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author | Jan Vangorp <jan.vangorp_ext@softathome.com> | 2016-06-09 00:00:18 +0200 |
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committer | Waldemar Brodkorb <wbx@uclibc-ng.org> | 2016-06-12 11:44:45 +0200 |
commit | 568ceebf6adfc58c64a95133311268db626cdec2 (patch) | |
tree | 0e39be51e840fac004596aec34c0de6c5c3f4f59 /libc/stdio/__flbf.c | |
parent | 0f541b5c48b7b0df80e2aaa8fdbf653a8b8bcd03 (diff) |
Fix infinite loop when fopencookie custom write returns 0 on error
The man page for fopencookie prescribes that custom write functions
should return 0 on error (and should definitely not return a negative
value) [1].
However, the uClibc implementation expects a negative return value in
case of an error (libc/stdio/_WRITE.c). If the write function returns 0
on error, we drop into an infinite loop if the error persists.
This patch wraps the user supplied write function such that a 0 return
value is converted to -1. errno is first set to EAGAIN such that if the
custom write function does not set errno in case of error, this is
treated as a "soft" error.
Custom write functions that cater towards uClibc and _do_ return a
negative value are not affected.
If no custom write function is supplied, set errno to EINVAL such that
this condition is treated as a "hard" error. Previously the behaviour
depended on whether the last error before the write happened to be a "hard"
or a "soft" error.
[1] http://git.kernel.org/cgit/docs/man-pages/man-pages.git/tree/man3/fopencookie.3?id=6c0d0ef0c7a9c4bcf805c6f9e9bc1ef1c3865ea0#n164
Signed-off-by: Jan Vangorp <jan.vangorp_ext@softathome.com>
Diffstat (limited to 'libc/stdio/__flbf.c')
0 files changed, 0 insertions, 0 deletions