[libpng15] Do png_check_keyword in png_set_*()

pngpriv.h

@@ -901,13 +901,6 @@ PNG_EXTERN void png_write_hIST PNGARG((png_structp png_ptr,
     png_const_uint_16p hist, int num_hist));
 #endif
 
-/* Chunks that have keywords */
-#if defined(PNG_TEXT_SUPPORTED) || defined(PNG_pCAL_SUPPORTED) || \
-    defined(PNG_iCCP_SUPPORTED) || defined(PNG_sPLT_SUPPORTED)
-PNG_EXTERN png_size_t png_check_keyword PNGARG((png_structp png_ptr,
-    png_const_charp key, png_charpp new_key));
-#endif
-
 #ifdef PNG_WRITE_tEXt_SUPPORTED
 PNG_EXTERN void png_write_tEXt PNGARG((png_structp png_ptr, png_const_charp key,
     png_const_charp text, png_size_t text_len));

pngset.c

@@ -20,6 +20,60 @@
 
 #if defined(PNG_READ_SUPPORTED) || defined(PNG_WRITE_SUPPORTED)
 
+#if defined(PNG_TEXT_SUPPORTED) || defined(PNG_pCAL_SUPPORTED) ||\
+    defined(PNG_iCCP_SUPPORTED) || defined(PNG_sPLT_SUPPORTED)
+/* Check that the tEXt or zTXt keyword is valid per PNG 1.0 specification,
+ * and if invalid, correct the keyword rather than discarding the entire
+ * chunk.  The PNG 1.0 specification requires keywords 1-79 characters in
+ * length, forbids leading or trailing whitespace, multiple internal spaces,
+ * and the non-break space (0x80) from ISO 8859-1.  Returns keyword length.
+ *
+ * The 'new_key' buffer must be 80 characters in size (for the keyword plus a
+ * trailing '\0').  If this routine returns 0 then there was no keyword, or a
+ * valid one could not be generated, and the caller must handle the error by not
+ * setting the keyword.
+ */
+static png_uint_32
+png_check_keyword(png_const_charp key, png_bytep new_key)
+{
+   png_uint_32 key_len = 0;
+   int space = 1;
+
+   if (key == NULL)
+   {
+      *new_key = 0;
+      return 0;
+   }
+
+   while (*key && key_len < 79)
+   {
+      png_byte ch = (png_byte)*key++;
+
+      if ((ch > 32 && ch <= 126) || (ch >= 161 /*&& ch <= 255*/))
+         *new_key++ = ch, ++key_len, space = 0;
+
+      else if (space == 0)
+      {
+         /* A space or an invalid character when one wasn't seen immediately
+          * before; output just a space.
+          */
+         *new_key++ = 32, ++key_len, space = 1;
+      }
+   }
+
+   if (key_len > 0 && space != 0) /* trailing space */
+      --key_len, --new_key;
+
+   /* Terminate the keyword */
+   *new_key = 0;
+
+   if (key_len == 0)
+      return 0;
+
+   return key_len;
+}
+#endif /* TEXT || pCAL || iCCP || sPLT */
+
 #ifdef PNG_bKGD_SUPPORTED
 void PNGAPI
 png_set_bKGD(png_structp png_ptr, png_infop info_ptr,
@@ -278,6 +332,7 @@ png_set_pCAL(png_structp png_ptr, png_infop info_ptr,
     png_const_charp purpose, png_int_32 X0, png_int_32 X1, int type,
     int nparams, png_const_charp units, png_charpp params)
 {
+   png_byte new_purpose[80];
    png_size_t length;
    int i;
 
@@ -286,7 +341,15 @@ png_set_pCAL(png_structp png_ptr, png_infop info_ptr,
    if (png_ptr == NULL || info_ptr == NULL)
       return;
 
-   length = png_strlen(purpose) + 1;
+   length = png_check_keyword(purpose, new_purpose);
+
+   if (length == 0)
+   {
+      png_warning(png_ptr, "pCAL: invalid purpose keyword");
+      return;
+   }
+      
+   ++length;
    png_debug1(3, "allocating purpose for info (%lu bytes)",
        (unsigned long)length);
 
@@ -309,7 +372,7 @@ png_set_pCAL(png_structp png_ptr, png_infop info_ptr,
       return;
    }
 
