[pacman-dev] [PATCH v3] Enable inverted patterns in NoExtract and NoUpgrade.

[Patrick Steinhardt]

It is now possible to invert patterns in NoExtract and NoUpgrade.
This feature allows users to whitelist certain files that were
previously blacklisted by another entry.
---

Fixed remarks by Andrew:

- docs now mention the need to escape leading exclamation mark or
  backslash.
- _alpm_fnmatch_patterns now iterates over NoExtract in reverse

 doc/pacman.conf.5.txt | 10 ++++++++--
 lib/libalpm/add.c     |  4 ++--
 lib/libalpm/util.c    | 31 +++++++++++++++++++++++++++++++
 lib/libalpm/util.h    |  1 +
 4 files changed, 42 insertions(+), 4 deletions(-)

diff --git a/doc/pacman.conf.5.txt b/doc/pacman.conf.5.txt
index 83a399e..049faee 100644
--- a/doc/pacman.conf.5.txt
+++ b/doc/pacman.conf.5.txt
@@ -128,7 +128,10 @@ Options
 	'.pacnew' extension.
 	These files refer to files in the package archive, so do not include the
 	leading slash (the RootDir) when specifying them. Shell-style glob patterns
-	are allowed.
+	are allowed. It is possible to invert matches by prepending a file with
+	an exclamation mark. Inverted files will result in previously blacklisted
+	files being whitelisted again. Subsequent matches will override previous
+	ones. A leading literal exclamation mark or backslash needs to be escaped.
 
 *NoExtract =* file ...::
 	All files listed with a `NoExtract` directive will never be extracted from
@@ -138,7 +141,10 @@ Options
 	from the 'apache' package.
 	These files refer to files in the package archive, so do not include the
 	leading slash (the RootDir) when specifying them. Shell-style glob patterns
-	are allowed.
+	are allowed. It is possible to invert matches by prepending a file with
+	an exclamation mark. Inverted files will result in previously blacklisted
+	files being whitelisted again. Subsequent matches will override previous
+	ones. A leading literal exclamation mark or backslash needs to be escaped.
 
 *CleanMethod =* KeepInstalled &| KeepCurrent::
 	If set to `KeepInstalled` (the default), the '-Sc' operation will clean
diff --git a/lib/libalpm/add.c b/lib/libalpm/add.c
index c20e7c6..6e12f56 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_fnmatch_patterns(handle->noextract, entryname) == 0) {
 		_alpm_log(handle, ALPM_LOG_DEBUG, "%s is in NoExtract,"
 				" skipping extraction of %s\n",
 				entryname, filename);
@@ -245,7 +245,7 @@ static int extract_single_file(alpm_handle_t *handle, struct archive *archive,
 		} else {
 			/* case 3: */
 			/* if file is in NoUpgrade, don't touch it */
-			if(alpm_list_find(handle->noupgrade, entryname, _alpm_fnmatch)) {
+			if(_alpm_fnmatch_patterns(handle->noupgrade, entryname) == 0) {
 				notouch = 1;
 			} else {
 				alpm_backup_t *backup;
diff --git a/lib/libalpm/util.c b/lib/libalpm/util.c
index f84fb66..15c1a67 100644
--- a/lib/libalpm/util.c
+++ b/lib/libalpm/util.c
@@ -1249,6 +1249,37 @@ int _alpm_access(alpm_handle_t *handle, const char *dir, const char *file, int a
 	return ret;
 }
 
+/** Checks whether a string matches at least one shell wildcard pattern.
+ * Checks for matches with fnmatch. Matches are inverted by prepending
+ * patterns with an exclamation mark. Preceding exclamation marks may be
+ * escaped. Subsequent matches override previous ones.
+ * @param patterns patterns to match against
+ * @param string string to check against pattern
+ * @return 0 if string matches pattern, negative if they don't match and
+ * positive if the last match was inverted
+ */
+int _alpm_fnmatch_patterns(alpm_list_t *patterns, const char *string)
+{
+	alpm_list_t *i;
+	char *pattern;
+	short inverted;
+
+	for(i = alpm_list_last(patterns); i; i = alpm_list_previous(i)) {
+		pattern = i->data;
+
+		inverted = pattern[0] == '!';
+		if(inverted || pattern[0] == '\\') {
+			pattern++;
+		}
+
+		if(_alpm_fnmatch(pattern, string) == 0) {
+			return inverted;
+		}
+	}
+
+	return -1;
+}
+
 /** Checks whether a string matches a shell wildcard pattern.
  * Wrapper around fnmatch.
  * @param pattern pattern to match against
diff --git a/lib/libalpm/util.h b/lib/libalpm/util.h
index 56031f3..24b7c22 100644
--- a/lib/libalpm/util.h
+++ b/lib/libalpm/util.h
@@ -140,6 +140,7 @@ alpm_time_t _alpm_parsedate(const char *line);
 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_patterns(alpm_list_t *patterns, const char *string);
 int _alpm_fnmatch(const void *pattern, const void *string);
 
 #ifndef HAVE_STRSEP
-- 
1.8.3.1

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