More consistent behaviour when invalid input is preceded by a shift sequence.

21 files changed, 371 insertions, 140 deletions

diff --git a/ChangeLog b/ChangeLog
index e292717..aea1bde 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,5 +1,39 @@
 2008-09-07  Bruno Haible  <bruno@clisp.org>
 
+	Make behaviour when encountering invalid input after a shift sequence
+	more consistent.
+	* lib/converters.h (RET_SHIFT_ILSEQ): New macro.
+	(RET_ILSEQ): Define in terms of RET_SHIFT_ILSEQ.
+	(RET_TOOFEW): Change to avoid collisions with RET_SHIFT_ILSEQ.
+	(DECODE_SHIFT_ILSEQ, DECODE_TOOFEW): New macros.
+	* lib/loop_unicode.h (unicode_loop_convert): Take into account the
+	shift count contained in the negative return values.
+	* lib/hz.h (hz_mbtowc): When encountering invalid input, store the
+	modified state and return RET_SHIFT_ILSEQ.
+	* lib/iso2022_cn.h (iso2022_cn_mbtowc): Likewise.
+	* lib/iso2022_cnext.h (iso2022_cn_ext_mbtowc): Likewise.
+	* lib/iso2022_jp.h (iso2022_jp_mbtowc): Likewise.
+	* lib/iso2022_jp1.h (iso2022_jp1_mbtowc): Likewise.
+	* lib/iso2022_jp2.h (iso2022_jp2_mbtowc): Likewise.
+	* lib/iso2022_jp3.h (iso2022_jp3_mbtowc): Likewise.
+	* lib/iso2022_kr.h (iso2022_kr_mbtowc): Likewise.
+	* lib/ucs2.h (ucs2_mbtowc): Likewise.
+	* lib/ucs4.h (ucs4_mbtowc): Likewise.
+	* lib/utf16.h (utf16_mbtowc): Likewise.
+	* lib/utf32.h (utf32_mbtowc): Likewise.
+	* lib/utf7.h (utf7_mbtowc): Likewise.
+	* lib/utf16be.h (utf16be_mbtowcutf16be_mbtowc): When encountering
+	invalid input, return RET_SHIFT_ILSEQ.
+	* lib/utf16le.h (utf16le_mbtowc): Likewise.
+	* tests/test-shiftseq.c: New file.
+	* tests/Makefile.in (check): Run test-shiftseq.
+	(test-shiftseq, test-shiftseq.@OBJEXT@): New rules.
+	(clean): Remove test-shiftseq executable.
+	Reported by Roman Rybalko <roman_rybalko@users.sourceforge.net>
+	at <http://savannah.gnu.org/bugs/?24216>.
+
+2008-09-07  Bruno Haible  <bruno@clisp.org>
+
 	* man/iconv.3: Clarify the processing of shift-sequences.
 
 2008-09-07  Bruno Haible  <bruno@clisp.org>
diff --git a/NEWS b/NEWS
index 997af69..3aa2cfc 100644
--- a/NEWS
+++ b/NEWS
@@ -2,6 +2,10 @@ New in 1.13:
 * The library and the iconv program now understand platform dependent aliases,
   for better compatibility with the platform's own iconv_open function.
   Examples: "646" on Solaris, "iso88591" on HP-UX, "IBM-1252" on AIX.
+* For stateful encodings, when the input ends with a shift sequence followed
+  by invalid input, the iconv function now increments the input pointer past
+  the shift sequence before returning (size_t)(-1) with errno = EILSEQ. This
+  is also like GNU libc's iconv() behaves.
 
 New in 1.12:
 * The iconv program is now licensed under the GPL version 3, instead of the
diff --git a/lib/converters.h b/lib/converters.h
index 7bc032b..4d93230 100644
--- a/lib/converters.h
+++ b/lib/converters.h
@@ -1,5 +1,5 @@
 /*
- * Copyright (C) 1999-2002, 2004-2007 Free Software Foundation, Inc.
+ * Copyright (C) 1999-2002, 2004-2008 Free Software Foundation, Inc.
  * This file is part of the GNU LIBICONV Library.
  *
  * The GNU LIBICONV Library is free software; you can redistribute it
@@ -51,10 +51,16 @@ struct mbtowc_funcs {
    */
 };
 
+/* Return code if invalid input after a shift sequence of n bytes was read.
+   (xxx_mbtowc) */
+#define RET_SHIFT_ILSEQ(n)  (-1-2*(n))
 /* Return code if invalid. (xxx_mbtowc) */
-#define RET_ILSEQ      -1
+#define RET_ILSEQ           RET_SHIFT_ILSEQ(0)
 /* Return code if only a shift sequence of n bytes was read. (xxx_mbtowc) */
-#define RET_TOOFEW(n)  (-2-(n))
+#define RET_TOOFEW(n)       (-2-2*(n))
+/* Retrieve the n from the encoded RET_... value. */
+#define DECODE_SHIFT_ILSEQ(r)  ((unsigned int)(RET_SHIFT_ILSEQ(0) - (r)) / 2)
+#define DECODE_TOOFEW(r)       ((unsigned int)(RET_TOOFEW(0) - (r)) / 2)
 
 /*
  * Data type for conversion unicode -> multibyte
diff --git a/lib/hz.h b/lib/hz.h
index ed47485..db0b4b1 100644
--- a/lib/hz.h
+++ b/lib/hz.h
@@ -1,5 +1,5 @@
 /*
- * Copyright (C) 1999-2001 Free Software Foundation, Inc.
+ * Copyright (C) 1999-2001, 2008 Free Software Foundation, Inc.
  * This file is part of the GNU LIBICONV Library.
  *
  * The GNU LIBICONV Library is free software; you can redistribute it
@@ -67,7 +67,7 @@ hz_mbtowc (conv_t conv, ucs4_t *pwc, const unsigned char *s, int n)
           continue;
         }
       }
-      return RET_ILSEQ;
+      goto ilseq;
     }
     break;
   }
@@ -81,7 +81,7 @@ hz_mbtowc (conv_t conv, ucs4_t *pwc, const unsigned char *s, int n)
       goto none;
     ret = gb2312_mbtowc(conv,pwc,s,2);
     if (ret == RET_ILSEQ)
-      return RET_ILSEQ;
+      goto ilseq;
     if (ret != 2) abort();
     conv->istate = state;
     return count+2;
@@ -90,6 +90,10 @@ hz_mbtowc (conv_t conv, ucs4_t *pwc, const unsigned char *s, int n)
 none:
   conv->istate = state;
   return RET_TOOFEW(count);
+
+ilseq:
+  conv->istate = state;
+  return RET_SHIFT_ILSEQ(count);
 }
 
