- Package:
- src:snappy-tools
- Source:
- src:snappy-tools
- Submitter:
- Santiago Vila
- Date:
- 2026-10-23 20:25:03 UTC
- Severity:
- normal
- Tags:
Dear maintainer: During a rebuild of all packages in unstable, this package failed to build. Below you will find the last part of the build log (probably the most relevant part, but not necessarily). If required, the full build log is available here: https://people.debian.org/~sanvila/build-logs/202609/ About the archive rebuild: The build was made on virtual machines from AWS, using sbuild and a reduced chroot with only build-essential packages. If you cannot reproduce the bug please contact me privately, as I am willing to provide ssh access to a virtual machine where the bug is fully reproducible. If this is really a bug in one of the build-depends, please use reassign and add an affects on src:snappy-tools, so that this is still visible in the BTS web page for this package. Thanks. -------------------------------------------------------------------------------- [...] make[1]: Entering directory '/<<PKGBUILDDIR>>' ! sed 's/^\.Dd/& February 15, 2024/' snappy.1 | groff -K utf8 -te -mdoc 2>&1 > /dev/null | grep . ./test ./test: /tmp/tmp.hVGev5CZK9/4G+1 compressed (file): cksum 4294967295 0 != 2636691535 201457667 ./test: /tmp/tmp.hVGev5CZK9/4G compressed (file): cksum 4294967295 0 != 3359713396 201457665 make[1]: *** [GNUmakefile:29: check] Error 1 make[1]: Leaving directory '/<<PKGBUILDDIR>>' dh_auto_test: error: make -j1 check returned exit code 2 make: *** [debian/rules:23: binary] Error 25 dpkg-buildpackage: error: debian/rules binary subprocess failed with exit status 2 --------------------------------------------------------------------------------
I repro this on sid, this is a regression in 1.3.1 against 1.2.
libsnappy snappy::Compress(), in 1.3.1-1 and onward,
treats files of size 2^32 bytes and larger, as empty:
ftruncate(source_file, 4 * 1024 * 1024 * 1024ull - 1); <- works
ftruncate(source_file, 4 * 1024 * 1024 * 1024ull); <- doesn't, empty output
ftruncate(source_file, 4 * 1024 * 1024 * 1024ull + 1); <- doesn't, empty output
# apt install ./*1.3*.deb
# c++ -O3 repro.cpp -orepro -lsnappy
# ltrace -Coll ./repro
size=4294967296 off=0; read=4294967296; available=4294967296
4G: 4294967296 -> 0 (0.00%)
# cat ll
open64("4G", 0x242, 0666) = 3
ftruncate64(3, 4294967296) = 0
close(1) = 0
open64("4G.s", 0x241, 0666) = 1
lseek64(3, 0, SEEK_END) = 4294967296
fprintf(0x7f1cde2b14a0, "size=%ld off=%ld; read=%llu; ava"..., 4294967296, 0, 4294967296) = 61
snappy::Compress(snappy::Source*, snappy::Sink*)(0x7ffeee916750, 0x7ffeee916740, 0, 0) = 0
fprintf(0x7f1cde2b14a0, "%s: %llu -> %llu (%.2f%%)\n", "4G", 4294967296, 0, 0.000000) = 28
snappy::Source::~Source()(0x7ffeee916750, 0x7ffeee916590, 0, 0) = 0x5575d8c55d58
snappy::Sink::~Sink()(0x7ffeee916740, 0x7ffeee916590, 0, 0) = 0x5575d8c55d90
+++ exited (status 0) +++
# apt install ./*1.2.2*.deb
# ltrace -Coll ./repro
size=4294967296 off=0; read=4294967296; available=4294967296
4G: 4294967296 -> 201457665 (4.69%)
# head ll
open64("4G", 0x242, 0666) = 3
ftruncate64(3, 4294967296) = 0
close(1) = 0
open64("4G.s", 0x241, 0666) = 1
lseek64(3, 0, SEEK_END) = 4294967296
fprintf(0x7f0af78084a0, "size=%ld off=%ld; read=%llu; ava"..., 4294967296, 0, 4294967296) = 61
snappy::Compress(snappy::Source*, snappy::Sink*)(0x7ffca4a5ec90, 0x7ffca4a5ec80, 0, 0 <unfinished ...>
fwrite("", 1, 1, 0x7f0af7808580) = 1
pread64(3, "", 65536, 0) = 65536
fwrite("", 1, 3074, 0x7f0af7808580) = 3074
pread64(3, "", 65536, 65536) = 65536
fwrite("", 1, 3074, 0x7f0af7808580) = 3074
pread64(3, "", 65536, 131072) = 65536
fwrite("", 1, 3074, 0x7f0af7808580) = 3074
pread64(3, "", 65536, 196608) = 65536
Reproducer:
-- >8 --
// SPDX-License-Identifier: 0BSD
#include <algorithm>
#include <atomic>
#include <clocale>
#include <cstdint>
#include <cstdio>
#include <cstring>
#include <err.h>
#include <fcntl.h>
#include <pthread.h>
#include <snappy-sinksource.h>
#include <snappy.h>
#include <unistd.h>
using namespace std::literals;
namespace {
static char buf[0xFFFFFF];
// A Source is an interface that yields a sequence of bytes
struct fd_source : snappy::Source {
int fd;
off_t size, off;
fd_source(int fd) : fd(fd), off(0) {
if((this->size = lseek(this->fd, 0, SEEK_END)) == -1)
this->off = -1;
}
// Return the number of bytes left to read from the source
virtual size_t Available() const { return this->size - this->off; }
// Peek at the next flat region of the source. Does not reposition
// the source. The returned region is empty iff Available()==0.
//
// Returns a pointer to the beginning of the region and store its
// length in *len.
//
// The returned region is valid until the next call to Skip() or
// until this object is destroyed, whichever occurs first.
//
// The returned region may be larger than Available() (for example
// if this ByteSource is a view on a substring of a larger source).
// The caller is responsible for ensuring that it only reads the
// Available() bytes.
virtual const char * Peek(size_t * len) {
static_assert(snappy::kBlockSize <= sizeof(buf));
ssize_t rd;
while((rd = pread(this->fd, buf, std::min(static_cast<off_t>(snappy::kBlockSize), this->size), this->off)) == -1 && errno == EINTR)
;
if(rd == -1)
err(2, "%s", "4G");
if(rd == 0)
this->off = this->size;
*len = rd;
return buf;
}
// Skip the next n bytes. Invalidates any buffer returned by
// a previous call to Peek().
// REQUIRES: Available() >= n
virtual void Skip(size_t n) { this->off += n; }
};
struct FILE_sink : snappy::Sink {
FILE * f;
FILE_sink(FILE * f) : f(f) {}
// Append "bytes[0,n-1]" to this.
virtual void Append(const char * bytes, size_t n) {
if(std::fwrite(bytes, 1, n, this->f) != n)
err(2, "write error");
}
};
}
int main() {
int source_file = open("4G", O_RDWR | O_CREAT | O_TRUNC, 0666);
ftruncate(source_file, 4 * 1024 * 1024 * 1024ull);
close(1);
open("4G.s", O_WRONLY | O_CREAT | O_TRUNC, 0666);
FILE_sink sink{stdout};
fd_source source{source_file};
unsigned long long read = source.size - source.off;
std::fprintf(stderr, "size=%ld off=%ld; read=%llu; available=%zu\n", source.size , source.off, read ,source.Available());
if(read != source.Available())
errno = EOVERFLOW, err(2, "%s", "4G");
unsigned long long written = Compress(&source, &sink);
std::fprintf(stderr, "%s: %llu -> %llu (%.2f%%)\n", "4G", read, written, 100. * ((double)written / read));
}
-- >8 --
Control: forwarded -1 https://github.com/google/snappy/issues/266 [...] [...] Thanks, unfortunately it affects more projects as well. It was reported upstream for more than a week. Until now, there has been no response. :( Laszlo/GCS
Dear Maintainer, I've built the package from the 1.3.1-3 sources, adding the patch from https://github.com/google/snappy/pull/269/changes It seems to pass the internal build tests, and the reproducer from the previous message is also giving reasonable output. Please consider releasing a version with this patch added. I am attaching the patch file to make it easy, please let me know if there's anything else I can do to help.
We believe that the bug you reported is fixed in the latest version of
snappy, which is due to be installed in the Debian FTP archive.
A summary of the changes between this version and the previous one is
attached.
Thank you for reporting the bug, which will now be closed. If you
have further comments please address them to 1149484@bugs.debian.org,
and the maintainer will reopen the bug report if appropriate.
Debian distribution maintenance software
pp.
Laszlo Boszormenyi (GCS) <gcs@debian.org> (supplier of updated snappy package)
(This message was generated automatically at their request; if you
believe that there is a problem with it please contact the archive
administrators by mailing ftpmaster@ftp-master.debian.org)
Format: 1.8
Date: Fri, 23 Oct 2026 21:23:07 +0200
Source: snappy
Architecture: source
Version: 1.3.1-4
Distribution: unstable
Urgency: medium
Maintainer: Laszlo Boszormenyi (GCS) <gcs@debian.org>
Changed-By: Laszlo Boszormenyi (GCS) <gcs@debian.org>
Closes: 1149484
Changes:
snappy (1.3.1-4) unstable; urgency=medium
.
* Backport upstream fix to use uint64_t for literal_length to prevent 32-bit
overflow (closes: #1149484).
Checksums-Sha1:
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6edc8537bd36fcc3c0dab78a2b620a84 17960 libs optional snappy_1.3.1-4.debian.tar.xz
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