Z: Fix atoe_vsnprintf to support null buffer

Std vsnprintf accepts null buffer and returns an estimate
Our implementation does not support that
Updated the atoe_vsnprintf implementation

Signed-off-by: ehsan kiani far ehsan.kianifar@gmail.com

fvtest/porttest/omrstrTest.cpp

@@ -1486,7 +1486,8 @@ printToBuffer(struct OMRPortLibrary *portLibrary, BOOLEAN precision, char *buffe
 	va_list args;
 
 	va_start(args, format);
-	stringLength = atoe_vsnprintf(buffer, bufferLength, format, args);
+	atoe_vsnprintf(buffer, bufferLength, format, args);
+	stringLength = strlen(buffer);
 	va_end(args);
 
 	if (stringLength >= 0) {

util/a2e/atoe_utils.c

@@ -39,6 +39,7 @@
 #include <stdio.h>
 #include <stdlib.h>   /* for malloc() via e2a_string()/a2e_string() */
 #include <string.h>
+#include <limits.h>
 
 /*
  * ======================================================================
@@ -55,11 +56,12 @@
 
 #define ERROR_RETVAL -1
 #define SUCCESS 0
-#define CheckRet(x) { if ((x) == ERROR_RETVAL) return ERROR_RETVAL; }
+#define CheckRet(x) { if ((x) < 0) return ERROR_RETVAL; }
 
 typedef struct InstanceData {
 	char *buffer;
 	char *end;
+	int counter;
 } InstanceData;
 
 /**************************************************************************
@@ -100,11 +102,12 @@ pchar(InstanceData *this, int c)
 		*this->buffer++ = '^';
 	}
 #endif /* 0 */
+	this->counter++;
 
-	if (this->buffer >= this->end) {
-		return ERROR_RETVAL;
+	if (this->buffer != NULL && this->buffer < this->end) {
+		*this->buffer++ = c;
 	}
-	*this->buffer++ = c;
+
 	return SUCCESS;
 }
 
@@ -418,18 +421,18 @@ atoe_vsnprintf(char *str, size_t count, const char *fmt, va_list args)
 	bool_t fPrecision;
 	int min_width, precision, ch;
 	static char NULLCHARSTRING[] = "[null]";                /*ibm@029013*/
+	this.counter = 0;
 	/*ibm@029013*/
 	if (fmt == NULL) {                                      /*ibm@029013*/
 		fmt = NULLCHARSTRING;                               /*ibm@029013*/
 	}                                                       /*ibm@029013*/
-	if (str == NULL) {
-		return ERROR_RETVAL;
-	}
-	str[0] = '\0';
-
 	this.buffer = str;
-	this.end = str + count - 1;
-	*this.end = '\0';          /* ensure null-termination in case of failure */
+	this.end = this.buffer + count - 1;
+
+	if(this.buffer != NULL){
+		this.buffer[0] = '\0';
+		*this.end = '\0';          /* ensure null-termination in case of failure */
+	}
 
 	while ((ch = *fmt++) != 0) {
 		if (ch == '%') {
@@ -440,7 +443,7 @@ atoe_vsnprintf(char *str, size_t count, const char *fmt, va_list args)
 			pattern = fmt - 1;                                 /*ibm@8665*/
 			left_justify = TRUE;
 			min_width = 0;
-			precision = this.end - this.buffer;
+			precision = INT_MAX;
 
 next_char:
 			ch = *fmt++;
@@ -545,22 +548,28 @@ atoe_vsnprintf(char *str, size_t count, const char *fmt, va_list args)
 					/* ibm@8665
 					 * Add floating point support for dbl2str & flt2str
 					 */
-					char *b;
-					int len;
+					char *tempPattern;
 
-					b = a2e((char *)pattern, fmt - pattern);
+					tempPattern = a2e((char *)pattern, fmt - pattern);
 
 					/* Extract a double from args, this works for both doubles
 					 * and floats,
 					 * NB if we use float for a single precision floating
 					 * point number the result is wrong.
 					 */
-					len = sprintf(this.buffer, b, va_arg(args, double));
-					free(b);
-					b = e2a_string(this.buffer);
-					strcpy(this.buffer, b);
-					free(b);
-					this.buffer += len;
+					size_t freeCap = count > this.counter ? count - this.counter : 0;
+					double argument = va_arg(args, double);
+					int requiredSpace = snprintf(this.buffer, freeCap, tempPattern, argument);
+					free(tempPattern);
+					CheckRet(requiredSpace);
+					this.counter += requiredSpace;
+					if ((freeCap > 0) && (requiredSpace > 0)) {
+						tempPattern = e2a_string(this.buffer);
+						strcpy(this.buffer, tempPattern);
+						int JumpLength = freeCap > requiredSpace ? requiredSpace : freeCap;
+						this.buffer += JumpLength;
+						free(tempPattern);
+					}
 				}
 				break;
 			default:
@@ -584,8 +593,10 @@ atoe_vsnprintf(char *str, size_t count, const char *fmt, va_list args)
 			CheckRet(pchar(&this, ch));
 		}
 	}
-	*this.buffer = '\0';
-	return strlen(str);
+	if(this.buffer != NULL){
+		*this.buffer = '\0';
+	}
+	return this.counter;
 }
 
 /* END OF FILE */