Re: Possible bug with file >2gb [patch]

[Andrew Brampton <brampton%gmail.com@localhost>]

On 30 May 2010 16:04, Andrew Brampton <brampton%gmail.com@localhost> wrote:
>
> If I understand it correctly libzip does not support zip64 yet, but
> regardless I think the assumption that the directory entries
> immediately proceed the EOCD is no longer valid, and instead the
> cd->offset field should be used. I will try and create a patch to this
> effect and see if I can get my zip useable.
>

Ok, sorry for the number of mails today. I have now written a patch
which changes half a dozen lines, but no longer assumes the central
directory entries are immediately before the end of central directory
record. Instead it uses the offset field, which I think is more true
to the original standard.

thanks
Andrew

Index: lib/zip_open.c
===================================================================
--- lib/zip_open.c      (revision 299964)
+++ lib/zip_open.c      (working copy)
@@ -52,7 +52,7 @@ static int _zip_headercomp(struct zip_di
                           struct zip_dirent *, int);
 static unsigned char *_zip_memmem(const unsigned char *, int,
                                  const unsigned char *, int);
-static struct zip_cdir *_zip_readcdir(FILE *, unsigned char *, unsigned char *,
+static struct zip_cdir *_zip_readcdir(FILE *, unsigned char *, off_t, unsigned 
char *,
                                 int, int, struct zip_error *);
 
 
@@ -156,7 +156,7 @@ set_error(int *zep, struct zip_error *er
    entries, or NULL if unsuccessful. */
 
 static struct zip_cdir *
-_zip_readcdir(FILE *fp, unsigned char *buf, unsigned char *eocd, int buflen,
+_zip_readcdir(FILE *fp, unsigned char *buf, off_t bufoff, unsigned char *eocd, 
int buflen,
              int flags, struct zip_error *error)
 {
     struct zip_cdir *cd;
@@ -216,9 +216,9 @@ _zip_readcdir(FILE *fp, unsigned char *b
        }
     }
 
-    if (cd->size < (unsigned int)(eocd-buf)) {
+    if (cd->offset >= bufoff) {
        /* if buffer already read in, use it */
-       cdp = eocd - cd->size;
+       cdp = buf + (cd->offset - bufoff);
        bufp = &cdp;
     }
     else {
@@ -481,6 +481,7 @@ _zip_find_central_dir(FILE *fp, int flag
 {
     struct zip_cdir *cdir, *cdirnew;
     unsigned char *buf, *match;
+    off_t bufoff;
     int a, best, buflen, i;
     struct zip_error zerr;
 
@@ -490,6 +491,7 @@ _zip_find_central_dir(FILE *fp, int flag
        set_error(zep, NULL, ZIP_ER_SEEK);
        return NULL;
     }
+    bufoff = ftello(fp);
 
     /* 64k is too much for stack */
     if ((buf=(unsigned char *)malloc(CDBUFSIZE)) == NULL) {
@@ -516,7 +518,7 @@ _zip_find_central_dir(FILE *fp, int flag
        /* found match -- check, if good */
        /* to avoid finding the same match all over again */
        match++;
-       if ((cdirnew=_zip_readcdir(fp, buf, match-1, buflen, flags,
+       if ((cdirnew=_zip_readcdir(fp, buf, bufoff, match-1, buflen, flags,
                                   &zerr)) == NULL)
            continue;