 static int
diff --git a/lib/iso2022_cn.h b/lib/iso2022_cn.h
index c41cfa4..d7e3e39 100644
--- a/lib/iso2022_cn.h
+++ b/lib/iso2022_cn.h
@@ -1,5 +1,5 @@
 /*
- * Copyright (C) 1999-2001 Free Software Foundation, Inc.
+ * Copyright (C) 1999-2001, 2008 Free Software Foundation, Inc.
  * This file is part of the GNU LIBICONV Library.
  *
  * The GNU LIBICONV Library is free software; you can redistribute it
@@ -92,26 +92,26 @@ iso2022_cn_mbtowc (conv_t conv, ucs4_t *pwc, const unsigned char *s, int n)
       if (s[1] == 'N') {
         switch (state3) {
           case STATE3_NONE:
-            return RET_ILSEQ;
+            goto ilseq;
           case STATE3_DESIGNATED_CNS11643_2:
             if (s[2] < 0x80 && s[3] < 0x80) {
               int ret = cns11643_2_mbtowc(conv,pwc,s+2,2);
               if (ret == RET_ILSEQ)
-                return RET_ILSEQ;
+                goto ilseq;
               if (ret != 2) abort();
               COMBINE_STATE;
               conv->istate = state;
               return count+4;
             } else
-              return RET_ILSEQ;
+              goto ilseq;
           default: abort();
         }
       }
-      return RET_ILSEQ;
+      goto ilseq;
     }
     if (c == SO) {
       if (state2 != STATE2_DESIGNATED_GB2312 && state2 != STATE2_DESIGNATED_CNS11643_1)
-        return RET_ILSEQ;
+        goto ilseq;
       state1 = STATE_TWOBYTE;
       s++; count++;
       if (n < count+1)
@@ -132,7 +132,7 @@ iso2022_cn_mbtowc (conv_t conv, ucs4_t *pwc, const unsigned char *s, int n)
       if (c < 0x80) {
         int ret = ascii_mbtowc(conv,pwc,s,1);
         if (ret == RET_ILSEQ)
-          return RET_ILSEQ;
+          goto ilseq;
         if (ret != 1) abort();
         if (*pwc == 0x000a || *pwc == 0x000d) {
           state2 = STATE2_NONE; state3 = STATE3_NONE;
@@ -141,7 +141,7 @@ iso2022_cn_mbtowc (conv_t conv, ucs4_t *pwc, const unsigned char *s, int n)
         conv->istate = state;
         return count+1;
       } else
-        return RET_ILSEQ;
+        goto ilseq;
     case STATE_TWOBYTE:
       if (n < count+2)
         goto none;
@@ -149,7 +149,7 @@ iso2022_cn_mbtowc (conv_t conv, ucs4_t *pwc, const unsigned char *s, int n)
         int ret;
         switch (state2) {
           case STATE2_NONE:
-            return RET_ILSEQ;
+            goto ilseq;
           case STATE2_DESIGNATED_GB2312:
             ret = gb2312_mbtowc(conv,pwc,s,2); break;
           case STATE2_DESIGNATED_CNS11643_1:
@@ -157,13 +157,13 @@ iso2022_cn_mbtowc (conv_t conv, ucs4_t *pwc, const unsigned char *s, int n)
           default: abort();
         }
         if (ret == RET_ILSEQ)
-          return RET_ILSEQ;
+          goto ilseq;
         if (ret != 2) abort();
         COMBINE_STATE;
         conv->istate = state;
         return count+2;
       } else
-        return RET_ILSEQ;
+        goto ilseq;
     default: abort();
   }
 
@@ -171,6 +171,11 @@ none:
   COMBINE_STATE;
   conv->istate = state;
   return RET_TOOFEW(count);
+
+ilseq:
+  COMBINE_STATE;
+  conv->istate = state;
+  return RET_SHIFT_ILSEQ(count);
 }
 
 static int
diff --git a/lib/iso2022_cnext.h b/lib/iso2022_cnext.h
index 276d820..f848870 100644
--- a/lib/iso2022_cnext.h
+++ b/lib/iso2022_cnext.h
@@ -1,5 +1,5 @@
 /*
- * Copyright (C) 1999-2001 Free Software Foundation, Inc.
+ * Copyright (C) 1999-2001, 2008 Free Software Foundation, Inc.
  * This file is part of the GNU LIBICONV Library.
  *
  * The GNU LIBICONV Library is free software; you can redistribute it
@@ -146,88 +146,88 @@ iso2022_cn_ext_mbtowc (conv_t conv, ucs4_t *pwc, const unsigned char *s, int n)
       if (s[1] == 'N') {
         switch (state3) {
           case STATE3_NONE:
-            return RET_ILSEQ;
+            goto ilseq;
           case STATE3_DESIGNATED_CNS11643_2:
             if (s[2] < 0x80 && s[3] < 0x80) {
               int ret = cns11643_2_mbtowc(conv,pwc,s+2,2);
               if (ret == RET_ILSEQ)
-                return RET_ILSEQ;
+                goto ilseq;
               if (ret != 2) abort();
               COMBINE_STATE;
               conv->istate = state;
               return count+4;
             } else
-              return RET_ILSEQ;
+              goto ilseq;
           default: abort();
         }
       }
       if (s[1] == 'O') {
         switch (state4) {
           case STATE4_NONE:
-            return RET_ILSEQ;
+            goto ilseq;
           case STATE4_DESIGNATED_CNS11643_3:
             if (s[2] < 0x80 && s[3] < 0x80) {
               int ret = cns11643_3_mbtowc(conv,pwc,s+2,2);
               if (ret == RET_ILSEQ)
-                return RET_ILSEQ;
+                goto ilseq;
               if (ret != 2) abort();
               COMBINE_STATE;
               conv->istate = state;
               return count+4;
             } else
-              return RET_ILSEQ;
+              goto ilseq;
           case STATE4_DESIGNATED_CNS11643_4:
             if (s[2] < 0x80 && s[3] < 0x80) {
               int ret = cns11643_4_mbtowc(conv,pwc,s+2,2);
               if (ret == RET_ILSEQ)
-                return RET_ILSEQ;
+                goto ilseq;
               if (ret != 2) abort();
               COMBINE_STATE;
               conv->istate = state;
               return count+4;
             } else
-              return RET_ILSEQ;
+              goto ilseq;
           case STATE4_DESIGNATED_CNS11643_5:
             if (s[2] < 0x80 && s[3] < 0x80) {
               int ret = cns11643_5_mbtowc(conv,pwc,s+2,2);
               if (ret == RET_ILSEQ)
-                return RET_ILSEQ;
+                goto ilseq;
               if (ret != 2) abort();
               COMBINE_STATE;
               conv->istate = state;
               return count+4;
             } else
-              return RET_ILSEQ;
+              goto ilseq;
           case STATE4_DESIGNATED_CNS11643_6:
             if (s[2] < 0x80 && s[3] < 0x80) {
               int ret = cns11643_6_mbtowc(conv,pwc,s+2,2);
               if (ret == RET_ILSEQ)
-                return RET_ILSEQ;
+                goto ilseq;
               if (ret != 2) abort();
               COMBINE_STATE;
               conv->istate = state;
               return count+4;
             } else
-              return RET_ILSEQ;
+              goto ilseq;
           case STATE4_DESIGNATED_CNS11643_7:
             if (s[2] < 0x80 && s[3] < 0x80) {
               int ret = cns11643_7_mbtowc(conv,pwc,s+2,2);
               if (ret == RET_ILSEQ)
-                return RET_ILSEQ;
+                goto ilseq;
               if (ret != 2) abort();
               COMBINE_STATE;
               conv->istate = state;
               return count+4;
             } else
-              return RET_ILSEQ;
+              goto ilseq;
           default: abort();
         }
       }
-      return RET_ILSEQ;
+      goto ilseq;
     }
     if (c == SO) {
       if (state2 != STATE2_DESIGNATED_GB2312 && state2 != STATE2_DESIGNATED_CNS11643_1 && state2 != STATE2_DESIGNATED_ISO_IR_165)
-        return RET_ILSEQ;
+        goto ilseq;
       state1 = STATE_TWOBYTE;
       s++; count++;
       if (n < count+1)
@@ -248,7 +248,7 @@ iso2022_cn_ext_mbtowc (conv_t conv, ucs4_t *pwc, const unsigned char *s, int n)
       if (c < 0x80) {
         int ret = ascii_mbtowc(conv,pwc,s,1);
         if (ret == RET_ILSEQ)
-          return RET_ILSEQ;
+          goto ilseq;
         if (ret != 1) abort();
         if (*pwc == 0x000a || *pwc == 0x000d) {
           state2 = STATE2_NONE; state3 = STATE3_NONE; state4 = STATE3_NONE;
@@ -257,7 +257,7 @@ iso2022_cn_ext_mbtowc (conv_t conv, ucs4_t *pwc, const unsigned char *s, int n)
         conv->istate = state;
         return count+1;
       } else
-        return RET_ILSEQ;
+        goto ilseq;
     case STATE_TWOBYTE:
       if (n < count+2)
         goto none;
@@ -265,7 +265,7 @@ iso2022_cn_ext_mbtowc (conv_t conv, ucs4_t *pwc, const unsigned char *s, int n)
         int ret;
         switch (state2) {
           case STATE2_NONE:
-            return RET_ILSEQ;
+            goto ilseq;
           case STATE2_DESIGNATED_GB2312:
             ret = gb2312_mbtowc(conv,pwc,s,2); break;
           case STATE2_DESIGNATED_CNS11643_1:
@@ -275,13 +275,13 @@ iso2022_cn_ext_mbtowc (conv_t conv, ucs4_t *pwc, const unsigned char *s, int n)
           default: abort();
         }
         if (ret == RET_ILSEQ)
-          return RET_ILSEQ;
+          goto ilseq;
         if (ret != 2) abort();
         COMBINE_STATE;
         conv->istate = state;
         return count+2;
       } else
-        return RET_ILSEQ;
+        goto ilseq;
     default: abort();
   }
 
