diff options
| -rw-r--r-- | libio/fileops.c | 10 | ||||
| -rw-r--r-- | stdio-common/Makefile | 1 | ||||
| -rw-r--r-- | stdio-common/tst-fclose-devzero.c | 50 |
3 files changed, 61 insertions, 0 deletions
diff --git a/libio/fileops.c b/libio/fileops.c index a59e248142..0cce828859 100644 --- a/libio/fileops.c +++ b/libio/fileops.c @@ -928,6 +928,16 @@ do_ftell (FILE *fp) if (result == EOF) return result; + if (result == 0 && offset < 0) + { + /* This happens for some character devices that always report + file offset 0 even after some data has been read (instead of + failing with ESPIPE). The fclose path ignores this + error. */ + __set_errno (ESPIPE); + return EOF; + } + result += offset; if (result < 0) diff --git a/stdio-common/Makefile b/stdio-common/Makefile index 3709222266..64b3575acb 100644 --- a/stdio-common/Makefile +++ b/stdio-common/Makefile @@ -262,6 +262,7 @@ tests := \ tst-bz11319-fortify2 \ tst-cookie \ tst-dprintf-length \ + tst-fclose-devzero \ tst-fclose-offset \ tst-fdopen \ tst-fdopen2 \ diff --git a/stdio-common/tst-fclose-devzero.c b/stdio-common/tst-fclose-devzero.c new file mode 100644 index 0000000000..1c7b39a3e0 --- /dev/null +++ b/stdio-common/tst-fclose-devzero.c @@ -0,0 +1,50 @@ +/* Test that always-zero lseek does not cause fclose failure after fread. + Copyright (C) 2025 Free Software Foundation, Inc. + This file is part of the GNU C Library. + + The GNU C Library is free software; you can redistribute it and/or + modify it under the terms of the GNU Lesser General Public + License as published by the Free Software Foundation; either + version 2.1 of the License, or (at your option) any later version. + + The GNU C Library 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 + Lesser General Public License for more details. + + You should have received a copy of the GNU Lesser General Public + License along with the GNU C Library; if not, see + <https://www.gnu.org/licenses/>. */ + +#include <errno.h> +#include <stdio.h> +#include <string.h> + +#include <support/check.h> +#include <support/xstdio.h> + +int +do_test (void) +{ + for (int do_ftello = 0; do_ftello < 2; ++do_ftello) + { + FILE *fp = xfopen ("/dev/zero", "r"); + char buf[17]; + memset (buf, 0xcc, sizeof (buf)); + xfread (buf, 1, sizeof (buf), fp); + static const char zeros[sizeof (buf)] = { 0 }; + TEST_COMPARE_BLOB (buf, sizeof (buf), zeros, sizeof (zeros)); + if (do_ftello) + { + errno = 0; + TEST_COMPARE (ftello (fp), -1); + TEST_COMPARE (errno, ESPIPE); + } + /* Do not use xfclose because it flushes first. */ + TEST_COMPARE (fclose (fp), 0); + } + + return 0; +} + +#include <support/test-driver.c> |