1 files changed, 109 insertions, 0 deletions
diff --git a/lib/libalpm/filelist.c b/lib/libalpm/filelist.c
new file mode 100644
index 00000000..04075a52
--- /dev/null
+++ b/lib/libalpm/filelist.c
@@ -0,0 +1,109 @@
+/*
+ *  filelist.c
+ *
+ *  Copyright (c) 2012 Pacman Development Team <pacman-dev@archlinux.org>
+ *
+ *  This program is free software; you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License as published by
+ *  the Free Software Foundation; either version 2 of the License, or
+ *  (at your option) any later version.
+ *
+ *  This program is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU General Public License for more details.
+ *
+ *  You should have received a copy of the GNU General Public License
+ *  along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include <string.h>
+
+/* libalpm */
+#include "filelist.h"
+
+/* Returns a set operation on the provided two lists of files.
+ * Pre-condition: both lists are sorted!
+ * When done, free the list but NOT the contained data.
+ *
+ * Operations:
+ *   DIFFERENCE - a difference operation is performed. filesA - filesB.
+ *   INTERSECT - an intersection operation is performed. filesA & filesB.
+ */
+alpm_list_t *_alpm_filelist_operation(alpm_filelist_t *filesA,
+		alpm_filelist_t *filesB, enum filelist_op operation)
+{
+	alpm_list_t *ret = NULL;
+	size_t ctrA = 0, ctrB = 0;
+
+	while(ctrA < filesA->count && ctrB < filesB->count) {
+		alpm_file_t *fileA = filesA->files + ctrA;
+		alpm_file_t *fileB = filesB->files + ctrB;
+		const char *strA = fileA->name;
+		const char *strB = fileB->name;
+		/* skip directories, we don't care about them */
+		if(strA[strlen(strA)-1] == '/') {
+			ctrA++;
+		} else if(strB[strlen(strB)-1] == '/') {
+			ctrB++;
+		} else {
+			int cmp = strcmp(strA, strB);
+			if(cmp < 0) {
+				if(operation == DIFFERENCE) {
+					/* item only in filesA, qualifies as a difference */
+					ret = alpm_list_add(ret, fileA);
+				}
+				ctrA++;
+			} else if(cmp > 0) {
+				ctrB++;
+			} else {
+				if(operation == INTERSECT) {
+					/* item in both, qualifies as an intersect */
+					ret = alpm_list_add(ret, fileA);
+				}
+				ctrA++;
+				ctrB++;
+			}
+	  }
+	}
+
+	/* if doing a difference, ensure we have completely emptied pA */
+	while(operation == DIFFERENCE && ctrA < filesA->count) {
+		alpm_file_t *fileA = filesA->files + ctrA;
+		const char *strA = fileA->name;
+		/* skip directories */
+		if(strA[strlen(strA)-1] != '/') {
+			ret = alpm_list_add(ret, fileA);
+		}
+		ctrA++;
+	}
+
+	return ret;
+}
+
+/* Helper function for comparing files list entries
+ */
+int _alpm_files_cmp(const void *f1, const void *f2)
+{
+	const alpm_file_t *file1 = f1;
+	const alpm_file_t *file2 = f2;
+	return strcmp(file1->name, file2->name);
+}
+
+
+alpm_file_t *alpm_filelist_contains(alpm_filelist_t *filelist,
+		const char *path)
+{
+	alpm_file_t key;
+
+	if(!filelist) {
+		return NULL;
+	}
+
+	key.name = (char *)path;
+
+	return bsearch(&key, filelist->files, filelist->count,
+			sizeof(alpm_file_t), _alpm_files_cmp);
+}
+
+/* vim: set ts=2 sw=2 noet: */