@@ -289,6 +289,11 @@ none:
   COMBINE_STATE;
   conv->istate = state;
   return RET_TOOFEW(count);
+
+ilseq:
+  COMBINE_STATE;
+  conv->istate = state;
+  return RET_SHIFT_ILSEQ(count);
 }
 
 static int
diff --git a/lib/iso2022_jp.h b/lib/iso2022_jp.h
index 46aa8c8..1c8abec 100644
--- a/lib/iso2022_jp.h
+++ b/lib/iso2022_jp.h
@@ -1,5 +1,5 @@
 /*
- * Copyright (C) 1999-2001 Free Software Foundation, Inc.
+ * Copyright (C) 1999-2001, 2008 Free Software Foundation, Inc.
  * This file is part of the GNU LIBICONV Library.
  *
  * The GNU LIBICONV Library is free software; you can redistribute it
@@ -59,7 +59,7 @@ iso2022_jp_mbtowc (conv_t conv, ucs4_t *pwc, const unsigned char *s, int n)
             goto none;
           continue;
         }
-        return RET_ILSEQ;
+        goto ilseq;
       }
       if (s[1] == '$') {
         if (s[2] == '@' || s[2] == 'B') {
@@ -70,9 +70,9 @@ iso2022_jp_mbtowc (conv_t conv, ucs4_t *pwc, const unsigned char *s, int n)
             goto none;
           continue;
         }
-        return RET_ILSEQ;
+        goto ilseq;
       }
-      return RET_ILSEQ;
+      goto ilseq;
     }
     break;
   }
@@ -81,40 +81,44 @@ iso2022_jp_mbtowc (conv_t conv, ucs4_t *pwc, const unsigned char *s, int n)
       if (c < 0x80) {
         int ret = ascii_mbtowc(conv,pwc,s,1);
         if (ret == RET_ILSEQ)
-          return RET_ILSEQ;
+          goto ilseq;
         if (ret != 1) abort();
         conv->istate = state;
         return count+1;
       } else
-        return RET_ILSEQ;
+        goto ilseq;
     case STATE_JISX0201ROMAN:
       if (c < 0x80) {
         int ret = jisx0201_mbtowc(conv,pwc,s,1);
         if (ret == RET_ILSEQ)
-          return RET_ILSEQ;
+          goto ilseq;
         if (ret != 1) abort();
         conv->istate = state;
         return count+1;
       } else
-        return RET_ILSEQ;
+        goto ilseq;
     case STATE_JISX0208:
       if (n < count+2)
         goto none;
       if (s[0] < 0x80 && s[1] < 0x80) {
         int ret = jisx0208_mbtowc(conv,pwc,s,2);
         if (ret == RET_ILSEQ)
-          return RET_ILSEQ;
+          goto ilseq;
         if (ret != 2) abort();
         conv->istate = state;
         return count+2;
       } else
-        return RET_ILSEQ;
+        goto ilseq;
     default: abort();
   }
 
 none:
   conv->istate = state;
   return RET_TOOFEW(count);
+
+ilseq:
+  conv->istate = state;
+  return RET_SHIFT_ILSEQ(count);
 }
 
