435. [bug] dns_zone_dump() overwrote existing zone files

                        rather than writing to a temporary file and
                        renaming.  This could lead to empty or partial
                        zone files being left around in certain error
                        conditions involving the initial transfer of a
                        slave zone, interfering with subsequent server
                        startup. [RT #282]

CHANGES

 
+ 435.	[bug]		dns_zone_dump() overwrote existing zone files 
+			rather than writing to a temporary file and
+			renaming.  This could lead to empty or partial
+			zone files being left around in certain error
+			conditions involving the initial transfer of a
+			slave zone, interfering with subsequent server
+			startup. [RT #282]
+
  434.	[func]		New function isc_file_isabsolute().
 
  433.	[func]		isc_base64_decodestring() now accepts newlines

lib/dns/masterdump.c

@@ -15,7 +15,7 @@
  * WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
  */
 
-/* $Id: masterdump.c,v 1.33 2000/08/16 22:33:32 gson Exp $ */
+/* $Id: masterdump.c,v 1.34 2000/09/08 21:47:03 gson Exp $ */
 
 #include <config.h>
 
@@ -882,27 +882,68 @@ dns_master_dump(isc_mem_t *mctx, dns_db_t *db, dns_dbversion_t *version,
 {
 	FILE *f = NULL;
 	isc_result_t result;
+	char *tempname;
+	int tempnamelen;
 
-	result = isc_stdio_open(filename, "w", &f);
+	tempnamelen = strlen(filename) + 20;
+	tempname = isc_mem_get(mctx, tempnamelen);
+	if (tempname == NULL)
+		return (ISC_R_NOMEMORY);
+
+	result = isc_file_mktemplate(filename, tempname, tempnamelen);
+	if (result != ISC_R_SUCCESS)
+		goto cleanup;
+
+	result = isc_file_openunique(tempname, &f);
 	if (result != ISC_R_SUCCESS) {
 		isc_log_write(dns_lctx, ISC_LOGCATEGORY_GENERAL,
 			      DNS_LOGMODULE_MASTERDUMP, ISC_LOG_ERROR,
-			      "dumping master file: %s: open: %s", filename,
-			      isc_result_totext(result));
-		return (ISC_R_UNEXPECTED);
+			      "dumping master file: %s: open: %s",
+			      tempname, isc_result_totext(result));
+		goto cleanup;
 	}
 
 	result = dns_master_dumptostream(mctx, db, version, style, f);
+	if (result != ISC_R_SUCCESS) {
+		isc_log_write(dns_lctx, ISC_LOGCATEGORY_GENERAL,
+			      DNS_LOGMODULE_MASTERDUMP, ISC_LOG_ERROR,
+			      "dumping master file: %s: %s",
+			      tempname, isc_result_totext(result));
+		(void)isc_stdio_close(f);
+		(void)isc_file_remove(tempname);
+		goto cleanup;
+	}
 
 	result = isc_stdio_close(f);
 	if (result != ISC_R_SUCCESS) {
 		isc_log_write(dns_lctx, ISC_LOGCATEGORY_GENERAL,
 			      DNS_LOGMODULE_MASTERDUMP, ISC_LOG_ERROR,
-			      "dumping master file: %s: close: %s", filename,
-			      isc_result_totext(result));
-		return (ISC_R_UNEXPECTED);
+			      "dumping master file: %s: close: %s",
+			      tempname, isc_result_totext(result));
+		(void)isc_file_remove(tempname);
+		goto cleanup;
+		
+	}
+
+	if (result != ISC_R_SUCCESS) {
+		isc_log_write(dns_lctx, ISC_LOGCATEGORY_GENERAL,
+			      DNS_LOGMODULE_MASTERDUMP, ISC_LOG_ERROR,
+			      "dumping master file: %s: close: %s",
+			      tempname, isc_result_totext(result));
+		goto cleanup;
+	}
+
+	result = isc_file_rename(tempname, filename);
+	if (result != ISC_R_SUCCESS) {
+		isc_log_write(dns_lctx, ISC_LOGCATEGORY_GENERAL,
+			      DNS_LOGMODULE_MASTERDUMP, ISC_LOG_ERROR,
+			      "dumping master file: rename: %s: %s",
+			      filename, isc_result_totext(result));
+		goto cleanup;		
 	}
 
+ cleanup:
+	isc_mem_put(mctx, tempname, tempnamelen);
 	return (result);
 }
 

lib/dns/zone.c

@@ -15,7 +15,7 @@
  * WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
  */
 
