MINOR: tools: add new functions to quote-encode strings

qstr() and cstr() will be used to quote-encode strings. The first one
does it unconditionally. The second one is aimed at CSV files where the
quote-encoding is only needed when the field contains a quote or a comma.

include/common/standard.h

@@ -52,6 +52,10 @@
 /* number of itoa_str entries */
 #define NB_ITOA_STR	10
 
+/* maximum quoted string length (truncated above) */
+#define QSTR_SIZE 200
+#define NB_QSTR 10
+
 /****** string-specific macros and functions ******/
 /* if a > max, then bound <a> to <max>. The macro returns the new <a> */
 #define UBOUND(a, max)	({ typeof(a) b = (max); if ((a) > b) (a) = b; (a); })
@@ -195,6 +199,29 @@ static inline const char *LIM2A(unsigned long n, const char *alt)
 	return ret;
 }
 
+/* returns a locally allocated string containing the quoted encoding of the
+ * input string. The output may be truncated to QSTR_SIZE chars, but it is
+ * guaranteed that the string will always be properly terminated. Quotes are
+ * encoded by doubling them as is commonly done in CSV files. QSTR_SIZE must
+ * always be at least 4 chars.
+ */
+const char *qstr(const char *str);
+
+/* returns <str> or its quote-encoded equivalent if it contains at least one
+ * quote or a comma. This is aimed at build CSV-compatible strings.
+ */
+static inline const char *cstr(const char *str)
+{
+	const char *p = str;
+
+	while (*p) {
+		if (*p == ',' || *p == '"')
+			return qstr(str);
+		p++;
+	}
+	return str;
+}
+
 /*
  * Returns non-zero if character <s> is a hex digit (0-9, a-f, A-F), else zero.
  */

src/standard.c

@@ -38,6 +38,12 @@
 char itoa_str[NB_ITOA_STR][171];
 int itoa_idx = 0; /* index of next itoa_str to use */
 
+/* sometimes we'll need to quote strings (eg: in stats), and we don't expect
+ * to quote strings larger than a max configuration line.
+ */
+char quoted_str[NB_QSTR][QSTR_SIZE + 1];
+int quoted_idx = 0;
+
 /*
  * unsigned long long ASCII representation
  *
@@ -444,6 +450,39 @@ const char *limit_r(unsigned long n, char *buffer, int size, const char *alt)
 	return (n) ? ultoa_r(n, buffer, size) : (alt ? alt : "");
 }
 
+/* returns a locally allocated string containing the quoted encoding of the
+ * input string. The output may be truncated to QSTR_SIZE chars, but it is
+ * guaranteed that the string will always be properly terminated. Quotes are
+ * encoded by doubling them as is commonly done in CSV files. QSTR_SIZE must
+ * always be at least 4 chars.
+ */
+const char *qstr(const char *str)
+{
+	char *ret = quoted_str[quoted_idx];
+	char *p, *end;
+
+	if (++quoted_idx >= NB_QSTR)
+		quoted_idx = 0;
+
+	p = ret;
+	end = ret + QSTR_SIZE;
+
+	*p++ = '"';
+
+	/* always keep 3 chars to support passing "" and the ending " */
+	while (*str && p < end - 3) {
+		if (*str == '"') {
+			*p++ = '"';
+			*p++ = '"';
+		}
+		else
+			*p++ = *str;
+		str++;
+	}
+	*p++ = '"';
+	return ret;
+}
+
 /*
  * Returns non-zero if character <s> is a hex digit (0-9, a-f, A-F), else zero.
  *