!995 optimize vsnprintf

Merge pull request !995 from Wang Yaofeng/vsnprintf_opt

libc-test/src/functionalext/supplement/stdio/vsnprintf.c

@@ -18,6 +18,7 @@
 #include <stdarg.h>
 #include <stdlib.h>
 #include "test.h"
+#include "functionalext.h"
 
 void vsnprintf_test(char *str, size_t n, char *fmt, const char *func_name, ...)
 {
@@ -49,6 +50,14 @@ void vsnprintf_zeron(char *str, char *fmt, const char *func_name, ...)
     }
 }
 
+void vsnprintf_zeron_all(char *str, char *fmt, const char *func_name, ...) {
+    va_list ap;
+    va_start(ap, func_name);
+    int result = vsnprintf(0, 0, fmt, ap);
+    va_end(ap);
+    EXPECT_EQ(func_name, result, strlen(str));
+}
+
 int main(int argc, char *argv[])
 {
     /**
@@ -75,5 +84,18 @@ int main(int argc, char *argv[])
      * @tc.level     : Level 2
      */
     vsnprintf_zeron("value is use", "value is %s", "vsnprintf_0400", "use");
+    /**
+     * @tc.name      : vsnprintf_0500
+     * @tc.desc      : truncate buffer, and bits to 0
+     * @tc.level     : Level 3
+     */
+    vsnprintf_zeron_all("value is use", "value is %s", "vsnprintf_0500", "use");
+    /**
+     * @tc.name      : vsnprintf_0600
+     * @tc.desc      : The number of bits to be 1
+     * @tc.level     : Level 2
+     */
+    vsnprintf_test("", 1, "value is %s", "vsnprintf_0600", "use");
+
     return t_status;
-}
\ No newline at end of file
+}

libc-test/src/functionalext/supplement/stdio/vsprintf.c

@@ -25,7 +25,7 @@
  */
 void vsprintf_0100(char *format, ...)
 {
-    char buffer[20];
+    char buffer[20] = {0};
     va_list aptr;
     va_start(aptr, format);
     int result = vsprintf(buffer, format, aptr);
@@ -34,7 +34,7 @@ void vsprintf_0100(char *format, ...)
         t_error("%s vsprintf get result is less than 0", __func__);
     }
     if (strcmp(buffer, "1")) {
-        t_error("%s wrong string written to buf", __func__);
+        t_error("%s wrong string written to buf %s\n", __func__, buffer);
     }
 }
 
@@ -45,16 +45,16 @@ void vsprintf_0100(char *format, ...)
  */
 void vsprintf_0200(char *format, ...)
 {
-    char buffer[20];
+    char buffer[20] = {0};
     va_list aptr;
     va_start(aptr, format);
     int result = vsprintf(buffer, format, aptr);
     va_end(aptr);
     if (result < 0) {
-        t_error("%s vsprintf get result is less than 0", __func__);
+        t_error("%s vsprintf get result is less than 0\n", __func__);
     }
     if (strncmp(buffer, "3.0", 3)) {
-        t_error("%s wrong string written to buf", __func__);
+        t_error("%s wrong string written to buf %s\n", __func__, buffer);
     }
 }
 
@@ -71,10 +71,10 @@ void vsprintf_0300(char *format, ...)
     int result = vsprintf(buffer, format, aptr);
     va_end(aptr);
     if (result < 0) {
-        t_error("%s vsprintf get result is less than 0", __func__);
+        t_error("%s vsprintf get result is less than 0\n", __func__);
     }
     if (strcmp(buffer, "vsprintf test")) {
-        t_error("%s wrong string written to buf", __func__);
+        t_error("%s wrong string written to buf %s\n", __func__, buffer);
     }
 }
 
