Bug#291338: apt: md5/sha1 checksum routines should work if length of file is unknown

[Anthony Towns <ajt@newraff.debian.org>]

Package: apt
Version: 0.5.4
Severity: wishlist
Tags: patch

SHA1Summation::AddFD should work on pipes as well as regular files
so files don't need to be uncompressed to disk to be summed. This
impacts python-apt too, since it doesn't offer a cumulative interface
to SHA1Summation.

Easy fix seems like it'd be:

 bool SHA1Summation::AddFD(int Fd,unsigned long Size)
 {
    unsigned char Buf[64 * 64];
    int Res = 0;
-   while (Size != 0)
+   int ToEOF = (Size == 0);
+   while (Size != 0 || ToEOF);
    {
-      Res = read(Fd,Buf,MIN(Size,sizeof(Buf)));
-      if (Res < 0 || (unsigned) Res != MIN(Size,sizeof(Buf)))
+      int n = sizeof(Buf);
+      if (!ToEOF) n = MIN(Size,n);
+      Res = read(Fd,Buf,n);
+      if (Res < 0 || (!ToEOF && (unsigned) Res != n)) // error, or short read
          return false;
+      if (ToEOF && Res == 0) // EOF
+         break;
       Size -= Res;
       Add(Buf,Res);
    }
    return true;
 }

-- System Information
Debian Release: 3.0
Architecture: i386
Kernel: Linux newraff 2.4.28-es #1 SMP Wed Jan 12 09:55:22 EST 2005 i686
Locale: LANG=C, LC_CTYPE=C

Versions of packages apt depends on:
ii  libc6                  2.2.5-11.8        GNU C Library: Shared libraries an
ii  libstdc++2.10-glibc2.2 1:2.95.4-11woody1 The GNU stdc++ library