-   png_memcpy(info_ptr->pcal_purpose, purpose, length);
+   png_memcpy(info_ptr->pcal_purpose, new_purpose, length);
 
    png_debug(3, "storing X0, X1, type, and nparams in info");
    info_ptr->pcal_X0 = X0;
@@ -614,6 +677,7 @@ png_set_iCCP(png_structp png_ptr, png_infop info_ptr,
     png_const_charp name, int compression_type,
     png_const_bytep profile, png_uint_32 proflen)
 {
+   png_byte new_name[80];
    png_charp new_iccp_name;
    png_bytep new_iccp_profile;
    png_size_t length;
@@ -623,7 +687,15 @@ png_set_iCCP(png_structp png_ptr, png_infop info_ptr,
    if (png_ptr == NULL || info_ptr == NULL || name == NULL || profile == NULL)
       return;
 
-   length = png_strlen(name)+1;
+   length = png_check_keyword(name, new_name);
+
+   if (length == 0)
+   {
+      png_warning(png_ptr, "iCCP: invalid keyword");
+      return;
+   }
+      
+   ++length;
    new_iccp_name = (png_charp)png_malloc_warn(png_ptr, length);
 
    if (new_iccp_name == NULL)
@@ -632,7 +704,7 @@ png_set_iCCP(png_structp png_ptr, png_infop info_ptr,
       return;
    }
 
-   png_memcpy(new_iccp_name, name, length);
+   png_memcpy(new_iccp_name, new_name, length);
    new_iccp_profile = (png_bytep)png_malloc_warn(png_ptr, proflen);
 
    if (new_iccp_profile == NULL)
@@ -748,6 +820,7 @@ png_set_text_2(png_structp png_ptr, png_infop info_ptr,
    }
    for (i = 0; i < num_text; i++)
    {
+      png_byte new_key[80], new_lang[80];
       png_size_t text_length, key_len;
       png_size_t lang_len, lang_key_len;
       png_textp textp = &(info_ptr->text[info_ptr->num_text]);
@@ -762,7 +835,13 @@ png_set_text_2(png_structp png_ptr, png_infop info_ptr,
          continue;
       }
 
-      key_len = png_strlen(text_ptr[i].key);
+      key_len = png_check_keyword(text_ptr[i].key, new_key);
+
+      if (key_len == 0)
+      {
+         png_warning(png_ptr, "invalid text keyword");
+         continue;
+      }
 
       if (text_ptr[i].compression <= 0)
       {
@@ -775,8 +854,9 @@ png_set_text_2(png_structp png_ptr, png_infop info_ptr,
       {
          /* Set iTXt data */
 
+        /* Zero length language is OK */
          if (text_ptr[i].lang != NULL)
-            lang_len = png_strlen(text_ptr[i].lang);
+            lang_len = png_check_keyword(text_ptr[i].lang, new_lang);
 
          else
             lang_len = 0;
@@ -824,7 +904,7 @@ png_set_text_2(png_structp png_ptr, png_infop info_ptr,
           (key_len + lang_len + lang_key_len + text_length + 4),
           textp->key);
 
-      png_memcpy(textp->key, text_ptr[i].key,(png_size_t)(key_len));
+      png_memcpy(textp->key, new_key, (png_size_t)(key_len));
       *(textp->key + key_len) = '\0';
 
       if (text_ptr[i].compression > 0)
@@ -976,7 +1056,7 @@ png_set_sPLT(png_structp png_ptr,
  */
 {
    png_sPLT_tp np;
-   int i;
+   int i, j;
    size_t element_size;
 
    if (png_ptr == NULL || info_ptr == NULL)
@@ -1008,13 +1088,22 @@ png_set_sPLT(png_structp png_ptr,
    png_free(png_ptr, info_ptr->splt_palettes);
    info_ptr->splt_palettes=NULL;
 
-   for (i = 0; i < nentries; i++)
+   for (i = j = 0; i < nentries; i++)
    {
-      png_sPLT_tp to = np + info_ptr->splt_palettes_num + i;
+      png_sPLT_tp to = np + info_ptr->splt_palettes_num + j;
       png_const_sPLT_tp from = entries + i;
+      png_byte new_name[80];
       png_size_t length;
 
