From ae03d26eeab7443dca21214382efdbd9e360aa0d Mon Sep 17 00:00:00 2001
From: Willy Tarreau <w@1wt.eu>
Date: Sat, 8 May 2021 07:35:00 +0200
Subject: [PATCH] MINOR: tools: add a float-to-ascii conversion function

We already had ultoa_r() and friends but nothing to emit inline floats.
This is now done with ftoa_r() and F2A/F2H. Note that the latter both use
the itoa_str[] as temporary storage and that the HTML format currently is
the exact same as the ASCII one. The trailing zeroes are always timmed so
these outputs are usable in user-visible output.
---
 include/haproxy/tools.h | 27 +++++++++++++++++++++++++++
 src/tools.c             | 11 +++++++++++
 2 files changed, 38 insertions(+)

diff --git a/include/haproxy/tools.h b/include/haproxy/tools.h
index 948207a38..37609ca21 100644
--- a/include/haproxy/tools.h
+++ b/include/haproxy/tools.h
@@ -75,6 +75,7 @@ extern char *lltoa_r(long long int n, char *buffer, int size);
 extern char *sltoa_r(long n, char *buffer, int size);
 extern const char *ulltoh_r(unsigned long long n, char *buffer, int size);
 size_t flt_trim(char *buffer, size_t num_start, size_t len);
+char *ftoa_r(double n, char *buffer, int size);
 static inline const char *ultoa(unsigned long n)
 {
 	return ultoa_r(n, itoa_str[0], sizeof(itoa_str[0]));
@@ -156,6 +157,32 @@ static inline const char *U2H(unsigned long long n)
 	return ret;
 }
 
+/* returns a locally allocated string containing the ASCII representation of
+ * the number 'n' in decimal. Up to NB_ITOA_STR calls may be used in the same
+ * function call (eg: printf), shared with the other similar functions making
+ * use of itoa_str[].
+ */
+static inline const char *F2A(double n)
+{
+	const char *ret = ftoa_r(n, itoa_str[itoa_idx], sizeof(itoa_str[0]));
+	if (++itoa_idx >= NB_ITOA_STR)
+		itoa_idx = 0;
+	return ret;
+}
+
+/* returns a locally allocated string containing the HTML representation of
+ * the number 'n' in decimal. Up to NB_ITOA_STR calls may be used in the same
+ * function call (eg: printf), shared with the other similar functions making
+ * use of itoa_str[].
+ */
+static inline const char *F2H(double n)
+{
+	const char *ret = ftoa_r(n, itoa_str[itoa_idx], sizeof(itoa_str[0]));
+	if (++itoa_idx >= NB_ITOA_STR)
+		itoa_idx = 0;
+	return ret;
+}
+
 /* returns a locally allocated string containing the ASCII representation of
  * the number 'n' in decimal. Up to NB_ITOA_STR calls may be used in the same
  * function call (eg: printf), shared with the other similar functions making
diff --git a/src/tools.c b/src/tools.c
index e94fed7e7..de5dfa8a3 100644
--- a/src/tools.c
+++ b/src/tools.c
@@ -568,6 +568,17 @@ size_t flt_trim(char *buffer, size_t num_start, size_t len)
 	return trim - buffer;
 }
 
+/*
+ * This function simply returns a locally allocated string containing
+ * the ascii representation for number 'n' in decimal with useless trailing
+ * zeroes trimmed.
+ */
+char *ftoa_r(double n, char *buffer, int size)
+{
+	flt_trim(buffer, 0, snprintf(buffer, size, "%f", n));
+	return buffer;
+}
+
 /* 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