Add a "fillchar" command line argument to dd(1) that permits the user

to specify an alternative padding character when using a conversion
mode, or when using noerror with sync and an input error occurs.  This
facilities reading old and error-prone media by allowing the user to
more effectively mark error blocks in the output stream.

1 files changed, 12 insertions, 0 deletions

diff --git a/bin/dd/args.c b/bin/dd/args.c
index c4d418b..161fbfc 100644
--- a/bin/dd/args.c
+++ b/bin/dd/args.c
@@ -58,6 +58,7 @@ static void	f_cbs(char *);
 static void	f_conv(char *);
 static void	f_count(char *);
 static void	f_files(char *);
+static void	f_fillchar(char *);
 static void	f_ibs(char *);
 static void	f_if(char *);
 static void	f_obs(char *);
@@ -77,6 +78,7 @@ static const struct arg {
 	{ "conv",	f_conv,		0,	 0 },
 	{ "count",	f_count,	C_COUNT, C_COUNT },
 	{ "files",	f_files,	C_FILES, C_FILES },
+	{ "fillchar",	f_fillchar,	C_FILL,	 C_FILL },
 	{ "ibs",	f_ibs,		C_IBS,	 C_BS|C_IBS },
 	{ "if",		f_if,		C_IF,	 C_IF },
 	{ "iseek",	f_skip,		C_SKIP,	 C_SKIP },
@@ -224,6 +226,16 @@ f_files(char *arg)
 }
 
 static void
+f_fillchar(char *arg)
+{
+
+	if (strlen(arg) != 1)
+		errx(1, "need exactly one fill char");
+
+	fill_char = arg[0];
+}
+
+static void
 f_ibs(char *arg)
 {
 	uintmax_t res;