Try to fix some buildbot warnings

Most interesting are:
 warning: cannot optimize loop, the loop counter may overflow [-Wunsafe-loop-optimizations]
 warning: ISO C forbids zero-size array [-Wpedantic]
 warning: ISO C90 doesn't support unnamed structs/unions [-Wpedantic]
 warning: cast discards '__attribute__((const))' qualifier from pointer target type [-Wcast-qual
 warning: initializer element is not computable at load time [enabled by default]

Change-Id: I5573c6bdca856a304877d9bef643f8c0fa93cdaf
Reviewed-on: https://code.wireshark.org/review/3174
Petri-Dish: Michal Labedzki <michal.labedzki@tieto.com>
Tested-by: Petri Dish Buildbot <buildbot-no-reply@wireshark.org>
Reviewed-by: Michal Labedzki <michal.labedzki@tieto.com>

6 files changed, 46 insertions, 38 deletions

diff --git a/wiretap/file_access.c b/wiretap/file_access.c
index 0ce14727c9..6e216d8010 100644
--- a/wiretap/file_access.c
+++ b/wiretap/file_access.c
@@ -1510,10 +1510,8 @@ init_file_types_subtypes(void)
 
 /* if subtype is WTAP_FILE_TYPE_SUBTYPE_UNKNOWN, then create a new subtype as well as register it, else replace the
    existing entry in that spot */
-int
-wtap_register_file_type_subtypes(const struct file_type_subtype_info* fi, const int subtype)
-{
-	struct file_type_subtype_info* finfo = NULL;
+int wtap_register_file_type_subtypes(const struct file_type_subtype_info* fi, const int subtype) {
+	struct file_type_subtype_info* finfo;
 	init_file_types_subtypes();
 
 	if (!fi || !fi->name || !fi->short_name || subtype > wtap_num_file_types_subtypes) {
@@ -1560,10 +1558,8 @@ wtap_register_file_type_subtypes(const struct file_type_subtype_info* fi, const
 
 /* De-registers a file writer - they can never be removed from the GArray, but we can "clear" an entry.
  */
-void
-wtap_deregister_file_type_subtype(const int subtype)
-{
-	struct file_type_subtype_info* finfo = NULL;
+void wtap_deregister_file_type_subtype(const int subtype) {
+	struct file_type_subtype_info* finfo;
 
 	if (subtype < 0 || subtype >= wtap_num_file_types_subtypes) {
 		g_error("invalid file type to de-register");
diff --git a/wiretap/file_wrappers.c b/wiretap/file_wrappers.c
index 65c35d1e6c..667727346e 100644
--- a/wiretap/file_wrappers.c
+++ b/wiretap/file_wrappers.c
@@ -1641,7 +1641,11 @@ gzwfile_write(GZWFILE_T state, const void *buf, guint len)
 
         /* directly compress user buffer to file */
         strm->avail_in = len;
+#if ZLIB_CONST
+        strm->next_in = (z_const Bytef *)buf;
+#else
         strm->next_in = (Bytef *)buf;
+#endif
         state->pos += len;
         if (gz_comp(state, Z_NO_FLUSH) == -1)
             return 0;
diff --git a/wiretap/logcat.c b/wiretap/logcat.c
index ff80f99a39..d71f583b9d 100644
--- a/wiretap/logcat.c
+++ b/wiretap/logcat.c
@@ -50,7 +50,9 @@ static gint detect_version(wtap *wth, int *err, gchar **err_info)
     struct logger_entry_v2  *log_entry_v2;
     guint8                  *buffer;
     guint16                  tmp;
-    guint8                  *msg_payload, *msg_part, *msg_end;
+    guint8                  *msg_payload;
+    guint8                  *msg_part;
+    guint8                  *msg_end;
     guint16                  msg_len;
 
