src/util/safe-format-string.c

b9d8c6172e48a2633ebe196b2e88bebdf9523c20Stef Walter/*
b9d8c6172e48a2633ebe196b2e88bebdf9523c20Stef Walter * This file originated in the realmd project
b9d8c6172e48a2633ebe196b2e88bebdf9523c20Stef Walter *
b9d8c6172e48a2633ebe196b2e88bebdf9523c20Stef Walter * Copyright 2013 Red Hat Inc
b9d8c6172e48a2633ebe196b2e88bebdf9523c20Stef Walter *
b9d8c6172e48a2633ebe196b2e88bebdf9523c20Stef Walter * This program is free software: you can redistribute it and/or modify
b9d8c6172e48a2633ebe196b2e88bebdf9523c20Stef Walter * it under the terms of the GNU Lesser General Public License as published
b9d8c6172e48a2633ebe196b2e88bebdf9523c20Stef Walter * by the Free Software Foundation; either version 2 of the licence or (at
b9d8c6172e48a2633ebe196b2e88bebdf9523c20Stef Walter * your option) any later version.
b9d8c6172e48a2633ebe196b2e88bebdf9523c20Stef Walter *
b9d8c6172e48a2633ebe196b2e88bebdf9523c20Stef Walter * See the included COPYING file for more information.
b9d8c6172e48a2633ebe196b2e88bebdf9523c20Stef Walter *
b9d8c6172e48a2633ebe196b2e88bebdf9523c20Stef Walter * Author: Stef Walter <stefw@redhat.com>
b9d8c6172e48a2633ebe196b2e88bebdf9523c20Stef Walter */
b9d8c6172e48a2633ebe196b2e88bebdf9523c20Stef Walter
b9d8c6172e48a2633ebe196b2e88bebdf9523c20Stef Walter/*
b9d8c6172e48a2633ebe196b2e88bebdf9523c20Stef Walter * Some snippets of code from gnulib, but have since been refactored
b9d8c6172e48a2633ebe196b2e88bebdf9523c20Stef Walter * to within an inch of their life...
b9d8c6172e48a2633ebe196b2e88bebdf9523c20Stef Walter *
b9d8c6172e48a2633ebe196b2e88bebdf9523c20Stef Walter * vsprintf with automatic memory allocation.
b9d8c6172e48a2633ebe196b2e88bebdf9523c20Stef Walter * Copyright (C) 1999, 2002-2003 Free Software Foundation, Inc.
b9d8c6172e48a2633ebe196b2e88bebdf9523c20Stef Walter *
b9d8c6172e48a2633ebe196b2e88bebdf9523c20Stef Walter * This program is free software; you can redistribute it and/or modify it
b9d8c6172e48a2633ebe196b2e88bebdf9523c20Stef Walter * under the terms of the GNU Library General Public License as published
b9d8c6172e48a2633ebe196b2e88bebdf9523c20Stef Walter * by the Free Software Foundation; either version 2, or (at your option)
b9d8c6172e48a2633ebe196b2e88bebdf9523c20Stef Walter * any later version.
b9d8c6172e48a2633ebe196b2e88bebdf9523c20Stef Walter *
b9d8c6172e48a2633ebe196b2e88bebdf9523c20Stef Walter * This program is distributed in the hope that it will be useful,
b9d8c6172e48a2633ebe196b2e88bebdf9523c20Stef Walter * but WITHOUT ANY WARRANTY; without even the implied warranty of
b9d8c6172e48a2633ebe196b2e88bebdf9523c20Stef Walter * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
b9d8c6172e48a2633ebe196b2e88bebdf9523c20Stef Walter * Library General Public License for more details.
