Corpus minification fails if corpus path contains whitespace

[nausicaea]

When trying to minify the corpus of a fuzzing target, spaces in paths are not properly escaped.

$ cargo fuzz --version
cargo-fuzz 0.13.1
# I am running this test on an Apple M1 (Sequoia 15.7.1) with case-insensitive APFS.

The paragraph below shows the error I'm getting when running the poc.sh script in my repo. At cargo-fuzz-poc I've created a minimal working example of the issue for verification. An additional issue I'm seeing is: if the corpus contains multiple files, cargo +nightly fuzz cmin parse_cbor runs into an infinite loop, and I have to kill the processes. Furthermore, I cannot reproduce the same behaviour in fuzzing mode (cargo +nightly fuzz run parse_cbor): there whitespace in paths doesn't seem to matter.

I'm willing to provide additional information, should you require anything.

$ sh poc.sh
    Finished `release` profile [optimized + debuginfo] target(s) in 0.02s
    Finished `release` profile [optimized + debuginfo] target(s) in 0.01s
    Finished `release` profile [optimized + debuginfo] target(s) in 0.02s
     Running `target/aarch64-apple-darwin/release/parse_cbor '-artifact_prefix=/private/var/folders/cv/jzjgfjdj42nbzk8_w7plqshm0000gn/T/tmp.VMmLUHg0FJ/poc/path with space/example-crate/fuzz/artifacts/parse_cbor/' -merge=1 '/private/var/folders/cv/jzjgfjdj42nbzk8_w7plqshm0000gn/T/tmp.VMmLUHg0FJ/poc/path with space/example-crate/fuzz/.tmpJMDfRb/corpus' '/private/var/folders/cv/jzjgfjdj42nbzk8_w7plqshm0000gn/T/tmp.VMmLUHg0FJ/poc/path with space/example-crate/fuzz/corpus/parse_cbor'`
parse_cbor(86522,0x20bdb2140) malloc: nano zone abandoned due to inability to reserve vm space.
INFO: Running with entropic power schedule (0xFF, 100).
INFO: Seed: 977339485
INFO: Loaded 1 modules   (3143 inline 8-bit counters): 3143 [0x1023b5ab0, 0x1023b66f7),
INFO: Loaded 1 PC tables (3143 PCs): 3143 [0x1023b66f8,0x1023c2b68),
MERGE-OUTER: 2 files, 0 in the initial corpus, 0 processed earlier
MERGE-OUTER: attempt 1
parse_cbor(86523,0x20bdb2140) malloc: nano zone abandoned due to inability to reserve vm space.
ERROR: The required directory "with" does not exist
MERGE-OUTER: attempt 2
parse_cbor(86524,0x20bdb2140) malloc: nano zone abandoned due to inability to reserve vm space.
ERROR: The required directory "with" does not exist
MERGE-OUTER: the control file has 313 bytes
MERGE-OUTER: consumed 0Mb (44Mb rss) to parse the control file
MERGE-OUTER: 0 new files with 0 new features added; 0 new coverage edges

[fitzgen]

cargo fuzz just forks out to the underlying libfuzzer binary, so this is probably an upstream libfuzzer bug.