dd: fix conv=ascii, conv=ebcdic, conv=ibm to match POSIX

Problem reported by Don Baggett in <http:/bugs.gnu.org/17422>.
* NEWS:
* doc/coreutils.texi (dd invocation): Document this.
* src/dd.c (conversions): conv=ascii implies conv=unblock.
conv=ebcdic and conv=ibm imply conv=block.
(ascii_to_ebcdic, ebcdic_to_ascii): Correct to match
POSIX 1003.1-2013.
* tests/dd/ascii.sh: New file.
* tests/local.mk (all_tests): Add it.

1 files changed, 21 insertions, 16 deletions

diff --git a/src/dd.c b/src/dd.c
index c7909e725..1e387f3d8 100644
--- a/src/dd.c
+++ b/src/dd.c
@@ -274,9 +274,9 @@ struct symbol_value
 /* Conversion symbols, for conv="...".  */
 static struct symbol_value const conversions[] =
 {
-  {"ascii", C_ASCII | C_TWOBUFS},	/* EBCDIC to ASCII. */
-  {"ebcdic", C_EBCDIC | C_TWOBUFS},	/* ASCII to EBCDIC. */
-  {"ibm", C_IBM | C_TWOBUFS},	/* Slightly different ASCII to EBCDIC. */
+  {"ascii", C_ASCII | C_UNBLOCK | C_TWOBUFS},	/* EBCDIC to ASCII. */
+  {"ebcdic", C_EBCDIC | C_BLOCK | C_TWOBUFS},	/* ASCII to EBCDIC. */
+  {"ibm", C_IBM | C_BLOCK | C_TWOBUFS},	/* Different ASCII to EBCDIC. */
   {"block", C_BLOCK | C_TWOBUFS},	/* Variable to fixed length records. */
   {"unblock", C_UNBLOCK | C_TWOBUFS},	/* Fixed to variable length records. */
   {"lcase", C_LCASE | C_TWOBUFS},	/* Translate upper to lower case. */
@@ -381,24 +381,29 @@ static struct symbol_value const statuses[] =
 /* Translation table formed by applying successive transformations. */
 static unsigned char trans_table[256];
 
