syntax-check: sc_avoid_write: Don't use blanket file exceptions

Adding an exception for the whole file usually defeats the purpose of a
syntax check and is also likely to get forgotten once the file is
removed.

In case of the suggestion of using 'safewrite' instead of write even the
comment for safewrite states that the function needs to be used only in
certain cases.

Remove the blanket exceptions for files and use an exclude string
instead. The only instance where we keep the full file exception is for
src/libvirt-stream.c as there are multiple uses in example code in
comments where I couldn't find a nicer targetted wapproach.

Signed-off-by: Peter Krempa <pkrempa@redhat.com>
Reviewed-by: Ján Tomko <jtomko@redhat.com>

build-aux/syntax-check.mk

@@ -116,6 +116,7 @@ VC_LIST_ALWAYS_EXCLUDE_REGEX = \
 # the safewrite wrapper.
 sc_avoid_write:
 	@prohibit='\<write *\(' \
+	exclude='sc_avoid_write' \
 	in_vc_files='\.c$$' \
 	halt='consider using safewrite instead of write' \
 	  $(_sc_search_regexp)
@@ -1569,10 +1570,7 @@ sc_prohibit_enum_impl_with_vir_prefix_in_virsh:
 # List all syntax-check exemptions:
 exclude_file_name_regexp--sc_avoid_strcase = ^tools/vsh\.h$$
 
-_src1=libvirt-stream|qemu/qemu_monitor|util/vir(command|file|fdstream)|rpc/virnetsocket|lxc/lxc_controller|locking/lock_daemon|logging/log_daemon|remote/remote_ssh_helper
-_test1=shunloadtest|virnettlscontexttest|virnettlssessiontest|vircgroupmock|commandhelper
-exclude_file_name_regexp--sc_avoid_write = \
-  ^(src/($(_src1))|tools/virsh-console|tests/($(_test1)))\.c$$
+exclude_file_name_regexp--sc_avoid_write = ^src/libvirt-stream\.c$$
 
 exclude_file_name_regexp--sc_bindtextdomain = .*
 

src/locking/lock_daemon.c

@@ -1104,7 +1104,7 @@ int main(int argc, char **argv) {
      */
     if (statuswrite != -1) {
         char status = 0;
-        while (write(statuswrite, &status, 1) == -1 &&
+        while (write(statuswrite, &status, 1) == -1 && /* sc_avoid_write */
                errno == EINTR)
             ;
         VIR_FORCE_CLOSE(statuswrite);
@@ -1133,7 +1133,7 @@ int main(int argc, char **argv) {
         if (ret != 0) {
             /* Tell parent of daemon what failed */
             char status = ret;
-            while (write(statuswrite, &status, 1) == -1 &&
+            while (write(statuswrite, &status, 1) == -1 && /* sc_avoid_write */
                    errno == EINTR)
                 ;
         }

src/logging/log_daemon.c

@@ -910,7 +910,7 @@ int main(int argc, char **argv) {
      */
     if (statuswrite != -1) {
         char status = 0;
-        while (write(statuswrite, &status, 1) == -1 &&
+        while (write(statuswrite, &status, 1) == -1 && /* sc_avoid_write */
                errno == EINTR)
             ;
         VIR_FORCE_CLOSE(statuswrite);
@@ -939,7 +939,7 @@ int main(int argc, char **argv) {
         if (ret != 0) {
             /* Tell parent of daemon what failed */
             char status = ret;
-            while (write(statuswrite, &status, 1) == -1 &&
+            while (write(statuswrite, &status, 1) == -1 && /* sc_avoid_write */
                    errno == EINTR)
                 ;
         }

src/lxc/lxc_controller.c

@@ -1222,7 +1222,7 @@ static void virLXCControllerConsoleIO(int watch, int fd, int events, void *opaqu
         }
 
      rewrite:
-        done = write(fd, buf, *len);
+        done = write(fd, buf, *len); /* sc_avoid_write */
         if (done == -1 && errno == EINTR)
             goto rewrite;
         if (done == -1 && errno != EAGAIN) {

src/qemu/qemu_monitor.c

@@ -344,7 +344,7 @@ qemuMonitorIOWrite(qemuMonitor *mon)
     buf = mon->msg->txBuffer + mon->msg->txOffset;
     len = mon->msg->txLength - mon->msg->txOffset;
     if (mon->msg->txFD == -1)
-        done = write(mon->fd, buf, len);
+        done = write(mon->fd, buf, len); /* sc_avoid_write */
     else
         done = qemuMonitorIOWriteWithFD(mon, buf, len, mon->msg->txFD);
 

src/remote/remote_ssh_helper.c

@@ -255,7 +255,7 @@ virRemoteSSHHelperEventOnStdout(int watch G_GNUC_UNUSED,
     if (events & VIR_EVENT_HANDLE_WRITABLE &&
         proxy->sockToTerminal.offset) {
         ssize_t done;
-        done = write(fd,
+        done = write(fd, /* sc_avoid_write */
                      proxy->sockToTerminal.data,
                      proxy->sockToTerminal.offset);
         if (done < 0) {

src/rpc/virnetsocket.c

@@ -1623,7 +1623,7 @@ static ssize_t virNetSocketTLSSessionWrite(const char *buf,
                                            void *opaque)
 {
     virNetSocket *sock = opaque;
-    return write(sock->fd, buf, len);
+    return write(sock->fd, buf, len); /* sc_avoid_write */
 }
 