 static int
diff --git a/lib/iso2022_jp1.h b/lib/iso2022_jp1.h
index a43a105..c309474 100644
--- a/lib/iso2022_jp1.h
+++ b/lib/iso2022_jp1.h
@@ -1,5 +1,5 @@
 /*
- * Copyright (C) 1999-2001 Free Software Foundation, Inc.
+ * Copyright (C) 1999-2001, 2008 Free Software Foundation, Inc.
  * This file is part of the GNU LIBICONV Library.
  *
  * The GNU LIBICONV Library is free software; you can redistribute it
@@ -60,7 +60,7 @@ iso2022_jp1_mbtowc (conv_t conv, ucs4_t *pwc, const unsigned char *s, int n)
             goto none;
           continue;
         }
-        return RET_ILSEQ;
+        goto ilseq;
       }
       if (s[1] == '$') {
         if (s[2] == '@' || s[2] == 'B') {
@@ -82,9 +82,9 @@ iso2022_jp1_mbtowc (conv_t conv, ucs4_t *pwc, const unsigned char *s, int n)
             continue;
           }
         }
-        return RET_ILSEQ;
+        goto ilseq;
       }
-      return RET_ILSEQ;
+      goto ilseq;
     }
     break;
   }
@@ -93,52 +93,56 @@ iso2022_jp1_mbtowc (conv_t conv, ucs4_t *pwc, const unsigned char *s, int n)
       if (c < 0x80) {
         int ret = ascii_mbtowc(conv,pwc,s,1);
         if (ret == RET_ILSEQ)
-          return RET_ILSEQ;
+          goto ilseq;
         if (ret != 1) abort();
         conv->istate = state;
         return count+1;
       } else
-        return RET_ILSEQ;
+        goto ilseq;
     case STATE_JISX0201ROMAN:
       if (c < 0x80) {
         int ret = jisx0201_mbtowc(conv,pwc,s,1);
         if (ret == RET_ILSEQ)
-          return RET_ILSEQ;
+          goto ilseq;
         if (ret != 1) abort();
         conv->istate = state;
         return count+1;
       } else
-        return RET_ILSEQ;
+        goto ilseq;
     case STATE_JISX0208:
       if (n < count+2)
         goto none;
       if (s[0] < 0x80 && s[1] < 0x80) {
         int ret = jisx0208_mbtowc(conv,pwc,s,2);
         if (ret == RET_ILSEQ)
-          return RET_ILSEQ;
+          goto ilseq;
         if (ret != 2) abort();
         conv->istate = state;
         return count+2;
       } else
-        return RET_ILSEQ;
+        goto ilseq;
     case STATE_JISX0212:
       if (n < count+2)
         goto none;
       if (s[0] < 0x80 && s[1] < 0x80) {
         int ret = jisx0212_mbtowc(conv,pwc,s,2);
         if (ret == RET_ILSEQ)
-          return RET_ILSEQ;
+          goto ilseq;
         if (ret != 2) abort();
         conv->istate = state;
         return count+2;
       } else
-        return RET_ILSEQ;
+        goto ilseq;
     default: abort();
   }
 
 none:
   conv->istate = state;
   return RET_TOOFEW(count);
+
+ilseq:
+  conv->istate = state;
+  return RET_SHIFT_ILSEQ(count);
 }
 
 static int
diff --git a/lib/iso2022_jp2.h b/lib/iso2022_jp2.h
index 4fcf439..5e3ca41 100644
--- a/lib/iso2022_jp2.h
+++ b/lib/iso2022_jp2.h
@@ -1,5 +1,5 @@
 /*
- * Copyright (C) 1999-2001 Free Software Foundation, Inc.
+ * Copyright (C) 1999-2001, 2008 Free Software Foundation, Inc.
  * This file is part of the GNU LIBICONV Library.
  *
  * The GNU LIBICONV Library is free software; you can redistribute it
@@ -84,7 +84,7 @@ iso2022_jp2_mbtowc (conv_t conv, ucs4_t *pwc, const unsigned char *s, int n)
             goto none;
           continue;
         }
-        return RET_ILSEQ;
+        goto ilseq;
       }
       if (s[1] == '$') {
         if (s[2] == '@' || s[2] == 'B') {
@@ -119,9 +119,9 @@ iso2022_jp2_mbtowc (conv_t conv, ucs4_t *pwc, const unsigned char *s, int n)
               goto none;
             continue;
           }
-          return RET_ILSEQ;
+          goto ilseq;
         }
-        return RET_ILSEQ;
+        goto ilseq;
       }
       if (s[1] == '.') {
         if (n < count+3)
@@ -140,40 +140,40 @@ iso2022_jp2_mbtowc (conv_t conv, ucs4_t *pwc, const unsigned char *s, int n)
             goto none;
           continue;
         }
-        return RET_ILSEQ;
+        goto ilseq;
       }
       if (s[1] == 'N') {
         switch (state2) {
           case STATE_G2_NONE:
-            return RET_ILSEQ;
+            goto ilseq;
           case STATE_G2_ISO8859_1:
             if (s[2] < 0x80) {
               unsigned char buf = s[2]+0x80;
               int ret = iso8859_1_mbtowc(conv,pwc,&buf,1);
               if (ret == RET_ILSEQ)
-                return RET_ILSEQ;
+                goto ilseq;
               if (ret != 1) abort();
               COMBINE_STATE;
               conv->istate = state;
               return count+3;
             } else
-              return RET_ILSEQ;
+              goto ilseq;
           case STATE_G2_ISO8859_7:
             if (s[2] < 0x80) {
               unsigned char buf = s[2]+0x80;
               int ret = iso8859_7_mbtowc(conv,pwc,&buf,1);
               if (ret == RET_ILSEQ)
-                return RET_ILSEQ;
+                goto ilseq;
               if (ret != 1) abort();
               COMBINE_STATE;
               conv->istate = state;
               return count+3;
             } else
-              return RET_ILSEQ;
+              goto ilseq;
           default: abort();
         }
       }
-      return RET_ILSEQ;
+      goto ilseq;
     }
     break;
   }
@@ -182,7 +182,7 @@ iso2022_jp2_mbtowc (conv_t conv, ucs4_t *pwc, const unsigned char *s, int n)
       if (c < 0x80) {
         int ret = ascii_mbtowc(conv,pwc,s,1);
         if (ret == RET_ILSEQ)
-          return RET_ILSEQ;
+          goto ilseq;
         if (ret != 1) abort();
         if (*pwc == 0x000a || *pwc == 0x000d)
           state2 = STATE_G2_NONE;
@@ -190,12 +190,12 @@ iso2022_jp2_mbtowc (conv_t conv, ucs4_t *pwc, const unsigned char *s, int n)
         conv->istate = state;
         return count+1;
       } else
-        return RET_ILSEQ;
+        goto ilseq;
     case STATE_JISX0201ROMAN:
       if (c < 0x80) {
         int ret = jisx0201_mbtowc(conv,pwc,s,1);
         if (ret == RET_ILSEQ)
-          return RET_ILSEQ;
+          goto ilseq;
         if (ret != 1) abort();
         if (*pwc == 0x000a || *pwc == 0x000d)
           state2 = STATE_G2_NONE;
@@ -203,71 +203,71 @@ iso2022_jp2_mbtowc (conv_t conv, ucs4_t *pwc, const unsigned char *s, int n)
         conv->istate = state;
         return count+1;
       } else
-        return RET_ILSEQ;
+        goto ilseq;
     case STATE_JISX0201KATAKANA:
       if (c < 0x80) {
         unsigned char buf = c+0x80;
         int ret = jisx0201_mbtowc(conv,pwc,&buf,1);
         if (ret == RET_ILSEQ)
-          return RET_ILSEQ;
+          goto ilseq;
         if (ret != 1) abort();
         COMBINE_STATE;
         conv->istate = state;
         return count+1;
       } else
-        return RET_ILSEQ;
+        goto ilseq;
     case STATE_JISX0208:
       if (n < count+2)
         goto none;
       if (s[0] < 0x80 && s[1] < 0x80) {
         int ret = jisx0208_mbtowc(conv,pwc,s,2);
         if (ret == RET_ILSEQ)
-          return RET_ILSEQ;
+          goto ilseq;
         if (ret != 2) abort();
         COMBINE_STATE;
         conv->istate = state;
         return count+2;
       } else
-        return RET_ILSEQ;
+        goto ilseq;
     case STATE_JISX0212:
       if (n < count+2)
         goto none;
       if (s[0] < 0x80 && s[1] < 0x80) {
         int ret = jisx0212_mbtowc(conv,pwc,s,2);
         if (ret == RET_ILSEQ)
-          return RET_ILSEQ;
+          goto ilseq;
         if (ret != 2) abort();
         COMBINE_STATE;
         conv->istate = state;
         return count+2;
       } else
-        return RET_ILSEQ;
+        goto ilseq;
     case STATE_GB2312:
       if (n < count+2)
         goto none;
       if (s[0] < 0x80 && s[1] < 0x80) {
         int ret = gb2312_mbtowc(conv,pwc,s,2);
         if (ret == RET_ILSEQ)
-          return RET_ILSEQ;
+          goto ilseq;
         if (ret != 2) abort();
         COMBINE_STATE;
         conv->istate = state;
         return count+2;
       } else
-        return RET_ILSEQ;
+        goto ilseq;
     case STATE_KSC5601:
       if (n < count+2)
         goto none;
       if (s[0] < 0x80 && s[1] < 0x80) {
         int ret = ksc5601_mbtowc(conv,pwc,s,2);
         if (ret == RET_ILSEQ)
-          return RET_ILSEQ;
+          goto ilseq;
         if (ret != 2) abort();
         COMBINE_STATE;
         conv->istate = state;
         return count+2;
       } else
-        return RET_ILSEQ;
+        goto ilseq;
     default: abort();
   }
 
