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54 lines
2.2 KiB
54 lines
2.2 KiB
1 month ago
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commit 2be0572f3a41d5d5a8bb3b2b04244b7c01ac0f58
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Author: Florian Weimer <fweimer@redhat.com>
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Date: Tue Aug 13 15:52:34 2024 +0200
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manual: Document dprintf and vdprintf
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Reviewed-by: Carlos O'Donell <carlos@redhat.com>
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diff --git a/manual/stdio.texi b/manual/stdio.texi
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index 41298b87a4a6c7d9..d3d855fc62b8768b 100644
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--- a/manual/stdio.texi
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+++ b/manual/stdio.texi
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@@ -2483,6 +2483,26 @@ store the result in which case @code{-1} is returned. This was
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changed in order to comply with the @w{ISO C99} standard.
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@end deftypefun
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+@deftypefun dprintf (int @var{fd}, @var{template}, ...)
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+@standards{POSIX, stdio.h}
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+@safety{@mtsafe{@mtslocale{}}@asunsafe{@ascuheap{}}@acunsafe{@acsmem{}}}
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+This function formats its arguments according to @var{template} and
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+writes the result to the file descriptor @var{fd}, using the
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+@code{write} function. It returns the number of bytes written, or a
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+negative value if there was an error. In the error case, @code{errno}
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+is set appropriately. The possible @code{errno} values depend on the
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+type of the file descriptor @var{fd}, in addition to the general
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+@code{printf} error codes.
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+
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+The number of calls to @code{write} is unspecified, and some @code{write}
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+calls may have happened even if @code{dprintf} returns with an error.
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+
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+@strong{Portability Note:} POSIX does not require that this function is
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+async-signal-safe, and @theglibc{} implementation is not. However, some
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+other systems offer this function as an async-signal-safe alternative to
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+@code{fprintf}. @xref{POSIX Safety Concepts}.
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+@end deftypefun
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+
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@node Dynamic Output
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@subsection Dynamically Allocating Formatted Output
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@@ -2696,6 +2716,13 @@ The @code{obstack_vprintf} function is the equivalent of
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as for @code{vprintf}.@refill
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@end deftypefun
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+@deftypefun int vdprintf (int @var{fd}, const char *@var{template}, va_list @var{ap})
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+@standards{POSIX, stdio.h}
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+@safety{@mtsafe{@mtslocale{}}@asunsafe{@ascuheap{}}@acunsafe{@acsmem{}}}
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+The @code{vdprintf} is the equivalent of @code{dprintf}, but processes
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+an argument list.
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+@end deftypefun
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+
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Here's an example showing how you might use @code{vfprintf}. This is a
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function that prints error messages to the stream @code{stderr}, along
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with a prefix indicating the name of the program
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