     /* 16-bit payload length */
@@ -90,11 +92,11 @@ static gint detect_version(wtap *wth, int *err, gchar **err_info)
      * version is in use. First assume the smallest msg. */
     for (version = 1; version <= 2; ++version) {
         if (version == 1) {
-            msg_payload = log_entry->msg;
+            msg_payload = (guint8 *) (log_entry + 1);
             entry_len = sizeof(*log_entry) + payload_length;
         } else if (version == 2) {
             /* v2 is 4 bytes longer */
-            msg_payload = log_entry_v2->msg;
+            msg_payload = (guint8 *) (log_entry_v2 + 1);
             entry_len = sizeof(*log_entry_v2) + payload_length;
             if (hdr_size != sizeof(*log_entry_v2))
                 continue;
@@ -137,18 +139,18 @@ static gint detect_version(wtap *wth, int *err, gchar **err_info)
 }
 
 gint logcat_exported_pdu_length(const guint8 *pd) {
-    guint16 *tag;
-    guint16 *tag_length;
-    gint     length = 0;
+    const guint16  *tag;
+    const guint16  *tag_length;
+    gint            length = 0;
 
-    tag = (guint16 *) pd;
+    tag = (const guint16 *) pd;
 
     while(GINT16_FROM_BE(*tag)) {
-        tag_length = (guint16 *) (pd + 2);
+        tag_length = (const guint16 *) (pd + 2);
         length += 2 + 2 + GINT16_FROM_BE(*tag_length);
 
         pd += 2 + 2 + GINT16_FROM_BE(*tag_length);
-        tag = (guint16 *) pd;
+        tag = (const guint16 *) pd;
     }
 
     length += 2 + 2;
diff --git a/wiretap/logcat.h b/wiretap/logcat.h
index 9b2ea5cc25..71a0e7da5b 100644
--- a/wiretap/logcat.h
+++ b/wiretap/logcat.h
@@ -39,7 +39,7 @@ struct logger_entry {
     gint32  tid;    /* generating process's tid */
     gint32  sec;    /* seconds since Epoch */
     gint32  nsec;   /* nanoseconds */
-    char    msg[0]; /* the entry's payload */
+/*    char    msg[0]; *//* the entry's payload */
 };
 
 struct logger_entry_v2 {
@@ -53,8 +53,8 @@ struct logger_entry_v2 {
                         /* v1: not present */
         guint32 euid;   /* v2: effective UID of logger */
         guint32 lid;    /* v3: log id of the payload */
-    };
-    char    msg[0]; /* the entry's payload */
+    } id;
+/*    char    msg[0]; *//* the entry's payload */
 };
 
 int      logcat_open(wtap *wth, int *err, gchar **err_info);
diff --git a/wiretap/logcat_text.c b/wiretap/logcat_text.c
index 75e651dca1..006e82c025 100644
--- a/wiretap/logcat_text.c
+++ b/wiretap/logcat_text.c
@@ -56,16 +56,16 @@ static gchar get_priority(const guint8 priority) {
 
 static gint buffered_detect_version(const guint8 *pd)
 {
-    struct logger_entry     *log_entry;
-    struct logger_entry_v2  *log_entry_v2;
+    const struct logger_entry     *log_entry;
+    const struct logger_entry_v2  *log_entry_v2;
     gint                     version;
-    guint8                  *msg_payload = NULL;
+    const guint8            *msg_payload = NULL;
     guint8                  *msg_part;
     guint8                  *msg_end;
     guint16                  msg_len;
 
-    log_entry_v2 = (struct logger_entry_v2 *) pd;
-    log_entry = (struct logger_entry *) pd;
+    log_entry_v2 = (const struct logger_entry_v2 *) pd;
+    log_entry = (const struct logger_entry *) pd;
 
