Fix gzopen/gzclose correctness issues - #66
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asonje
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July 30, 2026 19:37
- gzopen: check for open() failure (fd < 0) and gzdopen() failure (file == NULL) before registering the file in the map. Previously a failed open would pass fd=-1 to gzdopen, store a NULL-keyed map entry, and leak the fd on gzdopen failure. - gzclose: use off_t instead of int for the lseek return value to avoid truncation on files larger than 2 GiB. The truncated value caused truncate() to corrupt large files. Signed-off-by: Mulugeta Mammo <mulugeta.mammo@intel.com>
gzclose() called gzip_files.Unset(file) after orig_gzclose(file) had already freed the gzFile, on all three exit paths. The map is keyed by the gzFile address, so unsetting after the free can erase the entry of whatever file was allocated at that address in the meantime. Move the Unset to just after the lookup and drop the two trailing calls. The shared_ptr from ShardedMap::Get() keeps this file's state alive for the rest of the function. Defensive rather than a fix for an observed failure: under glibc a freed chunk returns to the freeing thread, so another thread's gzopen does not receive it. Allocators with cross-thread free lists offer no such guarantee, and unsetting once up front beats getting the ordering right on three exit paths. Signed-off-by: Olasoji <olasoji.denloye@intel.com>
asonje
approved these changes
Jul 30, 2026
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gzopen: check for open() failure (fd < 0) and gzdopen() failure (file == NULL) before registering the file in the map. Previously a failed open would pass fd=-1 to gzdopen, store a NULL-keyed map entry, and leak the fd on gzdopen failure.
gzclose: use off_t instead of int for the lseek return value to avoid truncation on files larger than 2 GiB. The truncated value caused truncate() to corrupt large files.