Makes a backup copy of the content file.

Before overwriting the existing content file, rename it
adding the .backup extension, but only if such content file
was read and validated.

HISTORY

@@ -5,6 +5,9 @@ SnapRAID HISTORY
 =================
  * The -N, --force-nocopy option now also works if you used previously
    "sync" commands without it.
+ * When saving the content file keep a copy of the previos one adding
+   the ".backup" extension.
+ * Auto exclude the lock file.
 
 6.2 2014/5
 ==========

TODO

@@ -5,13 +5,6 @@ This is the list of TODO items for SnapRAID.
 
 - Next
 
-* Keep backup copies of the content file.
-Like snapraid.content.1, snapraid.content.2, snapraid.content.3 and so on.
-Note that the rotation should happen only one time for each sync,
-and not for intermediate sync write.
-
-* Auto exclude lock files.
-
 * Measures the time waited in blocking syscall for each disk,
 and prints stats of the disk speeds when the command finish,
 or when it's running.

cmdline/elem.c

@@ -298,6 +298,16 @@ int filter_content(tommy_list* contentlist, const char* path)
 		pathprint(tmp, sizeof(tmp), "%s.tmp", content->content);
 		if (pathcmp(tmp, path) == 0)
 			return -1;
+
+		/* exclude also the ".backup" copy */
+		pathprint(tmp, sizeof(tmp), "%s.backup", content->content);
+		if (pathcmp(tmp, path) == 0)
+			return -1;
+
+		/* exclude also the ".lock" file */
+		pathprint(tmp, sizeof(tmp), "%s.lock", content->content);
+		if (pathcmp(tmp, path) == 0)
+			return -1;
 	}
 
 	return 0;

cmdline/state.c

@@ -4008,6 +4008,9 @@ void state_read(struct snapraid_state* state)
 	state_map(state);
 
 	state_content_check(state, path);
+
+	/* mark that we read the content file, and it passed all the checks */
+	state->checked_read = 1;
 }
 
 void state_write(struct snapraid_state* state)
@@ -4087,6 +4090,24 @@ void state_write(struct snapraid_state* state)
 	while (i) {
 		struct snapraid_content* content = i->data;
 		char tmp[PATH_MAX];
+		char backup[PATH_MAX];
+
+		/* if the content file was checked reading it, it's a good candidate */
+		/* to be renamed as backup copy */
+		if (state->checked_read) {
+			pathprint(backup, sizeof(backup), "%s.backup", content->content);
+			if (rename(content->content, backup) != 0) {
+				/* ignore the error for not existing */
+				if (errno != ENOENT) {
+					/* LCOV_EXCL_START */
+					fprintf(stderr, "Error renaming the content file '%s' to '%s' in rename(). %s.\n", content->content, backup, strerror(errno));
+					exit(EXIT_FAILURE);
+					/* LCOV_EXCL_STOP */
+				}
+			}
+		}
+
+		/* now renames the just written copy with the correct name */
 		pathprint(tmp, sizeof(tmp), "%s.tmp", content->content);
 		if (rename(tmp, content->content) != 0) {
 			/* LCOV_EXCL_START */
@@ -4094,10 +4115,12 @@ void state_write(struct snapraid_state* state)
 			exit(EXIT_FAILURE);
 			/* LCOV_EXCL_STOP */
 		}
+
 		i = i->next;
 	}
 
 	state->need_write = 0; /* no write needed anymore */
+	state->checked_read = 0; /* what we wrote is not checked in read */
 }
 
 void state_filter(struct snapraid_state* state, tommy_list* filterlist_file, tommy_list* filterlist_disk, int filter_missing, int filter_error)

cmdline/state.h

@@ -91,6 +91,7 @@ struct snapraid_state {
 	int filter_hidden; /**< Filter out hidden files. */
 	uint64_t autosave; /**< Autosave after the specified amount of data. 0 to disable. */
 	int need_write; /**< If the state is changed. */
+	int checked_read; /**< If the state was read and checked. */
 	uint32_t block_size; /**< Block size in bytes. */
 	unsigned raid_mode; /**< Raid mode to use. RAID_MODE_DEFAULT or RAID_MODE_ALTERNATE. */
 	char parity_path[LEV_MAX][PATH_MAX]; /**< Path of the parity file. One for each parity. */

snapraid.1

@@ -1389,10 +1389,11 @@ SnapRAID stores the list and checksums of your files in the content file.
 It\'s a binary file, listing all the files present in your disk array,
 with all the checksums to verify their integrity.
 .PP
-You do not need to understand its format to use SnapRAID.
-.PP
 This file is read and written by the \[dq]sync\[dq] and \[dq]scrub\[dq] commands, and
-only read by \[dq]fix\[dq], \[dq]check\[dq] and \[dq]status\[dq].
+read by \[dq]fix\[dq], \[dq]check\[dq] and \[dq]status\[dq].
+.PP
+When saving a new copy, the previous one is renamed adding the \[dq].backup\[dq]
+extension.
 .SH PARITY 
 SnapRAID stores the parity information of your array in the parity
 files.

snapraid.d

@@ -1007,10 +1007,11 @@ Content
 	It's a binary file, listing all the files present in your disk array,
 	with all the checksums to verify their integrity.
 
-	You do not need to understand its format to use SnapRAID.
-
 	This file is read and written by the "sync" and "scrub" commands, and
-	only read by "fix", "check" and "status".
+	read by "fix", "check" and "status".
+
+	When saving a new copy, the previous one is renamed adding the ".backup"
+	extension.
 
 Parity
 	SnapRAID stores the parity information of your array in the parity

snapraid.txt

@@ -1090,10 +1090,11 @@ SnapRAID stores the list and checksums of your files in the content file.
 It's a binary file, listing all the files present in your disk array,
 with all the checksums to verify their integrity.
 
-You do not need to understand its format to use SnapRAID.
-
 This file is read and written by the "sync" and "scrub" commands, and
-only read by "fix", "check" and "status".
+read by "fix", "check" and "status".
+
+When saving a new copy, the previous one is renamed adding the ".backup"
+extension.
 
 
 11 PARITY