[libvirt] [PATCH v2 07/13] qemu: introduce a qemuDomainLogContext object

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&gt; --- src/qemu/qemu_domain.c | 178 +++++++++++++++++++++++++++++++++++++++++++++++++ src/qemu/qemu_domain.h | 22 ++++++ 2 files changed, 200 insertions(+) diff --git a/src/qemu/qemu_domain.c b/src/qemu/qemu_domain.c index 1dd3cee..e92f8b4 100644 --- a/src/qemu/qemu_domain.c +++ b/src/qemu/qemu_domain.c @@ -40,6 +40,7 @@ #include "virstoragefile.h" #include "virstring.h" #include "virthreadjob.h" +#include "viratomic.h" #include "storage/storage_driver.h" @@ -76,6 +77,13 @@ VIR_ENUM_IMPL(qemuDomainAsyncJob, QEMU_ASYNC_JOB_LAST, ); +struct _qemuDomainLogContext { + int refs; + int writefd; + int readfd; + off_t pos; +}; + const char * qemuDomainAsyncJobPhaseToString(qemuDomainAsyncJob job, int phase ATTRIBUTE_UNUSED) @@ -2228,6 +2236,176 @@ void qemuDomainObjCheckNetTaint(virQEMUDriverPtr driver, } +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; + } + } + + virObjectUnref(cfg); + return ctxt; + + error: + virObjectUnref(cfg); + qemuDomainLogContextFree(ctxt); + return NULL; +} + + +int qemuDomainLogContextWrite(qemuDomainLogContextPtr ctxt, + const char *fmt, ...) +{ + va_list argptr; + char *message = NULL; + int ret = -1; + + va_start(argptr, fmt); + + if (virVasprintf(&message, fmt, argptr) < 0) + goto cleanup; + if (lseek(ctxt->writefd, 0, SEEK_END) < 0) { + virReportSystemError(errno, "%s", + _("Unable to see to end of domain logfile")); + goto cleanup; + } + if (safewrite(ctxt->writefd, message, strlen(message)) < 0) { + virReportSystemError(errno, "%s", + _("Unable to write to domain logfile")); + goto cleanup; + } + + ret = 0; + + cleanup: + va_end(argptr); + VIR_FREE(message); + return ret; +} + + +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")); + return -1; + } + + buf[got] = '\0'; + + ignore_value(VIR_REALLOC_N_QUIET(buf, got + 1)); + *msg = buf; + + return got; +} + + +int qemuDomainLogContextGetWriteFD(qemuDomainLogContextPtr ctxt) +{ + return ctxt->writefd; +} + + +int qemuDomainLogContextGetReadFD(qemuDomainLogContextPtr ctxt) +{ + return ctxt->readfd; +} + + +void qemuDomainLogContextMarkPosition(qemuDomainLogContextPtr ctxt) +{ + ctxt->pos = lseek(ctxt->writefd, 0, SEEK_END); +} + + +off_t qemuDomainLogContextGetPosition(qemuDomainLogContextPtr ctxt) +{ + return ctxt->pos; +} + + +void qemuDomainLogContextRef(qemuDomainLogContextPtr ctxt) +{ + virAtomicIntInc(&ctxt->refs); +} + + +void qemuDomainLogContextFree(qemuDomainLogContextPtr ctxt) +{ + bool lastRef; + + if (!ctxt) + return; + + lastRef = virAtomicIntDecAndTest(&ctxt->refs); + if (!lastRef) + return; + + VIR_FORCE_CLOSE(ctxt->writefd); + VIR_FORCE_CLOSE(ctxt->readfd); + VIR_FREE(ctxt); +} + + static int qemuDomainOpenLogHelper(virQEMUDriverConfigPtr cfg, virDomainObjPtr vm, diff --git a/src/qemu/qemu_domain.h b/src/qemu/qemu_domain.h index 16dc93c..fa0b14c 100644 --- a/src/qemu/qemu_domain.h +++ b/src/qemu/qemu_domain.h @@ -244,6 +244,9 @@ struct qemuProcessEvent { void *data; }; +typedef struct _qemuDomainLogContext qemuDomainLogContext; +typedef qemuDomainLogContext *qemuDomainLogContextPtr; + const char *qemuDomainAsyncJobPhaseToString(qemuDomainAsyncJob job, int phase); int qemuDomainAsyncJobPhaseFromString(qemuDomainAsyncJob job, @@ -348,6 +351,25 @@ void qemuDomainObjCheckNetTaint(virQEMUDriverPtr driver, virDomainNetDefPtr net, int logFD); +typedef enum { + QEMU_DOMAIN_LOG_CONTEXT_MODE_START, + QEMU_DOMAIN_LOG_CONTEXT_MODE_ATTACH, + QEMU_DOMAIN_LOG_CONTEXT_MODE_STOP, +} qemuDomainLogContextMode; + +qemuDomainLogContextPtr qemuDomainLogContextNew(virQEMUDriverPtr driver, + virDomainObjPtr vm, + qemuDomainLogContextMode mode); +int qemuDomainLogContextWrite(qemuDomainLogContextPtr ctxt, + const char *fmt, ...) ATTRIBUTE_FMT_PRINTF(2, 3); +ssize_t qemuDomainLogContextRead(qemuDomainLogContextPtr ctxt, + char **msg); +int qemuDomainLogContextGetWriteFD(qemuDomainLogContextPtr ctxt); +int qemuDomainLogContextGetReadFD(qemuDomainLogContextPtr ctxt); +void qemuDomainLogContextMarkPosition(qemuDomainLogContextPtr ctxt); +off_t qemuDomainLogContextGetPosition(qemuDomainLogContextPtr ctxt); +void qemuDomainLogContextRef(qemuDomainLogContextPtr ctxt); +void qemuDomainLogContextFree(qemuDomainLogContextPtr ctxt); int qemuDomainCreateLog(virQEMUDriverPtr driver, virDomainObjPtr vm, bool append); int qemuDomainOpenLog(virQEMUDriverPtr driver, virDomainObjPtr vm); -- 2.5.0