Improve tar-snapshot-edit
Support architecture-specific field ranges for the "-c" function. Better handle negative or larger-than-32-bit field values even when running in 32-bit Perl (for the default "print a summary" function)
This commit is contained in:
Nathan Stratton Treadway
committed by
Sergey Poznyakoff
Sergey Poznyakoff
parent
b41b004638
commit
5cb79ed519
@@ -28,7 +28,8 @@
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#
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# It can also run a check on all the field values found in the
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# snapshot file, printing out a detailed message when it finds values
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# that would cause an "Unexpected field value in snapshot file" error
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# that would cause an "Unexpected field value in snapshot file",
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# "Numerical result out of range", or "Invalid argument" error
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# if tar were run using that snapshot file as input. (See the
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# comments included in the definition of the check_field_values
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# routine for more detailed information regarding these checks.)
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@@ -47,9 +48,19 @@
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# or 2 files.
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# * tweak output formatting
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#
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#
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# Modified March 13, 2013 by Nathan Stratton Treadway <nathanst AT ontko.com>:
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# * configure field ranges used for -c option based on the system
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# architecture (in response to the December 2012 update to GNU tar
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# enabling support for systems with signed dev_t values).
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# * when printing the list of device ids found in the snapshot file
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# (when run in the default mode), print the raw device id values
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# instead of the hex-string version in those cases where they
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# can't be converted successfully.
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use Getopt::Std;
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use Config;
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my %snapshot_field_ranges; # used in check_field_values function
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## reading
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@@ -207,30 +218,151 @@ sub show_device_counts ($) {
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$devices{$dev}++;
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}
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my $devstr;
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foreach $dev (sort {$a <=> $b} keys %devices) {
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printf " Device 0x%04x occurs $devices{$dev} times.\n", $dev;
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$devstr = sprintf ("0x%04x", $dev);
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if ( $dev > 0xffffffff or $dev < 0 or hex($devstr) != $dev ) {
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# sprintf "%x" will not return a useful value for device ids
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# that are negative or which overflow the integer size on this
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# instance of Perl, so we convert the hex string back to a
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# number, and if it doesn't (numerically) equal the original
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# device id value, we know the hex conversion hasn't worked.
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#
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# Unfortunately, since we're running in "-w" mode, Perl will
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# also print a warning message if the hex() routine is called
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# on anything larger than "0xffffffff", even in 64-bit Perl
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# where such values are actually supported... so we have to
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# avoid calling hex() at all if the device id is too large or
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# negative. (If it's negative, the conversion to an unsigned
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# integer for the "%x" specifier will mean the result will
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# always trigger hex()'s warning on a 64-bit machine.)
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#
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# These situations don't seem to occur very often, so for now
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# when they do occur, we simply print the original text value
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# that was read from the snapshot file; it will look a bit
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# funny next to the values that do print in hex, but that's
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# preferable to printing values that aren't actually correct.
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$devstr = $dev;
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}
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printf " Device %s occurs $devices{$dev} times.\n", $devstr;
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}
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}
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## check field values
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# returns a warning message if $field isn't a valid string representation
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# of an integer, or if the resulting integer is out of the specified range
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sub validate_integer_field ($$$$) {
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my $field = shift;
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# initializes the global %snapshot_field_ranges hash, based on the "-a"
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# command-line option if given, otherwise based on the "archname" of
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# the current system.
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#
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# Each value in the hash is a two-element array containing the minimum
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# and maximum allowed values, respectively, for that field in the snapshot
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# file. GNU tar's allowed values for each architecture are determined
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# in the incremen.c source file, where the TYPE_MIN and TYPE_MAX
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# pre-processor expressions are used to determine the range that can be
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# expressed by the C data type used for each field; the values in the
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# array defined below should match those calculations.
