https://github.com/python/cpython/commit/ffdd751e6261dc2b3f9103e3cf4b90af29f52c48 commit: ffdd751e6261dc2b3f9103e3cf4b90af29f52c48 branch: 3.14 author: Miss Islington (bot) <[email protected]> committer: serhiy-storchaka <[email protected]> date: 2026-07-28T17:41:30Z summary:
[3.14] gh-154324: Fix os.sendfile() error reporting on illumos (GH-154327) (GH-154833) illumos sendfile(3EXT) returns the number of transferred bytes by adding it to the offset without initializing it, so the offset cannot be used to detect a partial write. Use sendfilev(3EXT), which reports the number of transferred bytes in an explicit out parameter. (cherry picked from commit e3634bb44f7f1395dcb1b7ab3736811e9e2a4589) Co-authored-by: Serhiy Storchaka <[email protected]> Co-authored-by: Claude Opus 4.8 <[email protected]> files: A Misc/NEWS.d/next/Library/2026-07-21-08-31-55.gh-issue-154324.vDxV5U.rst M Modules/posixmodule.c diff --git a/Misc/NEWS.d/next/Library/2026-07-21-08-31-55.gh-issue-154324.vDxV5U.rst b/Misc/NEWS.d/next/Library/2026-07-21-08-31-55.gh-issue-154324.vDxV5U.rst new file mode 100644 index 00000000000000..388e4deb7c4198 --- /dev/null +++ b/Misc/NEWS.d/next/Library/2026-07-21-08-31-55.gh-issue-154324.vDxV5U.rst @@ -0,0 +1,3 @@ +Fix :func:`os.sendfile` on illumos: +it no longer reports a successful transfer +when the underlying system call failed without writing any data. diff --git a/Modules/posixmodule.c b/Modules/posixmodule.c index 26e62a1a7c50dc..7bf8bc9e5d9049 100644 --- a/Modules/posixmodule.c +++ b/Modules/posixmodule.c @@ -12095,27 +12095,35 @@ os_sendfile_impl(PyObject *module, int out_fd, int in_fd, PyObject *offobj, return PyLong_FromLong(0); } - // On illumos specifically sendfile() may perform a partial write but - // return -1/an error (in one confirmed case the destination socket - // had a 5 second timeout set and errno was EAGAIN) and it's on the client - // code to check if the offset parameter was modified by sendfile(). - // - // We need this variable to track said change. - off_t original_offset = offset; -#endif + // sendfile() may perform a partial write and still return -1, so the + // number of transferred bytes must be taken from the out parameter. + // sendfile() reports it by adding it to the offset, but does not + // initialize it when the transfer fails before writing any data, so use + // sendfilev(), which reports it explicitly. + sendfilevec_t vec; + size_t xferred; + + vec.sfv_fd = in_fd; + vec.sfv_flag = 0; + vec.sfv_off = offset; + vec.sfv_len = count; do { Py_BEGIN_ALLOW_THREADS - ret = sendfile(out_fd, in_fd, &offset, count); -#if defined(__sun) && defined(__SVR4) - // This handles illumos-specific sendfile() partial write behavior, - // see a comment above for more details. - if (ret < 0 && offset != original_offset) { - ret = offset - original_offset; + xferred = 0; + ret = sendfilev(out_fd, &vec, 1, &xferred); + if (ret < 0 && xferred != 0) { + ret = (Py_ssize_t)xferred; } -#endif Py_END_ALLOW_THREADS } while (ret < 0 && errno == EINTR && !(async_err = PyErr_CheckSignals())); +#else + do { + Py_BEGIN_ALLOW_THREADS + ret = sendfile(out_fd, in_fd, &offset, count); + Py_END_ALLOW_THREADS + } while (ret < 0 && errno == EINTR && !(async_err = PyErr_CheckSignals())); +#endif if (ret < 0) return (!async_err) ? posix_error() : NULL; return PyLong_FromSsize_t(ret); _______________________________________________ Python-checkins mailing list -- [email protected] To unsubscribe send an email to [email protected] https://mail.python.org/mailman3//lists/python-checkins.python.org Member address: [email protected]
