[master] add %z format options to printf

4123. [port] Added %z (size_t) format options to the portable internal printf/sprintf implementation. [RT #39586]
2025-08-30 14:07:59 +00:00 · 2015-05-21 14:55:15 -07:00
parent f5c20627f4
commit cadf8d687b
9 changed files with 302 additions and 106 deletions
--- a/3
+++ b/3
@@ -1,3 +1,6 @@
+4123.	[port]		Added %z (size_t) format options to the portable
+			internal printf/sprintf implementation. [RT #39586]
+
 4122.	[bug]		The server could match a shorter prefix than what was
 			available in CLIENT-IP policy triggers, and so, an
 			unexpected action could be taken. This has been
--- a/42
+++ b/42
@@ -719,6 +719,8 @@ LWRES_PLATFORM_USEDECLSPEC
 ISC_PLATFORM_USEDECLSPEC
 ISC_PLATFORM_RLIMITTYPE
 ISC_PLATFORM_HAVESYSUNH
+ISC_PLATFORM_NEEDFPRINTF
+ISC_PLATFORM_NEEDPRINTF
 LWRES_PLATFORM_QUADFORMAT
 ISC_PLATFORM_QUADFORMAT
 DST_EXTRA_SRCS
@@ -18764,6 +18766,46 @@ fi



+{ $as_echo "$as_me:${as_lineno-$LINENO}: checking printf for %z support" >&5
+$as_echo_n "checking printf for %z support... " >&6; }
+if test "$cross_compiling" = yes; then :
+  { $as_echo "$as_me:${as_lineno-$LINENO}: result: assuming target platform supports %z" >&5
+$as_echo "assuming target platform supports %z" >&6; }
+        ISC_PLATFORM_NEEDPRINTF='#undef ISC_PLATFORM_NEEDPRINTF'
+        ISC_PLATFORM_NEEDFPRINTF='#undef ISC_PLATFORM_NEEDFPRINTF'
+else
+  cat confdefs.h - <<_ACEOF >conftest.$ac_ext
+/* end confdefs.h.  */
+
+#include <stdio.h>
+main() {
+	/* Assume sprintf matches printf/fprintf. */
+        size_t j = 0;
+        char buf[100];
+        buf[0] = 0;
+        sprintf(buf, "%zu", j);
+        exit(strcmp(buf, "0") != 0);
+}
+
+_ACEOF
+if ac_fn_c_try_run "$LINENO"; then :
+  { $as_echo "$as_me:${as_lineno-$LINENO}: result: yes" >&5
+$as_echo "yes" >&6; }
+        ISC_PLATFORM_NEEDPRINTF='#undef ISC_PLATFORM_NEEDPRINTF'
+        ISC_PLATFORM_NEEDFPRINTF='#undef ISC_PLATFORM_NEEDFPRINTF'
+else
+  { $as_echo "$as_me:${as_lineno-$LINENO}: result: no" >&5
+$as_echo "no" >&6; }
+        ISC_PLATFORM_NEEDPRINTF='#define ISC_PLATFORM_NEEDPRINTF 1'
+        ISC_PLATFORM_NEEDFPRINTF='#define ISC_PLATFORM_NEEDFPRINTF 1'
+fi
+rm -f core *.core core.conftest.* gmon.out bb.out conftest$ac_exeext \
+  conftest.$ac_objext conftest.beam conftest.$ac_ext
+fi
+
+
+
+
 #
 # Security Stuff
 #
--- a/configure.in
+++ b/configure.in
@@ -3345,6 +3345,30 @@ main() {
 AC_SUBST(ISC_PLATFORM_QUADFORMAT)
 AC_SUBST(LWRES_PLATFORM_QUADFORMAT)

