MDEV-35738 mariadb build -fsanitize=pointer-compare

invalid pointer pairs are when the length/memory of one string are
intermixed with another.

For comp_err, the end null pointer was compared to soffset within
my_strtoll10. As we didn't need the end position a NULL arg option
was compatble.

For uca-dump, Address Sanitizer raises invalid pointer pair because
argv options (opt) don't have an obvious correlation of having a start
at opt_X.length, even though the lstrncmp makes this true.

The DBUG_ASSERTS of strmov (added MDEV-11752) where incompatible with
pointer-compare. Replaced strmov with static inline version in
m_string.h using memmove that allows overlaps, and being inline allows
the uneeded parts of the implementation to be optimized away.

Author: grooverdan

extra/comp_err.c

@@ -623,7 +623,7 @@ static uint parse_input_file(const char *file_name, struct errors **top_error,
 
 static uint parse_error_offset(char *str)
 {
-  char *soffset, *end;
+  char *soffset;
   int error;
   uint ioffset;
 
@@ -651,8 +651,7 @@ static uint parse_error_offset(char *str)
   }
   DBUG_PRINT("info", ("str: %s", str));
 
-  end= 0;
-  ioffset= (uint) my_strtoll10(soffset, &end, &error);
+  ioffset= (uint) my_strtoll10(soffset, NULL, &error);
   my_free(soffset);
   DBUG_RETURN(ioffset);
 }

include/m_string.h

@@ -65,13 +65,22 @@
 extern "C" {
 #endif
 
-#ifdef DBUG_OFF
 #if defined(HAVE_STPCPY) && defined(__GNUC__) && !defined(__INTEL_COMPILER)
 #define strmov(A,B) __builtin_stpcpy((A),(B))
 #elif defined(HAVE_STPCPY)
 #define strmov(A,B) stpcpy((A),(B))
-#endif
-#endif
+#else
+static inline char *strmov(char *dst, const char *src) __attribute__((nonnull(1,2)))
+{
+  size_t l;
+  DBUG_ASSERT(dst != NULL);
+  DBUG_ASSERT(src != NULL);
+
+  l= strlen(src);
+  memmove(dst, src, l + 1);
+  return dst + l;
+}
+#endif /* strmov */
 
 /* Declared in int2str() */
 extern const char _dig_vec_upper[];

strings/CMakeLists.txt

@@ -24,7 +24,7 @@ SET(STRINGS_SOURCES bchange.c bmove_upp.c ctype-big5.c ctype-bin.c ctype-cp932.c
                 ctype-ucs2.c ctype-ujis.c ctype-utf8.c ctype-win1250ch.c ctype.c decimal.c dtoa.c int2str.c
                 ctype-unidata.c
                 is_prefix.c llstr.c longlong2str.c my_strtoll10.c my_vsnprintf.c
-                str2int.c strcend.c strend.c strfill.c strmake.c strmov.c strnmov.c
+                str2int.c strcend.c strend.c strfill.c strmake.c strnmov.c
                 strxmov.c strxnmov.c xml.c
                 strmov_overlapp.c
 		my_strchr.c strcont.c strappend.c json_lib.c json_normalize.c)

strings/strmov.c

@@ -417,14 +417,20 @@ static int process_option(OPT *options, const char *opt)
   static const LEX_CSTRING opt_levels= {STRING_WITH_LEN("--levels=")};
   static const LEX_CSTRING opt_no_contractions= {STRING_WITH_LEN("--no-contractions")};
   static const LEX_CSTRING opt_case_first= {STRING_WITH_LEN("--case-first=")};
+  const char *eq = strchr(opt, '=');
   if (!lstrncmp(opt, opt_name_prefix))
   {
-    options->name_prefix= opt + opt_name_prefix.length;
+    if (!eq)
+      return 1;
+
+    options->name_prefix = eq + 1;
     return 0;
   }
   if (!lstrncmp(opt, opt_levels))
   {
-    options->levels= (uint) strtoul(opt + opt_levels.length, NULL, 10);
+    if (!eq)
+      return 1;
+    options->levels= (uint) strtoul(eq + 1, NULL, 10);
     if (options->levels < 1 || options->levels > 3)
     {
       printf("Bad --levels value\n");
@@ -434,13 +440,15 @@ static int process_option(OPT *options, const char *opt)
   }
   if (!lstrncmp(opt, opt_case_first))
   {
-    const char *value= opt + opt_case_first.length;
-    if (!strcasecmp(value, "upper"))
+    if (!eq)
+      return 1;
+    eq++;
+    if (!strcasecmp(eq, "upper"))
     {
       options->case_first_upper= TRUE;
       return 0;
     }
-    if (!strcasecmp(value, "lower"))
+    if (!strcasecmp(eq, "lower"))
     {
       options->case_first_upper= FALSE;
       return 0;