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(Dynamic Output): Document the return value of asprintf. Also make the asprintf/snprintf examples a little better (check for some error returns).

This commit is contained in:
Ulrich Drepper 2000-12-25 00:44:08 +00:00
parent b708b1ca77
commit 7ba73c63c0
1 changed files with 15 additions and 6 deletions
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21
manual/stdio.texi
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@ -1613,6 +1613,9 @@ make_message (char *name, char *value)
int nchars; int nchars;
@end group @end group
@group @group
if (buffer == NULL)
return NULL;
/* @r{Try to print in the allocated space.} */ /* @r{Try to print in the allocated space.} */
nchars = snprintf (buffer, size, "value of %s is %s", nchars = snprintf (buffer, size, "value of %s is %s",
name, value); name, value);
@ -1624,9 +1627,10 @@ make_message (char *name, char *value)
how much space is needed.} */ how much space is needed.} */
buffer = (char *) xrealloc (buffer, nchars + 1); buffer = (char *) xrealloc (buffer, nchars + 1);
/* @r{Try again.} */ if (buffer != NULL)
snprintf (buffer, size, "value of %s is %s", /* @r{Try again.} */
name, value); snprintf (buffer, size, "value of %s is %s",
name, value);
@} @}
/* @r{The last call worked, return the string.} */ /* @r{The last call worked, return the string.} */
return buffer; return buffer;
@ -1659,6 +1663,10 @@ buffer you allocate in advance. The @var{ptr} argument should be the
address of a @code{char *} object, and @code{asprintf} stores a pointer address of a @code{char *} object, and @code{asprintf} stores a pointer
to the newly allocated string at that location. to the newly allocated string at that location.
The return value is the number of characters allocated for the buffer, or
less than zero if an error occured. Usually this means that the buffer
could not be allocated.
Here is how to use @code{asprintf} to get the same result as the Here is how to use @code{asprintf} to get the same result as the
@code{snprintf} example, but more easily: @code{snprintf} example, but more easily:
@ -1669,7 +1677,8 @@ char *
make_message (char *name, char *value) make_message (char *name, char *value)
@{ @{
char *result; char *result;
asprintf (&result, "value of %s is %s", name, value); if (asprintf (&result, "value of %s is %s", name, value) < 0)
return NULL;
return result; return result;
@} @}
@end smallexample @end smallexample
@ -3084,7 +3093,7 @@ For more information about the descriptor-level I/O functions, see
@node Error Recovery @node Error Recovery
@section Recovering from errors @section Recovering from errors
You may explicitly clear the error and EOF flags with the @code{clearerr} You may explicitly clear the error and EOF flags with the @code{clearerr}
function. function.
@comment stdio.h @comment stdio.h
@ -3112,7 +3121,7 @@ always fail again in the same way. So usually it is best to give up and
report the error to the user, rather than install complicated recovery report the error to the user, rather than install complicated recovery
logic. logic.
One important exception is @code{EINTR} (@pxref{Interrupted Primitives}). One important exception is @code{EINTR} (@pxref{Interrupted Primitives}).
Many stream I/O implementations will treat it as an ordinary error, which Many stream I/O implementations will treat it as an ordinary error, which
can be quite inconvenient. You can avoid this hassle by installing all can be quite inconvenient. You can avoid this hassle by installing all
signals with the @code{SA_RESTART} flag. signals with the @code{SA_RESTART} flag.