tac: handle NULs properly. +145 bytes

1 files changed, 35 insertions, 11 deletions

diff --git a/coreutils/tac.c b/coreutils/tac.c
index b1b47302f..7951be255 100644
--- a/coreutils/tac.c
+++ b/coreutils/tac.c
@@ -20,12 +20,17 @@
 
 /* This is a NOEXEC applet. Be very careful! */
 
+struct lstring {
+        int size;
+        char buf[];
+};
+
 int tac_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
 int tac_main(int argc, char **argv)
 {
         char **name;
         FILE *f;
-        char *line;
+        struct lstring *line = NULL;
         llist_t *list = NULL;
         int retval = EXIT_SUCCESS;
 
@@ -38,6 +43,8 @@ int tac_main(int argc, char **argv)
                 name++;
 
         do {
+                int ch, i;
+
                 name--;
                 f = fopen_or_warn_stdin(*name);
                 if (f == NULL) {
@@ -45,14 +52,26 @@ int tac_main(int argc, char **argv)
                         continue;
                 }
 
-                errno = 0;
-                /* FIXME: NUL bytes are mishandled. */
-                while ((line = xmalloc_fgets(f)) != NULL)
-                        llist_add_to(&list, line);
-
-                /* xmalloc_fgets uses getc and returns NULL on error or EOF. */
-                /* It sets errno to ENOENT on EOF, but fopen_or_warn_stdin would */
-                /* catch this error so we can filter it out here. */
+                errno = i = 0;
+                do {
+                        ch = fgetc(f);
+                        if (ch != EOF) {
+                                if (!(i & 0x7f))
+                                        /* Grow on every 128th char */
+                                        line = xrealloc(line, i + 0x7f + sizeof(int) + 1);
+                                line->buf[i++] = ch;
+                        }
+                        if ((ch == '\n' || ch == EOF) && i) {
+                                line = xrealloc(line, i + sizeof(int));
+                                line->size = i;
+                                llist_add_to(&list, line);
+                                line = NULL;
+                                i = 0;
+                        }
+                } while (ch != EOF);
+                /* fgetc sets errno to ENOENT on EOF, but     */
+                /* fopen_or_warn_stdin would catch this error */
+                /* so we can filter it out here.              */
                 if (errno && errno != ENOENT) {
                         bb_simple_perror_msg(*name);
                         retval = EXIT_FAILURE;
@@ -60,8 +79,13 @@ int tac_main(int argc, char **argv)
         } while (name != argv);
 
         while (list) {
-                printf("%s", list->data);
-                list = list->link;
+                line = (struct lstring *)list->data;
+                xwrite(STDOUT_FILENO, line->buf, line->size);
+                if (ENABLE_FEATURE_CLEAN_UP) {
+                        free(llist_pop(&list));
+                } else {
+                        list = list->link;
+                }
         }
 
         return retval;