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Diffstat (limited to 'manual/stdio.texi')
| -rw-r--r-- | manual/stdio.texi | 10 |
1 files changed, 9 insertions, 1 deletions
diff --git a/manual/stdio.texi b/manual/stdio.texi index dbb21ca4a9..29f3fed89b 100644 --- a/manual/stdio.texi +++ b/manual/stdio.texi @@ -316,7 +316,15 @@ actually done any output using the stream.) Then the file named by and associated with the same stream object @var{stream}. If the operation fails, a null pointer is returned; otherwise, -@code{freopen} returns @var{stream}. +@code{freopen} returns @var{stream}. On Linux, @code{freopen} may also +fail and set @code{errno} to @code{EBUSY} when the kernel structure for +the old file descriptor was not initialized completely before @code{freopen} +was called. This can only happen in multi-threaded programs, when two +threads race to allocate the same file descriptor number. To avoid the +possibility of this race, do not use @code{close} to close the underlying +file descriptor for a @code{FILE}; either use @code{freopen} while the +file is still open, or use @code{open} and then @code{dup2} to install +the new file descriptor. @code{freopen} has traditionally been used to connect a standard stream such as @code{stdin} with a file of your own choice. This is useful in |