-      length = png_strlen(from->name) + 1;
+      length = png_check_keyword(from->name, new_name);
+
+      if (length == 0)
+      {
+         png_warning(png_ptr, "sPLT: invalid keyword");
+         continue;
+      }
+
+      ++length; /* for trailing '\0' */
       to->name = (png_charp)png_malloc_warn(png_ptr, length);
 
       if (to->name == NULL)
@@ -1024,7 +1113,7 @@ png_set_sPLT(png_structp png_ptr,
          continue;
       }
 
-      png_memcpy(to->name, from->name, length);
+      png_memcpy(to->name, new_name, length);
       to->entries = (png_sPLT_entryp)png_malloc_warn(png_ptr,
           from->nentries * png_sizeof(png_sPLT_entry));
 
@@ -1042,10 +1131,11 @@ png_set_sPLT(png_structp png_ptr,
 
       to->nentries = from->nentries;
       to->depth = from->depth;
+      ++j;
    }
 
    info_ptr->splt_palettes = np;
-   info_ptr->splt_palettes_num += nentries;
+   info_ptr->splt_palettes_num = j;
    info_ptr->valid |= PNG_INFO_sPLT;
    info_ptr->free_me |= PNG_FREE_SPLT;
 }
@@ -1348,137 +1438,4 @@ png_set_check_for_invalid_index(png_structp png_ptr, int allowed)
       png_ptr->num_palette_max = -1;
 }
 #endif
-
-#if defined(PNG_TEXT_SUPPORTED) || defined(PNG_pCAL_SUPPORTED) || \
-    defined(PNG_iCCP_SUPPORTED) || defined(PNG_sPLT_SUPPORTED)
-/* Check that the tEXt or zTXt keyword is valid per PNG 1.0 specification,
- * and if invalid, correct the keyword rather than discarding the entire
- * chunk.  The PNG 1.0 specification requires keywords 1-79 characters in
- * length, forbids leading or trailing whitespace, multiple internal spaces,
- * and the non-break space (0x80) from ISO 8859-1.  Returns keyword length.
- *
- * The new_key is allocated to hold the corrected keyword and must be freed
- * by the calling routine.  This avoids problems with trying to write to
- * static keywords without having to have duplicate copies of the strings.
- */
-png_size_t /* PRIVATE */
-png_check_keyword(png_structp png_ptr, png_const_charp key, png_charpp new_key)
-{
-   png_size_t key_len;
-   png_const_charp ikp;
-   png_charp kp, dp;
-   int kflag;
-   int kwarn=0;
-
-   png_debug(1, "in png_check_keyword");
-
-   *new_key = NULL;
-
-   if (key == NULL || (key_len = png_strlen(key)) == 0)
-   {
-      png_warning(png_ptr, "zero length keyword");
-      return ((png_size_t)0);
-   }
-
-   png_debug1(2, "Keyword to be checked is '%s'", key);
-
-   *new_key = (png_charp)png_malloc_warn(png_ptr, (png_uint_32)(key_len + 2));
-
-   if (*new_key == NULL)
-   {
-      png_warning(png_ptr, "Out of memory while procesing keyword");
-      return ((png_size_t)0);
-   }
-
-   /* Replace non-printing characters with a blank and print a warning */
-   for (ikp = key, dp = *new_key; *ikp != '\0'; ikp++, dp++)
-   {
-      if ((png_byte)*ikp < 0x20 ||
-         ((png_byte)*ikp > 0x7E && (png_byte)*ikp < 0xA1))
-      {
-         PNG_WARNING_PARAMETERS(p)
-
-         png_warning_parameter_unsigned(p, 1, PNG_NUMBER_FORMAT_02x,
-            (png_byte)*ikp);
-         png_formatted_warning(png_ptr, p, "invalid keyword character 0x@1");
-         *dp = ' ';
-      }
-
-      else
-      {
-         *dp = *ikp;
-      }
-   }
-   *dp = '\0';
-
-   /* Remove any trailing white space. */
-   kp = *new_key + key_len - 1;
-   if (*kp == ' ')
-   {
-      png_warning(png_ptr, "trailing spaces removed from keyword");
-
-      while (key_len && *kp == ' ')
-      {
-         *(kp--) = '\0';
-         key_len--;
-      }
-   }
-
-   /* Remove any leading white space. */
-   kp = *new_key;
-   if (*kp == ' ')
-   {
-      png_warning(png_ptr, "leading spaces removed from keyword");
-
-      while (*kp == ' ')
-      {
-         kp++;
-         key_len--;
-      }
-   }
-
-   png_debug1(2, "Checking for multiple internal spaces in '%s'", kp);
-
-   /* Remove multiple internal spaces. */
-   for (kflag = 0, dp = *new_key; *kp != '\0'; kp++)
-   {
-      if (*kp == ' ' && kflag == 0)
-      {
-         *(dp++) = *kp;
-         kflag = 1;
-      }
-
-      else if (*kp == ' ')
-      {
-         key_len--;
-         kwarn = 1;
-      }
-
-      else
-      {
-         *(dp++) = *kp;
-         kflag = 0;
-      }
-   }
-   *dp = '\0';
-   if (kwarn != 0)
-      png_warning(png_ptr, "extra interior spaces removed from keyword");
-
-   if (key_len == 0)
-   {
-      png_free(png_ptr, *new_key);
-      png_warning(png_ptr, "Zero length keyword");
-   }
-
-   if (key_len > 79)
-   {
-      png_warning(png_ptr, "keyword length must be 1 - 79 characters");
-      (*new_key)[79] = '\0';
-      key_len = 79;
-   }
-
-   return (key_len);
-}
-#endif /* TEXT || pCAL) || iCCP || sPLT */
-
 #endif /* PNG_READ_SUPPORTED || PNG_WRITE_SUPPORTED */

