Add pmdelta_t structure and functions to libalpm.

Signed-off-by: Nathan Jones <nathanj@insightbb.com>
Signed-off-by: Dan McGee <dan@archlinux.org>

1 files changed, 265 insertions, 0 deletions

diff --git a/lib/libalpm/delta.c b/lib/libalpm/delta.c
new file mode 100644
index 00000000..00ed46cb
--- /dev/null
+++ b/lib/libalpm/delta.c
@@ -0,0 +1,265 @@
+/*
+ *  delta.c
+ *
+ *  Copyright (c) 2007 by Judd Vinet <jvinet@zeroflux.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, write to the Free Software
+ *  Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, 
+ *  USA.
+ */
+
+#include "config.h"
+
+#include <stdlib.h>
+#include <string.h>
+
+/* libalpm */
+#include "delta.h"
+#include "util.h"
+#include "log.h"
+#include "alpm_list.h"
+#include "alpm.h"
+
+/** \addtogroup alpm_deltas Delta Functions
+ * @brief Functions to manipulate libalpm deltas
+ * @{
+ */
+
+char SYMEXPORT *alpm_delta_get_from(pmdelta_t *delta)
+{
+	ALPM_LOG_FUNC;
+
+	/* Sanity checks */
+	ASSERT(delta != NULL, return(NULL));
+
+	return(delta->from);
+}
+
+char SYMEXPORT *alpm_delta_get_to(pmdelta_t *delta)
+{
+	ALPM_LOG_FUNC;
+
+	/* Sanity checks */
+	ASSERT(delta != NULL, return(NULL));
+
+	return(delta->to);
+}
+
+unsigned long SYMEXPORT alpm_delta_get_size(pmdelta_t *delta)
+{
+	ALPM_LOG_FUNC;
+
+	/* Sanity checks */
+	ASSERT(delta != NULL, return(-1));
+
+	return(delta->size);
+}
+
+char SYMEXPORT *alpm_delta_get_filename(pmdelta_t *delta)
+{
+	ALPM_LOG_FUNC;
+
+	/* Sanity checks */
+	ASSERT(delta != NULL, return(NULL));
+
+	return(delta->filename);
+}
+
+char SYMEXPORT *alpm_delta_get_md5sum(pmdelta_t *delta)
+{
+	ALPM_LOG_FUNC;
+
+	/* Sanity checks */
+	ASSERT(delta != NULL, return(NULL));
+
+	return(delta->md5sum);
+}
+
+/** @} */
+
+/** Calculates the combined size of a list of delta files.
+ *
+ * @param deltas the list of pmdelta_t * objects
+ *
+ * @return the combined size
+ */
+unsigned long _alpm_delta_path_size(alpm_list_t *deltas)
+{
+	unsigned long sum = 0;
+	alpm_list_t *dlts = deltas;
+
+	while(dlts) {
+		pmdelta_t *d = (pmdelta_t *)alpm_list_getdata(dlts);
+		sum += d->size;
+
+		dlts = alpm_list_next(dlts);
+	}
+
+	return(sum);
+}
+
+/** Calculates the combined size of a list of delta files that are not
+ * in the cache.
+ *
+ * @param deltas the list of pmdelta_t * objects
+ *
+ * @return the combined size
+ */
+unsigned long _alpm_delta_path_size_uncached(alpm_list_t *deltas)
+{
+	unsigned long sum = 0;
+	alpm_list_t *dlts = deltas;
+
+	while(dlts) {
+		pmdelta_t *d = (pmdelta_t *)alpm_list_getdata(dlts);
+		char *fname = _alpm_filecache_find(d->filename);
+
+		if(!fname) {
+			sum += d->size;
+		}
+
+		FREE(fname);
+
+		dlts = alpm_list_next(dlts);
+	}
+
+	return(sum);
+}
+
+/** Calculates the shortest path from one version to another.
+ *
+ * The shortest path is defined as the path with the smallest combined
+ * size, not the length of the path.
+ *
+ * The algorithm is based on Dijkstra's shortest path algorithm.
+ *
+ * @param deltas the list of pmdelta_t * objects that a package has
+ * @param from the version to start from
+ * @param to the version to end at