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sub choose_architecture ($) {
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my $opt_a = shift;
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my $arch = $opt_a ? $opt_a : $Config{'archname'};
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# These ranges apply to Linux 2.4/2.6 on iX86 systems, but are used
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# by default on unrecognized/unsupported systems, too.
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%iX86_linux_field_ranges = (
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timestamp_sec => [ -2147483648, 2147483647 ], # min/max of time_t
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timestamp_nsec => [ 0, 999999999 ], # 0 to BILLION-1
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nfs => [ 0, 1 ],
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dev => [ 0, 18446744073709551615 ], # min/max of dev_t
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ino => [ 0, 4294967295 ], # min/max of ino_t
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);
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if ( $arch =~ m/^i[\dxX]86-linux/i ) {
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%snapshot_field_ranges = %iX86_linux_field_ranges;
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print "Checking snapshot field values using \"iX86-linux\" ranges.\n\n";
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} elsif ( $arch =~ m/^x86_64-linux/i ) {
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%snapshot_field_ranges = (
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timestamp_sec => [ -9223372036854775808, 9223372036854775807 ],
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timestamp_nsec => [ 0, 999999999 ],
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nfs => [ 0, 1 ],
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dev => [ 0, 18446744073709551615 ],
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ino => [ 0, 18446744073709551615 ],
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);
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print "Checking snapshot field values using \"x86_64-linux\" ranges.\n\n";
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} elsif ( $arch =~ m/^IA64.ARCHREV_0/i ) {
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# HP/UX running on Itanium/ia64 architecture
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%snapshot_field_ranges = (
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timestamp_sec => [ -2147483648, 2147483647 ],
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timestamp_nsec => [ 0, 999999999 ],
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nfs => [ 0, 1 ],
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dev => [ -2147483648, 2147483647 ],
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ino => [ 0, 4294967295 ],
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);
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print "Checking snapshot field values using \"IA64.ARCHREV_0\" (HP/UX) ranges.\n\n";
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} else {
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%snapshot_field_ranges = %iX86_linux_field_ranges;
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print "Unrecognized architecture \"$arch\"; defaulting to \"iX86-linux\".\n";
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print "(Use -a option to override.)\n" unless $opt_a;
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print "\n";
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}
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if ( ref(1) ne "" ) {
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print "(\"bignum\" mode is in effect; skipping 64-bit-integer check.)\n\n"
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} else {
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# find the largest max value in the current set of ranges
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my $maxmax = 0;
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for $v (values %snapshot_field_ranges ) {
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$maxmax = $v->[1] if ($v->[1] > $maxmax);
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}
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# "~0" translates into a platform-native integer with all bits turned
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# on -- that is, the largest value that can be represented as
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# an integer. We print a warning if our $maxmax value is greater
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# than that largest integer, since in that case Perl will switch
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# to using floats for those large max values. The wording of
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# the message assumes that the only way this situation can exist
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# is that the platform uses 32-bit integers but some of the
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# snapshot-file fields have 64-bit values.
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if ( ~0 < $maxmax ) {
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print <<EOF
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Note: this version of Perl uses 32-bit integers, which means that it
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will switch to using floating-point numbers when checking the ranges
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for 64-bit snapshot-file fields. This normally will work fine, but
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might fail to detect cases where the value in the input field value is
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only slightly out of range. (For example, a "9223372036854775808"
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might not be recognized as being larger than 9223372036854775807.)
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If you suspect you are experiencing this problem, you can try running
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the program using the "-Mbignum" option, as in
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\$ perl $0 -Mbignum -c [FILES]
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(but doing so will make the program run *much* slower).
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EOF
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}
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}
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}
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# returns a warning message if $field_value isn't a valid string
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# representation of an integer, or if the resulting integer is out of range
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# defined by the two-element array retrieved using up the $field_name key in
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# the global %snapshot_field_ranges hash.
