don't download if md5 & sig match already

svn path=/trunk/boinc/; revision=1942

client/client_state.h

@@ -165,7 +165,7 @@ private:
     int link_workunit(PROJECT*, WORKUNIT*);
     int link_result(PROJECT*, RESULT*);
     int latest_version_num(char*);
-    int check_suspend_activities(int&);
+    void check_suspend_activities(int&);
     int suspend_activities(int reason);
     int resume_activities();
     int make_project_dirs();

client/cs_files.C

@@ -95,17 +95,20 @@ int verify_downloaded_file(char* pathname, FILE_INFO& file_info) {
             pathname, file_info.file_signature, project->code_sign_key, verified
         );
         if (retval) {
-            msg_printf(project, MSG_ERROR, "verify_downloaded_file(): internal error\n");
+            msg_printf(project, MSG_ERROR, "verify_downloaded_file(): %s: internal error\n",
+                pathname);
             return ERR_RSA_FAILED;
         }
         if (!verified) {
-            msg_printf(project, MSG_ERROR, "verify_downloaded_file(): file not verified\n");
+            msg_printf(project, MSG_ERROR, "verify_downloaded_file(): %s: file not verified\n",
+                pathname);
             return ERR_RSA_FAILED;
         }
     } else if (strlen(file_info.md5_cksum)) {
         retval = md5_file(pathname, cksum, file_info.nbytes);
         if (strcmp(cksum, file_info.md5_cksum) || retval) {
-            msg_printf(project, MSG_ERROR, "verify_downloaded_file(): MD5 check failed\n");
+            msg_printf(project, MSG_ERROR, "verify_downloaded_file(): %s: MD5 check failed\n",
+                pathname);
             return ERR_MD5_FAILED;
         }
     }

client/pers_file_xfer.C

@@ -30,6 +30,7 @@
 #include "parse.h"
 #include "util.h"
 #include "log_flags.h"
+#include "filesys.h"
 
 // PERS_FILE_XFER represents a persistent file transfer.
 // A set of URLs is given.
@@ -80,6 +81,31 @@ int PERS_FILE_XFER::start_xfer() {
         return ERR_IDLE_PERIOD;
     }
 
+    // Does the file exist already? this could happen for example if we are
+    // downloading an application which exists from a previous installation,
+    // or if we get the same input file (which is unlikely outside the beta
+    // test microcosm)
+    if (!is_upload) {
+        char pathname[256];
+        get_pathname(fip, pathname);
+        double existing_size = 0;
+        if (!file_size(pathname, existing_size) && existing_size == fip->nbytes) {
+            // file exists already and has the right size
+            retval = verify_downloaded_file(pathname, *fip);
+            if (!retval) {
+                // signature and checksum match
+                retval = fip->set_permissions();
+                fip->status = FILE_PRESENT;
+                xfer_done = true;
+
+                msg_printf(
+                    fip->project, MSG_INFO, "File %s exists already, skipping download", pathname);
+                
+                return retval;
+            }
+        }
+    }
+
     // Create a new FILE_XFER object and initialize a
     // download or upload for the persistent file transfer
     //