+AC_MSG_CHECKING([printf for %z support])
+AC_TRY_RUN([
+#include <stdio.h>
+main() {
+	/* Assume sprintf matches printf/fprintf. */
+        size_t j = 0;
+        char buf[100];
+        buf[0] = 0;
+        sprintf(buf, "%zu", j);
+        exit(strcmp(buf, "0") != 0);
+}
+],
+        [AC_MSG_RESULT(yes)
+        ISC_PLATFORM_NEEDPRINTF='#undef ISC_PLATFORM_NEEDPRINTF'
+        ISC_PLATFORM_NEEDFPRINTF='#undef ISC_PLATFORM_NEEDFPRINTF'],
+        [AC_MSG_RESULT(no)
+        ISC_PLATFORM_NEEDPRINTF='#define ISC_PLATFORM_NEEDPRINTF 1'
+        ISC_PLATFORM_NEEDFPRINTF='#define ISC_PLATFORM_NEEDFPRINTF 1'],
+        [AC_MSG_RESULT([assuming target platform supports %z])
+        ISC_PLATFORM_NEEDPRINTF='#undef ISC_PLATFORM_NEEDPRINTF'
+        ISC_PLATFORM_NEEDFPRINTF='#undef ISC_PLATFORM_NEEDFPRINTF'])
+AC_SUBST(ISC_PLATFORM_NEEDPRINTF)
+AC_SUBST(ISC_PLATFORM_NEEDFPRINTF)
+
 #
 # Security Stuff
 #
--- a/lib/dns/rpz.c
+++ b/lib/dns/rpz.c
@@ -1656,8 +1656,8 @@ fix_triggers(dns_rpz_zones_t *rpzs, dns_rpz_num_t rpz_num) {
 	isc_log_write(dns_lctx, DNS_LOGCATEGORY_RPZ,
 		      DNS_LOGMODULE_RBTDB, DNS_RPZ_INFO_LEVEL,
 		      "(re)loading policy zone '%s' changed from"
-		      " %ld to %ld qname, %ld to %ld nsdname,"
-		      " %ld to %ld IP, %ld to %ld NSIP entries",
+		      " %zd to %zd qname, %zd to %zd nsdname,"
+		      " %zd to %zd IP, %zd to %zd NSIP entries",
 		      namebuf,
 		      old_totals.qname, rpzs->total_triggers.qname,
 		      old_totals.nsdname, rpzs->total_triggers.nsdname,
--- a/lib/isc/include/isc/platform.h.in
+++ b/lib/isc/include/isc/platform.h.in
@@ -15,8 +15,6 @@
 * PERFORMANCE OF THIS SOFTWARE.
 */

-/* $Id: platform.h.in,v 1.56 2010/12/18 01:56:23 each Exp $ */
-
 #ifndef ISC_PLATFORM_H
 #define ISC_PLATFORM_H 1

@@ -171,6 +169,16 @@
 */
@ISC_PLATFORM_NEEDSPRINTF@

+/*! \brief
+ * If this system need a modern printf() that format size %z (size_t).
+ */
+@ISC_PLATFORM_NEEDPRINTF@
+
+/*! \brief
+ * If this system need a modern fprintf() that format size %z (size_t).
+ */
+@ISC_PLATFORM_NEEDFPRINTF@
+
 /*! \brief
 * The printf format string modifier to use with isc_uint64_t values.
 */
--- a/lib/isc/include/isc/print.h
+++ b/lib/isc/include/isc/print.h
@@ -15,8 +15,6 @@
 * PERFORMANCE OF THIS SOFTWARE.
 */

-/* $Id: print.h,v 1.26 2007/06/19 23:47:18 tbox Exp $ */
-
 #ifndef ISC_PRINT_H
 #define ISC_PRINT_H 1

@@ -47,6 +45,16 @@
 #undef sprintf
 #endif

+#if !defined(ISC_PLATFORM_NEEDFPRINTF) && defined(ISC__PRINT_SOURCE)
+#define ISC_PLATFORM_NEEDFPRINTF
+#undef fprintf
+#endif
+
+#if !defined(ISC_PLATFORM_NEEDPRINTF) && defined(ISC__PRINT_SOURCE)
+#define ISC_PLATFORM_NEEDPRINTF
+#undef printf
+#endif
+
 /***
 *** Macros
 ***/
@@ -85,6 +93,18 @@ isc_print_sprintf(char *str, const char *format, ...) ISC_FORMAT_PRINTF(2, 3);
 #define sprintf isc_print_sprintf
 #endif

+#ifdef ISC_PLATFORM_NEEDPRINTF
+int
+isc_print_printf(const char *format, ...) ISC_FORMAT_PRINTF(1, 2);
+#define printf isc_print_printf
+#endif
+
+#ifdef ISC_PLATFORM_NEEDFPRINTF
+int
+isc_print_fprintf(FILE * fp, const char *format, ...) ISC_FORMAT_PRINTF(2, 3);
+#define fprintf isc_print_fprintf
+#endif
+
 ISC_LANG_ENDDECLS

 #endif /* ISC_PRINT_H */
--- a/lib/isc/print.c
+++ b/lib/isc/print.c
@@ -15,8 +15,6 @@
 * PERFORMANCE OF THIS SOFTWARE.
 */