-/* $Id: zone.c,v 1.204 2000/09/08 00:07:44 explorer Exp $ */
+/* $Id: zone.c,v 1.205 2000/09/08 21:47:01 gson Exp $ */
 
 #include <config.h>
 
@@ -1734,11 +1734,6 @@ static isc_result_t
 zone_dump(dns_zone_t *zone) {
 	isc_result_t result;
 	dns_dbversion_t *version = NULL;
-	dns_db_t *db = NULL;
-	char *buf;
-	int buflen;
-	FILE *f = NULL;
-	int n;
 
 	/*
 	 * 'zone' locked by caller.
@@ -1747,47 +1742,19 @@ zone_dump(dns_zone_t *zone) {
 
 	REQUIRE(ISLOCKED(&zone->lock));
 
-	buflen = strlen(zone->dbname) + 20;
-	buf = isc_mem_get(zone->mctx, buflen);
-	if (buf == NULL)
-	    return (ISC_R_NOMEMORY);
+	dns_db_currentversion(zone->db, &version);
 
-	result = isc_file_mktemplate(zone->dbname, buf, buflen);
-	if (result != ISC_R_SUCCESS)
-		goto cleanup;
+	result = dns_master_dump(zone->mctx, zone->db, version,
+				 &dns_master_style_default,
+				 zone->dbname);
+
+	dns_db_closeversion(zone->db, &version, ISC_FALSE);
 
-	result = isc_file_openunique(buf, &f);
 	if (result != ISC_R_SUCCESS)
-		goto cleanup;
+		return (result);
 
-	dns_db_attach(zone->db, &db);
-	dns_db_currentversion(db, &version);
-	result = dns_master_dumptostream(zone->mctx, db, version,
-					 &dns_master_style_default, f);
-	dns_db_closeversion(db, &version, ISC_FALSE);
-	dns_db_detach(&db);
-	n = fflush(f);
-	if (n != 0 && result == ISC_R_SUCCESS)
-		result = ISC_R_UNEXPECTED;
-	n = ferror(f);
-	if (n != 0 && result == ISC_R_SUCCESS)
-		result = ISC_R_UNEXPECTED;
-	n = fclose(f);
-	if (n != 0 && result == ISC_R_SUCCESS)
-		result = ISC_R_UNEXPECTED;
-	if (result == ISC_R_SUCCESS) {
-		n = rename(buf, zone->dbname);
-		if (n == -1) {
-			(void)remove(buf);
-			result = ISC_R_UNEXPECTED;
-		} else {
-			zone->flags &= ~DNS_ZONEFLG_NEEDDUMP;
-		}
-	} else
-		(void)remove(buf);
- cleanup:
-	isc_mem_put(zone->mctx, buf, buflen);
-	return (result);
+	zone->flags &= ~DNS_ZONEFLG_NEEDDUMP;
+	return (ISC_R_SUCCESS);
 }
 
 isc_result_t

lib/isc/include/isc/file.h

@@ -15,7 +15,7 @@
  * WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
  */
 
-/* $Id: file.h,v 1.10 2000/09/08 18:37:25 gson Exp $ */
+/* $Id: file.h,v 1.11 2000/09/08 21:46:58 gson Exp $ */
 
 #ifndef ISC_FILE_H
 #define ISC_FILE_H 1
@@ -159,6 +159,12 @@ isc_file_remove(const char *filename);
  * Remove the file named by 'filename'.
  */
 
+isc_result_t
+isc_file_rename(const char *oldname, const char *newname);
+/*
+ * Rename the file 'oldname' to 'newname'.
+ */
+
 isc_boolean_t
 isc_file_isabsolute(const char *filename);
 /*

lib/isc/unix/file.c

@@ -15,7 +15,7 @@
  * WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
  */
 
-/* $Id: file.c,v 1.21 2000/09/08 18:37:26 gson Exp $ */
+/* $Id: file.c,v 1.22 2000/09/08 21:46:59 gson Exp $ */
 
 #include <config.h>
 
@@ -181,6 +181,17 @@ isc_file_remove(const char *filename) {
 		return (isc__errno2result(errno));
 }
 
+isc_result_t
+isc_file_rename(const char *oldname, const char *newname) {
+	int r;
+
+	r = rename(oldname, newname);
+	if (r == 0)
+		return (ISC_R_SUCCESS);
+	else
+		return (isc__errno2result(errno));
+}
+
 isc_boolean_t
 isc_file_isabsolute(const char *filename) {
 	return (ISC_TF(filename[0] == '/'));