[Patch v5 2/6] dump: when given output file name, write atomically

diff --git a/75/f64caf3af5163fb44ba16ce7ab4e835e8e9b01 b/75/f64caf3af5163fb44ba16ce7ab4e835e8e9b01
new file mode 100644 (file)
index 0000000..322f5ea
--- /dev/null
+++ b/75/f64caf3af5163fb44ba16ce7ab4e835e8e9b01
@@ -0,0 +1,140 @@
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+From: David Bremner <david@tethera.net>\r
+To: notmuch@notmuchmail.org\r
+Subject: [Patch v5 2/6] dump: when given output file name, write atomically\r
+Date: Tue,  1 Apr 2014 22:16:17 -0300\r
+Message-Id: <1396401381-18128-3-git-send-email-david@tethera.net>\r
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+References: <1396401381-18128-1-git-send-email-david@tethera.net>\r
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+\r
+It is useful to able to tell whether a dump completed successfully in\r
+situtions where we don't have access to the return code.\r
+---\r
+ notmuch-dump.c | 61 +++++++++++++++++++++++++++++++++++++++++++++-------------\r
+ 1 file changed, 48 insertions(+), 13 deletions(-)\r
+\r
+diff --git a/notmuch-dump.c b/notmuch-dump.c\r
+index 28342b7..05ed6b4 100644\r
+--- a/notmuch-dump.c\r
++++ b/notmuch-dump.c\r
+@@ -129,30 +129,65 @@ notmuch_database_dump (notmuch_database_t *notmuch,\r
+ {\r
+     gzFile output;\r
+     const char *mode = gzip_output ? "w9" : "wT";\r
++    const char *name_for_error = output_file_name ? output_file_name : "stdout";\r
+ \r
+-    int ret;\r
++    char *tempname = NULL;\r
++    int outfd = -1;\r
++\r
++    int ret = -1;\r
++\r
++    if (output_file_name) {\r
++      tempname = talloc_asprintf (notmuch, "%s.XXXXXX", output_file_name);\r
++      outfd = mkstemp (tempname);\r
++    } else {\r
++      outfd = fileno (stdout);\r
++    }\r
+ \r
+-    if (output_file_name)\r
+-      output = gzopen (output_file_name, mode);\r
+-    else\r
+-      output = gzdopen (fileno (stdout), mode);\r
++    if (outfd < 0) {\r
++      fprintf (stderr, "Bad output file %s\n", name_for_error);\r
++      goto DONE;\r
++    }\r
++\r
++    output = gzdopen (outfd, mode);\r
+ \r
+     if (output == NULL) {\r
+       fprintf (stderr, "Error opening %s for (gzip) writing: %s\n",\r
+-               output_file_name ? output_file_name : "stdout", strerror (errno));\r
+-      return EXIT_FAILURE;\r
++               name_for_error, strerror (errno));\r
++      goto DONE;\r
+     }\r
+ \r
+     ret = database_dump_file (notmuch, output, query_str, output_format);\r
++    if (ret) goto DONE;\r
+ \r
+-    if (gzflush (output, Z_FINISH)) {\r
+-      fprintf (stderr, "Error flushing output: %s\n",\r
+-               gzerror (output, NULL));\r
+-      return EXIT_FAILURE;\r
++    ret = gzflush (output, Z_FINISH);\r
++    if (ret) {\r
++      fprintf (stderr, "Error flushing output: %s\n", gzerror (output, NULL));\r
++      goto DONE;\r
+     }\r
+ \r
+-    if (output_file_name)\r
+-      gzclose_w (output);\r
++    ret = fdatasync (outfd);\r
++    if (ret) {\r
++      perror ("fdatasync");\r
++      goto DONE;\r
++    }\r
++\r
++    if (output_file_name) {\r
++      ret = gzclose_w (output);\r
++      if (ret != Z_OK) {\r
++          ret = EXIT_FAILURE;\r
++          goto DONE;\r
++      }\r
++\r
++      ret = rename (tempname, output_file_name);\r
++      if (ret) {\r
++          perror ("rename");\r
++          goto DONE;\r
++      }\r
++\r
++    }\r
++ DONE:\r
++    if (ret != EXIT_SUCCESS && output_file_name)\r
++      (void) unlink (tempname);\r
+ \r
+     return ret;\r
+ }\r
+-- \r
+1.9.0\r
+\r