Daniel P. Berrange wrote:
On Mon, Feb 01, 2010 at 10:18:27PM +0100, Jim Meyering wrote:
In src/qemu/qemu_driver.c, coverity reports this:
Event negative_return_fn: Called negative-returning function "lseek(logfile, 0L, 2)" Event var_assign: NEGATIVE return value of "lseek" assigned to signed variable "pos" At conditional (1): "(pos = lseek(logfile, 0L, 2)) < 0" taking true path 2877 if ((pos = lseek(logfile, 0, SEEK_END)) < 0) 2878 VIR_WARN(_("Unable to seek to end of logfile: %s"), 2879 virStrerror(errno, ebuf, sizeof ebuf));
I think it'd be less surprising to just set 'pos = 0' inside the if branch here, so later code doesn't have to worry about unexpected negative values.
Oh. I pushed after DV's ACK. That would let the later code continue, but using (lseek'ing to) an invalid position. Sounds like it could result in a cascade of additional errors, or worse, silent malfunction. But this is largely hypothetical, since failing to lseek-to-EOF on a valid file descriptor is not likely to happen.
diff --git a/src/qemu/qemu_driver.c b/src/qemu/qemu_driver.c index 22593bf..676a27b 100644 --- a/src/qemu/qemu_driver.c +++ b/src/qemu/qemu_driver.c @@ -558,8 +558,8 @@ qemudLogReadFD(virConnectPtr conn, const char* logDir, const char* name, off_t p close(fd); return -1; } - if (lseek(fd, pos, SEEK_SET) < 0) { - virReportSystemError(conn, errno, + if (pos < 0 || lseek(fd, pos, SEEK_SET) < 0) { + virReportSystemError(conn, pos < 0 ? 0 : errno, _("Unable to seek to %lld in %s"), (long long) pos, logfile); close(fd);