@node strstr
@section @code{strstr}
@findex strstr

POSIX specification:@* @url{https://pubs.opengroup.org/onlinepubs/9699919799/functions/strstr.html}

Gnulib module: strstr or strstr-simple

Portability problems fixed by either Gnulib module @code{strstr-simple}
or @code{strstr}:
@itemize
@item
This function can trigger memchr bugs on some platforms:
glibc 2.10.
@item
This function can trigger false positives for long periodic needles on
some platforms:
glibc 2.12, Cygwin 1.7.7.
@item
This function may fail to find matches on some platforms:
glibc 2.28.
@end itemize

Portability problems fixed by Gnulib @code{strstr}:
@itemize
@item
This function has quadratic instead of linear worst-case complexity on some
platforms:
glibc 2.8, macOS 11.1, FreeBSD 6.2, NetBSD 9.0, OpenBSD 4.0, AIX 5.1, HP-UX 11, IRIX 6.5, Solaris 11.4, Cygwin 1.5.x, mingw, MSVC 14.
@end itemize

Portability problems not fixed by Gnulib:
@itemize
@item
This function cannot work correctly on character strings in most multibyte
locales.  Gnulib provides an alternative function @code{mbsstr} that works
on character strings in all locales.
@end itemize