MDEV-22545: my_vsnprintf behaves not as in C standard

Added parameter %T for string which should be visibly truncated.

extra/comp_err.c

@@ -787,6 +787,7 @@ static ha_checksum checksum_format_specifier(const char* msg)
       case 'x':
       case 's':
       case 'M':
+      case 'T':
         chksum= my_checksum(chksum, (uchar*) start, (uint) (p + 1 - start));
         start= 0; /* Not in format specifier anymore */
         break;

include/mysql/service_my_snprintf.h

@@ -55,7 +55,8 @@
 
   Supported formats are 's' (null pointer is accepted, printed as
   "(null)"), 'b' (extension, see below), 'c', 'd', 'i', 'u', 'x', 'o',
-  'X', 'p' (works as 0x%x), 'f', 'g', 'M' (extension, see below).
+  'X', 'p' (works as 0x%x), 'f', 'g', 'M' (extension, see below),
+  'T' (extension, see below).
 
   Standard syntax for positional arguments $n is supported.
 
@@ -69,6 +70,9 @@
   Format 'M': takes one integer, prints this integer, space, double quote
   error message, double quote. In other words
     printf("%M", n) === printf("%d \"%s\"", n, strerror(n))
+
+  Format 'T': takes string and print it like s but if the strints should be
+  truncated puts "..." at the end.
 */
 
 #ifdef __cplusplus

mysql-test/r/perror-win.result

@@ -2,6 +2,6 @@ MySQL error code 150: Foreign key constraint is incorrectly formed
 Win32 error code 150: System trace information was not specified in your CONFIG.SYS file, or tracing is disallowed.
 OS error code  23:  Too many open files in system
 Win32 error code 23: Data error (cyclic redundancy check).
-MySQL error code 1062 (ER_DUP_ENTRY): Duplicate entry '%-.192s' for key %d
+MySQL error code 1062 (ER_DUP_ENTRY): Duplicate entry '%-.192T' for key %d
 Win32 error code 1062: The service has not been started.
 Illegal error code: 30000

mysql-test/r/perror.result

 Illegal error code: 10000
-MySQL error code 1062 (ER_DUP_ENTRY): Duplicate entry '%-.192s' for key %d
+MySQL error code 1062 (ER_DUP_ENTRY): Duplicate entry '%-.192T' for key %d
 MySQL error code 1408 (ER_STARTUP): %s: ready for connections.
 Version: '%s'  socket: '%s'  port: %d  %s
 MySQL error code 1459 (ER_TABLE_NEEDS_UPGRADE): Upgrade required. Please do "REPAIR %s %`s" or dump/reload to fix it!

mysql-test/suite/rpl/r/rpl_stm_EE_err2.result

@@ -11,7 +11,7 @@ drop table t1;
 connection slave;
 include/wait_for_slave_sql_to_stop.inc
 call mtr.add_suppression("Slave SQL.*Query caused different errors on master and slave.*Error on master:.* error code=1062.*Error on slave:.* error.* 0");
-Error: "Query caused different errors on master and slave.     Error on master: message (format)='Duplicate entry '%-.192s' for key %d' error code=1062 ; Error on slave: actual message='no error', error code=0. Default database: 'test'. Query: 'insert into t1 values(1),(2)'" (expected different error codes on master and slave)
+Error: "Query caused different errors on master and slave.     Error on master: message (format)='Duplicate entry '%-.192T' for key %d' error code=1062 ; Error on slave: actual message='no error', error code=0. Default database: 'test'. Query: 'insert into t1 values(1),(2)'" (expected different error codes on master and slave)
 Errno: "0" (expected 0)
 drop table t1;
 include/stop_slave.inc

sql/item.cc

@@ -6661,7 +6661,7 @@ Item_float::Item_float(THD *thd, const char *str_arg, uint length):
                     &error);
   if (error)
   {
-    char tmp[NAME_LEN + 1];
+    char tmp[NAME_LEN + 2];
     my_snprintf(tmp, sizeof(tmp), "%.*s", length, str_arg);
     my_error(ER_ILLEGAL_VALUE_FOR_TYPE, MYF(0), "double", tmp);
   }

sql/item_xmlfunc.cc

@@ -997,11 +997,16 @@ static Item *create_comparator(MY_XPATH *xpath,
            b->type() == Item::XPATH_NODESET)
   {
     uint len= (uint)(xpath->query.end - context->beg);
-    set_if_smaller(len, 32);
-    my_printf_error(ER_UNKNOWN_ERROR,
-                    "XPATH error: "
-                    "comparison of two nodesets is not supported: '%.*s'",
-                    MYF(0), len, context->beg);
+    if (len <= 32)
+      my_printf_error(ER_UNKNOWN_ERROR,
+                      "XPATH error: "
+                      "comparison of two nodesets is not supported: '%.*s'",
+                      MYF(0), len, context->beg);
+    else
+      my_printf_error(ER_UNKNOWN_ERROR,
+                      "XPATH error: "
+                      "comparison of two nodesets is not supported: '%.32T'",
+                      MYF(0), context->beg);
 