@@ -87,4 +87,4 @@ int main(int argc, char *argv[])
     vsprintf_0200("%f", f);
     vsprintf_0300("%s", str);
     return t_status;
-}
\ No newline at end of file
+}

musl_src.gni

@@ -2189,6 +2189,7 @@ musl_src_porting_file = [
   "src/stdio/__towrite.c",
   "src/stdio/stderr.c",
   "src/stdio/fgets.c",
+  "src/stdio/vsnprintf.c",
   "src/internal/stdio_impl.h",
   "src/internal/vdso.c",
   "src/time/clock_gettime.c",

porting/linux/user/src/internal/stdio_impl.h

@@ -18,6 +18,7 @@
 #define F_SVB 64
 #define F_APP 128
 #define F_NOBUF 256
+#define F_PBUF 512
 
 struct _IO_FILE {
 	unsigned flags;

porting/linux/user/src/stdio/vfprintf.c

@@ -132,7 +132,14 @@ static void pop_arg(union arg *arg, int type, va_list *ap)
 
 static void out(FILE *f, const char *s, size_t l)
 {
-	if (!(f->flags & F_ERR)) __fwritex((void *)s, l, f);
+	/* write to file buffer if flag F_PBUF is available */
+	if (!(f->flags & F_ERR) && !(f->flags & F_PBUF)) {
+		__fwritex((void *)s, l, f);
+		return;
+	}
+
+	/* otherwise, copy to buffer directly */
+	f->write(f, (void *)s, l);
 }
 
 static void pad(FILE *f, char c, int w, int l, int fl)
@@ -675,13 +682,7 @@ int vfprintf(FILE *restrict f, const char *restrict fmt, va_list ap)
 	olderr = f->flags & F_ERR;
 	if (f->mode < 1) f->flags &= ~F_ERR;
 
-	/* allocate file buffer if need */
-	if (__falloc_buf(f) < 0) {
-		f->flags |= F_ERR;
-		ret = -1;
-	}
-
-	if (!f->buf_size) {
+	if (!f->buf_size && f->buf != NULL) {
 		saved_buf = f->buf;
 		f->buf = internal_buf;
 		f->buf_size = sizeof internal_buf;
@@ -690,7 +691,9 @@ int vfprintf(FILE *restrict f, const char *restrict fmt, va_list ap)
 	if (!f->wend && __towrite(f)) ret = -1;
 	else ret = printf_core(f, fmt, &ap2, nl_arg, nl_type, 0);
 	if (saved_buf) {
-		f->write(f, 0, 0);
+		if (!(f->flags & F_PBUF)) {
+			f->write(f, 0, 0);
+		}
 		if (!f->wpos) ret = -1;
 		f->buf = saved_buf;
 		f->buf_size = 0;

porting/linux/user/src/stdio/vsnprintf.c

+#include "stdio_impl.h"
+#include <limits.h>
+#include <string.h>
+#include <errno.h>
+#include <stdint.h>
+
+struct cookie {
+	char *s;
+	size_t n;
+};
+
+#define MIN(a, b) ((a) < (b) ? (a) : (b))
+
+static size_t sn_write(FILE *f, const unsigned char *s, size_t l) {
+	struct cookie *c = f->cookie;
+	size_t already_size = f->wpos - f->wbase;
+	if (already_size <= c->n) {
+		size_t k = MIN(l, c->n - already_size);
+		memcpy(f->wpos, s, k);
+		f->wpos += k;
+		*f->wpos = '\0';
+	}
+	/* pretend to succeed, even if we discarded extra data */
+	return l;
+}
+
+int vsnprintf(char *restrict s, size_t n, const char *restrict fmt, va_list ap)
+{
+	unsigned char dummy[1];
+	struct cookie c = { .s = n ? s : dummy, .n = n ? n-1 : 0 };
+	FILE f = {
+		.lbf = EOF,
+		.lock = -1,
+		.buf = (unsigned char *)(n ? s: dummy),
+		.buf_size = n ? n - 1 : 0,
+		.flags = F_PBUF,
+		.cookie = &c,
+		.write = sn_write,
+	};
+
+	if (n > INT_MAX) {
+		errno = EOVERFLOW;
+		return -1;
+	}
+
+	return vfprintf(&f, fmt, ap);
+}