pngwutil.c

@@ -1099,7 +1099,6 @@ png_write_iCCP(png_structp png_ptr, png_const_charp name, int compression_type,
     png_const_charp profile, int profile_len)
 {
    png_size_t name_len;
-   png_charp new_name;
    compression_state comp;
    int embedded_profile_len = 0;
 
@@ -1111,8 +1110,7 @@ png_write_iCCP(png_structp png_ptr, png_const_charp name, int compression_type,
    comp.input = NULL;
    comp.input_len = 0;
 
-   if ((name_len = png_check_keyword(png_ptr, name, &new_name)) == 0)
-      return;
+   name_len = png_strlen(name);
 
    if (compression_type != PNG_COMPRESSION_TYPE_BASE)
       png_warning(png_ptr, "Unknown compression type in iCCP chunk");
@@ -1131,8 +1129,6 @@ png_write_iCCP(png_structp png_ptr, png_const_charp name, int compression_type,
    {
       png_warning(png_ptr,
           "Embedded profile length in iCCP chunk is negative");
-
-      png_free(png_ptr, new_name);
       return;
    }
 
@@ -1140,8 +1136,6 @@ png_write_iCCP(png_structp png_ptr, png_const_charp name, int compression_type,
    {
       png_warning(png_ptr,
           "Embedded profile length too large in iCCP chunk");
-
-      png_free(png_ptr, new_name);
       return;
    }
 
@@ -1161,10 +1155,14 @@ png_write_iCCP(png_structp png_ptr, png_const_charp name, int compression_type,
    png_write_chunk_header(png_ptr, png_iCCP,
        (png_uint_32)(name_len + profile_len + 2));
 
-   new_name[name_len + 1] = 0x00;
+   png_write_chunk_data(png_ptr, (png_bytep)name, name_len);
 
-   png_write_chunk_data(png_ptr, (png_bytep)new_name,
-       (png_size_t)(name_len + 2));
+   {
+      png_byte buffer[2];
+      buffer[0] = 0; /* terminate name */
+      buffer[1] = 0xFFU & compression_type;
+      png_write_chunk_data(png_ptr, buffer, 2);
+   }
 
    if (profile_len != 0)
    {
@@ -1172,7 +1170,6 @@ png_write_iCCP(png_structp png_ptr, png_const_charp name, int compression_type,
    }
 
    png_write_chunk_end(png_ptr);
-   png_free(png_ptr, new_name);
 }
 #endif
 
@@ -1182,7 +1179,6 @@ void /* PRIVATE */
 png_write_sPLT(png_structp png_ptr, png_const_sPLT_tp spalette)
 {
    png_size_t name_len;
-   png_charp new_name;
    png_byte entrybuf[10];
    png_size_t entry_size = (spalette->depth == 8 ? 6 : 10);
    png_size_t palette_size = entry_size * spalette->nentries;
@@ -1193,14 +1189,13 @@ png_write_sPLT(png_structp png_ptr, png_const_sPLT_tp spalette)
 
    png_debug(1, "in png_write_sPLT");
 
