On Fri, Mar 21, 2025 at 11:01 AM Iain Sandoe <iains....@gmail.com> wrote:
>
> It seems that libiberty already has replacements for most of the
> mem* functions, but they are not published via include/libiberty.h.
>
> Tested on x86_64 Linux, Darwin aarch64 Linux, OK for trunk?
OK.
Richard.
> thanks,
> Iain
>
> --- 8< ---
>
> This adds an implementation of memrchr to libiberty and arranges
> to configure gcc to use it, if the host does not have it.
>
> gcc/ChangeLog:
>
> * config.in: Regenerate.
> * configure: Regenerate.
> * configure.ac: Check for host memrchr.
>
> include/ChangeLog:
>
> * libiberty.h (memrchr): New.
>
> libiberty/ChangeLog:
>
> * Makefile.in: Add memrchr build rules.
> * config.in: Regenerate.
> * configure: Regenerate.
> * configure.ac: Check for memrchr.
> * functions.texi: Document memrchr.
> * memrchr.c: New file.
>
> Signed-off-by: Iain Sandoe <i...@sandoe.co.uk>
> ---
> gcc/config.in | 6 ++++++
> gcc/configure | 2 +-
> gcc/configure.ac | 2 +-
> include/libiberty.h | 10 ++++++++++
> libiberty/Makefile.in | 17 +++++++++++++----
> libiberty/config.in | 3 +++
> libiberty/configure | 5 +++--
> libiberty/configure.ac | 5 +++--
> libiberty/functions.texi | 14 ++++++++++++++
> libiberty/memrchr.c | 33 +++++++++++++++++++++++++++++++++
> 10 files changed, 87 insertions(+), 10 deletions(-)
> create mode 100644 libiberty/memrchr.c
>
> diff --git a/gcc/config.in b/gcc/config.in
> index 0d8a6ba1808..7c89cab7717 100644
> --- a/gcc/config.in
> +++ b/gcc/config.in
> @@ -1960,6 +1960,12 @@
> #endif
>
>
> +/* Define to 1 if you have the `memrchr' function. */
> +#ifndef USED_FOR_TARGET
> +#undef HAVE_MEMRCHR
> +#endif
> +
> +
> /* Define to 1 if you have the `mmap' function. */
> #ifndef USED_FOR_TARGET
> #undef HAVE_MMAP
> diff --git a/gcc/configure b/gcc/configure
> index 063b9ce6701..ab6bec1f0ae 100755
> --- a/gcc/configure
> +++ b/gcc/configure
> @@ -10640,7 +10640,7 @@ for ac_func in times clock kill getrlimit setrlimit
> atoq \
> popen sysconf strsignal getrusage nl_langinfo \
> gettimeofday mbstowcs wcswidth mmap posix_fallocate setlocale \
> clearerr_unlocked feof_unlocked ferror_unlocked fflush_unlocked
> fgetc_unlocked fgets_unlocked fileno_unlocked fprintf_unlocked
> fputc_unlocked fputs_unlocked fread_unlocked fwrite_unlocked
> getchar_unlocked getc_unlocked putchar_unlocked putc_unlocked madvise
> mallinfo mallinfo2 fstatat getauxval \
> - clock_gettime munmap msync get_current_dir_name
> + clock_gettime munmap msync get_current_dir_name memrchr
> do :
> as_ac_var=`$as_echo "ac_cv_func_$ac_func" | $as_tr_sh`
> ac_fn_cxx_check_func "$LINENO" "$ac_func" "$as_ac_var"
> diff --git a/gcc/configure.ac b/gcc/configure.ac
> index 3243472680c..fca0579574f 100644
> --- a/gcc/configure.ac
> +++ b/gcc/configure.ac
> @@ -1574,7 +1574,7 @@ AC_CHECK_FUNCS(times clock kill getrlimit setrlimit
> atoq \
> popen sysconf strsignal getrusage nl_langinfo \
> gettimeofday mbstowcs wcswidth mmap posix_fallocate setlocale \
> gcc_UNLOCKED_FUNCS madvise mallinfo mallinfo2 fstatat getauxval \
> - clock_gettime munmap msync get_current_dir_name)
> + clock_gettime munmap msync get_current_dir_name memrchr)
>
> # At least for glibc, clock_gettime is in librt. But don't pull that
> # in if it still doesn't give us the function we want.
