hexdump: stop after stdout write errors

Stop the display loop once stdout reports an error. Otherwise hexdump keeps formatting and writing after the output stream has already failed, which can loop for a long time on errors such as ENOSPC.

Save the errno from the first stdout error before cleanup can overwrite it. Report that saved error from hexdump itself and bypass close_stdout_atexit, as ferror() only preserves the stream error state and does not recover the original errno.

Add a regression test that writes hexdump output to /dev/full and checks that the command fails with the ENOSPC write error.

Addresses: https://github.com/util-linux/util-linux/issues/2205

Signed-off-by: WanBingjiang <wanbingjiang@webray.com.cn>

diff --git a/tests/expected/hexdump/write-error b/tests/expected/hexdump/write-error
new file mode 100644 (file)
index 0000000..e4793b7
--- /dev/null
+++ b/tests/expected/hexdump/write-error
@@ -0,0 +1 @@
+exit code: 1

diff --git a/tests/expected/hexdump/write-error.err b/tests/expected/hexdump/write-error.err
new file mode 100644 (file)
index 0000000..e5c3300
--- /dev/null
+++ b/tests/expected/hexdump/write-error.err
@@ -0,0 +1 @@
+hexdump: write error: No space left on device

diff --git a/tests/ts/hexdump/write-error b/tests/ts/hexdump/write-error
new file mode 100755 (executable)
index 0000000..ec70e59
--- /dev/null
+++ b/tests/ts/hexdump/write-error
@@ -0,0 +1,29 @@
+#!/usr/bin/env bash
+
+# This file is part of util-linux.
+#
+# This file is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This file is distributed in the hope that it will be useful, but
+# WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+# General Public License for more details.
+
+TS_TOPDIR="${0%/*}/../.."
+TS_DESC="write-error"
+
+. "$TS_TOPDIR"/functions.sh
+ts_init "$*"
+
+ts_check_test_command "$TS_CMD_HEXDUMP"
+
+[ -c /dev/full ] || ts_skip "/dev/full not found"
+
+$TS_CMD_HEXDUMP -C --no-squeezing -n 1048576 /dev/zero > /dev/full 2> "$TS_ERRLOG"
+rc=$?
+printf "exit code: %d\n" "$rc" >> "$TS_OUTPUT"
+
+ts_finalize

diff --git a/text-utils/hexdump-display.c b/text-utils/hexdump-display.c
index 5f0f48bfffe52199e1516c558ea331ff06da1518..d9630f5eed4defda06dbcda347fa9cbf94055bd1 100644 (file)
--- a/text-utils/hexdump-display.c
+++ b/text-utils/hexdump-display.c
@@ -454,6 +454,11 @@ void display(struct hexdump *hex)
                        rem = hex->blocksize;
                        address = saveaddress;
                }
+               if (ferror(stdout)) {
+                       hex->stdout_errno = errno;
+                       hex->exitval = errno == EPIPE ? EXIT_SUCCESS : EXIT_FAILURE;
+                       return;
+               }
        }
        if (endfu) {
                /*

diff --git a/text-utils/hexdump.c b/text-utils/hexdump.c
index c2456a762693c50e5f0a69ee0021acf1658b147a..08a38c5915452ee0db6232c906001f27b1bd63a8 100644 (file)
--- a/text-utils/hexdump.c
+++ b/text-utils/hexdump.c
@@ -196,7 +196,7 @@ int main(int argc, char **argv)
 {
        struct list_head *p;
        struct hexdump_fs *tfs;
-       int ret;
+       int ret, stdout_errno;
 
        struct hexdump *hex = xcalloc(1, sizeof (struct hexdump));
        hex->length = -1;
@@ -225,7 +225,21 @@ int main(int argc, char **argv)
        display(hex);
 
        ret = hex->exitval;
+       stdout_errno = hex->stdout_errno;
        hex_free(hex);
+       if (stdout_errno) {
+               /*
+                * The stream error flag does not preserve errno.  Report the
+                * saved write error here and bypass close_stdout_atexit() to
+                * avoid relying on unrelated errno values after cleanup.
+                */
+               errno = stdout_errno;
+               if (stdout_errno != EPIPE)
+                       warn(_("write error"));
+               if (flush_standard_stream(stderr) != 0)
+                       _exit(EXIT_FAILURE);
+               _exit(ret);
+       }
 
        return ret;
 }

diff --git a/text-utils/hexdump.h b/text-utils/hexdump.h
index 309fbee4f53f6b9abe950a19bc1ae8715cbc95dd..681f29d3ef4de42403c4fc3882bcccc90432bf6b 100644 (file)
--- a/text-utils/hexdump.h
+++ b/text-utils/hexdump.h
@@ -87,6 +87,7 @@ struct hexdump {
   struct list_head fshead;                             /* head of format strings */
   ssize_t blocksize;                   /* data block size */
   int exitval;                         /* final exit value */
+  int stdout_errno;                    /* errno from stdout error */
   ssize_t length;                      /* max bytes to read */
   off_t skip;                          /* bytes to skip */
   /* Sparse file optimization using FIEMAP (Linux only) */