Re: [libvirt] [PATCH v2 07/13] qemu: introduce a qemuDomainLogContext object
On 11/12/2015 12:19 PM, Daniel P. Berrange wrote:
Introduce a qemuDomainLogContext object to encapsulate
handling of I/O to/from the domain log file. This will
hide details of the log file implementation from the
rest of the driver, making it easier to introduce
support for virtlogd later.
Signed-off-by: Daniel P. Berrange <berrange(a)redhat.com>
---
src/qemu/qemu_domain.c | 178 +++++++++++++++++++++++++++++++++++++++++++++++++
src/qemu/qemu_domain.h | 22 ++++++
2 files changed, 200 insertions(+)
[...]
+qemuDomainLogContextPtr qemuDomainLogContextNew(virQEMUDriverPtr driver,
+ virDomainObjPtr vm,
+ qemuDomainLogContextMode mode)
+{
+ virQEMUDriverConfigPtr cfg = virQEMUDriverGetConfig(driver);
+ qemuDomainLogContextPtr ctxt = NULL;
+ char *logfile = NULL;
+
+ if (VIR_ALLOC(ctxt) < 0)
+ goto error;
+
+ ctxt->writefd = -1;
+ ctxt->readfd = -1;
+ virAtomicIntSet(&ctxt->refs, 1);
+
+ if (virAsprintf(&logfile, "%s/%s.log", cfg->logDir,
vm->def->name) < 0)
+ goto error;
+
+ if ((ctxt->writefd = open(logfile, O_WRONLY | O_CREAT | O_APPEND, S_IRUSR |
S_IWUSR)) < 0) {
+ virReportSystemError(errno, _("failed to create logfile %s"),
+ logfile);
+ goto error;
+ }
+ if (virSetCloseExec(ctxt->writefd) < 0) {
+ virReportSystemError(errno, _("failed to set close-on-exec flag on
%s"),
+ logfile);
+ goto error;
+ }
+
+ /* For unprivileged startup we must truncate the file since
+ * we can't rely on logrotate. We don't use O_TRUNC since
+ * it is better for SELinux policy if we truncate afterwards */
+ if (mode == QEMU_DOMAIN_LOG_CONTEXT_MODE_START &&
+ !virQEMUDriverIsPrivileged(driver) &&
+ ftruncate(ctxt->writefd, 0) < 0) {
+ virReportSystemError(errno, _("failed to truncate %s"),
+ logfile);
+ goto error;
+ }
+
+ if (mode == QEMU_DOMAIN_LOG_CONTEXT_MODE_START) {
+ if ((ctxt->readfd = open(logfile, O_RDONLY, S_IRUSR | S_IWUSR)) < 0) {
+ virReportSystemError(errno, _("failed to open logfile %s"),
+ logfile);
+ goto error;
+ }
+ if (virSetCloseExec(ctxt->readfd) < 0) {
+ virReportSystemError(errno, _("failed to set close-on-exec flag on
%s"),
+ logfile);
+ goto error;
+ }
+ }
should 'pos' be initialized here? Otherwise the first ContextRead would
use ctxt->pos == 0
+
+ virObjectUnref(cfg);
+ return ctxt;
+
+ error:
+ virObjectUnref(cfg);
+ qemuDomainLogContextFree(ctxt);
+ return NULL;
+}
+
+
[...]
+
+ssize_t qemuDomainLogContextRead(qemuDomainLogContextPtr ctxt,
+ char **msg)
+{
+ char *buf;
+ size_t buflen = 1024 * 128;
+ ssize_t got;
+
+ /* Best effort jump to start of messages */
+ ignore_value(lseek(ctxt->readfd, ctxt->pos, SEEK_SET));
+
+ if (VIR_ALLOC_N(buf, buflen) < 0)
+ return -1;
+
+ got = saferead(ctxt->readfd, buf, buflen - 1);
+ if (got < 0) {
+ virReportSystemError(errno, "%s",
+ _("Unable to read from log file"));
Coverity points out buf is leaked.
+ return -1;
+ }
+
+ buf[got] = '\0';
+
+ ignore_value(VIR_REALLOC_N_QUIET(buf, got + 1));
+ *msg = buf;
+
+ return got;
+}
+
+
ACK with the obvious adjustment - not quite sure how to handle 'pos'
(yet) - although perhaps future patches will allow the light to shine.
John