[PATCH][makedumpfile -R] Promptly return error on truncated regular file.

[Aureau, Georges (Kernel Tools ERT)]

[PATCH][makedumpfile -R] Promptly return error on truncated regular file.

When reaching the end-of-file on a truncated input regular file,
makedumpfile -R is looping for 10 minutes before producing an error.
This is confusing for users. When stdin is a regular file, an improved
behavior is to promptly return an EOF error.

Signed-off-by: Georges Aureau <georges.aureau at hpe.com>
--
diff --git a/makedumpfile.c b/makedumpfile.c
index 12fb0d8..295b3cc 100644
--- a/makedumpfile.c
+++ b/makedumpfile.c
@@ -5135,6 +5135,21 @@ write_cache_zero(struct cache_data *cd, size_t size)
        return write_cache_bufsz(cd);
 }
 
+int
+is_stdin_regular_file(void)
+{
+       struct stat st;
+       static int regular_file = -1;
+       if (regular_file == -1) {
+               if (fstat(STDIN_FILENO, &st) == -1) {
+                       regular_file = FALSE;
+               } else {
+                       regular_file = S_ISREG(st.st_mode) ? TRUE : FALSE;
+               }
+       }
+       return regular_file;
+}
+
 int
 read_buf_from_stdin(void *buf, int buf_size)
 {
@@ -5154,11 +5169,12 @@ read_buf_from_stdin(void *buf, int buf_size)
 
                } else if (0 == tmp_read_size) {
                        /*
-                        * If it cannot get any data from a standard input
+                        * If we reach end-of-file on regular file, or
+                        * if we cannot get any data from a standard input
                         * for a long time, break this loop.
                         */
                        tm = time(NULL);
-                       if (TIMEOUT_STDIN < (tm - last_time)) {
+                       if (is_stdin_regular_file() || TIMEOUT_STDIN < (tm - last_time)) {
                                ERRMSG("Can't get any data from STDIN.\n");
                                return FALSE;
                        }