8314114: Fix -Wconversion warnings in os code, primarily linux

src/hotspot/os/aix/attachListener_aix.cpp

@@ -108,7 +108,7 @@ class AixAttachListener: AllStatic {
   static bool is_shutdown()     { return _shutdown; }
 
   // write the given buffer to a socket
-  static int write_fully(int s, char* buf, int len);
+  static int write_fully(int s, char* buf, size_t len);
 
   static AixAttachOperation* dequeue();
 };
@@ -276,7 +276,7 @@ AixAttachOperation* AixAttachListener::read_request(int s) {
   // where <ver> is the protocol version (1), <cmd> is the command
   // name ("load", "datadump", ...), and <arg> is an argument
   int expected_str_count = 2 + AttachOperation::arg_count_max;
-  const int max_len = (sizeof(ver_str) + 1) + (AttachOperation::name_length_max + 1) +
+  const unsigned max_len = (sizeof(ver_str) + 1) + (AttachOperation::name_length_max + 1) +
     AttachOperation::arg_count_max*(AttachOperation::arg_length_max + 1);
 
   char buf[max_len];
@@ -285,15 +285,15 @@ AixAttachOperation* AixAttachListener::read_request(int s) {
   // Read until all (expected) strings have been read, the buffer is
   // full, or EOF.
 
-  int off = 0;
-  int left = max_len;
+  size_t off = 0;
+  size_t left = max_len;
 
   do {
-    int n;
+    ssize_t n;
     // Don't block on interrupts because this will
     // hang in the clean-up when shutting down.
     n = read(s, buf+off, left);
-    assert(n <= left, "buffer was too small, impossible!");
+    assert(n <= checked_cast<ssize_t>(left), "buffer was too small, impossible!");
     buf[max_len - 1] = '\0';
     if (n == -1) {
       return nullptr;      // reset by peer or other error
@@ -414,9 +414,9 @@ AixAttachOperation* AixAttachListener::dequeue() {
 }
 
 // write the given buffer to the socket
-int AixAttachListener::write_fully(int s, char* buf, int len) {
+int AixAttachListener::write_fully(int s, char* buf, size_t len) {
   do {
-    int n = ::write(s, buf, len);
+    ssize_t n = ::write(s, buf, len);
     if (n == -1) {
       if (errno != EINTR) return -1;
     } else {

src/hotspot/os/aix/os_aix.cpp

@@ -2985,7 +2985,7 @@ int os::get_core_path(char* buffer, size_t bufferSize) {
   jio_snprintf(buffer, bufferSize, "%s/core or core.%d",
                                                p, current_process_id());
 
-  return strlen(buffer);
+  return checked_cast<int>(strlen(buffer));
 }
 
 bool os::start_debugging(char *buf, int buflen) {
@@ -3023,7 +3023,7 @@ static inline time_t get_mtime(const char* filename) {
 int os::compare_file_modified_times(const char* file1, const char* file2) {
   time_t t1 = get_mtime(file1);
   time_t t2 = get_mtime(file2);
-  return t1 - t2;
+  return primitive_compare(t1, t2);
 }
 
 bool os::supports_map_sync() {

src/hotspot/os/aix/os_perf_aix.cpp

@@ -77,7 +77,7 @@ static bool read_psinfo(const u_longlong_t& pid, psinfo_t& psinfo) {
 
   FILE* fp;
   char buf[BUF_LENGTH];
-  int len;
+  size_t len;
 
   jio_snprintf(buf, BUF_LENGTH, "/proc/%llu/psinfo", pid);
   fp = fopen(buf, "r");

src/hotspot/os/bsd/attachListener_bsd.cpp

@@ -102,7 +102,7 @@ class BsdAttachListener: AllStatic {
   static int listener()                 { return _listener; }
 
   // write the given buffer to a socket
-  static int write_fully(int s, char* buf, int len);
+  static int write_fully(int s, char* buf, size_t len);
 
   static BsdAttachOperation* dequeue();
 };
@@ -257,7 +257,7 @@ BsdAttachOperation* BsdAttachListener::read_request(int s) {
   // where <ver> is the protocol version (1), <cmd> is the command
   // name ("load", "datadump", ...), and <arg> is an argument
   int expected_str_count = 2 + AttachOperation::arg_count_max;
-  const int max_len = (sizeof(ver_str) + 1) + (AttachOperation::name_length_max + 1) +
+  const unsigned max_len = (sizeof(ver_str) + 1) + (AttachOperation::name_length_max + 1) +
     AttachOperation::arg_count_max*(AttachOperation::arg_length_max + 1);
 
   char buf[max_len];
@@ -266,21 +266,21 @@ BsdAttachOperation* BsdAttachListener::read_request(int s) {
   // Read until all (expected) strings have been read, the buffer is
   // full, or EOF.
 