b9d8c6172e48a2633ebe196b2e88bebdf9523c20Stef Walter */
b9d8c6172e48a2633ebe196b2e88bebdf9523c20Stef Walter
b9d8c6172e48a2633ebe196b2e88bebdf9523c20Stef Walter#include "config.h"
b9d8c6172e48a2633ebe196b2e88bebdf9523c20Stef Walter
b9d8c6172e48a2633ebe196b2e88bebdf9523c20Stef Walter#include "safe-format-string.h"
b9d8c6172e48a2633ebe196b2e88bebdf9523c20Stef Walter
b9d8c6172e48a2633ebe196b2e88bebdf9523c20Stef Walter#include <errno.h>
b9d8c6172e48a2633ebe196b2e88bebdf9523c20Stef Walter#include <stdarg.h>
b9d8c6172e48a2633ebe196b2e88bebdf9523c20Stef Walter#include <string.h>
b9d8c6172e48a2633ebe196b2e88bebdf9523c20Stef Walter
b9d8c6172e48a2633ebe196b2e88bebdf9523c20Stef Walter#ifndef MIN
b9d8c6172e48a2633ebe196b2e88bebdf9523c20Stef Walter#define MIN(a, b)  (((a) < (b)) ? (a) : (b))
b9d8c6172e48a2633ebe196b2e88bebdf9523c20Stef Walter#endif
b9d8c6172e48a2633ebe196b2e88bebdf9523c20Stef Walter
b9d8c6172e48a2633ebe196b2e88bebdf9523c20Stef Walter#ifndef MAX
b9d8c6172e48a2633ebe196b2e88bebdf9523c20Stef Walter#define MAX(a, b)  (((a) > (b)) ? (a) : (b))
b9d8c6172e48a2633ebe196b2e88bebdf9523c20Stef Walter#endif
b9d8c6172e48a2633ebe196b2e88bebdf9523c20Stef Walter
b9d8c6172e48a2633ebe196b2e88bebdf9523c20Stef Walterstatic void
b9d8c6172e48a2633ebe196b2e88bebdf9523c20Stef Waltersafe_padding (int count,
b9d8c6172e48a2633ebe196b2e88bebdf9523c20Stef Walter              int *total,
b9d8c6172e48a2633ebe196b2e88bebdf9523c20Stef Walter              void (* copy_fn) (void *, const char *, size_t),
b9d8c6172e48a2633ebe196b2e88bebdf9523c20Stef Walter              void *data)
b9d8c6172e48a2633ebe196b2e88bebdf9523c20Stef Walter{
b9d8c6172e48a2633ebe196b2e88bebdf9523c20Stef Walter    char eight[] = "        ";
b9d8c6172e48a2633ebe196b2e88bebdf9523c20Stef Walter    int num;
b9d8c6172e48a2633ebe196b2e88bebdf9523c20Stef Walter
b9d8c6172e48a2633ebe196b2e88bebdf9523c20Stef Walter    while (count > 0) {
b9d8c6172e48a2633ebe196b2e88bebdf9523c20Stef Walter        num = MIN (count, 8);
b9d8c6172e48a2633ebe196b2e88bebdf9523c20Stef Walter        copy_fn (data, eight, num);
b9d8c6172e48a2633ebe196b2e88bebdf9523c20Stef Walter        count -= num;
b9d8c6172e48a2633ebe196b2e88bebdf9523c20Stef Walter        *total += num;
b9d8c6172e48a2633ebe196b2e88bebdf9523c20Stef Walter    }
b9d8c6172e48a2633ebe196b2e88bebdf9523c20Stef Walter}
b9d8c6172e48a2633ebe196b2e88bebdf9523c20Stef Walter
b9d8c6172e48a2633ebe196b2e88bebdf9523c20Stef Walterstatic void
b9d8c6172e48a2633ebe196b2e88bebdf9523c20Stef Walterdummy_copy_fn (void *data,
b9d8c6172e48a2633ebe196b2e88bebdf9523c20Stef Walter               const char *piece,
b9d8c6172e48a2633ebe196b2e88bebdf9523c20Stef Walter               size_t len)
b9d8c6172e48a2633ebe196b2e88bebdf9523c20Stef Walter{
b9d8c6172e48a2633ebe196b2e88bebdf9523c20Stef Walter
b9d8c6172e48a2633ebe196b2e88bebdf9523c20Stef Walter}
b9d8c6172e48a2633ebe196b2e88bebdf9523c20Stef Walter
b9d8c6172e48a2633ebe196b2e88bebdf9523c20Stef Walterint
