[svn] Fix a possible race condition when opening files.

[wget] / src / http.c

diff --git a/src/http.c b/src/http.c
index 93f072b53e3aaaf899104562d52551db4fbd4392..6bc4f3be5be0a41994c7bbf57bf837b2ed8d9540 100644 (file)
--- a/src/http.c
+++ b/src/http.c
@@ -1720,7 +1720,27 @@ gethttp (struct url *u, struct http_stat *hs, int *dt, struct url *proxy)
       mkalldirs (*hs->local_file);
       if (opt.backups)
        rotate_backups (*hs->local_file);
-      fp = fopen (*hs->local_file, hs->restval ? "ab" : "wb");
+      if (hs->restval)
+       fp = fopen (*hs->local_file, "ab");
+      else if (opt.noclobber || opt.always_rest || opt.timestamping || opt.dirstruct
+              || opt.output_document)
+       fp = fopen (*hs->local_file, "wb");
+      else
+       {
+         fp = fopen_excl (*hs->local_file, 0);
+         if (!fp && errno == EEXIST)
+           {
+             /* We cannot just invent a new name and use it (which is
+                what functions like unique_create typically do)
+                because we told the user we'd use this name.
+                Instead, return and retry the download.  */
+             logprintf (LOG_NOTQUIET,
+                        _("%s has sprung into existence.\n"),
+                        *hs->local_file);
+             CLOSE_INVALIDATE (sock);
+             return FOPEN_EXCL_ERR;
+           }
+       }
       if (!fp)
        {
          logprintf (LOG_NOTQUIET, "%s: %s\n", *hs->local_file, strerror (errno));
@@ -1992,12 +2012,35 @@ File `%s' already there, will not retrieve.\n"), *hstat.local_file);
        {
        case HERR: case HEOF: case CONSOCKERR: case CONCLOSED:
        case CONERROR: case READERR: case WRITEFAILED:
-       case RANGEERR:
+       case RANGEERR: case FOPEN_EXCL_ERR:
          /* Non-fatal errors continue executing the loop, which will
             bring them to "while" statement at the end, to judge
             whether the number of tries was exceeded.  */
          free_hstat (&hstat);
          printwhat (count, opt.ntry);
+         if (err == FOPEN_EXCL_ERR)
+           {
+             /* Re-determine the file name. */
+             if (local_file && *local_file)
+               {
+                 xfree (*local_file);
+                 *local_file = url_file_name (u);
+                 hstat.local_file = local_file;
+               }
+             else
+               {
+                 xfree (dummy);
+                 dummy = url_file_name (u);
+                 hstat.local_file = &dummy;
+               }
+             /* be honest about where we will save the file */
+             if (local_file && opt.output_document)
+               *local_file = HYPHENP (opt.output_document) ? NULL : xstrdup (opt.output_document);
+             if (!opt.output_document)
+               locf = *hstat.local_file;
+             else
+               locf = opt.output_document;
+           }
          continue;
          break;
        case HOSTERR: case CONIMPOSSIBLE: case PROXERR: case AUTHFAILED: