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[Libvir] [PATCH] 2/2: Use safewrite in place of write, in many cases.



Use safewrite in place of write, in many cases.

Also add "make syntax-check" rules to ensure no new uses sneak in.

There are many uses of write like this:

    if (write (fd, xml, towrite) != towrite)
        return -1;

The problem is that the syscall can succeed, yet write less than
the requested number of bytes, so the caller should retry
rather than simply failing.

This patch changes most of them to use util.c's safewrite wrapper,
which encapsulates the process.  Also, there were a few cases in
which the retry loop was open-coded, and I replaced those, too.

Note: the change to libvirt_proxy.c removes a diagnostic that
would have warned about an EINTR-interrupted (and retried) write,
but that seems ok.

* Makefile.maint (sc_avoid_write): New rule, to avoid recurrence.
* .x-sc_avoid_write: New file.  Record two legitimate exemptions.
* qemud/qemud.c (sig_handler, qemudClientWriteBuf): Use safewrite, not write.
* src/conf.c (__virConfWriteFile): Likewise.
* src/qemu_conf.c (qemudSaveConfig, qemudSaveNetworkConfig): Likewise.
* src/qemu_driver.c (qemudWaitForMonitor, qemudStartVMDaemon)
(qemudVMData, PROC_IP_FORWARD): Likewise.
* proxy/libvirt_proxy.c: Include "util.h".
(proxyWriteClientSocket): Use safewrite.
* src/test.c (testDomainSave, testDomainCoreDump): Likewise.
* src/proxy_internal.c (virProxyWriteClientSocket): Likewise.
* src/virsh.c: Include "util-lib.h".
(vshOutputLogFile): Use safewrite.
* src/console.c: Include "util-lib.h".
(vshRunConsole): Use safewrite.

Signed-off-by: Jim Meyering <meyering redhat com>
---
 .x-sc_avoid_write    |    2 ++
 Makefile.maint       |   11 +++++++++++
 qemud/qemud.c        |   10 ++++------
 src/conf.c           |    2 +-
 src/console.c        |    6 ++++--
 src/proxy_internal.c |   14 ++++----------
 src/qemu_conf.c      |    4 ++--
 src/qemu_driver.c    |   19 +++++++------------
 src/test.c           |    9 +++++----
 src/virsh.c          |    5 +++--
 10 files changed, 43 insertions(+), 39 deletions(-)
 create mode 100644 .x-sc_avoid_write

diff --git a/.x-sc_avoid_write b/.x-sc_avoid_write
new file mode 100644
index 0000000..72a196d
--- /dev/null
+++ b/.x-sc_avoid_write
@@ -0,0 +1,2 @@
+^src/util\.c$
+^src/xend_internal\.c$
diff --git a/Makefile.maint b/Makefile.maint
index 39320df..fe964a5 100644
--- a/Makefile.maint
+++ b/Makefile.maint
@@ -46,6 +46,17 @@ sc_avoid_if_before_free:
 	  { echo '$(ME): found useless "if" before "free" above' 1>&2;	\
 	    exit 1; } || :

+# Avoid uses of write(2).  Either switch to streams (fwrite), or use
+# the safewrite wrapper.
+sc_avoid_write:
+	@if $(CVS_LIST_EXCEPT) | grep '\.c$$' > /dev/null; then		\
+	  grep '\<write *(' $$($(CVS_LIST_EXCEPT) | grep '\.c$$') &&	\
+	    { echo "$(ME): the above files use write;"			\
+	      " consider using the safewrite wrapper instead"		\
+		  1>&2; exit 1; } || :;					\
+	else :;								\
+	fi
+
 sc_cast_of_argument_to_free:
 	@grep -nE '\<free \(\(' $$($(CVS_LIST_EXCEPT)) &&		\
 	  { echo '$(ME): don'\''t cast free argument' 1>&2;		\
diff --git a/qemud/qemud.c b/qemud/qemud.c
index a40dfcb..d53a813 100644
--- a/qemud/qemud.c
+++ b/qemud/qemud.c
@@ -118,7 +118,7 @@ static void sig_handler(int sig) {
         return;

     origerrno = errno;
-    r = write(sigwrite, &sigc, 1);
+    r = safewrite(sigwrite, &sigc, 1);
     if (r == -1) {
         sig_errors++;
         sig_lasterrno = errno;
@@ -1360,11 +1360,9 @@ static int qemudClientWriteBuf(struct qemud_server *server,
                                const char *data, int len) {
     int ret;
     if (!client->tlssession) {
-        if ((ret = write(client->fd, data, len)) == -1) {
-            if (errno != EAGAIN) {
-                qemudLog (QEMUD_ERR, _("write: %s"), strerror (errno));
-                qemudDispatchClientFailure(server, client);
-            }
+        if ((ret = safewrite(client->fd, data, len)) == -1) {
+            qemudLog (QEMUD_ERR, _("write: %s"), strerror (errno));
+            qemudDispatchClientFailure(server, client);
             return -1;
         }
     } else {
diff --git a/src/conf.c b/src/conf.c
index e0ecdea..53ea993 100644
--- a/src/conf.c
+++ b/src/conf.c
@@ -904,7 +904,7 @@ __virConfWriteFile(const char *filename, virConfPtr conf)
 	goto error;
     }