b9d8c6172e48a2633ebe196b2e88bebdf9523c20Stef Waltersafe_format_string_cb (void (* copy_fn) (void *, const char *, size_t),
b9d8c6172e48a2633ebe196b2e88bebdf9523c20Stef Walter                       void *data,
b9d8c6172e48a2633ebe196b2e88bebdf9523c20Stef Walter                       const char *format,
b9d8c6172e48a2633ebe196b2e88bebdf9523c20Stef Walter                       const char * const args[],
b9d8c6172e48a2633ebe196b2e88bebdf9523c20Stef Walter                       int num_args)
b9d8c6172e48a2633ebe196b2e88bebdf9523c20Stef Walter{
b9d8c6172e48a2633ebe196b2e88bebdf9523c20Stef Walter    int at_arg = 0;
b9d8c6172e48a2633ebe196b2e88bebdf9523c20Stef Walter    const char *cp;
b9d8c6172e48a2633ebe196b2e88bebdf9523c20Stef Walter    int precision;
b9d8c6172e48a2633ebe196b2e88bebdf9523c20Stef Walter    int width;
b9d8c6172e48a2633ebe196b2e88bebdf9523c20Stef Walter    int len;
b9d8c6172e48a2633ebe196b2e88bebdf9523c20Stef Walter    const char *value;
b9d8c6172e48a2633ebe196b2e88bebdf9523c20Stef Walter    int total;
b9d8c6172e48a2633ebe196b2e88bebdf9523c20Stef Walter    int left;
b9d8c6172e48a2633ebe196b2e88bebdf9523c20Stef Walter    int i;
b9d8c6172e48a2633ebe196b2e88bebdf9523c20Stef Walter
b9d8c6172e48a2633ebe196b2e88bebdf9523c20Stef Walter    if (!copy_fn)
b9d8c6172e48a2633ebe196b2e88bebdf9523c20Stef Walter        copy_fn = dummy_copy_fn;
b9d8c6172e48a2633ebe196b2e88bebdf9523c20Stef Walter
b9d8c6172e48a2633ebe196b2e88bebdf9523c20Stef Walter    total = 0;
b9d8c6172e48a2633ebe196b2e88bebdf9523c20Stef Walter    cp = format;
b9d8c6172e48a2633ebe196b2e88bebdf9523c20Stef Walter
b9d8c6172e48a2633ebe196b2e88bebdf9523c20Stef Walter    while (*cp) {
b9d8c6172e48a2633ebe196b2e88bebdf9523c20Stef Walter
b9d8c6172e48a2633ebe196b2e88bebdf9523c20Stef Walter        /* Piece of raw string */
b9d8c6172e48a2633ebe196b2e88bebdf9523c20Stef Walter        if (*cp != '%') {
b9d8c6172e48a2633ebe196b2e88bebdf9523c20Stef Walter            len = strcspn (cp, "%");
b9d8c6172e48a2633ebe196b2e88bebdf9523c20Stef Walter            copy_fn (data, cp, len);
b9d8c6172e48a2633ebe196b2e88bebdf9523c20Stef Walter            total += len;
b9d8c6172e48a2633ebe196b2e88bebdf9523c20Stef Walter            cp += len;
b9d8c6172e48a2633ebe196b2e88bebdf9523c20Stef Walter            continue;
b9d8c6172e48a2633ebe196b2e88bebdf9523c20Stef Walter        }
b9d8c6172e48a2633ebe196b2e88bebdf9523c20Stef Walter
b9d8c6172e48a2633ebe196b2e88bebdf9523c20Stef Walter        cp++;
b9d8c6172e48a2633ebe196b2e88bebdf9523c20Stef Walter
b9d8c6172e48a2633ebe196b2e88bebdf9523c20Stef Walter        /* An literal percent sign? */
b9d8c6172e48a2633ebe196b2e88bebdf9523c20Stef Walter        if (*cp == '%') {
b9d8c6172e48a2633ebe196b2e88bebdf9523c20Stef Walter            copy_fn (data, "%", 1);
b9d8c6172e48a2633ebe196b2e88bebdf9523c20Stef Walter            total++;
b9d8c6172e48a2633ebe196b2e88bebdf9523c20Stef Walter            cp++;
b9d8c6172e48a2633ebe196b2e88bebdf9523c20Stef Walter            continue;
