From: Tobias Stoeckmann <tobias@stoeckmann.org>
Date: Sun, 18 May 2025 13:41:59 +0000 (+0200)
Subject: man/man3/*printf.3: Document ERRORS
X-Git-Tag: man-pages-6.15~51
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=8bc318c60ffed8d698de2a94cb2a03ff611c3c7f;p=thirdparty%2Fman-pages.git

man/man3/*printf.3: Document ERRORS

The printf family of functions set errno if a negative value is returned.

Source is POSIX.1, see
<https://pubs.opengroup.org/onlinepubs/9799919799/functions/fprintf.html>
<https://pubs.opengroup.org/onlinepubs/9799919799/functions/fwprintf.html>

Also see manual pages of FreeBSD and OpenBSD.

Signed-off-by: Tobias Stoeckmann <tobias@stoeckmann.org>
Message-ID: <34octlcodbwm3kfqlouvrvhriiftmlzzobbohgzivlkgi53nfs@7gxajeb56klz>
Signed-off-by: Alejandro Colomar <alx@kernel.org>
---

diff --git a/man/man3/asprintf.3 b/man/man3/asprintf.3
index 21c55bc0d..68c372ed8 100644
--- a/man/man3/asprintf.3
+++ b/man/man3/asprintf.3
@@ -37,10 +37,18 @@ to release the allocated storage when it is no longer needed.
 When successful, these functions return the number of bytes printed,
 just like
 .BR sprintf (3).
-If memory allocation wasn't possible, or some other error occurs,
-these functions will return \-1, and the contents of
+On error,
+\-1 is returned,
+.I errno
+is set to indicate the error,
+and the contents of
 .I strp
 are undefined.
+.SH ERRORS
+See
+.BR sprintf (3)
+and
+.BR malloc (3).
 .SH ATTRIBUTES
 For an explanation of the terms used in this section, see
 .BR attributes (7).
diff --git a/man/man3/printf.3 b/man/man3/printf.3
index 6b33584e2..759539381 100644
--- a/man/man3/printf.3
+++ b/man/man3/printf.3
@@ -904,7 +904,30 @@ Thus, a return value of
 or more means that the output was truncated.
 (See also below under CAVEATS.)
 .P
-If an output error is encountered, a negative value is returned.
+On error,
+a negative value is returned,
+and
+.I errno
+is set to indicate the error.
+.SH ERRORS
+See
+.BR write (2)
+and
+.BR putwc (3).
+In addition, the following error may occur:
+.TP
+.B EOVERFLOW
+The value to be returned is greater than
+.BR INT_MAX .
+.P
+The
+.BR dprintf ()
+function may fail additionally if:
+.TP
+.B EBADF
+The
+.I fd
+argument is not a valid file descriptor.
 .SH ATTRIBUTES
 For an explanation of the terms used in this section, see
 .BR attributes (7).
diff --git a/man/man3/wprintf.3 b/man/man3/wprintf.3
index 46163464a..a7324426b 100644
--- a/man/man3/wprintf.3
+++ b/man/man3/wprintf.3
@@ -198,7 +198,30 @@ case of the functions
 .BR swprintf ()
 and
 .BR vswprintf ().
-They return \-1 when an error occurs.
+On error,
+\-1 is returned,
+and
+.I errno
+is set to indicate the error.
+.SH ERRORS
+See
+.BR write (2)
+and
+.BR putwc (3).
+In addition, the following error may occur:
+.TP
+.B EOVERFLOW
+The value to be returned is greater than
+.BR INT_MAX .
+.P
+The
+.BR fwprintf ()
+and
+.BR wprintf ()
+functions may fail additionally if:
+.TP
+.B ENOMEM
+Insufficient storage space is available.
 .SH ATTRIBUTES
 For an explanation of the terms used in this section, see
 .BR attributes (7).