From ec5eaff46da8384967abd2c618f5abe153691ad5 Mon Sep 17 00:00:00 2001
From: Wesley Pettit <wppttt@amazon.com>
Date: Thu, 19 Oct 2023 20:10:40 -0700
Subject: [PATCH] aws_util: add trailing zeros for millisecond and nanoaecond
 time precision

https://github.com/fluent/fluent-bit/issues/7538
---
 src/aws/flb_aws_util.c | 34 ++++++++++++++++++++++++++--------
 1 file changed, 26 insertions(+), 8 deletions(-)

diff --git a/src/aws/flb_aws_util.c b/src/aws/flb_aws_util.c
index 231e9aeb7ff..6408a32d8bd 100644
--- a/src/aws/flb_aws_util.c
+++ b/src/aws/flb_aws_util.c
@@ -957,6 +957,20 @@ flb_sds_t flb_get_s3_key(const char *format, time_t time, const char *tag,
         return NULL;
 }
 
+
+static void decimal_with_leading_zeros(char *dst, char *src, int expected_len)
+{
+    int src_len = strlen(src);
+    int zero_len = expected_len - src_len;
+    int i;
+
+    for (i = 0; i < zero_len; i++) {
+        dst[i] = '0';
+    }
+
+    strncat(dst + zero_len, src, src_len);
+}
+
 /*
  * This function is an extension to strftime which can support milliseconds with %3N,
  * support nanoseconds with %9N or %L. The return value is the length of formatted
@@ -967,6 +981,8 @@ size_t flb_aws_strftime_precision(char **out_buf, const char *time_format,
 {
     char millisecond_str[FLB_AWS_MILLISECOND_FORMATTER_LENGTH+1];
     char nanosecond_str[FLB_AWS_NANOSECOND_FORMATTER_LENGTH+1];
+    char millisecond_tmp_str[FLB_AWS_MILLISECOND_FORMATTER_LENGTH+1];
+    char nanosecond_tmp_str[FLB_AWS_NANOSECOND_FORMATTER_LENGTH+1];
     char *tmp_parsed_time_str;
     char *buf;
     size_t out_size;
@@ -1002,24 +1018,26 @@ size_t flb_aws_strftime_precision(char **out_buf, const char *time_format,
     }
 
     /* Replace %3N to millisecond, %9N and %L to nanosecond in time_format. */
-    snprintf(millisecond_str, FLB_AWS_MILLISECOND_FORMATTER_LENGTH+1,
+    snprintf(millisecond_tmp_str, FLB_AWS_MILLISECOND_FORMATTER_LENGTH+1,
              "%" PRIu64, (uint64_t) tms->tm.tv_nsec / 1000000);
-    snprintf(nanosecond_str, FLB_AWS_NANOSECOND_FORMATTER_LENGTH+1,
+    snprintf(nanosecond_tmp_str, FLB_AWS_NANOSECOND_FORMATTER_LENGTH+1,
              "%" PRIu64, (uint64_t) tms->tm.tv_nsec);
+
+
     for (i = 0; i < time_format_len; i++) {
         if (strncmp(time_format+i, FLB_AWS_MILLISECOND_FORMATTER, 3) == 0) {
-            strncat(tmp_parsed_time_str, millisecond_str,
-                    FLB_AWS_MILLISECOND_FORMATTER_LENGTH+1);
+            decimal_with_leading_zeros(tmp_parsed_time_str, millisecond_str,
+                                       FLB_AWS_MILLISECOND_FORMATTER_LENGTH);
             i += 2;
         }
         else if (strncmp(time_format+i, FLB_AWS_NANOSECOND_FORMATTER_N, 3) == 0) {
-            strncat(tmp_parsed_time_str, nanosecond_str,
-                    FLB_AWS_NANOSECOND_FORMATTER_LENGTH+1);
+            decimal_with_leading_zeros(tmp_parsed_time_str, nanosecond_str,
+                                       FLB_AWS_NANOSECOND_FORMATTER_LENGTH);
             i += 2;
         }
         else if (strncmp(time_format+i, FLB_AWS_NANOSECOND_FORMATTER_L, 2) == 0) {
-            strncat(tmp_parsed_time_str, nanosecond_str,
-                    FLB_AWS_NANOSECOND_FORMATTER_LENGTH+1);
+            decimal_with_leading_zeros(tmp_parsed_time_str, nanosecond_str,
+                                       FLB_AWS_NANOSECOND_FORMATTER_LENGTH);
             i += 1;
         }
         else {