diff options
Diffstat (limited to 'manual/stdio.texi')
| -rw-r--r-- | manual/stdio.texi | 34 |
1 files changed, 15 insertions, 19 deletions
diff --git a/manual/stdio.texi b/manual/stdio.texi index e40717034c..0326f29eae 100644 --- a/manual/stdio.texi +++ b/manual/stdio.texi @@ -270,7 +270,7 @@ Locks}. @safety{@prelim{}@mtsafe{}@asunsafe{@ascuheap{} @asulock{}}@acunsafe{@acsmem{} @acsfd{} @aculock{}}} This function is similar to @code{fopen} but the stream it returns a pointer for is opened using @code{open64}. Therefore this stream can be -used even on files larger than @math{2^31} bytes on 32 bit machines. +used even on files larger than @twoexp{31} bytes on 32 bit machines. Please note that the return type is still @code{FILE *}. There is no special @code{FILE} type for the LFS interface. @@ -336,7 +336,7 @@ interface replaces transparently the old interface. @safety{@prelim{}@mtsafe{}@asunsafe{@asucorrupt{}}@acunsafe{@acucorrupt{} @acsfd{}}} This function is similar to @code{freopen}. The only difference is that on 32 bit machine the stream returned is able to read beyond the -@math{2^31} bytes limits imposed by the normal interface. It should be +@twoexp{31} bytes limits imposed by the normal interface. It should be noted that the stream pointed to by @var{stream} need not be opened using @code{fopen64} or @code{freopen64} since its mode is not important for this function. @@ -2428,7 +2428,7 @@ the array @var{s}, not including the terminating null character. The behavior of this function is undefined if copying takes place between objects that overlap---for example, if @var{s} is also given as an argument to be printed under control of the @samp{%s} conversion. -@xref{Copying and Concatenation}. +@xref{Copying Strings and Arrays}. @strong{Warning:} The @code{sprintf} function can be @strong{dangerous} because it can potentially output more characters than can fit in the @@ -2621,20 +2621,16 @@ choice, you are ready to call @code{vprintf}. That argument and all subsequent arguments that were passed to your function are used by @code{vprintf} along with the template that you specified separately. -In some other systems, the @code{va_list} pointer may become invalid -after the call to @code{vprintf}, so you must not use @code{va_arg} -after you call @code{vprintf}. Instead, you should call @code{va_end} -to retire the pointer from service. However, you can safely call -@code{va_start} on another pointer variable and begin fetching the -arguments again through that pointer. Calling @code{vprintf} does not -destroy the argument list of your function, merely the particular -pointer that you passed to it. - -GNU C does not have such restrictions. You can safely continue to fetch -arguments from a @code{va_list} pointer after passing it to -@code{vprintf}, and @code{va_end} is a no-op. (Note, however, that -subsequent @code{va_arg} calls will fetch the same arguments which -@code{vprintf} previously used.) +@strong{Portability Note:} The value of the @code{va_list} pointer is +undetermined after the call to @code{vprintf}, so you must not use +@code{va_arg} after you call @code{vprintf}. Instead, you should call +@code{va_end} to retire the pointer from service. You can call +@code{va_start} again and begin fetching the arguments from the start of +the variable argument list. (Alternatively, you can use @code{va_copy} +to make a copy of the @code{va_list} pointer before calling +@code{vfprintf}.) Calling @code{vprintf} does not destroy the argument +list of your function, merely the particular pointer that you passed to +it. Prototypes for these functions are declared in @file{stdio.h}. @pindex stdio.h @@ -4412,7 +4408,7 @@ This function is similar to @code{ftello} with the only difference that the return value is of type @code{off64_t}. This also requires that the stream @var{stream} was opened using either @code{fopen64}, @code{freopen64}, or @code{tmpfile64} since otherwise the underlying -file operations to position the file pointer beyond the @math{2^31} +file operations to position the file pointer beyond the @twoexp{31} bytes limit might fail. If the sources are compiled with @code{_FILE_OFFSET_BITS == 64} on a 32 @@ -4473,7 +4469,7 @@ the @var{offset} parameter is of type @code{off64_t}. This also requires that the stream @var{stream} was opened using either @code{fopen64}, @code{freopen64}, or @code{tmpfile64} since otherwise the underlying file operations to position the file pointer beyond the -@math{2^31} bytes limit might fail. +@twoexp{31} bytes limit might fail. If the sources are compiled with @code{_FILE_OFFSET_BITS == 64} on a 32 bits machine this function is available under the name @code{fseeko} |