[Bug-tar] [PATCH] add --ignore-missing to ignore missing input files

[Stefan Tomanek]

When feeding filenames from 'find' to tar, it is possible for files to
disappear before being processed. This forces tar to signal an error
unless --ignore-failed-read has been specified. Using this switch
however covers a wide variety of error conditions. To simplify the
archival of big filesystems with find and tar, this change adds the
command line switch "--ignore-missing" to ignore files that disappeared
in the time between find identifying them and tar processing them.

Signed-off-by: Stefan Tomanek <address@hidden>
---
 src/common.h |    2 ++
 src/misc.c   |    2 +-
 src/tar.c    |    7 +++++++
 3 files changed, 10 insertions(+), 1 deletions(-)

diff --git a/src/common.h b/src/common.h
index c51ab11..996a05a 100644
--- a/src/common.h
+++ b/src/common.h
@@ -164,6 +164,8 @@ GLOBAL gid_t group_option;
 
 GLOBAL bool ignore_failed_read_option;
 
+GLOBAL bool ignore_missing_option;
+
 GLOBAL bool ignore_zeros_option;
 
 GLOBAL bool incremental_option;
diff --git a/src/misc.c b/src/misc.c
index 734dc4e..4e99afc 100644
--- a/src/misc.c
+++ b/src/misc.c
@@ -885,7 +885,7 @@ seek_diag_details (char const *name, off_t offset)
 void
 stat_diag (char const *name)
 {
-  if (ignore_failed_read_option)
+  if (ignore_failed_read_option || (errno == ENOENT && ignore_missing_option))
     stat_warn (name);
   else
     stat_error (name);
diff --git a/src/tar.c b/src/tar.c
index 8c4f656..1895506 100644
--- a/src/tar.c
+++ b/src/tar.c
@@ -279,6 +279,7 @@ enum
   IGNORE_CASE_OPTION,
   IGNORE_COMMAND_ERROR_OPTION,
   IGNORE_FAILED_READ_OPTION,
+  IGNORE_MISSING_OPTION,
   INDEX_FILE_OPTION,
   KEEP_NEWER_FILES_OPTION,
   LEVEL_OPTION,
@@ -426,6 +427,8 @@ static struct argp_option options[] = {
    N_("dump level for created listed-incremental archive"), GRID+1 },
   {"ignore-failed-read", IGNORE_FAILED_READ_OPTION, 0, 0,
    N_("do not exit with nonzero on unreadable files"), GRID+1 },
+  {"ignore-missing", IGNORE_MISSING_OPTION, 0, 0,
+   N_("do not exit with nonzero on missing input files"), GRID+1 },
   {"occurrence", OCCURRENCE_OPTION, N_("NUMBER"), OPTION_ARG_OPTIONAL,
    N_("process only the NUMBERth occurrence of each file in the archive;"
       " this option is valid only in conjunction with one of the subcommands"
@@ -1896,6 +1899,10 @@ parse_opt (int key, char *arg, struct argp_state *state)
       ignore_failed_read_option = true;
       break;
 
+    case IGNORE_MISSING_OPTION:
+      ignore_missing_option = true;
+      break;
+
     case KEEP_NEWER_FILES_OPTION:
       old_files_option = KEEP_NEWER_FILES;
       break;
-- 
1.7.9.1