Have iconv accept redundant escape sequences in IBM900, IBM903, IBM905,

IBM907, and IBM909.

Patch for bug #17197 changes the encoder to avoid generating redundant
shift sequences.  However, those sequences may already be present in
data encododed by prior versions of the encoder.  This change modifies
the decoder to also avoid rejecting redundant shift sequences.

        [BZ #19432]
        * iconvdata/Makefile: Add bug-iconv11.
        * iconvdata/bug-iconv11.c: New test.
        * iconvdata/ibm930.c: Do not reject redundant shift sequences.
        * iconvdata/ibm933.c: Same.
        * iconvdata/ibm935.c: Same.
        * iconvdata/ibm937.c: Same.
        * iconvdata/ibm939.c: Same.

7 files changed, 125 insertions, 61 deletions

diff --git a/iconvdata/Makefile b/iconvdata/Makefile
index ae5dde60b4..357530b558 100644
--- a/iconvdata/Makefile
+++ b/iconvdata/Makefile
@@ -68,7 +68,7 @@ modules.so := $(addsuffix .so, $(modules))
 ifeq (yes,$(build-shared))
 tests = bug-iconv1 bug-iconv2 tst-loading tst-e2big tst-iconv4 bug-iconv4 \
 	tst-iconv6 bug-iconv5 bug-iconv6 tst-iconv7 bug-iconv8 bug-iconv9 \
-	bug-iconv10
+	bug-iconv10 bug-iconv11
 ifeq ($(have-thread-library),yes)
 tests += bug-iconv3
 endif
diff --git a/iconvdata/bug-iconv11.c b/iconvdata/bug-iconv11.c
new file mode 100644
index 0000000000..6cdc07d798
--- /dev/null
+++ b/iconvdata/bug-iconv11.c
@@ -0,0 +1,114 @@
+/* bug 19432: iconv rejects redundant escape sequences in IBM903,
+              IBM905, IBM907, and IBM909
+
+   Copyright (C) 2016 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, see
+   <http://www.gnu.org/licenses/>.  */
+
+#include <iconv.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <errno.h>
+
+// The longest test input sequence.
+#define MAXINBYTES    8
+#define MAXOUTBYTES   (MAXINBYTES * MB_LEN_MAX)
+
+/* Verify that a conversion of the INPUT sequence consisting of
+   INBYTESLEFT bytes in the encoding specified by the codeset
+   named by FROM_SET is successful.
+   Return 0 on success, non-zero on iconv() failure.  */
+
+static int
+test_ibm93x (const char *from_set, const char *input, size_t inbytesleft)
+{
+  const char to_set[] = "UTF-8";
+  iconv_t cd = iconv_open (to_set, from_set);
+  if (cd == (iconv_t) -1)
+    {
+      printf ("iconv_open(\"%s\", \"%s\"): %s\n",
+              from_set, to_set, strerror (errno));
+      return 1;
+    }
+
+  char output [MAXOUTBYTES];
+  size_t outbytesleft = sizeof output;
+
+  char *inbuf = (char*)input;
+  char *outbuf = output;
+
+  printf ("iconv(cd, %p, %zu, %p, %zu)\n",
+          inbuf, inbytesleft, outbuf, outbytesleft);
+
+  errno = 0;
+  size_t ret = iconv (cd, &inbuf, &inbytesleft, &outbuf, &outbytesleft);
+  printf ("  ==> %td: %s\n"
+          "  inbuf%+td, inbytesleft=%zu, outbuf%+td, outbytesleft=%zu\n",
+          ret, strerror (errno),
+          inbuf - input, inbytesleft, outbuf - output, outbytesleft);
+
+  // Return 0 on success, non-zero on iconv() failure.
+  return ret == (size_t)-1 || errno;
+}
+
+static int
+do_test (void)
+{
+  // State-dependent encodings to exercise.
+  static const char* const to_code[] = {
+    "IBM930", "IBM933", "IBM935", "IBM937", "IBM939"
+  };
+
+  static const size_t ncodesets = sizeof to_code / sizeof *to_code;
+
+  static const struct {
+    char txt[MAXINBYTES];
+    size_t len;
