(DEC_POS, BUF_DEC_POS): Use BEG_BYTE.

Bound the search with MAX_MULTIBYTE_LENGTH to avoid pathological case.

diff --git a/src/charset.h b/src/charset.h
index d4e85d91ebfb9be14d97d90461a144125853fa57..42ab2308d68950b1d8e33f081d5ad863e80481ab 100644 (file)
--- a/src/charset.h
+++ b/src/charset.h
@@ -675,13 +675,15 @@ else
                                                                        \
     pos_byte--;                                                                \
     if (pos_byte < GPT_BYTE)                                           \
-      p = BEG_ADDR + pos_byte - 1, p_min = BEG_ADDR;                   \
+      p = BEG_ADDR + pos_byte - BEG_BYTE, p_min = BEG_ADDR;            \
     else                                                               \
-      p = BEG_ADDR + GAP_SIZE + pos_byte - 1, p_min = GAP_END_ADDR;    \
+      p = BEG_ADDR + GAP_SIZE + pos_byte - BEG_BYTE, p_min = GAP_END_ADDR;\
     if (p > p_min && !CHAR_HEAD_P (*p))                                        \
       {                                                                        \
        unsigned char *pend = p--;                                      \
        int len, bytes;                                                 \
+        if (p_min < p - MAX_MULTIBYTE_LENGTH)                          \
+          p_min = p - MAX_MULTIBYTE_LENGTH;                            \
        while (p > p_min && !CHAR_HEAD_P (*p)) p--;                     \
        len = pend + 1 - p;                                             \
        PARSE_MULTIBYTE_SEQ (p, len, bytes);                            \
@@ -755,18 +757,20 @@ while (0)
     pos_byte--;                                                                \
     if (pos_byte < BUF_GPT_BYTE (buf))                                 \
       {                                                                        \
-       p = BUF_BEG_ADDR (buf) + pos_byte - 1;                          \
+       p = BUF_BEG_ADDR (buf) + pos_byte - BEG_BYTE;                   \
        p_min = BUF_BEG_ADDR (buf);                                     \
       }                                                                        \
     else                                                               \
       {                                                                        \
-       p = BUF_BEG_ADDR (buf) + BUF_GAP_SIZE (buf) + pos_byte - 1;     \
+       p = BUF_BEG_ADDR (buf) + BUF_GAP_SIZE (buf) + pos_byte - BEG_BYTE;\
        p_min = BUF_GAP_END_ADDR (buf);                                 \
       }                                                                        \
     if (p > p_min && !CHAR_HEAD_P (*p))                                        \
       {                                                                        \
        unsigned char *pend = p--;                                      \
        int len, bytes;                                                 \
+        if (p_min < p - MAX_MULTIBYTE_LENGTH)                          \
+          p_min = p - MAX_MULTIBYTE_LENGTH;                            \
        while (p > p_min && !CHAR_HEAD_P (*p)) p--;                     \
        len = pend + 1 - p;                                             \
        PARSE_MULTIBYTE_SEQ (p, len, bytes);                            \