-  int off = 0;
-  int left = max_len;
+  size_t off = 0;
+  size_t left = max_len;
 
   do {
-    int n;
+    ssize_t n;
     RESTARTABLE(read(s, buf+off, left), n);
-    assert(n <= left, "buffer was too small, impossible!");
+    assert(n <= checked_cast<ssize_t>(left), "buffer was too small, impossible!");
     buf[max_len - 1] = '\0';
     if (n == -1) {
       return nullptr;      // reset by peer or other error
     }
     if (n == 0) {
       break;
     }
-    for (int i=0; i<n; i++) {
+    for (ssize_t i=0; i<n; i++) {
       if (buf[off+i] == 0) {
         // EOS found
         str_count++;
@@ -383,9 +383,9 @@ BsdAttachOperation* BsdAttachListener::dequeue() {
 }
 
 // write the given buffer to the socket
-int BsdAttachListener::write_fully(int s, char* buf, int len) {
+int BsdAttachListener::write_fully(int s, char* buf, size_t len) {
   do {
-    int n = ::write(s, buf, len);
+    ssize_t n = ::write(s, buf, len);
     if (n == -1) {
       if (errno != EINTR) return -1;
     } else {

src/hotspot/os/bsd/os_bsd.cpp

@@ -2208,9 +2208,9 @@ static inline struct timespec get_mtime(const char* filename) {
 int os::compare_file_modified_times(const char* file1, const char* file2) {
   struct timespec filetime1 = get_mtime(file1);
   struct timespec filetime2 = get_mtime(file2);
-  int diff = filetime1.tv_sec - filetime2.tv_sec;
+  int diff = primitive_compare(filetime1.tv_sec, filetime2.tv_sec);
   if (diff == 0) {
-    return filetime1.tv_nsec - filetime2.tv_nsec;
+    diff = primitive_compare(filetime1.tv_nsec, filetime2.tv_nsec);
   }
   return diff;
 }

src/hotspot/os/linux/attachListener_linux.cpp

@@ -103,7 +103,7 @@ class LinuxAttachListener: AllStatic {
   static int listener()                 { return _listener; }
 
   // write the given buffer to a socket
-  static int write_fully(int s, char* buf, int len);
+  static int write_fully(int s, char* buf, size_t len);
 
   static LinuxAttachOperation* dequeue();
 };
@@ -257,7 +257,7 @@ LinuxAttachOperation* LinuxAttachListener::read_request(int s) {
   // where <ver> is the protocol version (1), <cmd> is the command
   // name ("load", "datadump", ...), and <arg> is an argument
   int expected_str_count = 2 + AttachOperation::arg_count_max;
-  const int max_len = (sizeof(ver_str) + 1) + (AttachOperation::name_length_max + 1) +
+  const unsigned max_len = (sizeof(ver_str) + 1) + (AttachOperation::name_length_max + 1) +
     AttachOperation::arg_count_max*(AttachOperation::arg_length_max + 1);
 
   char buf[max_len];
@@ -266,21 +266,21 @@ LinuxAttachOperation* LinuxAttachListener::read_request(int s) {
   // Read until all (expected) strings have been read, the buffer is
   // full, or EOF.
 
-  int off = 0;
-  int left = max_len;
+  size_t off = 0;
+  size_t left = max_len;
 
   do {
-    int n;
+    ssize_t n;
     RESTARTABLE(read(s, buf+off, left), n);
-    assert(n <= left, "buffer was too small, impossible!");
+    assert(n <= checked_cast<ssize_t>(left), "buffer was too small, impossible!");
     buf[max_len - 1] = '\0';
     if (n == -1) {
       return nullptr;      // reset by peer or other error
     }
     if (n == 0) {
       break;
     }
-    for (int i=0; i<n; i++) {
+    for (ssize_t i=0; i<n; i++) {
       if (buf[off+i] == 0) {
         // EOS found
         str_count++;
@@ -383,7 +383,7 @@ LinuxAttachOperation* LinuxAttachListener::dequeue() {
 }
 
 // write the given buffer to the socket
-int LinuxAttachListener::write_fully(int s, char* buf, int len) {
+int LinuxAttachListener::write_fully(int s, char* buf, size_t len) {
   do {
     ssize_t n = ::write(s, buf, len);
     if (n == -1) {