Re: [PATCH 3/4] perf: zstd: add streaming decompression and format probe functions

[sashiko-bot@kernel.org]

Thank you for your contribution! Sashiko AI review found 2 potential issue(s) to consider:
- [Medium] perf tools: zstd_is_compressed() returns true on file open failure
- [Low] perf: missing explicit <stdint.h> and <endian.h> for musl compatibility
--

commit a4c94e50df0d36cb48138075042eb1c0c1527f18
Author: Ivan Shapovalov <intelfx@intelfx.name>

    perf: zstd: add streaming decompression and format probe functions
    
    Add an actual streaming zstd decompression (fd->fd) entry point,
    plus a file->fd wrapper and a helper to detect zstd magic on a file
    for compressions[] in dso.c.

> diff --git a/tools/perf/util/zstd.c b/tools/perf/util/zstd.c
> index 3af8910bb87cf..982655a1f1a51 100644
> --- a/tools/perf/util/zstd.c
> +++ b/tools/perf/util/zstd.c

[ ... ]

> @@ -172,3 +176,103 @@ size_t zstd_decompress_buffer(struct zstd_data *data, void *src, size_t src_size

[ ... ]

> +bool zstd_is_compressed(const char *file)
> +{
> +	int fd = open(file, O_RDONLY);
> +	const uint32_t magic_le = htole32(ZSTD_MAGICNUMBER);

[Severity: Low]
Does this code need explicit inclusions for <stdint.h> and <endian.h>?

It appears compiling perf tools with musl libc could result in a build failure
here, since musl enforces strict POSIX header namespace separation and does not
leak uint32_t and htole32 through other standard library headers.

> +	char buf[4];
> +	ssize_t rc;
> +
> +	if (fd < 0) {
> +		pr_err("zstd: failed to open(%s): %s\n", file, strerror(errno));
> +		return -1;

[Severity: Medium]
Since zstd_is_compressed() returns a bool, does returning -1 here implicitly
evaluate to true?

If open() fails, returning true could cause callers probing file formats to
erroneously identify missing or unreadable files as valid ZSTD-compressed
archives. This could break fallback logic and lead to downstream decompression
attempts on missing files.

> +	}
> +
> +	rc = read(fd, buf, sizeof(buf));
> +	close(fd);
> +	return rc == sizeof(buf) ?
> +	       memcmp(buf, (const char *) &magic_le, sizeof(buf)) == 0 : false;
> +}

-- 
Sashiko AI review · https://sashiko.dev/#/patchset/20261014-perf-zstd-v1-0-9652727886fa@intelfx.name?part=3