b9d8c6172e48a2633ebe196b2e88bebdf9523c20Stef Walter        }
b9d8c6172e48a2633ebe196b2e88bebdf9523c20Stef Walter
b9d8c6172e48a2633ebe196b2e88bebdf9523c20Stef Walter        value = NULL;
b9d8c6172e48a2633ebe196b2e88bebdf9523c20Stef Walter        left = 0;
b9d8c6172e48a2633ebe196b2e88bebdf9523c20Stef Walter        precision = -1;
b9d8c6172e48a2633ebe196b2e88bebdf9523c20Stef Walter        width = -1;
b9d8c6172e48a2633ebe196b2e88bebdf9523c20Stef Walter
b9d8c6172e48a2633ebe196b2e88bebdf9523c20Stef Walter        /* Test for positional argument.  */
b9d8c6172e48a2633ebe196b2e88bebdf9523c20Stef Walter        if (*cp >= '0' && *cp <= '9') {
b9d8c6172e48a2633ebe196b2e88bebdf9523c20Stef Walter            /* Look-ahead parsing, otherwise skipped */
b9d8c6172e48a2633ebe196b2e88bebdf9523c20Stef Walter            if (cp[strspn (cp, "0123456789")] == '$') {
b9d8c6172e48a2633ebe196b2e88bebdf9523c20Stef Walter                unsigned int n = 0;
b9d8c6172e48a2633ebe196b2e88bebdf9523c20Stef Walter                for (i = 0; i < 6 && *cp >= '0' && *cp <= '9'; i++, cp++) {
b9d8c6172e48a2633ebe196b2e88bebdf9523c20Stef Walter                    n = 10 * n + (*cp - '0');
b9d8c6172e48a2633ebe196b2e88bebdf9523c20Stef Walter                }
b9d8c6172e48a2633ebe196b2e88bebdf9523c20Stef Walter                /* Positional argument 0 is invalid. */
b9d8c6172e48a2633ebe196b2e88bebdf9523c20Stef Walter                if (n == 0) {
b9d8c6172e48a2633ebe196b2e88bebdf9523c20Stef Walter                    errno = EINVAL;
b9d8c6172e48a2633ebe196b2e88bebdf9523c20Stef Walter                    return -1;
b9d8c6172e48a2633ebe196b2e88bebdf9523c20Stef Walter                }
b9d8c6172e48a2633ebe196b2e88bebdf9523c20Stef Walter                /* Positional argument N too high */
b9d8c6172e48a2633ebe196b2e88bebdf9523c20Stef Walter                if (n > num_args) {
b9d8c6172e48a2633ebe196b2e88bebdf9523c20Stef Walter                    errno = EINVAL;
b9d8c6172e48a2633ebe196b2e88bebdf9523c20Stef Walter                    return -1;
b9d8c6172e48a2633ebe196b2e88bebdf9523c20Stef Walter                }
b9d8c6172e48a2633ebe196b2e88bebdf9523c20Stef Walter                value = args[n - 1];
b9d8c6172e48a2633ebe196b2e88bebdf9523c20Stef Walter                cp++; /* $ */
b9d8c6172e48a2633ebe196b2e88bebdf9523c20Stef Walter            }
b9d8c6172e48a2633ebe196b2e88bebdf9523c20Stef Walter        }
b9d8c6172e48a2633ebe196b2e88bebdf9523c20Stef Walter
b9d8c6172e48a2633ebe196b2e88bebdf9523c20Stef Walter        /* Read the supported flags. */
b9d8c6172e48a2633ebe196b2e88bebdf9523c20Stef Walter        for (; ; cp++) {
b9d8c6172e48a2633ebe196b2e88bebdf9523c20Stef Walter            if (*cp == '-')
b9d8c6172e48a2633ebe196b2e88bebdf9523c20Stef Walter                left = 1;
b9d8c6172e48a2633ebe196b2e88bebdf9523c20Stef Walter            /* Supported but ignored */
b9d8c6172e48a2633ebe196b2e88bebdf9523c20Stef Walter            else if (*cp != ' ')
b9d8c6172e48a2633ebe196b2e88bebdf9523c20Stef Walter                break;
