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authorJan Vangorp <jan.vangorp_ext@softathome.com>2016-06-08 22:00:18 (GMT)
committerWaldemar Brodkorb <wbx@uclibc-ng.org>2016-06-12 09:44:45 (GMT)
commit568ceebf6adfc58c64a95133311268db626cdec2 (patch)
tree0e39be51e840fac004596aec34c0de6c5c3f4f59
parent0f541b5c48b7b0df80e2aaa8fdbf653a8b8bcd03 (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>
-rw-r--r--libc/stdio/_stdio.h15
1 files changed, 14 insertions, 1 deletions
diff --git a/libc/stdio/_stdio.h b/libc/stdio/_stdio.h
index 310510d..727e331 100644
--- a/libc/stdio/_stdio.h
+++ b/libc/stdio/_stdio.h
@@ -110,6 +110,18 @@ do { \
cfile->__gcs.NAME(cfile->__cookie, ##ARGS); \
}
+#define __STDIO_STREAM_CUSTOM_WRITE_FUNC(S, ARGS...) \
+ if (__STDIO_STREAM_IS_CUSTOM((S))) { \
+ _IO_cookie_file_t *cfile = (_IO_cookie_file_t *) (S); \
+ if (cfile->__gcs.write == NULL) { \
+ __set_errno(EINVAL); \
+ return -1; \
+ } \
+ __set_errno(EAGAIN); \
+ ssize_t w = cfile->__gcs.write(cfile->__cookie, ##ARGS); \
+ return (w == 0 ? -1 : w); \
+ }
+
typedef struct {
struct __STDIO_FILE_STRUCT __fp;
void *__cookie;
@@ -121,6 +133,7 @@ typedef struct {
#undef __STDIO_STREAM_GLIBC_CUSTOM_FILEDES
#define __STDIO_STREAM_IS_CUSTOM(S) (0)
#define __STDIO_STREAM_CUSTOM_IO_FUNC(S, NAME, RC, ARGS...)
+#define __STDIO_STREAM_CUSTOM_WRITE_FUNC(S, ARGS...)
#endif /* __UCLIBC_HAS_GLIBC_CUSTOM_STREAMS__ */
@@ -135,7 +148,7 @@ static inline ssize_t __READ(FILE *stream, char *buf, size_t bufsize)
static inline ssize_t __WRITE(FILE *stream, const char *buf, size_t bufsize)
{
- __STDIO_STREAM_CUSTOM_IO_FUNC(stream, write, -1, buf, bufsize);
+ __STDIO_STREAM_CUSTOM_WRITE_FUNC(stream, buf, bufsize);
return write(stream->__filedes, buf, bufsize);
}