MDEV-29582 deprecate mysql* names

Eventually mysql symlinks will go away, as MariaDB and MySQL keep
diverging and we do not want to make it impossible to install
MariaDB and MySQL side-by-side when users want it.

It also useful if people start using MariaDB tools with MariaDB.

If the exe doesn't begine with "mariadb" or is a symlink,
print a warning to use the resolved name.

In my_readlink, add check on my_thread_var as its used by comp_err
and other build utils that also use my_init.

3 files changed, 17 insertions, 3 deletions

diff --git a/mysys/errors.c b/mysys/errors.c
index d88540fe277..a7b2f1ae603 100644
--- a/mysys/errors.c
+++ b/mysys/errors.c
@@ -60,6 +60,7 @@ const char *globerrs[GLOBERRS]=
   "Lock Pages in memory access rights required",
   "Memcntl %s cmd %s error",
   "Warning: Charset id '%d' csname '%s' trying to replace existing csname '%s'",
+  "Notice: %s is deprecated and will be removed in a future release, use command '%s'"
 };
 
 void init_glob_errs(void)
@@ -109,6 +110,7 @@ void init_glob_errs()
   EE(EE_PERM_LOCK_MEMORY)= "Lock Pages in memory access rights required";
   EE(EE_MEMCNTL)         = "Memcntl %s cmd %s error";
   EE(EE_DUPLICATE_CHARSET)= "Warning: Charset id %d trying to replace csname %s with %s";
+  EE(EE_NAME_DEPRECATED)  = "Notice: %s is deprecated and will be removed in a future release, use command '%s'"
 }
 #endif
 
diff --git a/mysys/my_init.c b/mysys/my_init.c
index 44488e5848a..9ca68e80c1d 100644
--- a/mysys/my_init.c
+++ b/mysys/my_init.c
@@ -170,7 +170,17 @@ my_bool my_init(void)
 
   my_progname_short= "unknown";
   if (my_progname)
+  {
+    char link_name[FN_REFLEN];
     my_progname_short= my_progname + dirname_length(my_progname);
+    /*
+      If its a link a different program that doesn't begin with mariadb
+      like mariadb-repair might link to mariadb-check.
+    */
+    if (strncmp(my_progname_short, "mariadb", 7)
+        && my_readlink(link_name, my_progname, MYF(0)) == 0)
+      my_error(EE_NAME_DEPRECATED, MYF(MY_WME), my_progname, link_name);
+  }
 
   /* Initialize our mutex handling */
   my_mutex_init();
diff --git a/mysys/my_symlink.c b/mysys/my_symlink.c
index 8238e501e7f..e7833992f0d 100644
--- a/mysys/my_symlink.c
+++ b/mysys/my_symlink.c
@@ -45,7 +45,7 @@ int (*mysys_test_invalid_symlink)(const char *filename)= always_valid;
 int my_readlink(char *to, const char *filename, myf MyFlags)
 {
 #ifndef HAVE_READLINK
-  strmov(to,filename);
+  strnmov(to, filename, FN_REFLEN);
   return 1;
 #else
   int result=0;
@@ -54,11 +54,13 @@ int my_readlink(char *to, const char *filename, myf MyFlags)
 
   if ((length=readlink(filename, to, FN_REFLEN-1)) < 0)
   {
+    if (my_thread_var)
+      my_errno= errno;
     /* Don't give an error if this wasn't a symlink */
-    if ((my_errno=errno) == EINVAL)
+    if (errno == EINVAL)
     {
       result= 1;
-      strmov(to,filename);
+      strnmov(to, filename, FN_REFLEN);
     }
     else
     {