> diff --git a/include/libiberty.h b/include/libiberty.h
> index f2e763a306a..d4e8791b14b 100644
> --- a/include/libiberty.h
> +++ b/include/libiberty.h
> @@ -215,6 +215,16 @@ extern int ffs(int);
> extern int mkstemps(char *, int);
> #endif
>
> +#if defined (HAVE_DECL_MKSTEMPS) && !HAVE_DECL_MKSTEMPS
> +extern int mkstemps(char *, int);
> +#endif
> +
> +/* Make memrchr available on systems that do not have it. */
> +#if !defined (__GNU_LIBRARY__ ) && !defined (__linux__) && \
> + !defined (HAVE_MEMRCHR)
> +extern void *memrchr(const void *, int, size_t);
> +#endif
> +
> /* Get the working directory. The result is cached, so don't call
> chdir() between calls to getpwd(). */
>
> diff --git a/libiberty/Makefile.in b/libiberty/Makefile.in
> index 4870fa95f2f..ce54d88278d 100644
> --- a/libiberty/Makefile.in
> +++ b/libiberty/Makefile.in
> @@ -139,8 +139,8 @@ CFILES = alloca.c argv.c asprintf.c atexit.c
> \
> ldirname.c \
> lrealpath.c \
> make-relative-prefix.c \
> - make-temp-file.c md5.c memchr.c memcmp.c memcpy.c memmem.c \
> - memmove.c mempcpy.c memset.c mkstemps.c \
> + make-temp-file.c md5.c memchr.c memrchr.c memcmp.c memcpy.c \
> + memmem.c memmove.c mempcpy.c memset.c mkstemps.c \
> objalloc.c obstack.c \
> partition.c pexecute.c \
> pex-common.c pex-djgpp.c pex-msdos.c pex-one.c \
> @@ -213,8 +213,8 @@ CONFIGURED_OFILES = ./asprintf.$(objext)
> ./atexit.$(objext) \
> ./getcwd.$(objext) ./getpagesize.$(objext) \
> ./gettimeofday.$(objext) \
> ./index.$(objext) ./insque.$(objext) \
> - ./memchr.$(objext) ./memcmp.$(objext) ./memcpy.$(objext) \
> - ./memmem.$(objext) ./memmove.$(objext) \
> + ./memchr.$(objext) ./memrchr.$(objext) ./memcmp.$(objext) \
> + ./memcpy.$(objext) ./memmem.$(objext) ./memmove.$(objext) \
> ./mempcpy.$(objext) ./memset.$(objext) ./mkstemps.$(objext) \
> ./pex-djgpp.$(objext) ./pex-msdos.$(objext) \
> ./pex-unix.$(objext) ./pex-win32.$(objext) \
> @@ -1025,6 +1025,15 @@ $(CONFIGURED_OFILES): stamp-picdir stamp-noasandir
> else true; fi
> $(COMPILE.c) $(srcdir)/memchr.c $(OUTPUT_OPTION)
>
> +./memrchr.$(objext): $(srcdir)/memrchr.c $(INCDIR)/ansidecl.h
> + if [ x"$(PICFLAG)" != x ]; then \
> + $(COMPILE.c) $(PICFLAG) $(srcdir)/memrchr.c -o pic/$@; \
> + else true; fi
> + if [ x"$(NOASANFLAG)" != x ]; then \
> + $(COMPILE.c) $(PICFLAG) $(NOASANFLAG) $(srcdir)/memrchr.c -o
> noasan/$@; \
> + else true; fi
> + $(COMPILE.c) $(srcdir)/memrchr.c $(OUTPUT_OPTION)
> +
> ./memcmp.$(objext): $(srcdir)/memcmp.c $(INCDIR)/ansidecl.h
> if [ x"$(PICFLAG)" != x ]; then \
> $(COMPILE.c) $(PICFLAG) $(srcdir)/memcmp.c -o pic/$@; \
> diff --git a/libiberty/config.in b/libiberty/config.in
> index b055150961c..3b8716511f0 100644
> --- a/libiberty/config.in
> +++ b/libiberty/config.in
> @@ -186,6 +186,9 @@
> /* Define to 1 if you have the <memory.h> header file. */
> #undef HAVE_MEMORY_H
>
> +/* Define to 1 if you have the `memrchr' function. */
> +#undef HAVE_MEMRCHR
> +
> /* Define to 1 if you have the `memset' function. */
> #undef HAVE_MEMSET
>
> diff --git a/libiberty/configure b/libiberty/configure
> index 347719c6262..02fbaabe89e 100755
> --- a/libiberty/configure
> +++ b/libiberty/configure
> @@ -6210,6 +6210,7 @@ funcs="$funcs gettimeofday"
> funcs="$funcs index"
> funcs="$funcs insque"
> funcs="$funcs memchr"
> +funcs="$funcs memrchr"
> funcs="$funcs memcmp"
> funcs="$funcs memcpy"
> funcs="$funcs memmem"
> @@ -6276,7 +6277,7 @@ if test "x" = "y"; then
> ffs __fsetlocking \
> getcwd getpagesize getrlimit getrusage getsysinfo gettimeofday \
> index insque \
> - memchr memcmp memcpy memmem memmove memset mkstemps \
> + memchr memrchr memcmp memcpy memmem memmove memset mkstemps \
> on_exit \
> pipe2 posix_spawn posix_spawnp psignal \
> pstat_getdynamic pstat_getstatic putenv \
> @@ -6691,7 +6692,7 @@ esac
>
