[pacman-dev] [PATCH] Enable Perl regular expressions in NoExtract.

[Dave Reisner]

On Tue, Jun 04, 2013 at 05:03:47PM +0200, Patrick Steinhardt wrote:
> Until now it was not easily possible to remove all files but some
> in a given directory. By enabling Perl regular expressions for
> NoExtract this is now made possible through negative lookahead.
> 
> Fixes FS#31749.
> ---
> 
> This patch is work in progress. I want to check if there is
> interest in having this feature available in pacman and how the
> extra dependency on libpcre is received. If it is well received I
> might still do some rework for the actual matching of NoExtract
> items, as currently I'm always recompiling the pattern for each
> match.

I've considered moving to PCRE, but I'm curious:

1) Why do you need this for NoExtract? Please be *specific*
2) What is insufficient about POSIX regex? (#include <regex.h>)

>  configure.ac            | 13 ++++++++++++-
>  lib/libalpm/Makefile.am |  6 ++++--
>  lib/libalpm/add.c       |  2 +-
>  lib/libalpm/util.c      | 22 ++++++++++++++++++++++
>  lib/libalpm/util.h      |  1 +
>  5 files changed, 40 insertions(+), 4 deletions(-)
> 
> diff --git a/configure.ac b/configure.ac
> index 1ea0fce..29ea101 100644
> --- a/configure.ac
> +++ b/configure.ac
> @@ -230,6 +230,17 @@ if test "x$with_libcurl" != "xno"; then
>  fi
>  AM_CONDITIONAL(HAVE_LIBCURL, [test "$have_libcurl" = "yes"])
>  
> +# Check for PCRE
> +have_libpcre=no
> +if test "x$with_libpcre" != "xno"; then
> +	PKG_CHECK_MODULES(LIBPCRE, [libpcre],
> +		[AC_DEFINE(HAVE_LIBPCRE, 1, [Define if libpcre is available]) have_libpcre=yes], have_libpcre=no)
> +	if test "x$have_libpcre" = xno -a "x$with_libpcre" = xyes; then
> +		AC_MSG_ERROR([*** libpcre is required for file matching support])
> +	fi
> +fi
> +AM_CONDITIONAL(HAVE_LIBPCRE, [test "$have_libpcre" = "yes"])
> +
>  # Check for gpgme
>  AC_MSG_CHECKING(whether to link with libgpgme)
>  AS_IF([test "x$with_gpgme" != "xno"],
> @@ -523,7 +534,7 @@ ${PACKAGE_NAME}:
>      compiler               : ${CC}
>      preprocessor flags     : ${CPPFLAGS}
>      compiler flags         : ${WARNING_CFLAGS} ${CFLAGS}
> -    library flags          : ${LIBS} ${LIBSSL_LIBS} ${LIBARCHIVE_LIBS} ${LIBCURL_LIBS} ${GPGME_LIBS}
> +    library flags          : ${LIBS} ${LIBSSL_LIBS} ${LIBPCRE_LIBS} ${LIBARCHIVE_LIBS} ${LIBCURL_LIBS} ${GPGME_LIBS}
>      linker flags           : ${LDFLAGS}
>  
>      Architecture           : ${CARCH}
> diff --git a/lib/libalpm/Makefile.am b/lib/libalpm/Makefile.am
> index 171bc46..0f71aed 100644
> --- a/lib/libalpm/Makefile.am
> +++ b/lib/libalpm/Makefile.am
> @@ -75,13 +75,15 @@ libalpm_la_CFLAGS = \
>  	$(GPGME_CFLAGS) \
>  	$(LIBARCHIVE_CFLAGS) \
>  	$(LIBCURL_CFLAGS) \
> -	$(LIBSSL_CFLAGS)
> +	$(LIBSSL_CFLAGS) \
> +	$(LIBPCRE_CFLAGS)
>  
>  libalpm_la_LIBADD = \
>  	$(LTLIBINTL) \
>  	$(GPGME_LIBS) \
>  	$(LIBARCHIVE_LIBS) \
>  	$(LIBCURL_LIBS) \
> -	$(LIBSSL_LIBS)
> +	$(LIBSSL_LIBS) \
> +	$(LIBPCRE_LIBS)
>  
>  # vim:set ts=2 sw=2 noet:
> diff --git a/lib/libalpm/add.c b/lib/libalpm/add.c
> index c20e7c6..d80dbe4 100644
> --- a/lib/libalpm/add.c
> +++ b/lib/libalpm/add.c
> @@ -183,7 +183,7 @@ static int extract_single_file(alpm_handle_t *handle, struct archive *archive,
>  	}
>  
>  	/* if a file is in NoExtract then we never extract it */
> -	if(alpm_list_find(handle->noextract, entryname, _alpm_fnmatch)) {
> +	if(alpm_list_find(handle->noextract, entryname, _alpm_regex)) {
>  		_alpm_log(handle, ALPM_LOG_DEBUG, "%s is in NoExtract,"
>  				" skipping extraction of %s\n",
>  				entryname, filename);
> diff --git a/lib/libalpm/util.c b/lib/libalpm/util.c
> index f84fb66..5858d28 100644
> --- a/lib/libalpm/util.c
> +++ b/lib/libalpm/util.c
> @@ -33,6 +33,7 @@
>  #include <sys/wait.h>
>  #include <locale.h> /* setlocale */
>  #include <fnmatch.h>
> +#include <pcre.h>
>  
>  /* libarchive */
>  #include <archive.h>
> @@ -1261,6 +1262,27 @@ int _alpm_fnmatch(const void *pattern, const void *string)
>  	return fnmatch(pattern, string, 0);
>  }
>  
> +/** Checks whether a string matches an extended Perl regular expression.
> + * @param pattern string to match against
> + * @param string string to check against pattern
> + * @return 0 if string matches pattern, non-zero if they don't match and on
> + * error
> + */
> +int _alpm_regex(const void *pattern, const void *string)
> +{
> +	const char *error;
> +	int erroroff;
> +
> +	pcre *pcre = pcre_compile(pattern, PCRE_EXTENDED | PCRE_ANCHORED, &error, &erroroff, NULL);
> +	if (error != NULL) {
> +		return -1;
> +	}
> +
> +	int ret = pcre_exec(pcre, NULL, string, strlen(string), 0, 0, NULL, 0);
> +	pcre_free(pcre);
> +	return ret < 0;
> +}
> +
>  void _alpm_alloc_fail(size_t size)
>  {
>  	fprintf(stderr, "alloc failure: could not allocate %zd bytes\n", size);
> diff --git a/lib/libalpm/util.h b/lib/libalpm/util.h
> index 56031f3..5ec36b6 100644
> --- a/lib/libalpm/util.h
> +++ b/lib/libalpm/util.h
> @@ -141,6 +141,7 @@ int _alpm_raw_cmp(const char *first, const char *second);
>  int _alpm_raw_ncmp(const char *first, const char *second, size_t max);
>  int _alpm_access(alpm_handle_t *handle, const char *dir, const char *file, int amode);
>  int _alpm_fnmatch(const void *pattern, const void *string);
> +int _alpm_regex(const void *pattern, const void *string);
>  
>  #ifndef HAVE_STRSEP
>  char *strsep(char **, const char *);
> -- 
> 1.8.3
> 



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