@@ -275,6 +275,11 @@ none:
   COMBINE_STATE;
   conv->istate = state;
   return RET_TOOFEW(count);
+
+ilseq:
+  COMBINE_STATE;
+  conv->istate = state;
+  return RET_SHIFT_ILSEQ(count);
 }
 
 #undef COMBINE_STATE
diff --git a/lib/iso2022_jp3.h b/lib/iso2022_jp3.h
index 75ef4f9..58cea1b 100644
--- a/lib/iso2022_jp3.h
+++ b/lib/iso2022_jp3.h
@@ -1,5 +1,5 @@
 /*
- * Copyright (C) 1999-2004 Free Software Foundation, Inc.
+ * Copyright (C) 1999-2004, 2008 Free Software Foundation, Inc.
  * This file is part of the GNU LIBICONV Library.
  *
  * The GNU LIBICONV Library is free software; you can redistribute it
@@ -81,7 +81,7 @@ iso2022_jp3_mbtowc (conv_t conv, ucs4_t *pwc, const unsigned char *s, int n)
               goto none;
             continue;
           }
-          return RET_ILSEQ;
+          goto ilseq;
         }
         if (s[1] == '$') {
           if (s[2] == '@' || s[2] == 'B') {
@@ -110,9 +110,9 @@ iso2022_jp3_mbtowc (conv_t conv, ucs4_t *pwc, const unsigned char *s, int n)
               continue;
             }
           }
-          return RET_ILSEQ;
+          goto ilseq;
         }
-        return RET_ILSEQ;
+        goto ilseq;
       }
       break;
     }
@@ -121,45 +121,45 @@ iso2022_jp3_mbtowc (conv_t conv, ucs4_t *pwc, const unsigned char *s, int n)
         if (c < 0x80) {
           int ret = ascii_mbtowc(conv,pwc,s,1);
           if (ret == RET_ILSEQ)
-            return RET_ILSEQ;
+            goto ilseq;
           if (ret != 1) abort();
           conv->istate = state;
           return count+1;
         } else
-          return RET_ILSEQ;
+          goto ilseq;
       case STATE_JISX0201ROMAN:
         if (c < 0x80) {
           int ret = jisx0201_mbtowc(conv,pwc,s,1);
           if (ret == RET_ILSEQ)
-            return RET_ILSEQ;
+            goto ilseq;
           if (ret != 1) abort();
           conv->istate = state;
           return count+1;
         } else
-          return RET_ILSEQ;
+          goto ilseq;
       case STATE_JISX0201KATAKANA:
         if (c < 0x80) {
           unsigned char buf = c+0x80;
           int ret = jisx0201_mbtowc(conv,pwc,&buf,1);
           if (ret == RET_ILSEQ)
-            return RET_ILSEQ;
+            goto ilseq;
           if (ret != 1) abort();
           conv->istate = state;
           return count+1;
         } else
-          return RET_ILSEQ;
+          goto ilseq;
       case STATE_JISX0208:
         if (n < count+2)
           goto none;
         if (s[0] < 0x80 && s[1] < 0x80) {
           int ret = jisx0208_mbtowc(conv,pwc,s,2);
           if (ret == RET_ILSEQ)
-            return RET_ILSEQ;
+            goto ilseq;
           if (ret != 2) abort();
           conv->istate = state;
           return count+2;
         } else
-          return RET_ILSEQ;
+          goto ilseq;
       case STATE_JISX02131:
       case STATE_JISX02132:
         if (n < count+2)
@@ -182,12 +182,16 @@ iso2022_jp3_mbtowc (conv_t conv, ucs4_t *pwc, const unsigned char *s, int n)
             return count+2;
           }
         }
-        return RET_ILSEQ;
+        goto ilseq;
       default: abort();
     }
   none:
     conv->istate = state;
     return RET_TOOFEW(count);
+
+  ilseq:
+    conv->istate = state;
+    return RET_SHIFT_ILSEQ(count);
   }
 }
 
diff --git a/lib/iso2022_kr.h b/lib/iso2022_kr.h
index d610b8c..8045d4e 100644
--- a/lib/iso2022_kr.h
+++ b/lib/iso2022_kr.h
@@ -1,5 +1,5 @@
 /*
- * Copyright (C) 1999-2001 Free Software Foundation, Inc.
+ * Copyright (C) 1999-2001, 2008 Free Software Foundation, Inc.
  * This file is part of the GNU LIBICONV Library.
  *
  * The GNU LIBICONV Library is free software; you can redistribute it
@@ -72,11 +72,11 @@ iso2022_kr_mbtowc (conv_t conv, ucs4_t *pwc, const unsigned char *s, int n)
           }
         }
       }
-      return RET_ILSEQ;
+      goto ilseq;
     }
     if (c == SO) {
       if (state2 != STATE2_DESIGNATED_KSC5601)
-        return RET_ILSEQ;
+        goto ilseq;
       state1 = STATE_TWOBYTE;
       s++; count++;
       if (n < count+1)
@@ -97,7 +97,7 @@ iso2022_kr_mbtowc (conv_t conv, ucs4_t *pwc, const unsigned char *s, int n)
       if (c < 0x80) {
         int ret = ascii_mbtowc(conv,pwc,s,1);
         if (ret == RET_ILSEQ)
-          return RET_ILSEQ;
+          goto ilseq;
         if (ret != 1) abort();
 #if 0 /* Accept ISO-2022-KR according to CJK.INF. */
         if (*pwc == 0x000a || *pwc == 0x000d)
@@ -107,7 +107,7 @@ iso2022_kr_mbtowc (conv_t conv, ucs4_t *pwc, const unsigned char *s, int n)
         conv->istate = state;
         return count+1;
       } else
-        return RET_ILSEQ;
+        goto ilseq;
     case STATE_TWOBYTE:
       if (n < count+2)
         goto none;
@@ -115,13 +115,13 @@ iso2022_kr_mbtowc (conv_t conv, ucs4_t *pwc, const unsigned char *s, int n)
       if (s[0] < 0x80 && s[1] < 0x80) {
         int ret = ksc5601_mbtowc(conv,pwc,s,2);
         if (ret == RET_ILSEQ)
-          return RET_ILSEQ;
+          goto ilseq;
         if (ret != 2) abort();
         COMBINE_STATE;
         conv->istate = state;
         return count+2;
       } else
-        return RET_ILSEQ;
+        goto ilseq;
     default: abort();
   }
 