 
@@ -1818,7 +1818,7 @@ static ssize_t virNetSocketWriteWire(virNetSocket *sock, const char *buf, size_t
         VIR_NET_TLS_HANDSHAKE_COMPLETE) {
         ret = virNetTLSSessionWrite(sock->tlsSession, buf, len);
     } else {
-        ret = write(sock->fd, buf, len);
+        ret = write(sock->fd, buf, len); /* sc_avoid_write */
     }
 
     if (ret < 0) {

src/util/vircommand.c

@@ -1794,7 +1794,7 @@ virCommandSendBuffersHandlePoll(virCommand *cmd,
     if (i == virCommandGetNumSendBuffers(cmd))
         return 0;
 
-    done = write(fds->fd,
+    done = write(fds->fd, /* sc_avoid_write */
                  cmd->sendBuffers[i].buffer + cmd->sendBuffers[i].offset,
                  cmd->sendBuffers[i].buflen - cmd->sendBuffers[i].offset);
     if (done < 0) {
@@ -2306,7 +2306,7 @@ virCommandProcessIO(virCommand *cmd)
                 fds[i].fd == cmd->inpipe) {
                 int done;
 
-                done = write(cmd->inpipe, cmd->inbuf + inoff,
+                done = write(cmd->inpipe, cmd->inbuf + inoff, /* sc_avoid_write */
                              inlen - inoff);
                 if (done < 0) {
                     if (errno == EPIPE) {

src/util/virfdstream.c

@@ -850,7 +850,7 @@ static int virFDStreamWrite(virStreamPtr st, const char *bytes, size_t nbytes)
         ret = nbytes;
     } else {
      retry:
-        ret = write(fdst->fd, bytes, nbytes);
+        ret = write(fdst->fd, bytes, nbytes); /* sc_avoid_write */
         if (ret < 0) {
             VIR_WARNINGS_NO_WLOGICALOP_EQUAL_EXPR
             if (errno == EAGAIN || errno == EWOULDBLOCK) {

src/util/virfile.c

@@ -1112,17 +1112,17 @@ saferead(int fd, void *buf, size_t count)
     return nread;
 }
 
-/* Like write(), but restarts after EINTR. Doesn't play
- * nicely with nonblocking FD and EAGAIN, in which case
- * you want to use bare write(). Or even use virSocket()
- * if the FD is related to a socket rather than a plain
+/* Like write(), but restarts after EINTR. Encouraged by sc_avoid_write.
+ * Doesn't play nicely with nonblocking FD and EAGAIN, in which case
+ * you want to use bare write() and mark it's use with sc_avoid_write.
+ * Or even use virSocket() if the FD is related to a socket rather than a plain
  * file or pipe. */
 ssize_t
 safewrite(int fd, const void *buf, size_t count)
 {
     size_t nwritten = 0;
     while (count > 0) {
-        ssize_t r = write(fd, buf, count);
+        ssize_t r = write(fd, buf, count); /* sc_avoid_write */
 
         if (r < 0 && errno == EINTR)
             continue;

tests/shunloadtest.c

@@ -81,7 +81,7 @@ static void *threadMain(void *arg)
 
 static void sigHandler(int sig)
 {
-    ignore_value(write(STDERR_FILENO, "FAIL\n", 5));
+    ignore_value(write(STDERR_FILENO, "FAIL\n", 5)); /* sc_avoid_write */
     signal(sig, SIG_DFL);
     raise(sig);
 }

tests/vircgroupmock.c

@@ -83,7 +83,7 @@ static int make_file(const char *path,
     if ((fd = real_open(filepath, O_CREAT|O_WRONLY, 0600)) < 0)
         goto cleanup;
 
-    if (write(fd, value, strlen(value)) != strlen(value))
+    if (write(fd, value, strlen(value)) != strlen(value)) /* sc_avoid_write */
         goto cleanup;
 
     ret = 0;

tests/virnettlssessiontest.c

@@ -54,7 +54,7 @@ static ssize_t testWrite(const char *buf, size_t len, void *opaque)
 {
     int *fd = opaque;
 
-    return write(*fd, buf, len);
+    return write(*fd, buf, len); /* sc_avoid_write */
 }
 
 static ssize_t testRead(char *buf, size_t len, void *opaque)

tools/virsh-console.c

@@ -316,7 +316,7 @@ virConsoleEventOnStdout(int watch G_GNUC_UNUSED,
         con->streamToTerminal.offset) {
         ssize_t done;
         size_t avail;
-        done = write(fd,
+        done = write(fd, /* sc_avoid_write */
                      con->streamToTerminal.data,
                      con->streamToTerminal.offset);
         if (done < 0) {