Allocate memory precisely. Avoid recomputions of sizes.

Based on Coverity report from pull request #844.

diff --git a/tar/read.c b/tar/read.c
index e94cb3da8ac704116d2f93ee9f59d36bed8b201c..3c6cb0c13c39c82b58e5a8bc16e5873d786c2f53 100644 (file)
--- a/tar/read.c
+++ b/tar/read.c
@@ -188,18 +188,17 @@ read_archive(struct bsdtar *bsdtar, char mode, struct archive *writer)
 
        reader_options = getenv(ENV_READER_OPTIONS);
        if (reader_options != NULL) {
+               size_t module_len = sizeof(IGNORE_WRONG_MODULE_NAME) - 1;
+               size_t opt_len = strlen(reader_options) + 1;
                char *p;
                /* Set default read options. */
-               p = (char *)malloc(sizeof(IGNORE_WRONG_MODULE_NAME)
-                   + strlen(reader_options) + 1);
-               if (p == NULL)
+               if ((p = malloc(module_len + opt_len)) == NULL)
                        lafe_errc(1, errno, "Out of memory");
                /* Prepend magic code to ignore options for
                 * a format or  modules which are not added to
                 *  the archive read object. */
-               strncpy(p, IGNORE_WRONG_MODULE_NAME,
-                   sizeof(IGNORE_WRONG_MODULE_NAME) -1);
-               strcpy(p + sizeof(IGNORE_WRONG_MODULE_NAME) -1, reader_options);
+               memcpy(p, IGNORE_WRONG_MODULE_NAME, module_len);
+               memcpy(p + module_len, reader_options, opt_len);
                r = archive_read_set_options(a, p);
                free(p);
                if (r == ARCHIVE_FATAL)