safe_read_from: bump default size limit to 1 MiB to match pmxcfs

[pve-common.git] / src / PVE / Tools.pm

diff --git a/src/PVE/Tools.pm b/src/PVE/Tools.pm
index 2038abf65fecc1318849628eb060a3edfccf59ed..a1571ea3d9fa8c05746fea45ad7c525b197d5c6d 100644 (file)
--- a/src/PVE/Tools.pm
+++ b/src/PVE/Tools.pm
@@ -302,7 +302,7 @@ sub safe_read_from {
     my ($fh, $max, $oneline, $filename) = @_;
 
     # pmxcfs file size limit
-    $max = 512*1024 if !$max;
+    $max = 1024 * 1024 if !$max;
 
     my $subject = defined($filename) ? "file '$filename'" : 'input';
 
@@ -1581,6 +1581,13 @@ sub sendmail {
     close($mail);
 }
 
+# creates a temporary file that does not shows up on the file system hierarchy.
+#
+# Uses O_TMPFILE if available, which makes it just an anon inode that never shows up in the FS.
+# If O_TMPFILE is not available, which unlikely nowadays (added in 3.11 kernel and all FS relevant
+# for us support it) back to open-create + immediate unlink while still holding the file  handle.
+#
+# TODO: to avoid FS dependent features we could (transparently) switch to memfd_create as backend
 sub tempfile {
     my ($perm, %opts) = @_;
 
@@ -1611,6 +1618,7 @@ sub tempfile {
     return $fh;
 }
 
+# create an (ideally) anon file with the $data as content and return its FD-path and FH
 sub tempfile_contents {
     my ($data, $perm, %opts) = @_;
 
@@ -1856,6 +1864,37 @@ sub mount($$$$$) {
     );
 }
 
+# size is optional and defaults to 256, note that xattr limits are FS specific and that xattrs can
+# get arbitrary long. pass `0` for $size in array context to get the actual size of a value
+sub getxattr($$;$) {
+    my ($path_or_handle, $name, $size) = @_;
+    $size //= 256;
+    my $buf = pack("x${size}");
+
+    my $xattr_size = -1; # the actual size of the xattr, can be zero
+    if (defined(my $fd = fileno($path_or_handle))) {
+       $xattr_size = syscall(&PVE::Syscall::fgetxattr, $fd, $name, $buf, $size);
+    } else {
+       $xattr_size = syscall(&PVE::Syscall::getxattr, $path_or_handle, $name, $buf, $size);
+    }
+    if ($xattr_size < 0) {
+       return undef;
+    }
+    return wantarray ? ($buf, $xattr_size) : $buf;
+}
+
+# NOTE: can take either a path or an open file handle, i.e., its multiplexing setxattr and fsetxattr
+sub setxattr($$$;$) {
+    my ($path_or_handle, $name, $value, $flags) = @_;
+    my $size = length($value); # NOTE: seems to get correct length also for wide-characters in text..
+
+    if (defined(my $fd = fileno($path_or_handle))) {
+       return 0 == syscall(&PVE::Syscall::fsetxattr, $fd, $name, $value, $size, $flags // 0);
+    } else {
+       return 0 == syscall(&PVE::Syscall::setxattr, $path_or_handle, $name, $value, $size, $flags // 0);
+    }
+}
+
 sub safe_compare {
     my ($left, $right, $cmp) = @_;