@@ -129,6 +129,11 @@ none:
   COMBINE_STATE;
   conv->istate = state;
   return RET_TOOFEW(count);
+
+ilseq:
+  COMBINE_STATE;
+  conv->istate = state;
+  return RET_SHIFT_ILSEQ(count);
 }
 
 static int
diff --git a/lib/loop_unicode.h b/lib/loop_unicode.h
index c5b0bf4..1c787b5 100644
--- a/lib/loop_unicode.h
+++ b/lib/loop_unicode.h
@@ -283,57 +283,62 @@ static size_t unicode_loop_convert (iconv_t icd,
     int outcount;
     incount = cd->ifuncs.xxx_mbtowc(cd,&wc,inptr,inleft);
     if (incount < 0) {
-      if (incount == RET_ILSEQ) {
-        /* Case 1: invalid input */
+      if ((unsigned int)(-1-incount) % 2 == (unsigned int)(-1-RET_ILSEQ) % 2) {
+        /* Case 1: invalid input, possibly after a shift sequence */
+        incount = DECODE_SHIFT_ILSEQ(incount);
         if (cd->discard_ilseq) {
           switch (cd->iindex) {
             case ei_ucs4: case ei_ucs4be: case ei_ucs4le:
             case ei_utf32: case ei_utf32be: case ei_utf32le:
             case ei_ucs4internal: case ei_ucs4swapped:
-              incount = 4; break;
+              incount += 4; break;
             case ei_ucs2: case ei_ucs2be: case ei_ucs2le:
             case ei_utf16: case ei_utf16be: case ei_utf16le:
             case ei_ucs2internal: case ei_ucs2swapped:
-              incount = 2; break;
+              incount += 2; break;
             default:
-              incount = 1; break;
+              incount += 1; break;
           }
           goto outcount_zero;
         }
         #ifndef LIBICONV_PLUG
         else if (cd->fallbacks.mb_to_uc_fallback != NULL) {
+          unsigned int incount2;
           struct mb_to_uc_fallback_locals locals;
           switch (cd->iindex) {
             case ei_ucs4: case ei_ucs4be: case ei_ucs4le:
             case ei_utf32: case ei_utf32be: case ei_utf32le:
             case ei_ucs4internal: case ei_ucs4swapped:
-              incount = 4; break;
+              incount2 = 4; break;
             case ei_ucs2: case ei_ucs2be: case ei_ucs2le:
             case ei_utf16: case ei_utf16be: case ei_utf16le:
             case ei_ucs2internal: case ei_ucs2swapped:
-              incount = 2; break;
+              incount2 = 2; break;
             default:
-              incount = 1; break;
+              incount2 = 1; break;
           }
           locals.l_cd = cd;
           locals.l_outbuf = outptr;
           locals.l_outbytesleft = outleft;
           locals.l_errno = 0;
-          cd->fallbacks.mb_to_uc_fallback((const char*)inptr, incount,
+          cd->fallbacks.mb_to_uc_fallback((const char*)inptr+incount, incount2,
                                           mb_to_uc_write_replacement,
                                           &locals,
                                           cd->fallbacks.data);
           if (locals.l_errno != 0) {
+            inptr += incount; inleft -= incount;
             errno = locals.l_errno;
             result = -1;
             break;
           }
+          incount += incount2;
           outptr = locals.l_outbuf;
           outleft = locals.l_outbytesleft;
           result += 1;
           goto outcount_zero;
         }
         #endif
+        inptr += incount; inleft -= incount;
         errno = EILSEQ;
         result = -1;
         break;
@@ -345,7 +350,7 @@ static size_t unicode_loop_convert (iconv_t icd,
         break;
       }
       /* Case 3: k bytes read, but only a shift sequence */
-      incount = -2-incount;
+      incount = DECODE_TOOFEW(incount);
     } else {
       /* Case 4: k bytes read, making up a wide character */
       if (outleft == 0) {
diff --git a/lib/ucs2.h b/lib/ucs2.h
index 6afc175..206b8cc 100644
--- a/lib/ucs2.h
+++ b/lib/ucs2.h
@@ -1,5 +1,5 @@
 /*
- * Copyright (C) 1999-2001 Free Software Foundation, Inc.
+ * Copyright (C) 1999-2001, 2008 Free Software Foundation, Inc.
  * This file is part of the GNU LIBICONV Library.
  *
  * The GNU LIBICONV Library is free software; you can redistribute it
@@ -37,7 +37,8 @@ ucs2_mbtowc (conv_t conv, ucs4_t *pwc, const unsigned char *s, int n)
     } else if (wc == 0xfffe) {
       state ^= 1;
     } else if (wc >= 0xd800 && wc < 0xe000) {
-      return RET_ILSEQ;
+      conv->istate = state;
+      return RET_SHIFT_ILSEQ(count);
     } else {
       *pwc = wc;
       conv->istate = state;
diff --git a/lib/ucs4.h b/lib/ucs4.h
index f480ba8..00d08d2 100644
--- a/lib/ucs4.h
+++ b/lib/ucs4.h
@@ -1,5 +1,5 @@
 /*
- * Copyright (C) 1999-2001 Free Software Foundation, Inc.
+ * Copyright (C) 1999-2001, 2008 Free Software Foundation, Inc.
  * This file is part of the GNU LIBICONV Library.
  *
  * The GNU LIBICONV Library is free software; you can redistribute it
@@ -42,8 +42,10 @@ ucs4_mbtowc (conv_t conv, ucs4_t *pwc, const unsigned char *s, int n)
       *pwc = wc;
       conv->istate = state;
       return count;
-    } else
-      return RET_ILSEQ;
+    } else {
+      conv->istate = state;
+      return RET_SHIFT_ILSEQ(count);
+    }
   }
   conv->istate = state;
   return RET_TOOFEW(count);
diff --git a/lib/utf16.h b/lib/utf16.h
index c13a233..99b5e2c 100644
--- a/lib/utf16.h
+++ b/lib/utf16.h
@@ -1,5 +1,5 @@
 /*
- * Copyright (C) 1999-2001 Free Software Foundation, Inc.
+ * Copyright (C) 1999-2001, 2008 Free Software Foundation, Inc.
  * This file is part of the GNU LIBICONV Library.
  *
  * The GNU LIBICONV Library is free software; you can redistribute it
@@ -45,14 +45,14 @@ utf16_mbtowc (conv_t conv, ucs4_t *pwc, const unsigned char *s, int n)
       if (n >= 4) {
         ucs4_t wc2 = (state ? s[2] + (s[3] << 8) : (s[2] << 8) + s[3]);
         if (!(wc2 >= 0xdc00 && wc2 < 0xe000))
-          return RET_ILSEQ;
+          goto ilseq;
         *pwc = 0x10000 + ((wc - 0xd800) << 10) + (wc2 - 0xdc00);
         conv->istate = state;
         return count+4;
       } else
         break;
     } else if (wc >= 0xdc00 && wc < 0xe000) {
-      return RET_ILSEQ;
+      goto ilseq;
     } else {
       *pwc = wc;
       conv->istate = state;
@@ -62,6 +62,10 @@ utf16_mbtowc (conv_t conv, ucs4_t *pwc, const unsigned char *s, int n)
   }
   conv->istate = state;
   return RET_TOOFEW(count);
+
+ilseq:
+  conv->istate = state;
+  return RET_SHIFT_ILSEQ(count);
 }
 