-/* $Id: print.c,v 1.37 2010/10/18 23:47:08 tbox Exp $ */
-
 /*! \file */

 #include <config.h>
@@ -34,6 +32,44 @@
 #include <isc/stdlib.h>
 #include <isc/util.h>

+static int
+isc__print_printf(void (*emit)(char, void *), void *arg, const char *format, va_list ap);
+
+static void
+file_emit(char c, void *arg) {
+	fputc(c, arg);
+}
+
+static int
+isc_print_vfprintf(FILE *fp, const char *format, va_list ap) {
+	INSIST(fp != NULL);
+	INSIST(format != NULL);
+
+	return (isc__print_printf(file_emit, fp, format, ap));
+}
+
+int
+isc_print_printf(const char *format, ...) {
+	va_list ap;
+	int n;
+
+	va_start(ap, format);
+	n = isc_print_vfprintf(stdout, format, ap);
+	va_end(ap);
+	return (n);
+}
+
+int
+isc_print_fprintf(FILE *fp, const char *format, ...) {
+	va_list ap;
+	int n;
+
+	va_start(ap, format);
+	n = isc_print_vfprintf(fp, format, ap);
+	va_end(ap);
+	return (n);
+}
+
 int
 isc_print_sprintf(char *str, const char *format, ...) {
 	va_list ap;
@@ -64,10 +100,40 @@ isc_print_snprintf(char *str, size_t size, const char *format, ...) {
 * Return length of string that would have been written if not truncated.
 */

+static void
+string_emit(char c, void *arg) {
+	struct { char *str; size_t size; } *p = arg;
+
+	if (p->size > 0) {
+		*(p->str)++ = c;
+		(p->size)--;
+	}
+}
+
 int
 isc_print_vsnprintf(char *str, size_t size, const char *format, va_list ap) {
+	struct { char *str; size_t size; } arg;
+	int n;
+
+	INSIST(str != NULL);
+	INSIST(format != NULL);
+
+	arg.str = str;
+	arg.size = size;
+
+	n = isc__print_printf(string_emit, &arg, format, ap);
+	if (arg.size > 0)
+		*arg.str = '\0';
+	return (n);
+}
+
+static int
+isc__print_printf(void (*emit)(char, void *), void *arg,
+		  const char *format, va_list ap)
+{
 	int h;
 	int l;
+	int z;
 	int q;
 	int alt;
 	int zero;
@@ -83,7 +149,6 @@ isc_print_vsnprintf(char *str, size_t size, const char *format, va_list ap) {
 	char buf[1024];
 	char c;
 	void *v;
-	char *save = str;
 	const char *cp;
 	const char *head;
 	int count = 0;
@@ -96,17 +161,14 @@ isc_print_vsnprintf(char *str, size_t size, const char *format, va_list ap) {
 #endif
 	char fmt[32];

-	INSIST(str != NULL);
+	INSIST(emit != NULL);
+	INSIST(arg != NULL);
 	INSIST(format != NULL);