b9d8c6172e48a2633ebe196b2e88bebdf9523c20Stef Walter        }
b9d8c6172e48a2633ebe196b2e88bebdf9523c20Stef Walter
b9d8c6172e48a2633ebe196b2e88bebdf9523c20Stef Walter        /* Parse the width. */
b9d8c6172e48a2633ebe196b2e88bebdf9523c20Stef Walter        if (*cp >= '0' && *cp <= '9') {
b9d8c6172e48a2633ebe196b2e88bebdf9523c20Stef Walter            width = 0;
b9d8c6172e48a2633ebe196b2e88bebdf9523c20Stef Walter            for (i = 0; i < 6 && *cp >= '0' && *cp <= '9'; i++, cp++) {
b9d8c6172e48a2633ebe196b2e88bebdf9523c20Stef Walter                width = 10 * width + (*cp - '0');
b9d8c6172e48a2633ebe196b2e88bebdf9523c20Stef Walter            }
b9d8c6172e48a2633ebe196b2e88bebdf9523c20Stef Walter        }
b9d8c6172e48a2633ebe196b2e88bebdf9523c20Stef Walter
b9d8c6172e48a2633ebe196b2e88bebdf9523c20Stef Walter        /* Parse the precision. */
b9d8c6172e48a2633ebe196b2e88bebdf9523c20Stef Walter        if (*cp == '.') {
b9d8c6172e48a2633ebe196b2e88bebdf9523c20Stef Walter            precision = 0;
b9d8c6172e48a2633ebe196b2e88bebdf9523c20Stef Walter            for (i = 0, cp++; i < 6 && *cp >= '0' && *cp <= '9'; cp++, i++) {
b9d8c6172e48a2633ebe196b2e88bebdf9523c20Stef Walter                precision = 10 * precision + (*cp - '0');
b9d8c6172e48a2633ebe196b2e88bebdf9523c20Stef Walter            }
b9d8c6172e48a2633ebe196b2e88bebdf9523c20Stef Walter        }
b9d8c6172e48a2633ebe196b2e88bebdf9523c20Stef Walter
b9d8c6172e48a2633ebe196b2e88bebdf9523c20Stef Walter        /* Read the conversion character.  */
b9d8c6172e48a2633ebe196b2e88bebdf9523c20Stef Walter        switch (*cp++) {
b9d8c6172e48a2633ebe196b2e88bebdf9523c20Stef Walter        case 's':
b9d8c6172e48a2633ebe196b2e88bebdf9523c20Stef Walter            /* Non-positional argument */
b9d8c6172e48a2633ebe196b2e88bebdf9523c20Stef Walter            if (value == NULL) {
b9d8c6172e48a2633ebe196b2e88bebdf9523c20Stef Walter                /* Too many arguments used */
b9d8c6172e48a2633ebe196b2e88bebdf9523c20Stef Walter                if (at_arg == num_args) {
b9d8c6172e48a2633ebe196b2e88bebdf9523c20Stef Walter                    errno = EINVAL;
b9d8c6172e48a2633ebe196b2e88bebdf9523c20Stef Walter                    return -1;
b9d8c6172e48a2633ebe196b2e88bebdf9523c20Stef Walter                }
b9d8c6172e48a2633ebe196b2e88bebdf9523c20Stef Walter                value = args[at_arg++];
b9d8c6172e48a2633ebe196b2e88bebdf9523c20Stef Walter            }
b9d8c6172e48a2633ebe196b2e88bebdf9523c20Stef Walter            break;
b9d8c6172e48a2633ebe196b2e88bebdf9523c20Stef Walter
b9d8c6172e48a2633ebe196b2e88bebdf9523c20Stef Walter        /* No other conversion characters are supported */
b9d8c6172e48a2633ebe196b2e88bebdf9523c20Stef Walter        default:
b9d8c6172e48a2633ebe196b2e88bebdf9523c20Stef Walter            errno = EINVAL;
b9d8c6172e48a2633ebe196b2e88bebdf9523c20Stef Walter            return -1;
b9d8c6172e48a2633ebe196b2e88bebdf9523c20Stef Walter        }
b9d8c6172e48a2633ebe196b2e88bebdf9523c20Stef Walter