-   if ((name_len = png_check_keyword(png_ptr,spalette->name, &new_name))==0)
-      return;
+   name_len = png_strlen(spalette->name);
 
    /* Make sure we include the NULL after the name */
    png_write_chunk_header(png_ptr, png_sPLT,
        (png_uint_32)(name_len + 2 + palette_size));
 
-   png_write_chunk_data(png_ptr, (png_bytep)new_name,
+   png_write_chunk_data(png_ptr, (png_bytep)spalette->name,
        (png_size_t)(name_len + 1));
 
    png_write_chunk_data(png_ptr, &spalette->depth, (png_size_t)1);
@@ -1256,7 +1251,6 @@ png_write_sPLT(png_structp png_ptr, png_const_sPLT_tp spalette)
 #endif
 
    png_write_chunk_end(png_ptr);
-   png_free(png_ptr, new_name);
 }
 #endif
 
@@ -1519,12 +1513,10 @@ png_write_tEXt(png_structp png_ptr, png_const_charp key, png_const_charp text,
     png_size_t text_len)
 {
    png_size_t key_len;
-   png_charp new_key;
 
    png_debug(1, "in png_write_tEXt");
 
-   if ((key_len = png_check_keyword(png_ptr, key, &new_key))==0)
-      return;
+   key_len = strlen(key);
 
    if (text == NULL || *text == '\0')
       text_len = 0;
@@ -1541,7 +1533,7 @@ png_write_tEXt(png_structp png_ptr, png_const_charp key, png_const_charp text,
     * any non-Latin-1 characters except for NEWLINE.  ISO PNG will forbid them.
     * The NUL character is forbidden by PNG-1.0 through PNG-1.2 and ISO PNG.
     */
-   png_write_chunk_data(png_ptr, (png_bytep)new_key,
+   png_write_chunk_data(png_ptr, (png_bytep)key,
        (png_size_t)(key_len + 1));
 
    if (text_len != 0)
@@ -1549,7 +1541,6 @@ png_write_tEXt(png_structp png_ptr, png_const_charp key, png_const_charp text,
           (png_size_t)text_len);
 
    png_write_chunk_end(png_ptr);
-   png_free(png_ptr, new_key);
 }
 #endif
 
@@ -1561,7 +1552,6 @@ png_write_zTXt(png_structp png_ptr, png_const_charp key, png_const_charp text,
 {
    png_size_t key_len;
    png_byte buf;
-   png_charp new_key;
    compression_state comp;
 
    png_debug(1, "in png_write_zTXt");
@@ -1572,16 +1562,11 @@ png_write_zTXt(png_structp png_ptr, png_const_charp key, png_const_charp text,
    comp.input = NULL;
    comp.input_len = 0;
 
-   if ((key_len = png_check_keyword(png_ptr, key, &new_key)) == 0)
-   {
-      png_free(png_ptr, new_key);
-      return;
-   }
+   key_len = strlen(key);
 
    if (text == NULL || *text == '\0' || compression==PNG_TEXT_COMPRESSION_NONE)
    {
-      png_write_tEXt(png_ptr, new_key, text, (png_size_t)0);
-      png_free(png_ptr, new_key);
+      png_write_tEXt(png_ptr, key, text, (png_size_t)0);
       return;
    }
 
@@ -1596,11 +1581,9 @@ png_write_zTXt(png_structp png_ptr, png_const_charp key, png_const_charp text,
        (png_uint_32)(key_len+text_len + 2));
 
    /* Write key */
-   png_write_chunk_data(png_ptr, (png_bytep)new_key,
+   png_write_chunk_data(png_ptr, (png_bytep)key,
        (png_size_t)(key_len + 1));
 
-   png_free(png_ptr, new_key);
-
    buf = (png_byte)compression;
 
    /* Write compression */
@@ -1621,8 +1604,6 @@ png_write_iTXt(png_structp png_ptr, int compression, png_const_charp key,
     png_const_charp lang, png_const_charp lang_key, png_const_charp text)
 {
    png_size_t lang_len, key_len, lang_key_len, text_len;
-   png_charp new_lang;
-   png_charp new_key = NULL;
    png_byte cbuf[2];
    compression_state comp;
 
@@ -1633,15 +1614,13 @@ png_write_iTXt(png_structp png_ptr, int compression, png_const_charp key,
    comp.output_ptr = NULL;
    comp.input = NULL;
 
