Add format support for efficient sparse file handling.

[cumulus.git] / metadata.cc

diff --git a/metadata.cc b/metadata.cc
index 7aa9822..f972b75 100644 (file)
--- a/metadata.cc
+++ b/metadata.cc
@@ -9,14 +9,15 @@
 
 #include <string>
 #include <iostream>
+#include <map>
 
 #include "metadata.h"
 #include "ref.h"
 #include "store.h"
-#include "statcache.h"
 #include "util.h"
 
 using std::list;
+using std::map;
 using std::string;
 using std::ostream;
 using std::ostringstream;
@@ -64,6 +65,27 @@ static int pathcmp(const char *path1, const char *path2)
     return pathcmp(slash1 + 1, slash2 + 1);
 }
 
+/* Encode a dictionary of string key/value pairs into a sequence of lines of
+ * the form "key: value".  If it exists, the key "name" is treated specially
+ * and will be listed first. */
+static string encode_dict(const map<string, string>& dict)
+{
+    string result;
+
+    if (dict.find("name") != dict.end()) {
+        result += "name: " + dict.at("name") + "\n";
+    }
+
+    for (map<string, string>::const_iterator i = dict.begin();
+         i != dict.end(); ++i) {
+        if (i->first == "name")
+            continue;
+        result += i->first + ": " + i->second + "\n";
+    }
+
+    return result;
+}
+
 MetadataWriter::MetadataWriter(TarSegmentStore *store,
                                const char *path,
                                const char *snapshot_name,
@@ -162,7 +184,7 @@ bool MetadataWriter::find(const string& path)
 {
     const char *path_str = path.c_str();
     while (!old_metadata_eof) {
-        string old_path = uri_decode(old_metadata["path"]);
+        string old_path = uri_decode(old_metadata["name"]);
         int cmp = pathcmp(old_path.c_str(), path_str);
         if (cmp == 0)
             return true;
@@ -175,6 +197,69 @@ bool MetadataWriter::find(const string& path)
     return false;
 }
 
+/* Does a file appear to be unchanged from the previous time it was backed up,
+ * based on stat information? */
+bool MetadataWriter::is_unchanged(const struct stat *stat_buf)
+{
+    if (old_metadata.find("volatile") != old_metadata.end()
+        && parse_int(old_metadata["volatile"]) != 0)
+        return false;
+
+    if (old_metadata.find("ctime") == old_metadata.end())
+        return false;
+    if (stat_buf->st_ctime != parse_int(old_metadata["ctime"]))
+        return false;
+
+    if (old_metadata.find("mtime") == old_metadata.end())
+        return false;
+    if (stat_buf->st_mtime != parse_int(old_metadata["mtime"]))
+        return false;
+
+    if (old_metadata.find("size") == old_metadata.end())
+        return false;
+    if (stat_buf->st_size != parse_int(old_metadata["size"]))
+        return false;
+
+    if (old_metadata.find("inode") == old_metadata.end())
+        return false;
+    string inode = encode_int(major(stat_buf->st_dev))
+        + "/" + encode_int(minor(stat_buf->st_dev))
+        + "/" + encode_int(stat_buf->st_ino);
+    if (inode != old_metadata["inode"])
+        return false;
+
+    return true;
+}
+
+list<ObjectReference> MetadataWriter::get_blocks()
+{
+    list<ObjectReference> blocks;
+
+    /* Parse the list of blocks. */
+    const char *s = old_metadata["data"].c_str();
+    while (*s != '\0') {
+        if (isspace(*s)) {
+            s++;
+            continue;
+        }
+
+        string ref = "";
+        while (*s != '\0' && !isspace(*s)) {
+            char buf[2];
+            buf[0] = *s;
+            buf[1] = '\0';
+            ref += buf;
+            s++;
+        }
+
+        ObjectReference r = ObjectReference::parse(ref);
+        if (!r.is_null())
+            blocks.push_back(r);
+    }
+
+    return blocks;
+}
+
 /* Ensure contents of metadata are flushed to an object. */
 void MetadataWriter::metadata_flush()
 {
@@ -259,11 +344,10 @@ void MetadataWriter::add(dictionary info)
     item.text += encode_dict(info) + "\n";
 
     if (info == old_metadata) {
-        ObjectReference *ref = ObjectReference::parse(old_metadata_loc);
-        if (ref != NULL) {
+        ObjectReference ref = ObjectReference::parse(old_metadata_loc);
+        if (!ref.is_null()) {
             item.reused = true;
-            item.ref = *ref;
-            delete ref;
+            item.ref = ref;
         }
     }