright (c) 2007-2019, The Tor Project, Inc. */ +/* See LICENSE for licensing information */ + +/** + * \file printf.c + * \brief Compatibility wrappers around snprintf and its friends + **/ + +#include "lib/string/printf.h" +#include "lib/err/torerr.h" +#include "lib/cc/torint.h" +#include "lib/malloc/malloc.h" + +#include <stdlib.h> +#include <stdio.h> + +/** Replacement for snprintf. Differs from platform snprintf in two + * ways: First, always NUL-terminates its output. Second, always + * returns -1 if the result is truncated. (Note that this return + * behavior does <i>not</i> conform to C99; it just happens to be + * easier to emulate "return -1" with conformant implementations than + * it is to emulate "return number that would be written" with + * non-conformant implementations.) */ +int +tor_snprintf(char *str, size_t size, const char *format, ...) +{ + va_list ap; + int r; + va_start(ap,format); + r = tor_vsnprintf(str,size,format,ap); + va_end(ap); + return r; +} + +/** Replacement for vsnprintf; behavior differs as tor_snprintf differs from + * snprintf. + */ +int +tor_vsnprintf(char *str, size_t size, const char *format, va_list args) +{ + int r; + if (size == 0) + return -1; /* no place for the NUL */ + if (size > SIZE_T_CEILING) + return -1; +#ifdef _WIN32 + r = _vsnprintf(str, size, format, args); +#else + r = vsnprintf(str, size, format, args); +#endif + str[size-1] = '\0'; + if (r < 0 || r >= (ssize_t)size) + return -1; + return r; +} + +/** + * Portable asprintf implementation. Does a printf() into a newly malloc'd + * string. Sets *<b>strp</b> to this string, and returns its length (not + * including the terminating NUL character). + * + * You can treat this function as if its implementation were something like + <pre> + char buf[_INFINITY_]; + tor_snprintf(buf, sizeof(buf), fmt, args); + *strp = tor_strdup(buf); + return strlen(*strp): + </pre> + * Where _INFINITY_ is an imaginary constant so big that any string can fit + * into it. + */ +int +tor_asprintf(char **strp, const char *fmt, ...) +{ + int r; + va_list args; + va_start(args, fmt); + r = tor_vasprintf(strp, fmt, args); + va_end(args); + if (!*strp || r < 0) { + /* LCOV_EXCL_START */ + raw_assert_unreached_msg("Internal error in asprintf"); + /* LCOV_EXCL_STOP */ + } + return r; +} + +/** + * Portable vasprintf implementation. Does a printf() into a newly malloc'd + * string. Differs from regular vasprintf in the same ways that + * tor_asprintf() differs from regular asprintf. + */ +int +tor_vasprintf(char **strp, const char *fmt, va_list args) +{ + /* use a temporary variable in case *strp is in args. */ + char *strp_tmp=NULL; +#ifdef HAVE_VASPRINTF + /* If the platform gives us one, use it. */ + int r = vasprintf(&strp_tmp, fmt, args); + if (r < 0) + *strp = NULL; // LCOV_EXCL_LINE -- no cross-platform way to force this + else + *strp = strp_tmp; + return r; +#elif defined(HAVE__VSCPRINTF) + /* On Windows, _vsnprintf won't tell us the length of the string if it + * overflows, so we need to use _vcsprintf to tell how much to allocate */ + int len, r; + va_list tmp_args; + va_copy(tmp_args, args); + len = _vscprintf(fmt, tmp_args); + va_end(tmp_args); + if (len < 0) { + *strp = NULL; + return -1; + } + strp_tmp = tor_malloc(len + 1); + r = _vsnprintf(strp_tmp, len+1, fmt, args); + if (r != len) { + tor_free(strp_tmp); + *strp = NULL; + return -1; + } + *strp = strp_tmp; + return len; +#else + /* Everywhere else, we have a decent vsnprintf that tells us how many + * characters we need. We give it a try on a short buffer first, since + * it might be nice to avoid the second vsnprintf call. + */ ++ /* XXXX This code spent a number of years broken (see bug 30651). It is ++ * possible that no Tor users actually run on systems without vasprintf() or ++ * _vscprintf(). If so, we should consider removing this code. */ + char buf[128]; + int len, r; + va_list tmp_args; + va_copy(tmp_args, args); - /* vsnprintf() was properly checked but tor_vsnprintf() available so - * why not use it? */ - len = tor_vsnprintf(buf, sizeof(buf), fmt, tmp_args); ++ /* Use vsnprintf to retrieve needed length. tor_vsnprintf() is not an ++ * option here because it will simply return -1 if buf is not large enough ++ * to hold the complete string. ++ */ ++ len = vsnprintf(buf, sizeof(buf), fmt, tmp_args); + va_end(tmp_args); ++ buf[sizeof(buf) - 1] = '\0'; ++ if (len < 0) { ++ *strp = NULL; ++ return -1; ++ } + if (len < (int)sizeof(buf)) { + *strp = tor_strdup(buf); + return len; + } + strp_tmp = tor_malloc(len+1); + /* use of tor_vsnprintf() will ensure string is null terminated */ + r = tor_vsnprintf(strp_tmp, len+1, fmt, args); + if (r != len) { + tor_free(strp_tmp); + *strp = NULL; + return -1; + } + *strp = strp_tmp; + return len; +#endif /* defined(HAVE_VASPRINTF) || ... */ +}