b9d8c6172e48a2633ebe196b2e88bebdf9523c20Stef Walter        /* How many characters are we printing? */
b9d8c6172e48a2633ebe196b2e88bebdf9523c20Stef Walter        len = strlen (value);
b9d8c6172e48a2633ebe196b2e88bebdf9523c20Stef Walter        if (precision >= 0)
b9d8c6172e48a2633ebe196b2e88bebdf9523c20Stef Walter            len = MIN (precision, len);
b9d8c6172e48a2633ebe196b2e88bebdf9523c20Stef Walter
b9d8c6172e48a2633ebe196b2e88bebdf9523c20Stef Walter        /* Do we need padding? */
b9d8c6172e48a2633ebe196b2e88bebdf9523c20Stef Walter        safe_padding (left ? 0 : width - len, &total, copy_fn, data);
b9d8c6172e48a2633ebe196b2e88bebdf9523c20Stef Walter
b9d8c6172e48a2633ebe196b2e88bebdf9523c20Stef Walter        /* The actual data */;
b9d8c6172e48a2633ebe196b2e88bebdf9523c20Stef Walter        copy_fn (data, value, len);
b9d8c6172e48a2633ebe196b2e88bebdf9523c20Stef Walter        total += len;
b9d8c6172e48a2633ebe196b2e88bebdf9523c20Stef Walter
b9d8c6172e48a2633ebe196b2e88bebdf9523c20Stef Walter        /* Do we need padding? */
b9d8c6172e48a2633ebe196b2e88bebdf9523c20Stef Walter        safe_padding (left ? width - len : 0, &total, copy_fn, data);
b9d8c6172e48a2633ebe196b2e88bebdf9523c20Stef Walter    }
b9d8c6172e48a2633ebe196b2e88bebdf9523c20Stef Walter
b9d8c6172e48a2633ebe196b2e88bebdf9523c20Stef Walter    return total;
b9d8c6172e48a2633ebe196b2e88bebdf9523c20Stef Walter}
b9d8c6172e48a2633ebe196b2e88bebdf9523c20Stef Walter
b9d8c6172e48a2633ebe196b2e88bebdf9523c20Stef Walterstatic const char **
b9d8c6172e48a2633ebe196b2e88bebdf9523c20Stef Waltervalist_to_args (va_list va,
b9d8c6172e48a2633ebe196b2e88bebdf9523c20Stef Walter                int *num_args)
b9d8c6172e48a2633ebe196b2e88bebdf9523c20Stef Walter{
b9d8c6172e48a2633ebe196b2e88bebdf9523c20Stef Walter    int alo_args;
b9d8c6172e48a2633ebe196b2e88bebdf9523c20Stef Walter    const char **args;
b9d8c6172e48a2633ebe196b2e88bebdf9523c20Stef Walter    const char *arg;
b9d8c6172e48a2633ebe196b2e88bebdf9523c20Stef Walter    void *mem;
b9d8c6172e48a2633ebe196b2e88bebdf9523c20Stef Walter
b9d8c6172e48a2633ebe196b2e88bebdf9523c20Stef Walter    *num_args = alo_args = 0;
b9d8c6172e48a2633ebe196b2e88bebdf9523c20Stef Walter    args = NULL;
b9d8c6172e48a2633ebe196b2e88bebdf9523c20Stef Walter
b9d8c6172e48a2633ebe196b2e88bebdf9523c20Stef Walter    for (;;) {
b9d8c6172e48a2633ebe196b2e88bebdf9523c20Stef Walter        arg = va_arg (va, const char *);
b9d8c6172e48a2633ebe196b2e88bebdf9523c20Stef Walter        if (arg == NULL)
b9d8c6172e48a2633ebe196b2e88bebdf9523c20Stef Walter            break;
b9d8c6172e48a2633ebe196b2e88bebdf9523c20Stef Walter        if (*num_args == alo_args) {
b9d8c6172e48a2633ebe196b2e88bebdf9523c20Stef Walter            alo_args += 8;
b9d8c6172e48a2633ebe196b2e88bebdf9523c20Stef Walter            mem = realloc (args, sizeof (const char *) * alo_args);
b9d8c6172e48a2633ebe196b2e88bebdf9523c20Stef Walter            if (!mem) {
