2 files changed, 143 insertions, 24 deletions

diff --git a/lib/libc/string/strerror.3 b/lib/libc/string/strerror.3
index 447e208c39c0..e64e79c4b17e 100644
--- a/lib/libc/string/strerror.3
+++ b/lib/libc/string/strerror.3
@@ -36,12 +36,13 @@
 .\"     @(#)strerror.3	8.1 (Berkeley) 6/9/93
 .\" $FreeBSD$
 .\"
-.Dd June 9, 1993
+.Dd Nov 26, 2001
 .Dt STRERROR 3
 .Os
 .Sh NAME
 .Nm perror ,
 .Nm strerror ,
+.Nm strerror_r ,
 .Nm sys_errlist ,
 .Nm sys_nerr
 .Nd system error messages
@@ -56,9 +57,12 @@
 .In string.h
 .Ft char *
 .Fn strerror "int errnum"
+.Ft int
+.Fn strerror_r "int errnum" "char * strerrbuf" "size_t buflen"
 .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 +72,18 @@ 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
@@ -94,9 +105,37 @@ otherwise, only the error message string is printed.
 If
 .Fa errnum
 is not a recognized error number,
-the error message string will contain
+.Fn strerror
+returns an error message string containing
 .Dq Li "Unknown error:\ "
-followed by the error number in decimal.
+followed by the error number in decimal and sets
+.Va errno
+to 
+.Er EINVAL .
+.Fn strerror_r
+leaves
+.Fa strerrbuf
+unchanged and returns 
+.Er EINVAL .
+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 nul 
+terminated to fit the length specified by 
+.Fa buflen .
 .Pp
 The message strings can be accessed directly using the external
 array
@@ -107,6 +146,8 @@ 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 ,
@@ -118,6 +159,13 @@ 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
diff --git a/lib/libc/string/strerror.c b/lib/libc/string/strerror.c
index d64120f225ca..085ea240be79 100644
--- a/lib/libc/string/strerror.c
+++ b/lib/libc/string/strerror.c
@@ -41,35 +41,106 @@ static const char rcsid[] =
 
 #include <stdio.h>
 #include <string.h>
+#include <errno.h>
+
+int
+strerror_r(int errnum, char *strerrbuf, size_t buflen)
+{
+	int             len;
+
+	if ((errnum >= 0) && (errnum < sys_nerr)) {
+		len = strlcpy(strerrbuf, (char *)sys_errlist[errnum], buflen);
+		return ((len < buflen) ? 0 : ERANGE);
+	}
+	return (EINVAL);
+}
 
 char *
 strerror(num)
-	int num;
+	int             num;
 {
-#define	UPREFIX	"Unknown error: "
-	static char ebuf[40] = UPREFIX;		/* 64-bit number + slop */
-	register unsigned int errnum;
-	register char *p, *t;
-	char tmp[40];
+	char           *p, *t;
+	unsigned int	uerr;
+	static char const unknown_prefix[] = "Unknown error: ";
+
+	/*
+	 * Define a buffer size big enough to describe a 64-bit
+	 * number in ASCII decimal (19), with optional leading sign
+	 * (+1) and trailing NUL (+1).
+	 */
+#       define		NUMLEN 21
+#	define		EBUFLEN (sizeof unknown_prefix + NUMLEN)
+	char            tmp[NUMLEN];	/* temporary number */
+	static char     ebuf[EBUFLEN];	/* error message */
 
-	errnum = num;				/* convert to unsigned */
-	if (errnum < sys_nerr)
-		return ((char *)sys_errlist[errnum]);
+	if ((num >= 0) && (num < sys_nerr))
+		return ((char *)sys_errlist[num]);
 
-	/* Do this by hand, so we don't link to stdio(3). */
+	/*
+	 * Set errno to EINVAL per P1003.1-200x Draft June 14, 2001.
+	 */
+	errno = EINVAL;
+
+	/*
+	 * Print unknown errno by hand so we don't link to stdio(3).
+	 * This collects the ASCII digits in reverse order.
+	 */
+	uerr = (num > 0) ? num : -num;
 	t = tmp;
-	if (num < 0)
-		errnum = -errnum;
 	do {
-		*t++ = "0123456789"[errnum % 10];
-	} while (errnum /= 10);
+		*t++ = "0123456789"[uerr % 10];
+	} while (uerr /= 10);
 	if (num < 0)
 		*t++ = '-';
-	for (p = ebuf + sizeof(UPREFIX) - 1;;) {
+
+	/*
+	 * Copy the "unknown" message and the number into the caller
+	 * supplied buffer, inverting the number string.
+	 */
+	strcpy(ebuf, unknown_prefix);
+	for (p = ebuf + sizeof unknown_prefix - 1; t >= tmp; )
 		*p++ = *--t;
-		if (t <= tmp)
-			break;
-	}
 	*p = '\0';
 	return (ebuf);
 }
+
+#ifdef STANDALONE_TEST
+
+#include <limits.h>
+
+main()
+{
+	char            mybuf[64];
+	int             ret;
+
+	errno = 0;
+
+	printf("strerror(0) yeilds: %s\n", strerror(0));
+	printf("strerror(1) yeilds: %s\n", strerror(1));
+	printf("strerror(47) yeilds: %s\n", strerror(47));
+	printf("strerror(sys_nerr - 1) yeilds: %s\n", strerror(sys_nerr - 1));
+	printf("errno = %d\n", errno); errno = 0;
+
+	printf("strerror(sys_nerr) yeilds: %s\n", strerror(sys_nerr));
+	printf("errno = %d\n", errno);  errno = 0;
+
+	printf("strerror(437) yeilds: %s\n", strerror(437));
+	printf("errno = %d\n", errno);  errno = 0;
+
+	printf("strerror(LONG_MAX) yeilds: %s\n", strerror(LONG_MAX));
+	printf("strerror(LONG_MIN) yeilds: %s\n", strerror(LONG_MIN));
+	printf("strerror(ULONG_MAX) yeilds: %s\n", strerror(ULONG_MAX));
+
+	memset(mybuf, '*', 63); mybuf[63] = '\0';
+	strerror_r(11, mybuf, 64);
+	printf("strerror_r(11) yeilds: %s\n", mybuf);
+
+	memset(mybuf, '*', 63); mybuf[63] = '\0';
+	ret = strerror_r(1234, mybuf, 64);
+	printf("strerror_r(1234) returns %d (%s)\n", ret, mybuf);
+
+	memset(mybuf, '*', 63); mybuf[63] = '\0';
+	ret = strerror_r(1, mybuf, 10);
+	printf("strerror_r on short buffer returns %d (%s)\n", ret, mybuf);
+}
+#endif