executor: warn about C89-style var declarations

We generally use the newer C99 var declarations combined with initialization because:
 - declarations are more local, reduced scope
 - fewer lines of code
 - less potential for using uninit vars and other bugs
However, we have some relic code from times when we did not understand
if we need to stick with C89 or not. Also some external contributions
that don't follow style around.

Add a static check for C89-style declarations and fix existing precedents.

Akaros toolchain uses -std=gnu89 (or something) and does not allow
variable declarations inside of for init statement. And we can't switch
it to -std=c99 because Akaros headers are C89 themselves.
So in common.h we need to declare loop counters outside of for.

1 files changed, 9 insertions, 10 deletions

diff --git a/executor/common.h b/executor/common.h
index 77bbfc8b5..7fd4b255e 100644
--- a/executor/common.h
+++ b/executor/common.h
@@ -206,11 +206,10 @@ static void use_temporary_dir(void)
 
 static void remove_dir(const char* dir)
 {
-	DIR* dp;
-	struct dirent* ep;
-	dp = opendir(dir);
+	DIR* dp = opendir(dir);
 	if (dp == NULL)
 		exitf("opendir(%s) failed", dir);
+	struct dirent* ep = 0;
 	while ((ep = readdir(dp))) {
 		if (strcmp(ep->d_name, ".") == 0 || strcmp(ep->d_name, "..") == 0)
 			continue;
@@ -260,11 +259,11 @@ static void thread_start(void* (*fn)(void*), void* arg)
 	pthread_attr_t attr;
 	pthread_attr_init(&attr);
 	pthread_attr_setstacksize(&attr, 128 << 10);
-	int i;
 	// Clone can fail spuriously with EAGAIN if there is a concurrent execve in progress.
 	// (see linux kernel commit 498052bba55ec). But it can also be a true limit imposed by cgroups.
 	// In one case we want to retry infinitely, in another -- fail immidiately...
-	for (i = 0; i < 100; i++) {
+	int i = 0;
+	for (; i < 100; i++) {
 		if (pthread_create(&th, &attr, fn, arg) == 0) {
 			pthread_attr_destroy(&attr);
 			return;
@@ -379,8 +378,8 @@ static void csum_inet_update(struct csum_inet* csum, const uint8* data, size_t l
 	if (length == 0)
 		return;
 
-	size_t i;
-	for (i = 0; i < length - 1; i += 2)
+	size_t i = 0;
+	for (; i < length - 1; i += 2)
 		csum->acc += *(uint16*)&data[i];
 
 	if (length & 1)
@@ -545,11 +544,11 @@ static void loop(void)
 	if (pipe(child_pipe))
 		fail("pipe failed");
 #endif
-	int iter;
+	int iter = 0;
 #if SYZ_REPEAT_TIMES
-	for (iter = 0; iter < /*{{{REPEAT_TIMES}}}*/; iter++) {
+	for (; iter < /*{{{REPEAT_TIMES}}}*/; iter++) {
 #else
-	for (iter = 0;; iter++) {
+	for (;; iter++) {
 #endif
 #if SYZ_EXECUTOR || SYZ_USE_TMP_DIR
 		// Create a new private work dir for this test (removed at the end of the loop).