b9d8c6172e48a2633ebe196b2e88bebdf9523c20Stef Walter                free (args);
b9d8c6172e48a2633ebe196b2e88bebdf9523c20Stef Walter                return NULL;
b9d8c6172e48a2633ebe196b2e88bebdf9523c20Stef Walter            }
b9d8c6172e48a2633ebe196b2e88bebdf9523c20Stef Walter            args = mem;
b9d8c6172e48a2633ebe196b2e88bebdf9523c20Stef Walter        }
b9d8c6172e48a2633ebe196b2e88bebdf9523c20Stef Walter        args[(*num_args)++] = arg;
b9d8c6172e48a2633ebe196b2e88bebdf9523c20Stef Walter    }
b9d8c6172e48a2633ebe196b2e88bebdf9523c20Stef Walter
b9d8c6172e48a2633ebe196b2e88bebdf9523c20Stef Walter    return args;
b9d8c6172e48a2633ebe196b2e88bebdf9523c20Stef Walter}
b9d8c6172e48a2633ebe196b2e88bebdf9523c20Stef Walter
b9d8c6172e48a2633ebe196b2e88bebdf9523c20Stef Walterstruct sprintf_ctx {
b9d8c6172e48a2633ebe196b2e88bebdf9523c20Stef Walter    char *data;
b9d8c6172e48a2633ebe196b2e88bebdf9523c20Stef Walter    size_t length;
b9d8c6172e48a2633ebe196b2e88bebdf9523c20Stef Walter    size_t alloc;
b9d8c6172e48a2633ebe196b2e88bebdf9523c20Stef Walter};
b9d8c6172e48a2633ebe196b2e88bebdf9523c20Stef Walter
b9d8c6172e48a2633ebe196b2e88bebdf9523c20Stef Walterstatic void
b9d8c6172e48a2633ebe196b2e88bebdf9523c20Stef Waltersnprintf_copy_fn (void *data,
b9d8c6172e48a2633ebe196b2e88bebdf9523c20Stef Walter                  const char *piece,
b9d8c6172e48a2633ebe196b2e88bebdf9523c20Stef Walter                  size_t length)
b9d8c6172e48a2633ebe196b2e88bebdf9523c20Stef Walter{
b9d8c6172e48a2633ebe196b2e88bebdf9523c20Stef Walter    struct sprintf_ctx *cx = data;
b9d8c6172e48a2633ebe196b2e88bebdf9523c20Stef Walter
b9d8c6172e48a2633ebe196b2e88bebdf9523c20Stef Walter    /* Don't copy if too much data */
b9d8c6172e48a2633ebe196b2e88bebdf9523c20Stef Walter    if (cx->length > cx->alloc)
b9d8c6172e48a2633ebe196b2e88bebdf9523c20Stef Walter        length = 0;
b9d8c6172e48a2633ebe196b2e88bebdf9523c20Stef Walter    else if (cx->length + length > cx->alloc)
b9d8c6172e48a2633ebe196b2e88bebdf9523c20Stef Walter        length = cx->alloc - cx->length;
b9d8c6172e48a2633ebe196b2e88bebdf9523c20Stef Walter
b9d8c6172e48a2633ebe196b2e88bebdf9523c20Stef Walter    if (length > 0)
b9d8c6172e48a2633ebe196b2e88bebdf9523c20Stef Walter        memcpy (cx->data + cx->length, piece, length);
b9d8c6172e48a2633ebe196b2e88bebdf9523c20Stef Walter
b9d8c6172e48a2633ebe196b2e88bebdf9523c20Stef Walter    /* Null termination happens later */
b9d8c6172e48a2633ebe196b2e88bebdf9523c20Stef Walter    cx->length += length;
b9d8c6172e48a2633ebe196b2e88bebdf9523c20Stef Walter}
b9d8c6172e48a2633ebe196b2e88bebdf9523c20Stef Walter
b9d8c6172e48a2633ebe196b2e88bebdf9523c20Stef Walterint
b9d8c6172e48a2633ebe196b2e88bebdf9523c20Stef Waltersafe_format_string (char *str,
b9d8c6172e48a2633ebe196b2e88bebdf9523c20Stef Walter                    size_t len,
b9d8c6172e48a2633ebe196b2e88bebdf9523c20Stef Walter                    const char *format,
b9d8c6172e48a2633ebe196b2e88bebdf9523c20Stef Walter                    ...)
