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From: Bruce Richardson <bruce.richardson@intel.com>
To: dev@dpdk.org
Cc: ciara.power@intel.com, roretzla@linux.microsoft.com,
	Bruce Richardson <bruce.richardson@intel.com>
Subject: [PATCH v2 3/5] telemetry: split out body of json string format fn
Date: Wed,  5 Apr 2023 16:44:12 +0100	[thread overview]
Message-ID: <20230405154414.183915-4-bruce.richardson@intel.com> (raw)
In-Reply-To: <20230405154414.183915-1-bruce.richardson@intel.com>

To enable further rework to (efficiently) avoid using variable-length
arrays, we first separate out the body of the __json_format_str
function. This means that the actual VLA buffer is in the wrapper
function, and means we can reuse the actual writing code in multiple
code paths without duplication.

Signed-off-by: Bruce Richardson <bruce.richardson@intel.com>
---
 lib/telemetry/telemetry_json.h | 32 ++++++++++++++++++++++++--------
 1 file changed, 24 insertions(+), 8 deletions(-)

diff --git a/lib/telemetry/telemetry_json.h b/lib/telemetry/telemetry_json.h
index cb18453449..4c1941ad15 100644
--- a/lib/telemetry/telemetry_json.h
+++ b/lib/telemetry/telemetry_json.h
@@ -76,15 +76,13 @@ static const char control_chars[0x20] = {
 
 /**
  * @internal
- * This function acts the same as __json_snprintf(buf, len, "%s%s%s", prefix, str, suffix)
- * except that it does proper escaping of "str" as necessary. Prefix and suffix should be compile-
- * time constants, or values not needing escaping.
- * Drops any invalid characters we don't support
+ * Function that does the actual printing, used by __json_format_str. Modifies buffer
+ * directly, but returns 0 on overflow. Otherwise returns number of chars written to buffer.
  */
 static inline int
-__json_format_str(char *buf, const int len, const char *prefix, const char *str, const char *suffix)
+__json_format_str_to_buf(char *tmp, const int len,
+		const char *prefix, const char *str, const char *suffix)
 {
-	char tmp[len];
 	int tmpidx = 0;
 
 	while (*prefix != '\0' && tmpidx < len)
@@ -119,11 +117,29 @@ __json_format_str(char *buf, const int len, const char *prefix, const char *str,
 		return 0;
 
 	tmp[tmpidx] = '\0';
-
-	strcpy(buf, tmp);
 	return tmpidx;
 }
 
+/**
+ * @internal
+ * This function acts the same as __json_snprintf(buf, len, "%s%s%s", prefix, str, suffix)
+ * except that it does proper escaping of "str" as necessary. Prefix and suffix should be compile-
+ * time constants, or values not needing escaping.
+ * Drops any invalid characters we don't support
+ */
+static inline int
+__json_format_str(char *buf, const int len, const char *prefix, const char *str, const char *suffix)
+{
+	char tmp[len];
+	int ret;
+
+	ret = __json_format_str_to_buf(tmp, len, prefix, str, suffix);
+	if (ret > 0)
+		strcpy(buf, tmp);
+
+	return ret;
+}
+
 /* Copies an empty array into the provided buffer. */
 static inline int
 rte_tel_json_empty_array(char *buf, const int len, const int used)
-- 
2.37.2


  parent reply	other threads:[~2023-04-05 15:44 UTC|newest]

Thread overview: 25+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2023-03-10 18:18 [PATCH] telemetry: fix autotest failures on Alpine Bruce Richardson
2023-03-10 19:08 ` Stephen Hemminger
2023-03-13  9:38   ` Bruce Richardson
2023-04-05 15:44 ` [PATCH v2 0/5] telemetry: remove variable length arrays Bruce Richardson
2023-04-05 15:44   ` [PATCH v2 1/5] telemetry: fix autotest failures on Alpine Bruce Richardson
2023-04-07 19:21     ` Tyler Retzlaff
2023-04-11  8:43       ` Bruce Richardson
2023-04-05 15:44   ` [PATCH v2 2/5] telemetry: remove variable length array in printf fn Bruce Richardson
2023-04-05 15:44   ` Bruce Richardson [this message]
2023-04-05 15:44   ` [PATCH v2 4/5] telemetry: rename local variables Bruce Richardson
2023-04-05 15:44   ` [PATCH v2 5/5] telemetry: remove VLA in json string format function Bruce Richardson
2023-04-05 16:03 ` [PATCH v3 0/5] telemetry: remove variable length arrays Bruce Richardson
2023-04-05 16:03   ` [PATCH v3 1/5] telemetry: fix autotest failures on Alpine Bruce Richardson
2023-04-07 19:22     ` Tyler Retzlaff
2023-04-05 16:03   ` [PATCH v3 2/5] telemetry: remove variable length array in printf fn Bruce Richardson
2023-04-07 19:25     ` Tyler Retzlaff
2023-04-05 16:03   ` [PATCH v3 3/5] telemetry: split out body of json string format fn Bruce Richardson
2023-04-07 19:28     ` Tyler Retzlaff
2023-04-05 16:03   ` [PATCH v3 4/5] telemetry: rename local variables Bruce Richardson
2023-04-07 19:50     ` Tyler Retzlaff
2023-04-11  8:58       ` Bruce Richardson
2023-04-05 16:03   ` [PATCH v3 5/5] telemetry: remove VLA in json string format function Bruce Richardson
2023-04-07 19:54     ` Tyler Retzlaff
2023-05-25  7:12     ` David Marchand
2023-05-24 20:47   ` [PATCH v3 0/5] telemetry: remove variable length arrays Thomas Monjalon

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