> for f in atexit basename bcmp bcopy bsearch bzero calloc clock ffs \
> getcwd getpagesize getrusage gettimeofday \
> - index insque memchr memcmp memcpy memmove memset psignal \
> + index insque memchr memrchr memcmp memcpy memmove memset
> psignal \
> putenv random rename rindex sbrk setenv stpcpy strcasecmp \
> strchr strdup strerror strncasecmp strrchr strstr strtod \
> strtol strtoul sysconf times tmpnam vfprintf vprintf \
> diff --git a/libiberty/configure.ac b/libiberty/configure.ac
> index 5bad0f93692..3de5eca0df2 100644
> --- a/libiberty/configure.ac
> +++ b/libiberty/configure.ac
> @@ -370,6 +370,7 @@ funcs="$funcs gettimeofday"
> funcs="$funcs index"
> funcs="$funcs insque"
> funcs="$funcs memchr"
> +funcs="$funcs memrchr"
> funcs="$funcs memcmp"
> funcs="$funcs memcpy"
> funcs="$funcs memmem"
> @@ -436,7 +437,7 @@ if test "x" = "y"; then
> ffs __fsetlocking \
> getcwd getpagesize getrlimit getrusage getsysinfo gettimeofday \
> index insque \
> - memchr memcmp memcpy memmem memmove memset mkstemps \
> + memchr memrchr memcmp memcpy memmem memmove memset mkstemps \
> on_exit \
> pipe2 posix_spawn posix_spawnp psignal \
> pstat_getdynamic pstat_getstatic putenv \
> @@ -555,7 +556,7 @@ if test -n "${with_target_subdir}"; then
>
> for f in atexit basename bcmp bcopy bsearch bzero calloc clock ffs \
> getcwd getpagesize getrusage gettimeofday \
> - index insque memchr memcmp memcpy memmove memset psignal \
> + index insque memchr memrchr memcmp memcpy memmove memset
> psignal \
> putenv random rename rindex sbrk setenv stpcpy strcasecmp \
> strchr strdup strerror strncasecmp strrchr strstr strtod \
> strtol strtoul sysconf times tmpnam vfprintf vprintf \
> diff --git a/libiberty/functions.texi b/libiberty/functions.texi
> index b56b02e0686..7c7da1ba296 100644
> --- a/libiberty/functions.texi
> +++ b/libiberty/functions.texi
> @@ -749,6 +749,20 @@ returned.
>
> @end deftypefn
>
> +@c memrchr.c:3
> +@deftypefn Supplemental void* memrchr (const void *@var{s}, int @var{c}, @
> + size_t @var{n})
> +
> +This function searches memory for the character @var{c} in reverse order,
> +starting at @code{*@var{s}+@var{n}-1} . The search only ends with
> +the first occurrence of @var{c}, or when the start us reached; in particular,
> +a null character does not terminate the search. If the character @var{c} is
> +found within @var{length} characters of @code{*@var{s}}, a pointer
> +to the character is returned. If @var{c} is not found, then @code{NULL} is
> +returned.
> +
> +@end deftypefn
> +
> @c memcmp.c:6
> @deftypefn Supplemental int memcmp (const void *@var{x}, const void
> *@var{y}, @
> size_t @var{count})
> diff --git a/libiberty/memrchr.c b/libiberty/memrchr.c
> new file mode 100644
> index 00000000000..fe7713ecce5
> --- /dev/null
> +++ b/libiberty/memrchr.c
> @@ -0,0 +1,33 @@
> +/*
> +
> +@deftypefn Supplemental void* memrchr (const void *@var{s}, int @var{c}, @
> + size_t @var{n})
> +
> +This function searches memory for the character @var{c} in reverse order,
> +starting at @code{*@var{s}+@var{n}-1} . The search only ends with
> +the first occurrence of @var{c}, or when the start us reached; in particular,
> +a null character does not terminate the search. If the character @var{c} is
> +found within @var{length} characters of @code{*@var{s}}, a pointer
> +to the character is returned. If @var{c} is not found, then @code{NULL} is
> +returned.
> +
> +@end deftypefn
> +
> +*/
> +
> +#include <ansidecl.h>
> +#include <stddef.h>
> +
> +void *
> +memrchr (const void *src_void, int c, size_t length)
> +{
> + if (length == 0)
> + return NULL;
> +
> + const unsigned char *p = (const unsigned char*)src_void;
> + p += length;
> + while (*--p != (unsigned char)c)
> + if (src_void == p)
> + return NULL;
> + return (void *)p;
> +}
> --
> 2.39.2 (Apple Git-143)
>