b9d8c6172e48a2633ebe196b2e88bebdf9523c20Stef Walter{
b9d8c6172e48a2633ebe196b2e88bebdf9523c20Stef Walter    struct sprintf_ctx cx;
b9d8c6172e48a2633ebe196b2e88bebdf9523c20Stef Walter    int num_args;
b9d8c6172e48a2633ebe196b2e88bebdf9523c20Stef Walter    va_list va;
b9d8c6172e48a2633ebe196b2e88bebdf9523c20Stef Walter    const char **args;
b9d8c6172e48a2633ebe196b2e88bebdf9523c20Stef Walter    int error = 0;
b9d8c6172e48a2633ebe196b2e88bebdf9523c20Stef Walter    int ret;
b9d8c6172e48a2633ebe196b2e88bebdf9523c20Stef Walter
b9d8c6172e48a2633ebe196b2e88bebdf9523c20Stef Walter    cx.data = str;
b9d8c6172e48a2633ebe196b2e88bebdf9523c20Stef Walter    cx.length = 0;
b9d8c6172e48a2633ebe196b2e88bebdf9523c20Stef Walter    cx.alloc = len;
b9d8c6172e48a2633ebe196b2e88bebdf9523c20Stef Walter
b9d8c6172e48a2633ebe196b2e88bebdf9523c20Stef Walter    va_start (va, format);
b9d8c6172e48a2633ebe196b2e88bebdf9523c20Stef Walter    args = valist_to_args (va, &num_args);
b9d8c6172e48a2633ebe196b2e88bebdf9523c20Stef Walter    va_end (va);
b9d8c6172e48a2633ebe196b2e88bebdf9523c20Stef Walter
b9d8c6172e48a2633ebe196b2e88bebdf9523c20Stef Walter    if (args == NULL) {
b9d8c6172e48a2633ebe196b2e88bebdf9523c20Stef Walter        errno = ENOMEM;
b9d8c6172e48a2633ebe196b2e88bebdf9523c20Stef Walter        return -1;
b9d8c6172e48a2633ebe196b2e88bebdf9523c20Stef Walter    }
b9d8c6172e48a2633ebe196b2e88bebdf9523c20Stef Walter
b9d8c6172e48a2633ebe196b2e88bebdf9523c20Stef Walter    if (len)
b9d8c6172e48a2633ebe196b2e88bebdf9523c20Stef Walter        cx.data[0] = '\0';
b9d8c6172e48a2633ebe196b2e88bebdf9523c20Stef Walter
b9d8c6172e48a2633ebe196b2e88bebdf9523c20Stef Walter    ret = safe_format_string_cb (snprintf_copy_fn, &cx, format, args, num_args);
b9d8c6172e48a2633ebe196b2e88bebdf9523c20Stef Walter    if (ret < 0) {
b9d8c6172e48a2633ebe196b2e88bebdf9523c20Stef Walter        error = errno;
b9d8c6172e48a2633ebe196b2e88bebdf9523c20Stef Walter    } else if (len > 0) {
b9d8c6172e48a2633ebe196b2e88bebdf9523c20Stef Walter        cx.data[MIN (cx.length, len - 1)] = '\0';
b9d8c6172e48a2633ebe196b2e88bebdf9523c20Stef Walter    }
b9d8c6172e48a2633ebe196b2e88bebdf9523c20Stef Walter
b9d8c6172e48a2633ebe196b2e88bebdf9523c20Stef Walter    free (args);
b9d8c6172e48a2633ebe196b2e88bebdf9523c20Stef Walter
b9d8c6172e48a2633ebe196b2e88bebdf9523c20Stef Walter    if (error)
b9d8c6172e48a2633ebe196b2e88bebdf9523c20Stef Walter        errno = error;
b9d8c6172e48a2633ebe196b2e88bebdf9523c20Stef Walter    return ret;
b9d8c6172e48a2633ebe196b2e88bebdf9523c20Stef Walter}