+/* Standard translation tables, taken from POSIX 1003.1-2013.
+   Beware of imitations; there are lots of ASCII<->EBCDIC tables
+   floating around the net, perhaps valid for some applications but
+   not correct here.  */
+
 static char const ascii_to_ebcdic[] =
 {
   '\000', '\001', '\002', '\003', '\067', '\055', '\056', '\057',
   '\026', '\005', '\045', '\013', '\014', '\015', '\016', '\017',
   '\020', '\021', '\022', '\023', '\074', '\075', '\062', '\046',
   '\030', '\031', '\077', '\047', '\034', '\035', '\036', '\037',
-  '\100', '\117', '\177', '\173', '\133', '\154', '\120', '\175',
+  '\100', '\132', '\177', '\173', '\133', '\154', '\120', '\175',
   '\115', '\135', '\134', '\116', '\153', '\140', '\113', '\141',
   '\360', '\361', '\362', '\363', '\364', '\365', '\366', '\367',
   '\370', '\371', '\172', '\136', '\114', '\176', '\156', '\157',
   '\174', '\301', '\302', '\303', '\304', '\305', '\306', '\307',
   '\310', '\311', '\321', '\322', '\323', '\324', '\325', '\326',
   '\327', '\330', '\331', '\342', '\343', '\344', '\345', '\346',
-  '\347', '\350', '\351', '\112', '\340', '\132', '\137', '\155',
+  '\347', '\350', '\351', '\255', '\340', '\275', '\232', '\155',
   '\171', '\201', '\202', '\203', '\204', '\205', '\206', '\207',
   '\210', '\211', '\221', '\222', '\223', '\224', '\225', '\226',
   '\227', '\230', '\231', '\242', '\243', '\244', '\245', '\246',
-  '\247', '\250', '\251', '\300', '\152', '\320', '\241', '\007',
+  '\247', '\250', '\251', '\300', '\117', '\320', '\137', '\007',
   '\040', '\041', '\042', '\043', '\044', '\025', '\006', '\027',
   '\050', '\051', '\052', '\053', '\054', '\011', '\012', '\033',
   '\060', '\061', '\032', '\063', '\064', '\065', '\066', '\010',
@@ -408,10 +413,10 @@ static char const ascii_to_ebcdic[] =
   '\130', '\131', '\142', '\143', '\144', '\145', '\146', '\147',
   '\150', '\151', '\160', '\161', '\162', '\163', '\164', '\165',
   '\166', '\167', '\170', '\200', '\212', '\213', '\214', '\215',
-  '\216', '\217', '\220', '\232', '\233', '\234', '\235', '\236',
-  '\237', '\240', '\252', '\253', '\254', '\255', '\256', '\257',
+  '\216', '\217', '\220', '\152', '\233', '\234', '\235', '\236',
+  '\237', '\240', '\252', '\253', '\254', '\112', '\256', '\257',
   '\260', '\261', '\262', '\263', '\264', '\265', '\266', '\267',
-  '\270', '\271', '\272', '\273', '\274', '\275', '\276', '\277',
+  '\270', '\271', '\272', '\273', '\274', '\241', '\276', '\277',
   '\312', '\313', '\314', '\315', '\316', '\317', '\332', '\333',
   '\334', '\335', '\336', '\337', '\352', '\353', '\354', '\355',
   '\356', '\357', '\372', '\373', '\374', '\375', '\376', '\377'
@@ -464,21 +469,21 @@ static char const ebcdic_to_ascii[] =
   '\220', '\221', '\026', '\223', '\224', '\225', '\226', '\004',
   '\230', '\231', '\232', '\233', '\024', '\025', '\236', '\032',
   '\040', '\240', '\241', '\242', '\243', '\244', '\245', '\246',
-  '\247', '\250', '\133', '\056', '\074', '\050', '\053', '\041',
+  '\247', '\250', '\325', '\056', '\074', '\050', '\053', '\174',
   '\046', '\251', '\252', '\253', '\254', '\255', '\256', '\257',
-  '\260', '\261', '\135', '\044', '\052', '\051', '\073', '\136',
+  '\260', '\261', '\041', '\044', '\052', '\051', '\073', '\176',
   '\055', '\057', '\262', '\263', '\264', '\265', '\266', '\267',
-  '\270', '\271', '\174', '\054', '\045', '\137', '\076', '\077',
+  '\270', '\271', '\313', '\054', '\045', '\137', '\076', '\077',
   '\272', '\273', '\274', '\275', '\276', '\277', '\300', '\301',
   '\302', '\140', '\072', '\043', '\100', '\047', '\075', '\042',
   '\303', '\141', '\142', '\143', '\144', '\145', '\146', '\147',
   '\150', '\151', '\304', '\305', '\306', '\307', '\310', '\311',
   '\312', '\152', '\153', '\154', '\155', '\156', '\157', '\160',
-  '\161', '\162', '\313', '\314', '\315', '\316', '\317', '\320',
-  '\321', '\176', '\163', '\164', '\165', '\166', '\167', '\170',
-  '\171', '\172', '\322', '\323', '\324', '\325', '\326', '\327',
+  '\161', '\162', '\136', '\314', '\315', '\316', '\317', '\320',
+  '\321', '\345', '\163', '\164', '\165', '\166', '\167', '\170',
+  '\171', '\172', '\322', '\323', '\324', '\133', '\326', '\327',
   '\330', '\331', '\332', '\333', '\334', '\335', '\336', '\337',
-  '\340', '\341', '\342', '\343', '\344', '\345', '\346', '\347',
+  '\340', '\341', '\342', '\343', '\344', '\135', '\346', '\347',
   '\173', '\101', '\102', '\103', '\104', '\105', '\106', '\107',
   '\110', '\111', '\350', '\351', '\352', '\353', '\354', '\355',
   '\175', '\112', '\113', '\114', '\115', '\116', '\117', '\120',