Add vasprintf/asprintf

The only hardening being done here is to set the char** parameter to thos
functions to NULL in case of an error, to prevent it from being used should
people forget to check return values. This is already done on some BSD, as well
as in Rocky Linux.

README.md

@@ -59,6 +59,7 @@ At this point, the program will safely crash.
 
 - `FD_CLR`
 - `FD_SET`
+- `asprintf`
 - `bcopy`
 - `bzero`
 - `calloc`
@@ -121,6 +122,7 @@ At this point, the program will safely crash.
 - `umask` 
 - `vfprintf` 
 - `vprintf` 
+- `vasprintf`
 - `vsnprintf`
 - `vsprintf`
 - `wcrtomb`

include/stdio.h

@@ -220,6 +220,26 @@ _FORTIFY_FN(vprintf) int vprintf(const char *__f, __builtin_va_list __v)
 	return __orig_vprintf(__f, __v);
 #endif
 }
+
+#if defined(_GNU_SOURCE) || defined(_BSD_SOURCE)
+#if __has_builtin(__builtin_vasprintf)
+__diagnose_as_builtin(__builtin_vasprintf, 1, 2, 3)
+#endif
+_FORTIFY_FN(vasprintf) int vasprintf(char **restrict strp, const char *restrict fmt, __builtin_va_list ap)
+{
+#if __has_builtin(__builtin___vasprintf_chk) && USE_NATIVE_CHK
+	return __builtin___vasprintf_chk(_FORTIFY_SOURCE, strp, fmt, ap);
+#else
+	int ret = __orig_vasprintf(strp, fmt, ap);
+	if (ret < 0)
+		*strp = NULL;
+	return ret;
+#endif
+}
+
+
+#endif // defined(_GNU_SOURCE) || defined(_BSD_SOURCE)
+       //
 #endif  // __clang__
 
 
@@ -312,6 +332,26 @@ _FORTIFY_FN(fprintf) int fprintf(FILE *__s, const char *__f, ...)
 #endif
 }
 
+#if defined(_GNU_SOURCE) || defined(_BSD_SOURCE)
+#undef asprintf
+__fh_access(read_only, 2)
+__fh_format(printf, 2, 0)
+#if __has_builtin(__builtin_asprintf)
+__diagnose_as_builtin(__builtin_asprintf, 2, 3)
+#endif
+_FORTIFY_FN(asprintf) int asprintf(char **restrict strp, const char *restrict fmt, ...)
+{
+#if __has_builtin(__builtin___asprintf_chk) && USE_NATIVE_CHK
+	return __builtin___asprintf_chk(_FORTIFY_SOURCE, strp, fmt, __builtin_va_arg_pack());
+#else
+	int ret = __orig_asprintf(strp, fmt, __builtin_va_arg_pack());
+	if (ret<0)
+		*strp = NULL;
+	return ret;
+#endif
+}
+#endif
+
 #pragma GCC diagnostic pop
 #endif /* __has_builtin(__builtin_va_arg_pack) */
 

tests/Makefile

@@ -1,4 +1,4 @@
-CFLAGS+=-I../include/ -D_FORTIFY_SOURCE=3 -static -O2 -DPEDANTIC_CHECKS
+CFLAGS+=-I../include/ -D_FORTIFY_SOURCE=3 -static -O2 -DPEDANTIC_CHECKS -Wno-format
 
 COMPTIME_TARGETS= \
 	test_memcpy_overwrite_under  \
@@ -12,6 +12,7 @@ RUNTIME_TARGETS= \
 	test_FD_SET_negative         \
 	test_FD_ISSET_SETSIZE        \
 	test_FD_ISSET_negative       \
+	test_asprintf                \
 	test_bcopy_dynamic_read      \
 	test_bcopy_dynamic_write     \
 	test_bcopy_static_read       \
@@ -126,11 +127,12 @@ RUNTIME_TARGETS= \
 	test_ttyname_r_dynamic       \
 	test_ttyname_r_static        \
 	test_umask                   \
+	test_vasprintf               \
+	test_vfprintf                \
+	test_vprintf                 \
 	test_vsnprintf_dynamic       \
 	test_vsnprintf_static        \
 	test_vsprintf                \
-	test_vfprintf                \
-	test_vprintf                 \
 	test_wcscat_static_write     \
 	test_wcscpy_static_write     \
 	test_wcsncat_static_write    \

tests/test_asprintf.c

@@ -0,0 +1,20 @@
+#define _GNU_SOURCE
+#include "common.h"
+
+#include <assert.h>
+#include <stdio.h>
+#include <stdlib.h>
+
+int main(int argc, char** argv) {
+    char* buf;
+    asprintf(&buf, "total: %d+%d=%d", 1, 2, 3);
+    puts(buf);
+    free(buf);
+
+#ifndef __clang__
+    asprintf(&buf, "total: %", 1);
+    assert(buf == NULL);
+#endif
+
+    return 0;
+}

tests/test_vasprintf.c

@@ -0,0 +1,36 @@
+#define _GNU_SOURCE
+#include "common.h"
+
+#include <assert.h>
+#include <stdarg.h>
+#include <stdio.h>
+#include <stdlib.h>
+
+void test(const char *fmt, ...)
+{
+    char* buf;
+    va_list args;
+    va_start(args, fmt);
+    vasprintf(&buf, fmt, args);
+    va_end(args);
+    puts(buf);
+    free(buf);
+}
+
+void test2(const char *fmt, ...)
+{
+    char* buf;
+    va_list args;
+    va_start(args, fmt);
+    vasprintf(&buf, fmt, args);
+    va_end(args);
+    assert(buf == NULL);
+}
+
+int main(int argc, char** argv) {
+    test("Total: %d+%d=%d", 1, 2, 3);
+#ifndef __clang__
+    test2("Total: %", 1, 2, 3);
+#endif
+    return 0;
+}