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sub validate_integer_field ($$) {
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my $field_value = shift;
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my $field_name = shift;
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my $min = shift;
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my $max = shift;
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my ($min, $max) = @{$snapshot_field_ranges{$field_name}};
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my $msg = "";
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if ( not $field =~ /^-?\d+$/ ) {
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$msg = " $field_name value contains invalid characters: \"$field\"\n";
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if ( not $field_value =~ /^-?\d+$/ ) {
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$msg = " $field_name value contains invalid characters: \"$field_value\"\n";
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} else {
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if ( $field < $min ) {
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$msg = " $field_name value too low: \"$field\" < $min \n";
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} elsif ( $field > $max ) {
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$msg = " $field_name value too high: \"$field\" > $max \n";
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if ( $field_value < $min ) {
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$msg = " $field_name value too low: \"$field_value\" < $min \n";
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} elsif ( $field_value > $max ) {
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$msg = " $field_name value too high: \"$field_value\" > $max \n";
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}
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}
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return $msg;
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@@ -239,28 +371,18 @@ sub validate_integer_field ($$$$) {
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# This routine loops through each directory entry in the $info data
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# structure and prints a warning message if tar would abort with an
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# "Unexpected field value in snapshot file" error upon reading this
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# snapshot file.
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# "Unexpected field value in snapshot file", "Numerical result out of
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# range", or "Invalid argument" error upon reading this snapshot file.
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#
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# (Note that this specific error message was introduced along with the
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# change to snapshot file format "2", starting with tar v1.16 [or,
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# more precisely, v1.15.91].)
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# (Note that the "Unexpected field value in snapshot file" error message
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# was introduced along with the change to snapshot file format "2",
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# starting with tar v1.16 [or, more precisely, v1.15.91], while the
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# other two were introduced in v1.27.)
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#
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# The checks here are intended to match those found in the incremen.c
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# source file (as of tar v1.16.1).
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#
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# In that code, the checks are done against pre-processor expressions,
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# as defined in the C header files at compile time. In the routine
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# below, a Perl variable is created for each expression used as part of
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# one of these checks, assigned the value of the related pre-processor
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# expression as found on a Linux 2.6.8/i386 system.
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#
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# It seems likely that these settings will catch most invalid
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# field values found in actual snapshot files on all systems. However,
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# if "tar" is erroring out on a snapshot file that this check routine
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# does not complain about, that probably indicates that the values
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# below need to be adjusted to match those used by "tar" in that
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# particular environment.
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# source file. See the choose_architecture() function (above) for more
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# information on how to configure the range of values considered valid
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# by this script.
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#
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# (Note: the checks here are taken from the code that processes
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# version 2 snapshot files, but to keep things simple we apply those
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@@ -270,16 +392,6 @@ sub validate_integer_field ($$$$) {
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sub check_field_values ($) {
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my $info = shift;
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# set up a variable with the value of each pre-processor
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# expression used for field-value checks in incremen.c
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# (these values here are from a Linux 2.6.8/i386 system)
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my $BILLION = 1000000000; # BILLION
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my $MIN_TIME_T = -2147483648; # TYPE_MINIMUM(time_t)
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my $MAX_TIME_T = 2147483647; # TYPE_MAXIUMUM(time_t)
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my $MAX_DEV_T = 4294967295; # TYPE_MAXIUMUM(dev_t)
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my $MAX_INO_T = 4294967295; # TYPE_MAXIUMUM(ino_t)
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my $msg;
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my $error_found = 0;
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@@ -288,11 +400,9 @@ sub check_field_values ($) {
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$snapver = $info->[0];
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$msg = "";