     return 0; // TODO: Comparison of two nodesets
   }
@@ -2634,9 +2639,12 @@ my_xpath_parse_VariableReference(MY_XPATH *xpath)
       xpath->item= NULL;
       DBUG_ASSERT(xpath->query.end > dollar_pos);
       uint len= (uint)(xpath->query.end - dollar_pos);
-      set_if_smaller(len, 32);
-      my_printf_error(ER_UNKNOWN_ERROR, "Unknown XPATH variable at: '%.*s'", 
-                      MYF(0), len, dollar_pos);
+      if (len <= 32)
+        my_printf_error(ER_UNKNOWN_ERROR, "Unknown XPATH variable at: '%.*s'",
+                        MYF(0), len, dollar_pos);
+      else
+        my_printf_error(ER_UNKNOWN_ERROR, "Unknown XPATH variable at: '%.32T'",
+                        MYF(0), dollar_pos);
     }
   }
   return xpath->item ? 1 : 0;
@@ -2767,9 +2775,13 @@ bool Item_xml_str_func::fix_fields(THD *thd, Item **ref)
   if (!rc)
   {
     uint clen= (uint)(xpath.query.end - xpath.lasttok.beg);
-    set_if_smaller(clen, 32);
-    my_printf_error(ER_UNKNOWN_ERROR, "XPATH syntax error: '%.*s'",
-                    MYF(0), clen, xpath.lasttok.beg);
+    if (clen <= 32)
+      my_printf_error(ER_UNKNOWN_ERROR, "XPATH syntax error: '%.*s'",
+                      MYF(0), clen, xpath.lasttok.beg);
+    else
+      my_printf_error(ER_UNKNOWN_ERROR, "XPATH syntax error: '%.32T'",
+                      MYF(0), xpath.lasttok.beg);
+
     return true;
   }
 

strings/my_vsnprintf.c

@@ -224,7 +224,8 @@ static char *backtick_string(CHARSET_INFO *cs, char *to, const char *end,
 */
 
 static char *process_str_arg(CHARSET_INFO *cs, char *to, const char *end,
-                             size_t width, char *par, uint print_type)
+                             size_t width, char *par, uint print_type,
+                             my_bool nice_cut)
 {
   int well_formed_error;
   uint dots= 0;
@@ -232,24 +233,34 @@ static char *process_str_arg(CHARSET_INFO *cs, char *to, const char *end,
   if (!par)
     par = (char*) "(null)";
 
-  plen= slen= strnlen(par, width + 1);
-  if (plen > width)
-    plen= width;
-  if (left_len <= plen)
-    plen = left_len - 1;
-  if ((slen > plen))
+  if (nice_cut)
   {
-    if (plen < 3)
+    plen= slen= strnlen(par, width + 1);
+    if (plen > width)
+      plen= width;
+    if (left_len <= plen)
+      plen = left_len - 1;
+    if ((slen > plen))
     {
-      dots= (uint) plen;
-      plen= 0;
-    }
-    else
-    {
-      dots= 3;
-      plen-= 3;
+      if (plen < 3)
+      {
+        dots= (uint) plen;
+        plen= 0;
+      }
+      else
+      {
+        dots= 3;
+        plen-= 3;
+      }
     }
   }
+  else
+  {
+    plen= slen= strnlen(par, width);
+    dots= 0;
+    if (left_len <= plen)
+      plen = left_len - 1;
+  }
 
   plen= my_well_formed_length(cs, par, par + plen, width, &well_formed_error);
   if (print_type & ESCAPED_ARG)
@@ -446,6 +457,7 @@ static char *process_args(CHARSET_INFO *cs, char *to, char *end,
       switch (args_arr[i].arg_type) {
       case 's':
       case 'b':
+      case 'T':
         args_arr[i].str_arg= va_arg(ap, char *);
         break;
       case 'f':
@@ -480,12 +492,14 @@ static char *process_args(CHARSET_INFO *cs, char *to, char *end,
       size_t width= 0, length= 0;
       switch (print_arr[i].arg_type) {
       case 's':
+      case 'T':
       {
         char *par= args_arr[print_arr[i].arg_idx].str_arg;
         width= (print_arr[i].flags & WIDTH_ARG)
           ? (size_t)args_arr[print_arr[i].width].longlong_arg
           : print_arr[i].width;
-        to= process_str_arg(cs, to, end, width, par, print_arr[i].flags);
+        to= process_str_arg(cs, to, end, width, par, print_arr[i].flags,
+                            (print_arr[i].arg_type == 'T'));
         break;
       }
       case 'b':
@@ -552,7 +566,7 @@ static char *process_args(CHARSET_INFO *cs, char *to, char *end,
           *to++= '"';
           my_strerror(errmsg_buff, sizeof(errmsg_buff), (int) larg);
           to= process_str_arg(cs, to, real_end, width, errmsg_buff,
-                              print_arr[i].flags);
+                              print_arr[i].flags, 1);
           if (real_end > to) *to++= '"';
         }
         break;
@@ -676,10 +690,10 @@ size_t my_vsnprintf_ex(CHARSET_INFO *cs, char *to, size_t n,
 
     fmt= check_longlong(fmt, &have_longlong);
 