-    ret = write(fd, buf->content, buf->use);
+    ret = safewrite(fd, buf->content, buf->use);
     close(fd);
     if (ret != (int) buf->use) {
         virConfError(NULL, VIR_ERR_WRITE_FAILED, _("failed to save content"), 0);
diff --git a/src/console.c b/src/console.c
index 02a9c7f..079d4ef 100644
--- a/src/console.c
+++ b/src/console.c
@@ -1,7 +1,7 @@
 /*
  * console.c: A dumb serial console client
  *
- * Copyright (C) 2007 Red Hat, Inc.
+ * Copyright (C) 2007, 2008 Red Hat, Inc.
  *
  * This library is free software; you can redistribute it and/or
  * modify it under the terms of the GNU Lesser General Public
@@ -37,6 +37,7 @@

 #include "console.h"
 #include "internal.h"
+#include "util-lib.h"

 /* ie  Ctrl-]  as per telnet */
 #define CTRL_CLOSE_BRACKET '\35'
@@ -161,7 +162,8 @@ int vshRunConsole(const char *tty) {

                 while (sent < got) {
                     int done;
-                    if ((done = write(destfd, buf + sent, got - sent)) <= 0) {
+                    if ((done = safewrite(destfd, buf + sent, got - sent))
+                        <= 0) {
                         fprintf(stderr, _("failure writing output: %s\n"),
                                 strerror(errno));
                         goto cleanup;
diff --git a/src/proxy_internal.c b/src/proxy_internal.c
index bc94763..c3e50c6 100644
--- a/src/proxy_internal.c
+++ b/src/proxy_internal.c
@@ -1,7 +1,7 @@
 /*
  * proxy_client.c: client side of the communication with the libvirt proxy.
  *
- * Copyright (C) 2006 Red Hat, Inc.
+ * Copyright (C) 2006, 2008 Red Hat, Inc.
  *
  * See COPYING.LIB for the License of this software
  *
@@ -26,6 +26,7 @@
 #include "internal.h"
 #include "driver.h"
 #include "proxy_internal.h"
+#include "util.h"
 #include "xen_unified.h"

 #define STANDALONE
@@ -345,17 +346,10 @@ virProxyWriteClientSocket(int fd, const char *data, int len) {
     if ((fd < 0) || (data == NULL) || (len < 0))
         return(-1);

-retry:
-    ret = write(fd, data, len);
+    ret = safewrite(fd, data, len);
     if (ret < 0) {
-        if (errno == EINTR) {
-	    if (debug > 0)
-	        fprintf(stderr, "write socket %d, %d bytes interrupted\n",
-		        fd, len);
-	    goto retry;
-	}
         fprintf(stderr, _("Failed to write to socket %d\n"), fd);
-	return(-1);
+        return(-1);
     }
     if (debug)
 	fprintf(stderr, "wrote %d bytes to socket %d\n",
diff --git a/src/qemu_conf.c b/src/qemu_conf.c
index ac1cc1e..fc82a6d 100644
--- a/src/qemu_conf.c
+++ b/src/qemu_conf.c
@@ -1866,7 +1866,7 @@ static int qemudSaveConfig(virConnectPtr conn,
     }

     towrite = strlen(xml);
-    if (write(fd, xml, towrite) != towrite) {
+    if (safewrite(fd, xml, towrite) < 0) {
         qemudReportError(conn, NULL, NULL, VIR_ERR_INTERNAL_ERROR,
                          "cannot write config file %s: %s",
                          vm->configFile, strerror(errno));
@@ -2089,7 +2089,7 @@ static int qemudSaveNetworkConfig(virConnectPtr conn,
     }

     towrite = strlen(xml);
-    if (write(fd, xml, towrite) != towrite) {
+    if (safewrite(fd, xml, towrite) < 0) {
         qemudReportError(conn, NULL, NULL, VIR_ERR_INTERNAL_ERROR,
                          "cannot write config file %s: %s",
                          network->configFile, strerror(errno));
diff --git a/src/qemu_driver.c b/src/qemu_driver.c
index 15cd52c..85d042f 100644
--- a/src/qemu_driver.c
+++ b/src/qemu_driver.c
@@ -539,11 +539,9 @@ static int qemudWaitForMonitor(virConnectPtr conn,
                                      "console");

     buf[sizeof(buf)-1] = '\0';
- retry:
-    if (write(vm->logfile, buf, strlen(buf)) < 0) {
+
+    if (safewrite(vm->logfile, buf, strlen(buf)) < 0) {
         /* Log, but ignore failures to write logfile for VM */
-        if (errno == EINTR)
-            goto retry;
         qemudLog(QEMUD_WARN, _("Unable to log VM console data: %s"),
                  strerror(errno));
     }
@@ -656,15 +654,15 @@ static int qemudStartVMDaemon(virConnectPtr conn,

