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https://https.git.savannah.gnu.org/git/gnulib.git
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Paul Eggert
6f013454d4
Also, port better to non-glibc, and in documentation update the list of platforms needing a fix. This includes 32-bit platforms using AddressSanitizer, unfortunately. * m4/malloc.m4 (gl_CHECK_MALLOC_PTRDIFF): Invoke gl_MUSL_LIBC. musl is safe, as is FreeBSD 11+, NetBSD 8+, OpenBSD 5.6+, AIX, Microsoft Windows. However, the AddressSanitizer is unsafe.
61 lines
2.0 KiB
Plaintext
61 lines
2.0 KiB
Plaintext
@node reallocarray
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@subsection @code{reallocarray}
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@findex reallocarray
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POSIX specification:@* @url{https://pubs.opengroup.org/onlinepubs/9799919799/functions/reallocarray.html}
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Documentation:
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@itemize
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@item
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@ifinfo
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@ref{Changing Block Size,,Changing the Size of a Block,libc},
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@end ifinfo
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@ifnotinfo
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@url{https://www.gnu.org/software/libc/manual/html_node/Changing-Block-Size.html},
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@end ifnotinfo
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@item
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@uref{https://www.kernel.org/doc/man-pages/online/pages/man3/reallocarray.3.html,,man reallocarray}.
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@end itemize
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Gnulib module: reallocarray
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@mindex reallocarray
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Portability problems fixed by Gnulib:
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@itemize
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@item
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This function is missing on many platforms:
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glibc 2.25, macOS 14, FreeBSD 10, NetBSD 7, OpenBSD 5.5, Minix 3.3.0, AIX 7.2, HP-UX 11, Solaris 11.4, Cygwin 1.7.x, mingw, MSVC 14, Android 9.0.
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@item
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On some platforms, when the function fails it might set @code{errno}
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to @code{EAGAIN} instead of to @code{ENOMEM}. Although POSIX allows
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@code{EAGAIN}, the @code{reallocarray} module insists on @code{ENOMEM}
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which also conforms to POSIX and is GNU-compatible:
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Solaris 11.4.
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@item
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On some 32-bit platforms, @code{reallocarray (p, n, s)} can succeed even if
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multiplying @code{n} by @code{s} would exceed @code{PTRDIFF_MAX},
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which can lead to undefined behavior later:
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AddressSanitizer of gcc 16.1 or clang 22.1, glibc 2.29, Solaris 11.4.
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Although this behavior is arguably
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allowed by POSIX it is not compatible with GNU and
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can lead to behavior not defined by POSIX later,
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so @code{realloc-posix} does not allow going over the limit.
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@item
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It is not portable to call
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@code{reallocarray (p, n, s)} when either @code{n} or @code{s} is zero,
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as @code{reallocarray} has the same issues with zero sizes
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that @code{realloc} does. @xref{realloc}.
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@end itemize
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Portability problems not fixed by Gnulib:
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@itemize
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@item
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When not growing an already-allocated region,
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@code{reallocarray}, like @code{realloc}, can fail and return a null pointer:
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glibc 2.44 and probably other platforms.
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@end itemize
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