+  } input[] = {
+#define DATA(s) { s, sizeof s - 1 }
+    /* <SI>: denotes the shift-in 1-byte escape sequence, changing
+             the encoder from a sigle-byte encoding to multibyte
+       <SO>: denotes the shift-out 1-byte escape sequence, switching
+             the encoder from a multibyte to a single-byte state  */
+
+    DATA ("\x0e"),               // <SI> (not redundant)
+    DATA ("\x0f"),               // <S0> (redundant with initial state)
+    DATA ("\x0e\x0e"),           // <SI><SI>
+    DATA ("\x0e\x0f\x0f"),       // <SI><SO><SO>
+    DATA ("\x0f\x0f"),           // <SO><SO>
+    DATA ("\x0f\x0e\x0e"),       // <SO><SI><SI>
+    DATA ("\x0e\x0f\xc7\x0f"),   // <SI><SO><G><SO>
+    DATA ("\xc7\x0f")            // <G><SO> (redundant with initial state)
+  };
+
+  static const size_t ninputs = sizeof input / sizeof *input;
+
+  int ret = 0;
+
+  size_t i, j;
+
+  /* Iterate over the IBM93x codesets above and exercise each with
+     the input sequences above.  */
+  for (i = 0; i != ncodesets; ++i)
+    for (j = 0; j != ninputs; ++j)
+      ret += test_ibm93x (to_code [i], input [i].txt, input [i].len);
+
+  return ret;
+}
+
+#define TEST_FUNCTION do_test ()
+#include "../test-skeleton.c"
diff --git a/iconvdata/ibm930.c b/iconvdata/ibm930.c
index 1f60962d86..9d35734b3a 100644
--- a/iconvdata/ibm930.c
+++ b/iconvdata/ibm930.c
@@ -110,24 +110,14 @@ enum
 									      \
     if (__builtin_expect (ch, 0) == SO)					      \
       {									      \
-	/* Shift OUT, change to DBCS converter.  */			      \
-	if (curcs == db)						      \
-	  {								      \
-	    result = __GCONV_ILLEGAL_INPUT;				      \
-	    break;							      \
-	  }								      \
+	/* Shift OUT, change to DBCS converter (redundant escape okay).  */   \
 	curcs = db;							      \
 	++inptr;							      \
 	continue;							      \
       }									      \
     else if (__builtin_expect (ch, 0) == SI)				      \
       {									      \
-	/* Shift IN, change to SBCS converter */			      \
-	if (curcs == sb)						      \
-	  {								      \
-	    result = __GCONV_ILLEGAL_INPUT;				      \
-	    break;							      \
-	  }								      \
+	/* Shift IN, change to SBCS converter (redundant escape okay).  */    \
 	curcs = sb;							      \
 	++inptr;							      \
 	continue;							      \
diff --git a/iconvdata/ibm933.c b/iconvdata/ibm933.c
index c984cd1733..669e357066 100644
--- a/iconvdata/ibm933.c
+++ b/iconvdata/ibm933.c
@@ -108,24 +108,14 @@ enum
 									      \
     if (__builtin_expect (ch, 0) == SO)					      \
       {									      \
-	/* Shift OUT, change to DBCS converter.  */			      \
-	if (curcs == db)						      \
-	  {								      \
-	    result = __GCONV_ILLEGAL_INPUT;				      \
-	    break;							      \
-	  }								      \
+	/* Shift OUT, change to DBCS converter (redundant escape okay).  */   \
 	curcs = db;							      \
 	++inptr;							      \
 	continue;							      \
       }									      \
     else if (__builtin_expect (ch, 0) == SI)				      \
       {									      \
-	/* Shift IN, change to SBCS converter.  */			      \
-	if (curcs == sb)						      \
-	  {								      \
-	    result = __GCONV_ILLEGAL_INPUT;				      \
-	    break;							      \
-	  }								      \
+	/* Shift IN, change to SBCS converter (redundant escape okay).  */    \