 /* We output UTF-16 in big-endian order, with byte-order mark.
diff --git a/lib/utf16be.h b/lib/utf16be.h
index 62a28c6..a6d90ff 100644
--- a/lib/utf16be.h
+++ b/lib/utf16be.h
@@ -1,5 +1,5 @@
 /*
- * Copyright (C) 1999-2001 Free Software Foundation, Inc.
+ * Copyright (C) 1999-2001, 2008 Free Software Foundation, Inc.
  * This file is part of the GNU LIBICONV Library.
  *
  * The GNU LIBICONV Library is free software; you can redistribute it
@@ -34,18 +34,21 @@ utf16be_mbtowc (conv_t conv, ucs4_t *pwc, const unsigned char *s, int n)
       if (n >= 4) {
         ucs4_t wc2 = (s[2] << 8) + s[3];
         if (!(wc2 >= 0xdc00 && wc2 < 0xe000))
-          return RET_ILSEQ;
+          goto ilseq;
         *pwc = 0x10000 + ((wc - 0xd800) << 10) + (wc2 - 0xdc00);
         return count+4;
       }
     } else if (wc >= 0xdc00 && wc < 0xe000) {
-      return RET_ILSEQ;
+      goto ilseq;
     } else {
       *pwc = wc;
       return count+2;
     }
   }
   return RET_TOOFEW(count);
+
+ilseq:
+  return RET_SHIFT_ILSEQ(count);
 }
 
 static int
diff --git a/lib/utf16le.h b/lib/utf16le.h
index fb339a2..5bb2b02 100644
--- a/lib/utf16le.h
+++ b/lib/utf16le.h
@@ -1,5 +1,5 @@
 /*
- * Copyright (C) 1999-2001 Free Software Foundation, Inc.
+ * Copyright (C) 1999-2001, 2008 Free Software Foundation, Inc.
  * This file is part of the GNU LIBICONV Library.
  *
  * The GNU LIBICONV Library is free software; you can redistribute it
@@ -34,18 +34,21 @@ utf16le_mbtowc (conv_t conv, ucs4_t *pwc, const unsigned char *s, int n)
       if (n >= 4) {
         ucs4_t wc2 = s[2] + (s[3] << 8);
         if (!(wc2 >= 0xdc00 && wc2 < 0xe000))
-          return RET_ILSEQ;
+          goto ilseq;
         *pwc = 0x10000 + ((wc - 0xd800) << 10) + (wc2 - 0xdc00);
         return count+4;
       }
     } else if (wc >= 0xdc00 && wc < 0xe000) {
-      return RET_ILSEQ;
+      goto ilseq;
     } else {
       *pwc = wc;
       return count+2;
     }
   }
   return RET_TOOFEW(count);
+
+ilseq:
+  return RET_SHIFT_ILSEQ(count);
 }
 
 static int
diff --git a/lib/utf32.h b/lib/utf32.h
index 4be0db7..bc579ae 100644
--- a/lib/utf32.h
+++ b/lib/utf32.h
@@ -1,5 +1,5 @@
 /*
- * Copyright (C) 1999-2001 Free Software Foundation, Inc.
+ * Copyright (C) 1999-2001, 2008 Free Software Foundation, Inc.
  * This file is part of the GNU LIBICONV Library.
  *
  * The GNU LIBICONV Library is free software; you can redistribute it
@@ -49,8 +49,10 @@ utf32_mbtowc (conv_t conv, ucs4_t *pwc, const unsigned char *s, int n)
         *pwc = wc;
         conv->istate = state;
         return count;
-      } else
-        return RET_ILSEQ;
+      } else {
+        conv->istate = state;
+        return RET_SHIFT_ILSEQ(count);
+      }
     }
     s += 4; n -= 4;
   }
diff --git a/lib/utf7.h b/lib/utf7.h
index 4cce995..888bfb4 100644
--- a/lib/utf7.h
+++ b/lib/utf7.h
@@ -1,5 +1,5 @@
 /*
- * Copyright (C) 1999-2001 Free Software Foundation, Inc.
+ * Copyright (C) 1999-2001, 2008 Free Software Foundation, Inc.
  * This file is part of the GNU LIBICONV Library.
  *
  * The GNU LIBICONV Library is free software; you can redistribute it
@@ -99,7 +99,7 @@ inactive:
         state = 1;
         goto active;
       }
-      return RET_ILSEQ;
+      goto ilseq;
     }
   }
 
@@ -127,9 +127,9 @@ active:
       else {
         /* c terminates base64 encoding */
         if (base64state & -4)
-          return RET_ILSEQ; /* data must be 0, otherwise illegal */
+          goto ilseq; /* data must be 0, otherwise illegal */
         if (base64count)
-          return RET_ILSEQ; /* partial UTF-16 characters are invalid */
+          goto ilseq; /* partial UTF-16 characters are invalid */
         if (c == '-') {
           s++; count++;
         }
@@ -168,7 +168,7 @@ active:
       ucs4_t wc1 = wc >> 16;
       ucs4_t wc2 = wc & 0xffff;
       if (!(wc1 >= 0xd800 && wc1 < 0xdc00)) abort();
-      if (!(wc2 >= 0xdc00 && wc2 < 0xe000)) return RET_ILSEQ;
+      if (!(wc2 >= 0xdc00 && wc2 < 0xe000)) goto ilseq;
       *pwc = 0x10000 + ((wc1 - 0xd800) << 10) + (wc2 - 0xdc00);
     } else {
       *pwc = wc;
@@ -180,6 +180,10 @@ active:
 none:
   conv->istate = state;
   return RET_TOOFEW(count);
+
+ilseq:
+  conv->istate = state;
+  return RET_SHIFT_ILSEQ(count);
 }
 
 /*
diff --git a/tests/Makefile.in b/tests/Makefile.in
index 0c5b6dd..bd236e2 100644
--- a/tests/Makefile.in
+++ b/tests/Makefile.in
@@ -28,7 +28,7 @@ top_builddir = ..
 
 all :
 
