Fix several coverity issues in UnRAR interface code

Fix Coverity issues 192935, 192932, 192928, and 192917.

None of these are particularly serious. I thought I'd clean them up
while trying to track down a strange crash that occurs in Windows debug
builds with my specific setup when freeing the metadata filename pointer
malloced by the UnRAR iface "peek" function.

I wasn't able to figure out why freeing that causes a crash, so instead
I converted it to an array that need not be freed, and my troubles
melted away.

libclamav/scanners.c

@@ -473,10 +473,6 @@ static cl_error_t cli_scanrar_file(const char *filepath, int desc, cli_ctx *ctx)
         /*
          * Free up any malloced metadata...
          */
-        if (metadata.filename != NULL) {
-            free(metadata.filename);
-            metadata.filename = NULL;
-        }
         if (NULL != filename_base) {
             free(filename_base);
             filename_base = NULL;
@@ -512,11 +508,6 @@ static cl_error_t cli_scanrar_file(const char *filepath, int desc, cli_ctx *ctx)
         filename_base = NULL;
     }
 
-    if (metadata.filename != NULL) {
-        free(metadata.filename);
-        metadata.filename = NULL;
-    }
-
     if (NULL != extract_fullpath) {
         free(extract_fullpath);
         extract_fullpath = NULL;

libclamunrar_iface/unrar_iface.cpp

@@ -212,6 +212,7 @@ cl_unrar_error_t unrar_open(const char* filename, void** hArchive, char** commen
     if (archiveData == NULL) {
         unrar_dbgmsg("unrar_open: Not enough memory to allocate main archive header data structure.\n");
         status = UNRAR_EMEM;
+        goto done;
     }
     archiveData->ArcName  = (char*)filename;
     archiveData->OpenMode = RAR_OM_EXTRACT;
@@ -220,6 +221,7 @@ cl_unrar_error_t unrar_open(const char* filename, void** hArchive, char** commen
     if (archiveData->CmtBuf == NULL) {
         unrar_dbgmsg("unrar_open: Not enough memory to allocate main archive header comment buffer.\n");
         status = UNRAR_EMEM;
+        goto done;
     }
     archiveData->CmtBufSize = CMTBUFSIZE;
 
@@ -231,23 +233,24 @@ cl_unrar_error_t unrar_open(const char* filename, void** hArchive, char** commen
     }
 
     switch (archiveData->CmtState) {
-        case 0: {
+        case ERAR_SUCCESS: {
             unrar_dbgmsg("unrar_open: Comments are not present in this archive.\n");
             break;
         }
         case ERAR_BAD_DATA: {
             unrar_dbgmsg("unrar_open: Archive Comments may be broken.\n");
+            break;
         }
         case ERAR_SMALL_BUF: {
-            unrar_dbgmsg("unrar_open: Archive Comments are not present in this file.\n");
+            unrar_dbgmsg("unrar_open: Comment buffer was too small, comments are not read completely.\n");
+            break;
         }
         case 1: {
-            unrar_dbgmsg("unrar_open: Archive Comments:\n\t %s\n", archiveData->CmtBuf);
+            unrar_dbgmsg("unrar_open: Archive Comments read completely.\n");
             break;
         }
         case ERAR_NO_MEMORY: {
-            unrar_dbgmsg("unrar_open: Memory error when reading archive comments!\n");
-            status = UNRAR_EMEM;
+            unrar_dbgmsg("unrar_open: Not enough memory to extract comments!\n");
             break;
         }
         default: {
@@ -261,7 +264,6 @@ cl_unrar_error_t unrar_open(const char* filename, void** hArchive, char** commen
         if (NULL == *comment) {
             unrar_dbgmsg("unrar_open: Error duplicating comment buffer.\n");
             *comment_size = 0;
-            status        = UNRAR_EMEM;
         }
     }
 
@@ -306,7 +308,7 @@ cl_unrar_error_t unrar_peek_file_header(void* hArchive, unrar_metadata_t* file_m
     struct RARHeaderDataEx headerData;
     int read_header_ret = 0;
 
-    wchar_t RedirName[1024];
+    wchar_t RedirName[2048];
 
     memset(&headerData, 0, sizeof(struct RARHeaderDataEx));
 
@@ -324,9 +326,9 @@ cl_unrar_error_t unrar_peek_file_header(void* hArchive, unrar_metadata_t* file_m
     headerData.CmtBuf     = NULL;
     headerData.CmtBufSize = 0;
 
-    headerData.RedirNameSize = 1024 * sizeof(wchar_t);
+    headerData.RedirNameSize = 2048;
     headerData.RedirName     = (wchar_t*)&RedirName;
-    memset(headerData.RedirName, 0, headerData.RedirNameSize);
+    memset(headerData.RedirName, 0, headerData.RedirNameSize * sizeof(wchar_t));
 
     read_header_ret = RARReadHeaderEx(hArchive, &headerData);
     if (ERAR_SUCCESS != read_header_ret) {
@@ -336,11 +338,11 @@ cl_unrar_error_t unrar_peek_file_header(void* hArchive, unrar_metadata_t* file_m
 
     file_metadata->unpack_size = headerData.UnpSize + ((int64_t)headerData.UnpSizeHigh << 32);
     file_metadata->pack_size   = headerData.PackSize + ((int64_t)headerData.PackSizeHigh << 32);
-    file_metadata->filename    = unrar_strndup(headerData.FileName, 1024);
-    file_metadata->crc         = headerData.FileCRC;
-    file_metadata->encrypted   = (headerData.Flags & RHDF_ENCRYPTED) ? 1 : 0;
-    file_metadata->is_dir      = (headerData.Flags & RHDF_DIRECTORY) ? 1 : 0;
-    file_metadata->method      = headerData.Method;
+    strncpy(file_metadata->filename, headerData.FileName, 1024);
+    file_metadata->crc       = headerData.FileCRC;
+    file_metadata->encrypted = (headerData.Flags & RHDF_ENCRYPTED) ? 1 : 0;
+    file_metadata->is_dir    = (headerData.Flags & RHDF_DIRECTORY) ? 1 : 0;
+    file_metadata->method    = headerData.Method;
 
     unrar_dbgmsg("unrar_peek_file_header:   Name:          %s\n", headerData.FileName);
     unrar_dbgmsg("unrar_peek_file_header:   Directory?:    %u\n", file_metadata->is_dir);

libclamunrar_iface/unrar_iface.h

@@ -57,7 +57,7 @@ typedef enum cl_unrar_error_tag {
 typedef struct unrar_metadata_tag {
     uint64_t pack_size;
     uint64_t unpack_size;
-    char *filename;
+    char filename[1024];
     uint32_t crc;
     unsigned int encrypted;
     uint8_t method;