fix: guard for locations < 1 in alpmdb parse

[spiffcs]

Summary

Attempts to address #1094 - syft would continue to try and resolve file contents when no locations were found for FilesByPath causing a panic when trying to access position 0 of an empty slice.

Error message just before panic on windows:

DEBUG directory resolver unable to evaluate symlink for 
path="C:\msys64\var\lib\pacman\local\libp11-kit-0.24.1-4\mtree" : 
CreateFile C:\C:: The filename, directory name, or volume label syntax is incorrect.

This fix removes the possibility of panic by checking the locations found before FilesBypath is called.

It does not address the fact that C:\msys64\var\lib\pacman\local\libp11-kit-0.24.1-4\mtree is a valid path that should be able to be parsed.

Also note: this error will eventually surface to:

syft/syft/pkg/cataloger/catalog.go

Lines 54 to 58 in b290a44

	packages, relationships, err := c.Catalog(resolver)
	if err != nil {
	errs = multierror.Append(errs, err)
	continue
	}

This is an error condition for syft and will result in the program status code 1.

A follow-up PR will be made that can address the correct parsing of the above mtree file on windows.

Signed-off-by: Christopher Phillips [email protected]

[github-actions]

Benchmark Test Results

Benchmark results from the latest changes vs base branch

name                                                       old time/op    new time/op    delta
ImagePackageCatalogers/alpmdb-cataloger-2                    11.5ms ± 1%    11.2ms ± 1%  -2.34%  (p=0.016 n=4+5)
ImagePackageCatalogers/ruby-gemspec-cataloger-2              1.25ms ± 0%    1.28ms ± 1%  +2.01%  (p=0.016 n=5+4)
ImagePackageCatalogers/python-package-cataloger-2            3.25ms ± 0%    3.27ms ± 1%  +0.80%  (p=0.016 n=5+5)
ImagePackageCatalogers/php-composer-installed-cataloger-2    1.03ms ± 0%    1.07ms ± 2%  +3.88%  (p=0.008 n=5+5)
ImagePackageCatalogers/javascript-package-cataloger-2         712µs ± 0%     744µs ± 1%  +4.49%  (p=0.008 n=5+5)
ImagePackageCatalogers/node-binary-cataloger-2               6.71µs ± 1%    6.32µs ± 2%  -5.78%  (p=0.008 n=5+5)
ImagePackageCatalogers/dpkgdb-cataloger-2                     816µs ± 1%     846µs ± 2%  +3.77%  (p=0.008 n=5+5)
ImagePackageCatalogers/rpm-db-cataloger-2                    1.20ms ± 1%    1.27ms ± 2%  +5.51%  (p=0.016 n=4+5)
ImagePackageCatalogers/java-cataloger-2                      13.9ms ± 1%    14.1ms ± 1%  +1.99%  (p=0.016 n=5+5)
ImagePackageCatalogers/apkdb-cataloger-2                     1.24ms ± 2%    1.26ms ± 3%    ~     (p=0.421 n=5+5)
ImagePackageCatalogers/go-module-binary-cataloger-2          6.76µs ± 1%    6.46µs ± 1%  -4.50%  (p=0.008 n=5+5)
ImagePackageCatalogers/dotnet-deps-cataloger-2               1.32ms ± 1%    1.34ms ± 2%    ~     (p=0.095 n=5+5)
ImagePackageCatalogers/portage-cataloger-2                    670µs ± 1%     704µs ± 1%  +5.11%  (p=0.008 n=5+5)
ImagePackageCatalogers/sbom-cataloger-2                      4.21ms ± 0%    4.39ms ± 1%  +4.21%  (p=0.016 n=4+5)

