[pacman-dev] Checking free space before transaction

[Nezmer]

On Thu, Nov 11, 2010 at 09:42:13AM -0600, Dan McGee wrote:
> On Thu, Nov 11, 2010 at 9:05 AM, Allan McRae <allan at archlinux.org> wrote:
> > On 12/11/10 00:49, Nezmer wrote:
> >>
> >> On Thu, Nov 11, 2010 at 04:46:44PM +0200, Nezmer wrote:
> >>>
> >>> On Thu, Nov 11, 2010 at 09:09:27AM +1000, Allan McRae wrote:
> >>>>
> >>>> On 11/11/10 07:29, Nezmer wrote:
> >>>>>
> >>>>> But with those changes pacman did not like my ZFS pool.
> >>>>
> >>>>  From a bit of google, it looks like the statvfs call is probably
> >>>> returning EOVERFLOW on that so we can probably just assume LOTS of
> >>>> space and move on in those conditions...
> >>>>
> >>>> Allan
> >>>>
> >>>>
> >>>
> >>> That's over-simplification. This is the quick patch I needed to make
> >>> this even compile.
> >>
> >>> diff --git a/lib/libalpm/diskspace.c b/lib/libalpm/diskspace.c
> >>> index 51c25ed..f382d3c 100644
> >>> --- a/lib/libalpm/diskspace.c
> >>> +++ b/lib/libalpm/diskspace.c
> >>> @@ -80,7 +80,7 @@ static alpm_list_t *mount_point_list()
> >>>        endmntent(fp);
> >>>  #elif defined HAVE_GETMNTINFO
> >>>        int entries;
> >>> -       struct statvfs *fsp;
> >>> +       struct statfs *fsp;
> >>>
> >>>        entries = getmntinfo(&fsp, MNT_NOWAIT);
> >>>
> >>
> >> from /usr/include/sys/mount.h:
> >> int getmntinfo(struct statfs **, int);
> >
> > And here comes the joys of various BSDs doing whatever they feel like...   I
> > have programmed based on the NetBSD man page which does use a statvfs
> > struct...
> 
> This seems to explain it well:
> http://stackoverflow.com/questions/1653163/difference-between-statvfs-and-statfs-system-calls
> 
> FreeBSD also seems to define the function and type elsewhere, so we
> might just need to be smarter about what header we include:
> http://www.cygwin.com/ml/cygwin-developers/2003-12/msg00020.html
> 
> So we shouldn't be using statfs() if possible. What was the error,
> Nezmer? Compile output would have been nice; is it that the type and
> function aren't even defined? Can you grep /usr/include/ for us to see
> if statvfs is defined but needs some sort of #define to turn it on?
> 
> -Dan
> 

I'm probably not the best person to answer those questions (Did I
mention I don't know much in C ?).

The 1st error was as I already mentioned in getmntinfo expecting statfs
struct.

statfs is defined in sys/mount.h :

struct statfs {
  uint32_t f_version;   /* structure version number */
  uint32_t f_type;    /* type of filesystem */
  uint64_t f_flags;   /* copy of mount exported flags */
  uint64_t f_bsize;   /* filesystem fragment size */
  uint64_t f_iosize;    /* optimal transfer block size */
  uint64_t f_blocks;    /* total data blocks in filesystem */
  uint64_t f_bfree;   /* free blocks in filesystem */
  int64_t  f_bavail;    /* free blocks avail to non-superuser */
  uint64_t f_files;   /* total file nodes in filesystem */
  int64_t  f_ffree;   /* free nodes avail to non-superuser */
  uint64_t f_syncwrites;    /* count of sync writes since mount */
  uint64_t f_asyncwrites;   /* count of async writes since mount */
  uint64_t f_syncreads;   /* count of sync reads since mount */
  uint64_t f_asyncreads;    /* count of async reads since mount */
  uint64_t f_spare[10];   /* unused spare */
  uint32_t f_namemax;   /* maximum filename length */
  uid_t   f_owner;    /* user that mounted the filesystem */
  fsid_t    f_fsid;   /* filesystem id */
  char    f_charspare[80];      /* spare string space */
  char    f_fstypename[MFSNAMELEN]; /* filesystem type name */
  char    f_mntfromname[MNAMELEN];  /* mounted filesystem */
  char    f_mntonname[MNAMELEN];    /* directory on which mounted */
};


statvfs is defined in sys/statvfs.h :

struct statvfs {
  fsblkcnt_t  f_bavail; /* Number of blocks */
  fsblkcnt_t  f_bfree;
  fsblkcnt_t  f_blocks;
  fsfilcnt_t  f_favail; /* Number of files (e.g., inodes) */
  fsfilcnt_t  f_ffree;
  fsfilcnt_t  f_files;
  unsigned long f_bsize;  /* Size of blocks counted above */
  unsigned long f_flag;
  unsigned long f_frsize; /* Size of fragments */
  unsigned long f_fsid;   /* Not meaningful */
  unsigned long f_namemax;  /* Same as pathconf(_PC_NAME_MAX) */
};