 	while (*format != '\0') {
 		if (*format != '%') {
-			if (size > 1) {
-				*str++ = *format;
-				size--;
-			}
+			emit(*format++, arg);
 			count++;
-			format++;
 			continue;
 		}
 		format++;
@@ -114,7 +176,7 @@ isc_print_vsnprintf(char *str, size_t size, const char *format, va_list ap) {
 		/*
 		 * Reset flags.
 		 */
-		dot = neg = space = plus = left = zero = alt = h = l = q = 0;
+		dot = neg = space = plus = left = zero = alt = h = l = q = z = 0;
 		width = precision = 0;
 		head = "";
 		pad = zeropad = 0;
@@ -175,10 +237,7 @@ isc_print_vsnprintf(char *str, size_t size, const char *format, va_list ap) {
 		case '\0':
 			continue;
 		case '%':
-			if (size > 1) {
-				*str++ = *format;
-				size--;
-			}
+			emit(*format, arg);
 			count++;
 			break;
 		case 'q':
@@ -197,6 +256,10 @@ isc_print_vsnprintf(char *str, size_t size, const char *format, va_list ap) {
 				format++;
 			}
 			goto doint;
+		case 'z':
+			z = 1;
+			format++;
+			goto doint;
 		case 'n':
 		case 'i':
 		case 'd':
@@ -213,17 +276,22 @@ isc_print_vsnprintf(char *str, size_t size, const char *format, va_list ap) {
 					short int *p;
 					p = va_arg(ap, short *);
 					REQUIRE(p != NULL);
-					*p = str - save;
+					*p = count;
 				} else if (l) {
 					long int *p;
 					p = va_arg(ap, long *);
 					REQUIRE(p != NULL);
-					*p = str - save;
+					*p = count;
+				} else if (z) {
+					size_t *p;
+					p = va_arg(ap, size_t *);
+					REQUIRE(p != NULL);
+					*p = count;
 				} else {
 					int *p;
 					p = va_arg(ap, int *);
 					REQUIRE(p != NULL);
-					*p = str - save;
+					*p = count;
 				}
 				break;
 			case 'i':
@@ -232,6 +300,8 @@ isc_print_vsnprintf(char *str, size_t size, const char *format, va_list ap) {
 					tmpi = va_arg(ap, isc_int64_t);
 				else if (l)
 					tmpi = va_arg(ap, long int);
+				else if (z)
+					tmpi = va_arg(ap, ssize_t);
 				else
 					tmpi = va_arg(ap, int);
 				if (tmpi < 0) {
@@ -270,6 +340,8 @@ isc_print_vsnprintf(char *str, size_t size, const char *format, va_list ap) {
 					tmpui = va_arg(ap, isc_uint64_t);
 				else if (l)
 					tmpui = va_arg(ap, long int);
+				else if (z)
+					tmpui = va_arg(ap, size_t);
 				else
 					tmpui = va_arg(ap, int);
 				if (tmpui <= 0xffffffffU)
@@ -301,6 +373,8 @@ isc_print_vsnprintf(char *str, size_t size, const char *format, va_list ap) {
 					tmpui = va_arg(ap, isc_uint64_t);
 				else if (l)
 					tmpui = va_arg(ap, unsigned long int);
+				else if (z)
+					tmpui = va_arg(ap, size_t);
 				else
 					tmpui = va_arg(ap, unsigned int);
 				if (tmpui <= 0xffffffffU)
@@ -327,6 +401,8 @@ isc_print_vsnprintf(char *str, size_t size, const char *format, va_list ap) {
 					tmpui = va_arg(ap, isc_uint64_t);
 				else if (l)
 					tmpui = va_arg(ap, unsigned long int);
+				else if (z)
+					tmpui = va_arg(ap, size_t);
 				else
 					tmpui = va_arg(ap, unsigned int);
 				if (alt) {
@@ -349,6 +425,8 @@ isc_print_vsnprintf(char *str, size_t size, const char *format, va_list ap) {
 					tmpui = va_arg(ap, isc_uint64_t);
 				else if (l)
 					tmpui = va_arg(ap, unsigned long int);
+				else if (z)
+					tmpui = va_arg(ap, size_t);
 				else
 					tmpui = va_arg(ap, unsigned int);
 				if (alt) {
@@ -383,30 +461,23 @@ isc_print_vsnprintf(char *str, size_t size, const char *format, va_list ap) {
 				count += strlen(head) + strlen(buf) + pad +
 					 zeropad;
 				if (!left) {
-					while (pad > 0 && size > 1) {
-						*str++ = ' ';
-						size--;
+					while (pad > 0) {
+						emit(' ', arg);
 						pad--;
 					}
 				}
 				cp = head;
-				while (*cp != '\0' && size > 1) {
-					*str++ = *cp++;
-					size--;
-				}
-				while (zeropad > 0 && size > 1) {
-					*str++ = '0';
-					size--;
+				while (*cp != '\0')
+					emit(*cp++, arg);