     /* must contain at least priority and two nulls as separator */
     if (log_entry->len < 3)
@@ -79,10 +79,10 @@ static gint buffered_detect_version(const guint8 *pd)
      * version is in use. First assume the smallest msg. */
     for (version = 1; version <= 2; ++version) {
         if (version == 1) {
-            msg_payload = log_entry->msg;
+            msg_payload = (const guint8 *) (log_entry + 1);
         } else if (version == 2) {
             /* v2 is 4 bytes longer */
-            msg_payload = log_entry_v2->msg;
+            msg_payload = (const guint8 *) (log_entry_v2 + 1);
             if (log_entry_v2->hdr_size != sizeof(*log_entry_v2))
                 continue;
         }
@@ -427,6 +427,7 @@ static gboolean logcat_text_dump_text(wtap_dumper *wdh,
     gint32                          tid;
     gint32                          seconds;
     gint32                          milliseconds;
+    const guint8                   *msg_payload = NULL;
     const gchar                    *msg_begin;
     gint                            msg_pre_skip;
     gchar                          *log;
@@ -458,8 +459,8 @@ static gboolean logcat_text_dump_text(wtap_dumper *wdh,
             logcat_version = pseudo_header->logcat.version;
         }
 
-        log_entry = (struct logger_entry *) pd;
-        log_entry_v2 = (struct logger_entry_v2 *) pd;
+        log_entry = (const struct logger_entry *) pd;
+        log_entry_v2 = (const struct logger_entry_v2 *) pd;
 
         payload_length = GINT32_FROM_LE(log_entry->len);
         pid = GINT32_FROM_LE(log_entry->pid);
@@ -469,15 +470,19 @@ static gboolean logcat_text_dump_text(wtap_dumper *wdh,
 
         /* msg: <prio:1><tag:N>\0<msg:N>\0 with N >= 0, last \0 can be missing */
         if (logcat_version == 1) {
-            priority = get_priority(log_entry->msg[0]);
-            tag = log_entry->msg + 1;
+            msg_payload = (const guint8 *) (log_entry + 1);
+
+            priority = get_priority(msg_payload[0]);
+            tag = msg_payload + 1;
             msg_pre_skip = 1 + (gint) strlen(tag) + 1;
-            msg_begin = log_entry->msg + msg_pre_skip;
+            msg_begin = msg_payload + msg_pre_skip;
         } else if (logcat_version == 2) {
-            priority = get_priority(log_entry_v2->msg[0]);
-            tag = log_entry_v2->msg + 1;
+            msg_payload = (const guint8 *) (log_entry_v2 + 1);
+
+            priority = get_priority(msg_payload[0]);
+            tag = msg_payload + 1;
             msg_pre_skip = 1 + (gint) strlen(tag) + 1;
-            msg_begin = log_entry_v2->msg + msg_pre_skip;
+            msg_begin = msg_payload + msg_pre_skip;
         } else {
             *err = WTAP_ERR_UNSUPPORTED;
             return FALSE;
@@ -533,7 +538,7 @@ static gboolean logcat_text_dump_text(wtap_dumper *wdh,
     case WTAP_ENCAP_LOGCAT_THREADTIME:
     case WTAP_ENCAP_LOGCAT_LONG:
         if (dumper->type == wdh->encap) {
-            if (!wtap_dump_file_write(wdh, (gchar*) pd, phdr->caplen, err)) {
+            if (!wtap_dump_file_write(wdh, (const gchar*) pd, phdr->caplen, err)) {
                 return FALSE;
             }
         } else {
diff --git a/wiretap/merge.c b/wiretap/merge.c
index bea6b53220..bf10f4ccdc 100644
--- a/wiretap/merge.c
+++ b/wiretap/merge.c
@@ -50,7 +50,8 @@ merge_open_in_files(int in_file_count, char *const *in_file_names,
                     merge_in_file_t **in_files, int *err, gchar **err_info,
                     int *err_fileno)
 {
-  int i, j;
+  gint i;
+  gint j;
   size_t files_size = in_file_count * sizeof(merge_in_file_t);
   merge_in_file_t *files;
   gint64 size;
@@ -73,7 +74,7 @@ merge_open_in_files(int in_file_count, char *const *in_file_names,
     }
     size = wtap_file_size(files[i].wth, err);
     if (size == -1) {
-      for (j = 0; j <= i; j++)
+      for (j = 0; j + 1 > j && j <= i; j++)
         wtap_close(files[j].wth);
       *err_fileno = i;
       return FALSE;