gh-116541: Handle errors correctly in _pystatvfs_fromstructstatvfs

[sobolevn]

• Issue: Handle errors correctly in _pystatvfs_fromstructstatvfs in posixmodule #116541

[serhiy-storchaka]

It seems that some code is the same in both branches.

Also, on Linux some of fields are defined as unsigned long instead of long. Did not check other Posix systems. There may be a problem, but this is another issue.

[sobolevn]

Yes, I found this:

struct statvfs {
               unsigned long  f_bsize;    /* Filesystem block size */
               unsigned long  f_frsize;   /* Fragment size */
               fsblkcnt_t     f_blocks;   /* Size of fs in f_frsize units */
               fsblkcnt_t     f_bfree;    /* Number of free blocks */
               fsblkcnt_t     f_bavail;   /* Number of free blocks for
                                             unprivileged users */
               fsfilcnt_t     f_files;    /* Number of inodes */
               fsfilcnt_t     f_ffree;    /* Number of free inodes */
               fsfilcnt_t     f_favail;   /* Number of free inodes for
                                             unprivileged users */
               unsigned long  f_fsid;     /* Filesystem ID */
               unsigned long  f_flag;     /* Mount flags */
               unsigned long  f_namemax;  /* Maximum filename length */
           };

My proposal:

• Let's keep this PR focused on a new error handling
• I will open a new issue about this and do more research: why is it like this
• Probably I will send a second PR fixing the type

Since posixmodule is rather hard, I would prefer not to do any semantic changes now.

[serhiy-storchaka]

If you are going to backport this change, you can merge it first. Otherwise it is better to wait until the other issue be solved.

[sobolevn]

I am going to backport this change, like all others. Thanks a lot for finding this and reviewing my PRs! 👍

Here's a link for the statvfs issue: #116642

[miss-islington-app]

Thanks @sobolevn for the PR 🌮🎉.. I'm working now to backport this PR to: 3.11, 3.12.
🐍🍒⛏🤖

[bedevere-app]

GH-116643 is a backport of this pull request to the 3.12 branch.

[bedevere-app]

GH-116644 is a backport of this pull request to the 3.11 branch.