Coverage Report

Created: 2024-05-04 12:45

/proc/self/cwd/external/gif/openbsd-reallocarray.c
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/*
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 * Copyright (c) 2008 Otto Moerbeek <otto@drijf.net>
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 * SPDX-License-Identifier: MIT
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 */
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#include <sys/types.h>
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#include <errno.h>
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#include <stdint.h>
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#include <stdlib.h>
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#ifndef SIZE_MAX
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    #define SIZE_MAX     UINTPTR_MAX
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#endif
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/*
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 * This is sqrt(SIZE_MAX+1), as s1*s2 <= SIZE_MAX
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 * if both s1 < MUL_NO_OVERFLOW and s2 < MUL_NO_OVERFLOW
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 */
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28.0k
#define MUL_NO_OVERFLOW ((size_t)1 << (sizeof(size_t) * 4))
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void *
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openbsd_reallocarray(void *optr, size_t nmemb, size_t size)
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9.34k
{
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  if ((nmemb >= MUL_NO_OVERFLOW || size >= MUL_NO_OVERFLOW) &&
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9.34k
      nmemb > 0 && SIZE_MAX / nmemb < size) {
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0
    errno = ENOMEM;
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0
    return NULL;
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0
  }
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  /*
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   * Head off variations in realloc behavior on different
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   * platforms (reported by MarkR <mrogers6@users.sf.net>)
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   *
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   * The behaviour of reallocarray is implementation-defined if
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   * nmemb or size is zero. It can return NULL or non-NULL
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   * depending on the platform.
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   * https://www.securecoding.cert.org/confluence/display/c/MEM04-C.Beware+of+zero-lengthallocations
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   *
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   * Here are some extracts from realloc man pages on different platforms.
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   *
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   * void realloc( void memblock, size_t size );
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   *
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   * Windows:
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   *
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   * If there is not enough available memory to expand the block
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   * to the given size, the original block is left unchanged,
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   * and NULL is returned.  If size is zero, then the block
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   * pointed to by memblock is freed; the return value is NULL,
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   * and memblock is left pointing at a freed block.
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   *
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   * OpenBSD:
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   *
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   * If size or nmemb is equal to 0, a unique pointer to an
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   * access protected, zero sized object is returned. Access via
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   * this pointer will generate a SIGSEGV exception.
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   *
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   * Linux:
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   *
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   * If size was equal to 0, either NULL or a pointer suitable
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   * to be passed to free() is returned.
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   *
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   * OS X:
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   *
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   * If size is zero and ptr is not NULL, a new, minimum sized
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   * object is allocated and the original object is freed.
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   *
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   * It looks like images with zero width or height can trigger
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   * this, and fuzzing behaviour will differ by platform, so
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   * fuzzing on one platform may not detect zero-size allocation
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   * problems on other platforms.
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   */
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  if (size == 0 || nmemb == 0)
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      return NULL;
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  return realloc(optr, size * nmemb);
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}