Libc-498.1.7.tar.gz

[apple/libc.git] / string / strerror.3

diff --git a/string/strerror.3 b/string/strerror.3
index c82aebf57317889556f6c54c99e9c649ccdc9159..b7166f1103f443cfc5f007318e0a456a6e75e703 100644 (file)
--- a/string/strerror.3
+++ b/string/strerror.3
@@ -34,14 +34,15 @@
 .\" SUCH DAMAGE.
 .\"
 .\"     @(#)strerror.3 8.1 (Berkeley) 6/9/93
-.\" $FreeBSD: src/lib/libc/string/strerror.3,v 1.12 2001/10/01 16:09:00 ru Exp $
+.\" $FreeBSD: src/lib/libc/string/strerror.3,v 1.23 2004/10/12 14:52:52 keramida Exp $
 .\"
-.Dd June 9, 1993
+.Dd October 12, 2004
 .Dt STRERROR 3
 .Os
 .Sh NAME
 .Nm perror ,
 .Nm strerror ,
+.Nm strerror_r ,
 .Nm sys_errlist ,
 .Nm sys_nerr
 .Nd system error messages
@@ -50,15 +51,26 @@
 .Sh SYNOPSIS
 .In stdio.h
 .Ft void
-.Fn perror "const char *string"
+.Fo perror
+.Fa "const char *s"
+.Fc
 .Vt extern const char * const sys_errlist[] ;
 .Vt extern const int sys_nerr ;
 .In string.h
-.Ft char *
-.Fn strerror "int errnum"
+.Ft "char *"
+.Fo strerror
+.Fa "int errnum"
+.Fc
+.Ft int
+.Fo strerror_r
+.Fa "int errnum"
+.Fa "char *strerrbuf"
+.Fa "size_t buflen"
+.Fc
 .Sh DESCRIPTION
 The
-.Fn strerror
+.Fn strerror ,
+.Fn strerror_r ,
 and
 .Fn perror
 functions look up the error message string corresponding to an
@@ -68,11 +80,18 @@ The
 .Fn strerror
 function accepts an error number argument
 .Fa errnum
-and
-returns a pointer to the corresponding
+and returns a pointer to the corresponding
 message string.
 .Pp
 The
+.Fn strerror_r
+function renders the same result into
+.Fa strerrbuf
+for a maximum of
+.Fa buflen
+characters and returns 0 upon success.
+.Pp
+The
 .Fn perror
 function finds the error message corresponding to the current
 value of the global variable
@@ -81,22 +100,47 @@ value of the global variable
 and writes it, followed by a newline, to the
 standard error file descriptor.
 If the argument
-.Fa string
+.Fa s
 is
 .Pf non- Dv NULL
 and does not point to the null character,
 this string is prepended to the message
 string and separated from it by
 a colon and space
-.Pq Ql \&:\ \& ;
+.Pq Dq Li ":\ " ;
 otherwise, only the error message string is printed.
 .Pp
-If
-.Fa errnum
-is not a recognized error number,
-the error message string will contain
+If the error number is not recognized, these functions return an error message
+string containing
 .Dq Li "Unknown error:\ "
 followed by the error number in decimal.
+The
+.Fn strerror
+and
+.Fn strerror_r
+functions return
+.Er EINVAL
+as a warning.
+Error numbers recognized by this implementation fall in
+the range 0 <
+.Fa errnum
+<
+.Fa sys_nerr .
+.Pp
+If insufficient storage is provided in
+.Fa strerrbuf
+(as specified in
+.Fa buflen )
+to contain the error string,
+.Fn strerror_r
+returns
+.Er ERANGE
+and
+.Fa strerrbuf
+will contain an error message that has been truncated and
+.Dv NUL
+terminated to fit the length specified by
+.Fa buflen .
 .Pp
 The message strings can be accessed directly using the external
 array
@@ -107,10 +151,23 @@ contains a count of the messages in
 .Va sys_errlist .
 The use of these variables is deprecated;
 .Fn strerror
+or
+.Fn strerror_r
 should be used instead.
 .Sh SEE ALSO
 .Xr intro 2 ,
 .Xr psignal 3
+.Sh STANDARDS
+The
+.Fn perror
+and
+.Fn strerror
+functions conform to
+.St -isoC-99 .
+The
+.Fn strerror_r
+function conforms to
+.St -p1003.1-2001 .
 .Sh HISTORY
 The
 .Fn strerror
@@ -118,12 +175,23 @@ and
 .Fn perror
 functions first appeared in
 .Bx 4.4 .
+The
+.Fn strerror_r
+function was implemented in
+.Fx 4.4
+by
+.An Wes Peters Aq wes@FreeBSD.org .
 .Sh BUGS
 For unknown error numbers, the
 .Fn strerror
 function will return its result in a static buffer which
 may be overwritten by subsequent calls.
 .Pp
+The return type for
+.Fn strerror
+is missing a type-qualifier; it should actually be
+.Vt const char * .
+.Pp
 Programs that use the deprecated
 .Va sys_errlist
 variable often fail to compile because they declare it