name                                                       old alloc/op   new alloc/op   delta
ImagePackageCatalogers/alpmdb-cataloger-2                    5.26MB ± 0%    5.26MB ± 0%    ~     (p=0.690 n=5+5)
ImagePackageCatalogers/ruby-gemspec-cataloger-2               205kB ± 0%     205kB ± 0%    ~     (p=0.095 n=5+5)
ImagePackageCatalogers/python-package-cataloger-2             963kB ± 0%     962kB ± 0%  -0.14%  (p=0.008 n=5+5)
ImagePackageCatalogers/php-composer-installed-cataloger-2     218kB ± 0%     217kB ± 0%  -0.12%  (p=0.008 n=5+5)
ImagePackageCatalogers/javascript-package-cataloger-2         159kB ± 0%     159kB ± 0%    ~     (p=0.310 n=5+5)
ImagePackageCatalogers/node-binary-cataloger-2               1.12kB ± 0%    1.12kB ± 0%    ~     (all equal)
ImagePackageCatalogers/dpkgdb-cataloger-2                     199kB ± 0%     199kB ± 0%  -0.13%  (p=0.032 n=5+5)
ImagePackageCatalogers/rpm-db-cataloger-2                     303kB ± 0%     303kB ± 0%    ~     (p=1.000 n=5+5)
ImagePackageCatalogers/java-cataloger-2                      3.49MB ± 0%    3.49MB ± 0%    ~     (p=0.548 n=5+5)
ImagePackageCatalogers/apkdb-cataloger-2                     1.26MB ± 0%    1.26MB ± 0%  -0.08%  (p=0.008 n=5+5)
ImagePackageCatalogers/go-module-binary-cataloger-2          1.12kB ± 0%    1.12kB ± 0%    ~     (all equal)
ImagePackageCatalogers/dotnet-deps-cataloger-2                374kB ± 0%     374kB ± 0%    ~     (p=0.389 n=5+5)
ImagePackageCatalogers/portage-cataloger-2                    139kB ± 0%     138kB ± 0%    ~     (p=0.056 n=5+5)
ImagePackageCatalogers/sbom-cataloger-2                       722kB ± 0%     721kB ± 0%  -0.04%  (p=0.008 n=5+5)

name                                                       old allocs/op  new allocs/op  delta
ImagePackageCatalogers/alpmdb-cataloger-2                     85.7k ± 0%     85.7k ± 0%    ~     (p=0.484 n=5+5)
ImagePackageCatalogers/ruby-gemspec-cataloger-2               4.24k ± 0%     4.24k ± 0%    ~     (all equal)
ImagePackageCatalogers/python-package-cataloger-2             16.5k ± 0%     16.5k ± 0%    ~     (p=1.000 n=5+5)
ImagePackageCatalogers/php-composer-installed-cataloger-2     5.50k ± 0%     5.50k ± 0%    ~     (p=1.000 n=5+5)
ImagePackageCatalogers/javascript-package-cataloger-2         3.33k ± 0%     3.33k ± 0%    ~     (all equal)
ImagePackageCatalogers/node-binary-cataloger-2                 38.0 ± 0%      38.0 ± 0%    ~     (all equal)
ImagePackageCatalogers/dpkgdb-cataloger-2                     4.46k ± 0%     4.46k ± 0%    ~     (all equal)
ImagePackageCatalogers/rpm-db-cataloger-2                     8.11k ± 0%     8.11k ± 0%    ~     (all equal)
ImagePackageCatalogers/java-cataloger-2                       57.5k ± 0%     57.5k ± 0%    ~     (p=1.000 n=5+5)
ImagePackageCatalogers/apkdb-cataloger-2                      5.45k ± 0%     5.45k ± 0%    ~     (all equal)
ImagePackageCatalogers/go-module-binary-cataloger-2            38.0 ± 0%      38.0 ± 0%    ~     (all equal)
ImagePackageCatalogers/dotnet-deps-cataloger-2                7.12k ± 0%     7.12k ± 0%    ~     (all equal)
ImagePackageCatalogers/portage-cataloger-2                    3.58k ± 0%     3.58k ± 0%    ~     (all equal)
ImagePackageCatalogers/sbom-cataloger-2                       24.4k ± 0%     24.4k ± 0%    ~     (all equal)