+				while (zeropad > 0) {
+					emit('0', arg);
 					zeropad--;
 				}
 				cp = buf;
-				while (*cp != '\0' && size > 1) {
-					*str++ = *cp++;
-					size--;
-				}
-				while (pad > 0 && size > 1) {
-					*str++ = ' ';
-					size--;
+				while (*cp != '\0')
+					emit(*cp++, arg);
+				while (pad > 0) {
+					emit(' ', arg);
 					pad--;
 				}
 				break;
@@ -440,26 +511,20 @@ isc_print_vsnprintf(char *str, size_t size, const char *format, va_list ap) {
 			}
 			count += pad + length;
 			if (!left)
-				while (pad > 0 && size > 1) {
-					*str++ = ' ';
-					size--;
+				while (pad > 0) {
+					emit(' ', arg);
 					pad--;
 				}
 			if (precision != 0)
-				while (precision > 0 && *cp != '\0' &&
-				       size > 1) {
-					*str++ = *cp++;
-					size--;
+				while (precision > 0 && *cp != '\0') {
+					emit(*cp++, arg);
 					precision--;
 				}
 			else
-				while (*cp != '\0' && size > 1) {
-					*str++ = *cp++;
-					size--;
-				}
-			while (pad > 0 && size > 1) {
-				*str++ = ' ';
-				size--;
+				while (*cp != '\0')
+					emit(*cp++, arg);
+			while (pad > 0) {
+				emit(' ', arg);
 				pad--;
 			}
 			break;
@@ -468,24 +533,15 @@ isc_print_vsnprintf(char *str, size_t size, const char *format, va_list ap) {
 			if (width > 0) {
 				count += width;
 				width--;
-				if (left && size > 1) {
-					*str++ = c;
-					size--;
-				}
-				while (width-- > 0 && size > 1) {
-					*str++ = ' ';
-					size--;
-				}
-				if (!left && size > 1) {
-					*str++ = c;
-					size--;
-				}
+				if (left)
+					emit(c, arg);
+				while (width-- > 0)
+					emit(' ', arg);
+				if (!left)
+					emit(c, arg);
 			} else {
 				count++;
-				if (size > 1) {
-					*str++ = c;
-					size--;
-				}
+				emit(c, arg);
 			}
 			break;
 		case 'p':
@@ -501,35 +557,24 @@ isc_print_vsnprintf(char *str, size_t size, const char *format, va_list ap) {
 			}
 			count += length + pad + zeropad;
 			if (!left)
-				while (pad > 0 && size > 1) {
-					*str++ = ' ';
-					size--;
+				while (pad > 0) {
+					emit(' ', arg);
 					pad--;
 				}
 			cp = buf;
 			if (zeropad > 0 && buf[0] == '0' &&
 			    (buf[1] == 'x' || buf[1] == 'X')) {
-				if (size > 1) {
-					*str++ = *cp++;
-					size--;
-				}
-				if (size > 1) {
-					*str++ = *cp++;
-					size--;
-				}
-				while (zeropad > 0 && size > 1) {
-					*str++ = '0';
-					size--;
+				emit(*cp++, arg);
+				emit(*cp++, arg);
+				while (zeropad > 0) {
+					emit('0', arg);
 					zeropad--;
 				}
 			}
-			while (*cp != '\0' && size > 1) {
-				*str++ = *cp++;
-				size--;
-			}
-			while (pad > 0 && size > 1) {
-				*str++ = ' ';
-				size--;
+			while (*cp != '\0')
+				emit(*cp++, arg);
+			while (pad > 0) {
+				emit(' ', arg);
 				pad--;
 			}
 			break;
@@ -593,19 +638,15 @@ isc_print_vsnprintf(char *str, size_t size, const char *format, va_list ap) {
 				}
 				count += length + pad;
 				if (!left)
-					while (pad > 0 && size > 1) {
-						*str++ = ' ';
-						size--;
+					while (pad > 0) {
+						emit(' ', arg);
 						pad--;
 					}
 				cp = buf;
-				while (*cp != ' ' && size > 1) {
-					*str++ = *cp++;
-					size--;
-				}
-				while (pad > 0 && size > 1) {
-					*str++ = ' ';
-					size--;
+				while (*cp != ' ')
+					emit(*cp++, arg);
+				while (pad > 0) {
+					emit(' ', arg);
 					pad--;
 				}
 				break;
@@ -618,7 +659,5 @@ isc_print_vsnprintf(char *str, size_t size, const char *format, va_list ap) {
 		}
 		format++;
 	}
-	if (size > 0)
-		*str = '\0';
 	return (count);
 }
--- a/lib/isc/tests/Makefile.in
+++ b/lib/isc/tests/Makefile.in
@@ -99,7 +99,8 @@ sockaddr_test@EXEEXT@: sockaddr_test.@O@ isctest.@O@ ${ISCDEPLIBS}
 	${LIBTOOL_MODE_LINK} ${PURIFY} ${CC} ${CFLAGS} ${LDFLAGS} -o $@ \
 			sockaddr_test.@O@ isctest.@O@ ${ISCLIBS} ${LIBS}