     tmp = argv;
     while (*tmp) {
-        if (write(vm->logfile, *tmp, strlen(*tmp)) < 0)
+        if (safewrite(vm->logfile, *tmp, strlen(*tmp)) < 0)
             qemudLog(QEMUD_WARN, _("Unable to write argv to logfile %d: %s"),
                      errno, strerror(errno));
-        if (write(vm->logfile, " ", 1) < 0)
+        if (safewrite(vm->logfile, " ", 1) < 0)
             qemudLog(QEMUD_WARN, _("Unable to write argv to logfile %d: %s"),
                      errno, strerror(errno));
         tmp++;
     }
-    if (write(vm->logfile, "\n", 1) < 0)
+    if (safewrite(vm->logfile, "\n", 1) < 0)
         qemudLog(QEMUD_WARN, _("Unable to write argv to logfile %d: %s"),
                  errno, strerror(errno));

@@ -733,11 +731,8 @@ static int qemudVMData(struct qemud_driver *driver ATTRIBUTE_UNUSED,
         }
         buf[ret] = '\0';

-    retry:
-        if (write(vm->logfile, buf, ret) < 0) {
+        if (safewrite(vm->logfile, buf, ret) < 0) {
             /* Log, but ignore failures to write logfile for VM */
-            if (errno == EINTR)
-                goto retry;
             qemudLog(QEMUD_WARN, _("Unable to log VM console data: %s"),
                      strerror(errno));
         }
@@ -1113,7 +1108,7 @@ qemudEnableIpForwarding(void)
     if ((fd = open(PROC_IP_FORWARD, O_WRONLY|O_TRUNC)) == -1)
         return 0;

-    if (write(fd, "1\n", 2) < 0)
+    if (safewrite(fd, "1\n", 2) < 0)
         ret = 0;

     close (fd);
diff --git a/src/test.c b/src/test.c
index f860e49..1d064d3 100644
--- a/src/test.c
+++ b/src/test.c
@@ -42,6 +42,7 @@
 #include "test.h"
 #include "xml.h"
 #include "buf.h"
+#include "util.h"
 #include "uuid.h"

 /* Flags that determine the action to take on a shutdown or crash of a domain
@@ -1293,19 +1294,19 @@ static int testDomainSave(virDomainPtr domain,
         return (-1);
     }
     len = strlen(xml);
-    if (write(fd, TEST_SAVE_MAGIC, sizeof(TEST_SAVE_MAGIC)) != sizeof(TEST_SAVE_MAGIC)) {
+    if (safewrite(fd, TEST_SAVE_MAGIC, sizeof(TEST_SAVE_MAGIC)) < 0) {
         testError(domain->conn, domain, NULL, VIR_ERR_INTERNAL_ERROR,
                   "cannot write header");
         close(fd);
         return (-1);
     }
-    if (write(fd, (char*)&len, sizeof(len)) != sizeof(len)) {
+    if (safewrite(fd, (char*)&len, sizeof(len)) < 0) {
         testError(domain->conn, domain, NULL, VIR_ERR_INTERNAL_ERROR,
                   "cannot write metadata length");
         close(fd);
         return (-1);
     }
-    if (write(fd, xml, len) != len) {
+    if (safewrite(fd, xml, len) < 0) {
         testError(domain->conn, domain, NULL, VIR_ERR_INTERNAL_ERROR,
                   "cannot write metadata");
         free(xml);
@@ -1398,7 +1399,7 @@ static int testDomainCoreDump(virDomainPtr domain,
                   "cannot save domain core");
         return (-1);
     }
-    if (write(fd, TEST_SAVE_MAGIC, sizeof(TEST_SAVE_MAGIC)) != sizeof(TEST_SAVE_MAGIC)) {
+    if (safewrite(fd, TEST_SAVE_MAGIC, sizeof(TEST_SAVE_MAGIC)) < 0) {
         testError(domain->conn, domain, NULL, VIR_ERR_INTERNAL_ERROR,
                   "cannot write header");
         close(fd);
diff --git a/src/virsh.c b/src/virsh.c
index 5a5f04e..356c496 100644
--- a/src/virsh.c
+++ b/src/virsh.c
@@ -46,9 +46,10 @@
 #include <readline/history.h>
 #endif

+#include "buf.h"
 #include "console.h"
 #include "util.h"
-#include "buf.h"
+#include "util-lib.h"

 static char *progname;

@@ -6170,7 +6171,7 @@ vshOutputLogFile(vshControl *ctl, int log_level, const char *msg_format, va_list
         snprintf(msg_buf + strlen(msg_buf), sizeof(msg_buf) - strlen(msg_buf), "\n");

     /* write log */
-    if (write(ctl->log_fd, msg_buf, strlen(msg_buf)) == -1) {
+    if (safewrite(ctl->log_fd, msg_buf, strlen(msg_buf)) < 0) {
         vshCloseLogFile(ctl);
         vshError(ctl, FALSE, "%s", _("failed to write the log file"));
     }
--
1.5.4.2.185.gf5f8


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