 	curcs = sb;							      \
 	++inptr;							      \
 	continue;							      \
diff --git a/iconvdata/ibm935.c b/iconvdata/ibm935.c
index 07f4bf2558..2d3065e54c 100644
--- a/iconvdata/ibm935.c
+++ b/iconvdata/ibm935.c
@@ -109,24 +109,14 @@ enum
 									      \
     if (__builtin_expect(ch, 0) == SO)					      \
       {									      \
-	/* Shift OUT, change to DBCS converter.  */			      \
-	if (curcs == db)						      \
-	  {								      \
-	    result = __GCONV_ILLEGAL_INPUT;				      \
-	    break;							      \
-	  }								      \
+	/* Shift OUT, change to DBCS converter (redundant escape okay).  */   \
 	curcs = db;							      \
 	++inptr;							      \
 	continue;							      \
       }									      \
     else if (__builtin_expect (ch, 0) == SI)				      \
       {									      \
-	/* Shift IN, change to SBCS converter.  */			      \
-	if (curcs == sb)						      \
-	  {								      \
-	    result = __GCONV_ILLEGAL_INPUT;				      \
-	    break;							      \
-	  }								      \
+	/* Shift IN, change to SBCS converter (redundant escape okay).  */    \
 	curcs = sb;							      \
 	++inptr;							      \
 	continue;							      \
diff --git a/iconvdata/ibm937.c b/iconvdata/ibm937.c
index 88344a445b..3ed6479366 100644
--- a/iconvdata/ibm937.c
+++ b/iconvdata/ibm937.c
@@ -109,24 +109,14 @@ enum
 									      \
     if (__builtin_expect (ch, 0) == SO)					      \
       {									      \
-	/* Shift OUT, change to DBCS converter.  */			      \
-	if (curcs == db)						      \
-	  {								      \
-	    result = __GCONV_ILLEGAL_INPUT;				      \
-	    break;							      \
-	  }								      \
+	/* Shift OUT, change to DBCS converter (redundant escape okay).  */   \
 	curcs = db;							      \
 	++inptr;							      \
 	continue;							      \
       }									      \
     else if (__builtin_expect (ch, 0) == SI)				      \
       {									      \
-	/* Shift IN, change to SBCS converter.  */			      \
-	if (curcs == sb)						      \
-	  {								      \
-	    result = __GCONV_ILLEGAL_INPUT;				      \
-	    break;							      \
-	  }								      \
+	/* Shift IN, change to SBCS converter (redundant escape okay).  */    \
 	curcs = sb;							      \
 	++inptr;							      \
 	continue;							      \
diff --git a/iconvdata/ibm939.c b/iconvdata/ibm939.c
index dbdda628a3..c0a75f7797 100644
--- a/iconvdata/ibm939.c
+++ b/iconvdata/ibm939.c
@@ -109,24 +109,14 @@ enum
 									      \
     if (__builtin_expect (ch, 0) == SO)					      \
       {									      \
-	/* Shift OUT, change to DBCS converter.  */			      \
-	if (curcs == db)						      \
-	  {								      \
-	    result = __GCONV_ILLEGAL_INPUT;				      \
-	    break;							      \
-	  }								      \
+	/* Shift OUT, change to DBCS converter (redundant escape okay).  */   \
 	curcs = db;							      \
 	++inptr;							      \
 	continue;							      \
       }									      \
     else if (__builtin_expect (ch, 0) == SI)				      \
       {									      \
-	/* Shift IN, change to SBCS converter.  */			      \
-	if (curcs == sb)						      \
-	  {								      \
-	    result = __GCONV_ILLEGAL_INPUT;				      \
-	    break;							      \
-	  }								      \
+	/* Shift IN, change to SBCS converter (redundant escape okay).  */    \
 	curcs = sb;							      \
 	++inptr;							      \
 	continue;							      \