Re: [xml] No stat, no catalog.

[Justin Fletcher <justin fletcher ntlworld com>]

In message <000501c14a0d$608ce040$4c09a8c0 home loc>
          Igor Zlatkovic <igor stud fh-frankfurt de> wrote:

> Hello everyone.
>
> Again we have an issue regarding HAVE_STAT. Somewhere in catalog.c, in the
> function xmlLoadCatalog, we can find the following lines:
>
>
>     #ifdef HAVE_STAT
>         if (stat(filename, &info) < 0)
>         return(-1);
>     #endif
>
>
> Later in the same function we can see the following:
>
>
>     content = xmlMalloc(info.st_size + 10);
>
>
> If HAVE_STAT is not defined, the local variable 'info' remains
> uninitialised. This leads to a problem, because the actual value of what we
> pass into xmlMalloc is unpredictable in this case. Unfortunately, the proper
> operation of the code that follows depends on successful execution of the
> stat function.
>
> If there is no alternative portable way to discover the size of the file
> 'filename', I would suggest to either make the catalog feature dependent on
> the availability of the function stat, or let the xmlLoadCatalog function
> fail if the function stat is not available. The way things are, the
> successful execution of the xmlLoadCatalog function depends on nothing but
> luck, if HAVE_STAT is undefined.

For the RISC OS version of this routine, we have a rather large collection
of somewhat unrelated conditionals. Primarily, RISC OS does not have a stat
routine in its standard library, so I don't use one - I prefer to use the
core C library alone. Similarly, there are no open/close/read/write
routines.

Thus, we assume that if no stat function exists, we must resort to the
standard filing system calls. Thus, the xmlLoadCatalog routine becomes to
following section. Apologies for the size of this section, but very little
is gained by making this into a diff.

Obviously this is not directly related to Igor's comments, but I feel that
the ability to fall back on functions that are known to exist has got to
be worthwhile :-)

--8<--------
int
xmlLoadCatalog(const char *filename) {
#ifdef HAVE_STAT
    int fd;
#else
    FILE *fd;
#endif
    int len, ret, i;
    long size;
#ifdef HAVE_STAT
    struct stat info;
#endif
    xmlChar *content;

    if (filename == NULL)
        return(-1);

    if (xmlDefaultCatalog == NULL)
        xmlDefaultCatalog = xmlHashCreate(20);
    if (xmlDefaultCatalog == NULL)
        return(-1);

    /*
     * Need to be done after ...
     */
    if (!xmlCatalogInitialized)
        xmlInitializeCatalog();

#ifdef HAVE_STAT
    if (stat(filename, &info) < 0)
        return(-1);
#endif

    /*
     * Prevent loops
     */
    for (i = 0;i < catalNr;i++) {
        if (xmlStrEqual((const xmlChar *)catalTab[i],
                        (const xmlChar *)filename)) {
            xmlGenericError(xmlGenericErrorContext,
                "xmlLoadCatalog: %s seems to induce a loop\n",
                            filename);
            return(-1);
        }
    }
    if (catalNr >= catalMax) {
        xmlGenericError(xmlGenericErrorContext,
            "xmlLoadCatalog: %s catalog list too deep\n",
                        filename);
            return(-1);
    }
    catalTab[catalNr++] = filename;

#ifdef HAVE_STAT
    if ((fd = open(filename, O_RDONLY)) < 0) {
#else
    if ((fd = fopen(riscosfilename(filename), "rb")) == NULL) {
#endif
        catalNr--;
        return(-1);
    }

#ifdef HAVE_STAT
    size=info.st_size;
#else
    if (fseek(fd, 0, SEEK_END) ||
        (size=ftell(fd))==EOF ||
        fseek(fd, 0, SEEK_SET))
    { /* File operations denied? ok, just close and return failure */
      fclose(fd);
      return(-1);
    }
#endif
    content = xmlMalloc(size + 10);
    if (content == NULL) {
        xmlGenericError(xmlGenericErrorContext,
                "realloc of %d byte failed\n", size + 10);
        catalNr--;
        return(-1);
    }
#ifdef HAVE_STAT
    len = read(fd, content, size);
#else
    len = fread(content, 1, size, fd);
#endif
    if (len < 0) {
        xmlFree(content);
        catalNr--;
        return(-1);
    }
    content[len] = 0;
#ifdef HAVE_STAT
    close(fd);
#else
    fclose(fd);
#endif

    if ((content[0] == ' ') || (content[0] == '-') ||
        ((content[0] >= 'A') && (content[0] <= 'Z')) ||
        ((content[0] >= 'a') && (content[0] <= 'z')))
        ret = xmlParseSGMLCatalog(content, filename);
    else {
        xmlCatalogEntryPtr catal, tmp;
        /* TODO: allow to switch the default preference */
        catal = xmlParseXMLCatalog(content, XML_CATA_PREFER_PUBLIC, filename);
        if (catal != NULL) {
            if (xmlDefaultXMLCatalogList == NULL)
                xmlDefaultXMLCatalogList = catal;
            else {
                tmp = xmlDefaultXMLCatalogList;
                while (tmp->next != NULL)
                    tmp = tmp->next;
                tmp->next = catal;
            }
            ret = 0;
        } else
            ret = -1;
    }
    xmlFree(content);
    catalNr--;
    return(ret);
}
--8<--------

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