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.

* 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.

.x-sc_avoid_write

+^src/util\.c$
+^src/xend_internal\.c$

ChangeLog

 Fri Feb 22 13:32:11 CET 2008 Jim Meyering <meyering@redhat.com>
 
+	Use safewrite in place of write, in many cases.
+	Also add "make syntax-check" rules to ensure no new uses sneak in.
+	* 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.
+
 	Move safewrite and saferead to a separate file.
 	* src/util.c (saferead, safewrite): Move function definitions to
 	util-lib.c and include that .c file.

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;		\

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) {
+        if ((ret = safewrite(client->fd, data, len)) == -1) {
             qemudLog (QEMUD_ERR, _("write: %s"), strerror (errno));
             qemudDispatchClientFailure(server, client);
-            }
             return -1;
         }
     } else {

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);

src/console.c

 /*
  * 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;

src/proxy_internal.c

 /*
  * 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
@@ -345,15 +346,8 @@ 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);
     }

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));

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);

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);

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"));
     }