New subject: #1163(FFprobe:open): ffprobe can produce invalid XML

2 Apr 2012

      #1163: ffprobe can produce invalid XML
----------------------------------+---------------------------------
               Reporter:  Ian     |                  Owner:  stefano
                   Type:  defect  |                 Status:  new
               Priority:  normal  |              Component:  FFprobe
                Version:  0.10.2  |               Keywords:
             Blocked By:          |               Blocking:
Reproduced by developer:  0       |  Analyzed by developer:  0
----------------------------------+---------------------------------
 ffprobe can output invalid XML as xml_escape_str only handles < > '  " and
 &. For example most escape characters below 32 are invalid UTF-8.

 This replacement version of the function replaces any invalid UTF-8
 characters by the inverted question mark.

 {{{#!C
 static const char *xml_escape_str(char **dst, size_t *dst_size, const char
 *src,
                                   void *log_ctx)
 {
     // the unknown character (inverted question mark)
     const unsigned char BAD_CHARACTER_1 = 194, BAD_CHARACTER_2 = 191;

     const char *p;
     char *q;
     int copyAll = 1;
     size_t size = 1;

     /* precompute size */
     for (p = src; *p;) {
         int badChar = 0;
         unsigned char byte;

         ESCAPE_CHECK_SIZE(src, size, SIZE_MAX-10);

         byte = (unsigned char)*p;
         if (byte < 32 && byte != 9 && byte != 10 && byte != 13) {
             badChar = 1;
             ++p;
         } else if (byte < 128) {
             switch (byte) {
                 case '&' : size += 5; /* & */  copyAll = 0; break;
                 case '<' : size += 4; /* < */   copyAll = 0; break;
                 case '>' : size += 4; /* > */   copyAll = 0; break;
                 case '\"': size += 6; /* " */ copyAll = 0; break;
                 case '\'': size += 6; /* ' */ copyAll = 0; break;
                 default: size++;
                 }
             ++p;
             ++size;
             }
         else if (byte < 0xC0)
             {
             badChar = 1;
             ++p;
             }
         else
             {
             int extra;

             copyAll = 0;
             if (byte < 0xe0)
                 extra = 1;
             else if (byte < 0xf0)
                 extra = 2;
             else if (byte < 0xf8)
                 extra = 3;
             else
                 badChar = 1;

             if (badChar)
                 ++p;
             else
                 {
                 ++p;
                 for (int i = 0; i < extra && *p; ++i, ++p)
                     {
                     byte = (unsigned char)*p;
                     if ((byte & 0xc0) != 0x80)
                         badChar = 1;
                     }
                 if (!badChar)
                     size += extra;
                 }
             }
         if (badChar) {
             size += 2;
             copyAll = 0;
             }
         }

     ESCAPE_REALLOC_BUF(dst_size, dst, src, size);

 #define COPY_STR(str) {      \
         const char *s = str; \
         while (*s)           \
             *q++ = *s++;     \
     }

     p = src;
     q = *dst;
     if (copyAll)
         COPY_STR(p)
     else {
         while (*p) {
             int badChar = 0;
             unsigned char byte;

             byte = (unsigned char)*p;
             if (byte < 32 && byte != 9 && byte != 10 && byte != 13) {
                 badChar = 1;
                 ++p;
             } else if (byte < 128) {
                 switch (byte) {
                     case '&' : COPY_STR("&");  break;
                     case '<' : COPY_STR("<");   break;
                     case '>' : COPY_STR(">");   break;
                     case '\"': COPY_STR("""); break;
                     case '\'': COPY_STR("'"); break;
                     default: *q++ = *p;
                     }
                 ++p;
                 ++size;
                 }
             else if (byte < 0xC0)
                 {
                 badChar = 1;
                 ++p;
                 }
             else
                 {
                 int extra;

                 copyAll = 0;
                 if (byte < 0xe0)
                     extra = 1;
                 else if (byte < 0xf0)
                     extra = 2;
                 else if (byte < 0xf8)
                     extra = 3;
                 else
                     badChar = 1;

                 if (badChar)
                     ++p;
                 else
                     {
                     const char *startChar = p;
                     int i;
                     ++p;
                     for (i = 0; i < extra && *p; ++i, ++p)
                         {
                         byte = (unsigned char)*p;
                         if ((byte & 0xc0) != 0x80)
                             badChar = 1;
                         }
                     if (!badChar) {
                         for (i = 0; i < extra;)
                             *q++ = *startChar++;
                     }
                 }
             }
             if (badChar) {
                 *q++ = BAD_CHARACTER_1;
                 *q++ = BAD_CHARACTER_2;
             }
         }
     }
     *q = 0;

     return *dst;
 }
 }}}

-- 
Ticket URL: <https://ffmpeg.org/trac/ffmpeg/ticket/1163>
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FFmpeg issue tracker

#1163(FFprobe:new): ffprobe can produce invalid XML

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