-print_test@EXEEXT@: print_test.@O@ ${ISCDEPLIBS} ${top_srcdir}/lib/isc/print.c
+print_test.@O@:	${top_srcdir}/lib/isc/print.c
+print_test@EXEEXT@: print_test.@O@ ${ISCDEPLIBS}
 	${LIBTOOL_MODE_LINK} ${PURIFY} ${CC} ${CFLAGS} ${LDFLAGS} -o $@ \
 			print_test.@O@ ${ISCLIBS} ${LIBS}

--- a/lib/isc/tests/print_test.c
+++ b/lib/isc/tests/print_test.c
@@ -28,11 +28,17 @@
 * it on all platforms even if we don't include it in libisc.
 */
 #include <isc/platform.h>
-#if !defined(ISC_PLATFORM_NEEDVSNPRINTF) && !defined(ISC_PLATFORM_NEEDSPRINTF)
+#if !defined(ISC_PLATFORM_NEEDPRINTF) && \
+    !defined(ISC_PLATFORM_NEEDFPRINTF) && \
+    !defined(ISC_PLATFORM_NEEDSPRINTF) && \
+    !defined(ISC_PLATFORM_NEEDVSNPRINTF)
 #define ISC__PRINT_SOURCE
 #include "../print.c"
 #else
-#if !defined(ISC_PLATFORM_NEEDVSNPRINTF) || !defined(ISC_PLATFORM_NEEDSPRINTF)
+#if !defined(ISC_PLATFORM_NEEDPRINTF) || \
+    !defined(ISC_PLATFORM_NEEDFPRINTF) || \
+    !defined(ISC_PLATFORM_NEEDSPRINTF) || \
+    !defined(ISC_PLATFORM_NEEDVSNPRINTF)
 #define ISC__PRINT_SOURCE
 #endif
 #include <isc/print.h>
@@ -48,6 +54,7 @@ ATF_TC_BODY(snprintf, tc) {
 	char buf[10000];
 	isc_uint64_t ll = 8589934592ULL;
 	int n;
+	size_t size;

 	UNUSED(tc);

@@ -65,6 +72,57 @@ ATF_TC_BODY(snprintf, tc) {
 	n = isc_print_snprintf(buf, sizeof(buf), "%llu", ll);
 	ATF_CHECK_EQ(n, 10);
 	ATF_CHECK_STREQ(buf, "8589934592");
+
+	size = 1000;
+	memset(buf, 0xff, sizeof(buf));
+	n = isc_print_snprintf(buf, sizeof(buf), "%zu", size);
+	ATF_CHECK_EQ(n, 4);
+	ATF_CHECK_STREQ(buf, "1000");
+
+	size = 1000;
+	memset(buf, 0xff, sizeof(buf));
+	n = isc_print_snprintf(buf, sizeof(buf), "%zx", size);
+	ATF_CHECK_EQ(n, 3);
+	ATF_CHECK_STREQ(buf, "3e8");
+
+	size = 1000;
+	memset(buf, 0xff, sizeof(buf));
+	n = isc_print_snprintf(buf, sizeof(buf), "%zo", size);
+	ATF_CHECK_EQ(n, 4);
+	ATF_CHECK_STREQ(buf, "1750");
+}
+
+ATF_TC(fprintf);
+ATF_TC_HEAD(fprintf, tc) {
+	atf_tc_set_md_var(tc, "descr", "fprintf implementation");
+}
+ATF_TC_BODY(fprintf, tc) {
+	FILE *f;
+	int n;
+	size_t size;
+	char buf[10000];
+
+	UNUSED(tc);
+
+	f = fopen("fprintf.test", "w+");
+	ATF_REQUIRE(f != NULL);
+
+	size = 1000;
+	n = isc_print_fprintf(f, "%zu", size);
+	ATF_CHECK_EQ(n, 4);
+
+	rewind(f);
+
+	memset(buf, 0, sizeof(buf));
+	n = fread(buf, 1, sizeof(buf), f);
+	ATF_CHECK_EQ(n, 4);
+
+	fclose(f);
+
+	ATF_CHECK_STREQ(buf, "1000");
+
+	if ((n > 0) && (!strcmp(buf, "1000")))
+		unlink("fprintf.test");
 }

 /*
@@ -72,5 +130,6 @@ ATF_TC_BODY(snprintf, tc) {
 */
 ATF_TP_ADD_TCS(tp) {
 	ATF_TP_ADD_TC(tp, snprintf);
+	ATF_TP_ADD_TC(tp, fprintf);
 	return (atf_no_error());
 }