-   if ((key_len = png_check_keyword(png_ptr, key, &new_key)) == 0)
-      return;
+   key_len = png_strlen(key);
 
-   if ((lang_len = png_check_keyword(png_ptr, lang, &new_lang)) == 0)
-   {
-      png_warning(png_ptr, "Empty language field in iTXt chunk");
-      new_lang = NULL;
+   if (lang == NULL)
       lang_len = 0;
-   }
+
+   else
+      lang_len = png_strlen(lang);
 
    if (lang_key == NULL)
       lang_key_len = 0;
@@ -1676,7 +1655,7 @@ png_write_iTXt(png_structp png_ptr, int compression, png_const_charp key,
     * any non-Latin-1 characters except for NEWLINE.  ISO PNG will forbid them.
     * The NUL character is forbidden by PNG-1.0 through PNG-1.2 and ISO PNG.
     */
-   png_write_chunk_data(png_ptr, (png_bytep)new_key, (png_size_t)(key_len + 1));
+   png_write_chunk_data(png_ptr, (png_bytep)key, (png_size_t)(key_len + 1));
 
    /* Set the compression flag */
    if (compression == PNG_ITXT_COMPRESSION_NONE ||
@@ -1692,7 +1671,7 @@ png_write_iTXt(png_structp png_ptr, int compression, png_const_charp key,
    png_write_chunk_data(png_ptr, cbuf, (png_size_t)2);
 
    cbuf[0] = 0;
-   png_write_chunk_data(png_ptr, (new_lang ? (png_const_bytep)new_lang : cbuf),
+   png_write_chunk_data(png_ptr, (lang ? (png_const_bytep)lang : cbuf),
        (png_size_t)(lang_len + 1));
 
    png_write_chunk_data(png_ptr, (lang_key ? (png_const_bytep)lang_key : cbuf),
@@ -1701,9 +1680,6 @@ png_write_iTXt(png_structp png_ptr, int compression, png_const_charp key,
    png_write_compressed_data_out(png_ptr, &comp, text_len);
 
    png_write_chunk_end(png_ptr);
-
-   png_free(png_ptr, new_key);
-   png_free(png_ptr, new_lang);
 }
 #endif
 
@@ -1737,7 +1713,6 @@ png_write_pCAL(png_structp png_ptr, png_charp purpose, png_int_32 X0,
    png_size_t purpose_len, units_len, total_len;
    png_size_tp params_len;
    png_byte buf[10];
-   png_charp new_purpose;
    int i;
 
    png_debug1(1, "in png_write_pCAL (%d parameters)", nparams);
@@ -1745,7 +1720,7 @@ png_write_pCAL(png_structp png_ptr, png_charp purpose, png_int_32 X0,
    if (type >= PNG_EQUATION_LAST)
       png_warning(png_ptr, "Unrecognized equation type for pCAL chunk");
 
-   purpose_len = png_check_keyword(png_ptr, purpose, &new_purpose) + 1;
+   purpose_len = strlen(purpose) + 1;
    png_debug1(3, "pCAL purpose length = %d", (int)purpose_len);
    units_len = png_strlen(units) + (nparams == 0 ? 0 : 1);
    png_debug1(3, "pCAL units length = %d", (int)units_len);
@@ -1767,7 +1742,7 @@ png_write_pCAL(png_structp png_ptr, png_charp purpose, png_int_32 X0,
 
    png_debug1(3, "pCAL total length = %d", (int)total_len);
    png_write_chunk_header(png_ptr, png_pCAL, (png_uint_32)total_len);
-   png_write_chunk_data(png_ptr, (png_const_bytep)new_purpose, purpose_len);
+   png_write_chunk_data(png_ptr, (png_const_bytep)purpose, purpose_len);
    png_save_int_32(buf, X0);
    png_save_int_32(buf + 4, X1);
    buf[8] = (png_byte)type;
@@ -1775,8 +1750,6 @@ png_write_pCAL(png_structp png_ptr, png_charp purpose, png_int_32 X0,
    png_write_chunk_data(png_ptr, buf, (png_size_t)10);
    png_write_chunk_data(png_ptr, (png_const_bytep)units, (png_size_t)units_len);
 
-   png_free(png_ptr, new_purpose);
-
    for (i = 0; i < nparams; i++)
    {
       png_write_chunk_data(png_ptr, (png_const_bytep)params[i], params_len[i]);