-    if (*fmt == 's')				/* String parameter */
+    if (*fmt == 's' || *fmt == 'T')			/* String parameter */
     {
       reg2 char *par= va_arg(ap, char *);
-      to= process_str_arg(cs, to, end, width, par, print_type);
+      to= process_str_arg(cs, to, end, width, par, print_type, (*fmt == 'T'));
       continue;
     }
     else if (*fmt == 'b')				/* Buffer parameter */
@@ -731,7 +745,8 @@ size_t my_vsnprintf_ex(CHARSET_INFO *cs, char *to, size_t n,
         *to++= ' ';
         *to++= '"';
         my_strerror(errmsg_buff, sizeof(errmsg_buff), (int) larg);
-        to= process_str_arg(cs, to, real_end, width, errmsg_buff, print_type);
+        to= process_str_arg(cs, to, real_end, width, errmsg_buff,
+                            print_type, 1);
         if (real_end > to) *to++= '"';
       }
       continue;

unittest/mysys/my_vsnprintf-t.c

@@ -61,7 +61,7 @@ static void test_many(const char **res, const char *fmt, ...)
 
 int main(void)
 {
-  plan(43);
+  plan(47);
 
   test1("Constant string",
         "Constant string");
@@ -99,27 +99,33 @@ int main(void)
   test1("Width is ignored for strings <x> <y>",
         "Width is ignored for strings <%04s> <%5s>", "x", "y");
 
-  test1("Precision works for strings <ab...>",
+  test1("Precision works for strings <abcde>",
         "Precision works for strings <%.5s>", "abcdef!");
+  test1("Precision works for strings <ab...>",
+        "Precision works for strings <%.5T>", "abcdef!");
+
+  test1("Flag '`' (backtick) works: `abcd` `op``q` (mysql extension)",
+        "Flag '`' (backtick) works: %`s %`.4s (mysql extension)",
+        "abcd", "op`qrst");
 
   test1("Flag '`' (backtick) works: `abcd` `op``q...` (mysql extension)",
-        "Flag '`' (backtick) works: %`s %`.7s (mysql extension)",
+        "Flag '`' (backtick) works: %`T %`.7T (mysql extension)",
         "abcd", "op`qrstuuuuuuuuu");
 
   test1("Flag '`' (backtick) works: `abcd` `.` (mysql extension)",
-        "Flag '`' (backtick) works: %`s %`.1s (mysql extension)",
+        "Flag '`' (backtick) works: %`T %`.1T (mysql extension)",
         "abcd", "op`qrstuuuuuuuuu");
 
   test1("Flag '`' (backtick) works: `abcd` `...` (mysql extension)",
-        "Flag '`' (backtick) works: %`s %`.3s (mysql extension)",
+        "Flag '`' (backtick) works: %`T %`.3T (mysql extension)",
         "abcd", "op`qrstuuuuuuuuu");
 
   test1("Flag '`' (backtick) works: `abcd` `op...` (mysql extension)",
-        "Flag '`' (backtick) works: %`s %`.5s (mysql extension)",
+        "Flag '`' (backtick) works: %`T %`.5T (mysql extension)",
         "abcd", "op`qrstuuuuuuuuu");
 
   test1("Flag '`' (backtick) works: `abcd` `op``...` (mysql extension)",
-        "Flag '`' (backtick) works: %`s %`.6s (mysql extension)",
+        "Flag '`' (backtick) works: %`T %`.6T (mysql extension)",
         "abcd", "op`qrstuuuuuuuuu");
 
   test1("Length modifiers work: 1 * -1 * 2 * 3",
@@ -141,15 +147,21 @@ int main(void)
   test1("Asterisk '*' as a width works: <    4>",
         "Asterisk '*' as a width works: <%*d>", 5, 4);
 
-  test1("Asterisk '*' as a precision works: <qwe...>",
+  test1("Asterisk '*' as a precision works: <qwerty>",
         "Asterisk '*' as a precision works: <%.*s>", 6, "qwertyuiop");
 
+  test1("Asterisk '*' as a precision works: <qwe...>",
+        "Asterisk '*' as a precision works: <%.*T>", 6, "qwertyuiop");
+
   test1("Positional arguments for a width: <    4>",
         "Positional arguments for a width: <%1$*2$d>", 4, 5);
 
-  test1("Positional arguments for a precision: <qwe...>",
+  test1("Positional arguments for a precision: <qwerty>",
         "Positional arguments for a precision: <%1$.*2$s>", "qwertyuiop", 6);
 
+  test1("Positional arguments for a precision: <qwe...>",
+        "Positional arguments for a precision: <%1$.*2$T>", "qwertyuiop", 6);
+
   test1("Positional arguments and a width: <0000ab>",
         "Positional arguments and a width: <%1$06x>", 0xab);