-check : all table-from table-to ../src/iconv_no_i18n
+check : all table-from table-to ../src/iconv_no_i18n test-shiftseq
 	$(srcdir)/check-stateless $(srcdir) ASCII
 #	/* General multi-byte encodings */
 	$(CC) $(LDFLAGS) $(INCLUDES) $(CFLAGS) $(CPPFLAGS) $(srcdir)/genutf8.c -o genutf8 && \
@@ -154,6 +154,8 @@ check : all table-from table-to ../src/iconv_no_i18n
 	$(srcdir)/check-translitfailure $(srcdir) TranslitFail1 ISO-8859-1 ASCII
 #	/* substitution */
 	$(srcdir)/check-subst
+#	/* shift sequence before invalid multibyte character */
+	./test-shiftseq
 
 check-extra: check-extra-@USE_EXTRA_ENCODINGS@
 check-extra-no:
@@ -208,6 +210,12 @@ table-to : table-to.@OBJEXT@ ../lib/libiconv.la
 table-to.@OBJEXT@ : $(srcdir)/table-to.c
 	$(CC) -c $(INCLUDES) $(CFLAGS) $(CPPFLAGS) $(srcdir)/table-to.c
 
+test-shiftseq : test-shiftseq.@OBJEXT@ ../lib/libiconv.la
+	$(LIBTOOL_LINK) $(CC) $(LDFLAGS) $(CFLAGS) test-shiftseq.@OBJEXT@ ../lib/libiconv.la -o $@
+
+test-shiftseq.@OBJEXT@ : $(srcdir)/test-shiftseq.c
+	$(CC) -c $(INCLUDES) $(CFLAGS) $(CPPFLAGS) $(srcdir)/test-shiftseq.c
+
 # The following rule is necessary to avoid a toplevel "make -n check" failure.
 ../lib/libiconv.la :
 	cd ../lib && $(MAKE) libiconv.la
@@ -215,7 +223,7 @@ table-to.@OBJEXT@ : $(srcdir)/table-to.c
 mostlyclean : clean
 
 clean : force
-	$(RM) *.@OBJEXT@ *.lo table-from table-from@EXEEXT@ table-to table-to@EXEEXT@ tmp-* genutf8 genutf8@EXEEXT@ UTF-8.TXT gengb18030z gengb18030z@EXEEXT@ GB18030.TXT core *.stackdump
+	$(RM) *.@OBJEXT@ *.lo table-from table-from@EXEEXT@ table-to table-to@EXEEXT@ test-shiftseq test-shiftseq@EXEEXT@ tmp-* genutf8 genutf8@EXEEXT@ UTF-8.TXT gengb18030z gengb18030z@EXEEXT@ GB18030.TXT core *.stackdump
 	$(RM) -r .libs _libs
 
 distclean : clean
diff --git a/tests/test-shiftseq.c b/tests/test-shiftseq.c
new file mode 100644
index 0000000..f887f0c
--- /dev/null
+++ b/tests/test-shiftseq.c
@@ -0,0 +1,119 @@
+/* Copyright (C) 2008 Free Software Foundation, Inc.
+   This file is part of the GNU LIBICONV Library.
+
+   The GNU LIBICONV Library is free software; you can redistribute it
+   and/or modify it under the terms of the GNU Library General Public
+   License as published by the Free Software Foundation; either version 2
+   of the License, or (at your option) any later version.
+
+   The GNU LIBICONV 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
+   Library General Public License for more details.
+
+   You should have received a copy of the GNU Library General Public
+   License along with the GNU LIBICONV Library; see the file COPYING.LIB.
+   If not, write to the Free Software Foundation, Inc., 51 Franklin Street,
+   Fifth Floor, Boston, MA 02110-1301, USA.  */
+
+#include "config.h"
+
+#include <stdlib.h>
+#include <iconv.h>
+#include <errno.h>
+
+/* This test checks that the behaviour of iconv() in the situation of an
+   invalid multibyte character after a shift sequence is consistent whether
+   the entire buffer is passed at once, or whether it is passed in two
+   subsequent calls.  Based on a bug report from
+   Roman Rybalko <roman_rybalko@users.sourceforge.net>
+   at <http://savannah.gnu.org/bugs/?24216>.  */
+
+void main1 (void)
+{
+  static const char input[] = "+2D/YQNhB";
+  iconv_t cd;
+  char buf[20];
+
+  const char * inptr;
+  size_t inleft;
+  char * outptr;
+  size_t outleft;
+
+  cd = iconv_open ("UTF-8", "UTF-7");
+  {
+    size_t r;
+
+    inptr = input;
+    inleft = 9;
+    outptr = buf;
+    outleft = sizeof (buf);
+    r = iconv (cd, (char **) &inptr, &inleft, &outptr, &outleft);
+    /*
+    printf ("r = %d  errno = %d  inconsumed = %d outproduced = %d\n",
+            r, errno, inptr - input, outptr - buf);
+    // glibc:
+    //   r = -1  errno = 84  inconsumed = 4 outproduced = 0
+    // libiconv:
+    //   r = -1  errno = 84  inconsumed = 1 outproduced = 0
+    */
+    if (!(r == (size_t)(-1) && errno == EILSEQ
+          && inptr - input == 1 && outptr - buf == 0))
+      abort();
+  }
+}
+
+void main2 (void)
+{
+  static const char input[] = "+2D/YQNhB";
+  iconv_t cd;
+  char buf[20];
+
+  const char * inptr;
+  size_t inleft;
+  char * outptr;
+  size_t outleft;
+
+  cd = iconv_open ("UTF-8", "UTF-7");
+  {
+    size_t r;
+
+    inptr = input;
+    inleft = 5;
+    outptr = buf;
+    outleft = sizeof (buf);
+    r = iconv (cd, (char **) &inptr, &inleft, &outptr, &outleft);
+    /*
+    printf ("r = %d  errno = %d  inconsumed = %d outproduced = %d\n",
+            r, errno, inptr - input, outptr - buf);
+    // glibc:
+    //   r = -1  errno = 84 (EILSEQ)  inconsumed = 4 outproduced = 0
+    // libiconv:
+    //   r = -1  errno = 22 (EINVAL)  inconsumed = 1 outproduced = 0
+    */
+    if (!(r == (size_t)(-1) && errno == EINVAL
+          && inptr - input == 1 && outptr - buf == 0))
+      abort();
+
+    inleft = input + 20 - inptr;
+    r = iconv (cd, (char **) &inptr, &inleft, &outptr, &outleft);
+    /*
+    printf ("r = %d  errno = %d  inconsumed = %d outproduced = %d\n",
+            r, errno, inptr - input, outptr - buf);
+    // glibc:
+    //   r = -1  errno = 84 (EILSEQ)  inconsumed = 4 outproduced = 0
+    // libiconv:
+    //   r = -1  errno = 84 (EILSEQ)  inconsumed = 1 outproduced = 0
+    */
+    if (!(r == (size_t)(-1) && errno == EILSEQ
+          && inptr - input == 1 && outptr - buf == 0))
+      abort();
+  }
+}
+
+int main ()
+{
+  main1 ();
+  main2 ();
+  return 0;
+}