+ * @param path the current path
+ *
+ * @return the list of pmdelta_t * objects that has the smallest size.
+ * NULL (the empty list) is returned if there is no path between the
+ * versions.
+ */
+static alpm_list_t *shortest_delta_path(alpm_list_t *deltas,
+		const char *from, const char *to, alpm_list_t *path)
+{
+	alpm_list_t *d;
+	alpm_list_t *shortest = NULL;
+
+	/* Found the 'to' version, this is a good path so return it. */
+	if(strcmp(from, to) == 0) {
+		return(path);
+	}
+
+	for(d = deltas; d; d = alpm_list_next(d)) {
+		pmdelta_t *v = alpm_list_getdata(d);
+
+		/* If this vertex has already been visited in the path, go to the
+		 * next vertex. */
+		if(alpm_list_find(path, v))
+			continue;
+
+		/* Once we find a vertex that starts at the 'from' version,
+		 * recursively find the shortest path using the 'to' version of this
+		 * current vertex as the 'from' version in the function call. */
+		if(strcmp(v->from, from) == 0) {
+			alpm_list_t *newpath = alpm_list_copy(path);
+			alpm_list_free(path);
+			newpath = alpm_list_add(newpath, v);
+			newpath = shortest_delta_path(deltas, v->to, to, newpath);
+
+			if(newpath != NULL) {
+				/* The path returned works, now use it unless there is already a
+				 * shorter path found. */
+				if(shortest == NULL) {
+					shortest = newpath;
+				} else if(_alpm_delta_path_size(shortest) > _alpm_delta_path_size(newpath)) {
+					alpm_list_free(shortest);
+					shortest = newpath;
+				} else {
+					alpm_list_free(newpath);
+				}
+			}
+		}
+	}
+
+	return(shortest);
+}
+
+/** Calculates the shortest path from one version to another.
+ *
+ * The shortest path is defined as the path with the smallest combined
+ * size, not the length of the path.
+ *
+ * @param deltas the list of pmdelta_t * objects that a package has
+ * @param from the version to start from
+ * @param to the version to end at
+ *
+ * @return the list of pmdelta_t * objects that has the smallest size.
+ * NULL (the empty list) is returned if there is no path between the
+ * versions.
+ */
+alpm_list_t *_alpm_shortest_delta_path(alpm_list_t *deltas, const char *from,
+		const char *to)
+{
+	alpm_list_t *path = NULL;
+
+	path = shortest_delta_path(deltas, from, to, path);
+
+	return(path);
+}
+
+/** Parses the string representation of a pmdelta_t object.
+ *
+ * This function assumes that the string is in the correct format.
+ *
+ * @param line the string to parse
+ *
+ * @return A pointer to the new pmdelta_t object
+ */
+pmdelta_t *_alpm_delta_parse(char *line)
+{
+	pmdelta_t *delta;
+	char *tmp = line, *tmp2;
+
+	delta = malloc(sizeof(pmdelta_t));
+
+	tmp2 = tmp;
+	tmp = strchr(tmp, ' ');
+	*(tmp++) = '\0';
+	strncpy(delta->from, tmp2, DLT_VERSION_LEN);
+
+	tmp2 = tmp;
+	tmp = strchr(tmp, ' ');
+	*(tmp++) = '\0';
+	strncpy(delta->to, tmp2, DLT_VERSION_LEN);
+
+	tmp2 = tmp;
+	tmp = strchr(tmp, ' ');
+	*(tmp++) = '\0';
+	delta->size = atol(tmp2);
+
+	tmp2 = tmp;
+	tmp = strchr(tmp, ' ');
+	*(tmp++) = '\0';
+	strncpy(delta->filename, tmp2, DLT_FILENAME_LEN);
+
+	strncpy(delta->md5sum, tmp, DLT_MD5SUM_LEN);
+
+	return(delta);
+}
+
+/* vim: set ts=2 sw=2 noet: */