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$msg .= validate_integer_field($info->[1],
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'timestamp_sec', $MIN_TIME_T, $MAX_TIME_T);
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$msg .= validate_integer_field($info->[1], 'timestamp_sec');
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if ($snapver >= 1) {
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$msg .= validate_integer_field($info->[2],
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'timestamp_nsec', 0, $BILLION-1);
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$msg .= validate_integer_field($info->[2], 'timestamp_nsec');
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}
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if ( $msg ne "" ) {
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$error_found = 1;
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@@ -305,15 +415,13 @@ sub check_field_values ($) {
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$msg = "";
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$msg .= validate_integer_field($dir->{'nfs'}, 'nfs', 0, 1);
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$msg .= validate_integer_field($dir->{'nfs'}, 'nfs');
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if ($snapver >= 1) {
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$msg .= validate_integer_field($dir->{'timestamp_sec'},
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'timestamp_sec', $MIN_TIME_T, $MAX_TIME_T);
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$msg .= validate_integer_field($dir->{'timestamp_nsec'},
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'timestamp_nsec', 0, $BILLION-1);
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$msg .= validate_integer_field($dir->{'timestamp_sec'}, 'timestamp_sec');
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$msg .= validate_integer_field($dir->{'timestamp_nsec'}, 'timestamp_nsec');
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}
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$msg .= validate_integer_field($dir->{'dev'}, 'dev', 0, $MAX_DEV_T);
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$msg .= validate_integer_field($dir->{'ino'}, 'ino', 0, $MAX_INO_T);
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$msg .= validate_integer_field($dir->{'dev'}, 'dev');
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$msg .= validate_integer_field($dir->{'ino'}, 'ino');
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if ( $msg ne "" ) {
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$error_found = 1;
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@@ -438,10 +546,10 @@ sub write_incr_db_2 ($$) {
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## main
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sub main {
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our ($opt_b, $opt_r, $opt_h, $opt_c);
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getopts('br:hc');
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our ($opt_b, $opt_r, $opt_h, $opt_c, $opt_a);
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getopts('br:hca:');
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HELP_MESSAGE() if ($opt_h || $#ARGV == -1 || ($opt_b && !$opt_r) ||
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($opt_r && $opt_c) );
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($opt_a && !$opt_c) || ($opt_r && $opt_c) );
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my @repl;
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if ($opt_r) {
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@@ -451,9 +559,11 @@ sub main {
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}
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}
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choose_architecture($opt_a) if ($opt_c);
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foreach my $snapfile (@ARGV) {
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my $info = read_incr_db($snapfile);
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if ($opt_r ) {
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if ($opt_r) {
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if ($opt_b) {
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rename($snapfile, $snapfile . "~") || die "Could not rename '$snapfile' to backup";
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}
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@@ -474,7 +584,7 @@ sub HELP_MESSAGE {
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Usage:
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tar-snapshot-edit SNAPFILE [SNAPFILE [...]]
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tar-snapshot-edit -r 'DEV1-DEV2[,DEV3-DEV4...]' [-b] SNAPFILE [SNAPFILE [...]]
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tar-snapshot-edit -c SNAPFILE [SNAPFILE [...]]
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tar-snapshot-edit -c [-aARCH] SNAPFILE [SNAPFILE [...]]
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With no options specified: print a summary of the 'device' values
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found in each SNAPFILE.
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@@ -487,9 +597,21 @@ Usage:
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With -c: Check the field values in each SNAPFILE and print warning
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messages if any invalid values are found. (An invalid value is one
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that would cause \"tar\" to generate an
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Unexpected field value in snapshot file
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error message as it processed the snapshot file.)
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that would cause \"tar\" to abort with an error message such as
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Unexpected field value in snapshot file
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Numerical result out of range
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or
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Invalid argument
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as it processed the snapshot file.)
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Normally the program automatically chooses the valid ranges for
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the fields based on the current system's architecture, but the
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-a option can be used to override the selection, e.g. in order
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to validate a snapshot file generated on a some other system.
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(Currently only three architectures are supported, "iX86-linux",
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"x86_64-linux", and "IA64.ARCHREV_0" [HP/UX running on Itanium/ia64],
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and if the current system isn't recognized, then the iX86-linux
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values are used by default.)
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EOF
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exit 1;
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