WL#1895 - Print message to error log in case of detected MyISAM corruption

Changed my_error() to print error messages, which come from
arbitrary registered ranges of error messages. Messages can
be unregistered (and should be at end of the program).
Added registration of handler error messages.
Added a new mi_print_error() macro and a new 
mi_report_error() function, which supply error
messages with a table name.
Added calls to mi_print_error() or mi_report_error()
at all places in MyISAM, where table corruption is detected.

1 files changed, 151 insertions, 12 deletions

diff --git a/mysys/my_error.c b/mysys/my_error.c
index 175f8cf516b..0c18bbf6e8b 100644
--- a/mysys/my_error.c
+++ b/mysys/my_error.c
@@ -31,10 +31,31 @@
   my_printf_error(ER_CODE, format, MYF(N), ...)
 */
 
-const char ** NEAR my_errmsg[MAXMAPS]={0,0,0,0};
 char NEAR errbuff[NRERRBUFFS][ERRMSGSIZE];
 
 /*
+  Message texts are registered into a linked list of 'my_err_head' structs.
+  Each struct contains (1.) an array of pointers to C character strings with
+  '\0' termination, (2.) the error number for the first message in the array
+  (array index 0) and (3.) the error number for the last message in the array
+  (array index (last - first)).
+  The array may contain gaps with NULL pointers and pointers to empty strings.
+  Both kinds of gaps will be translated to "Unknown error %d.", if my_error()
+  is called with a respective error number.
+  The list of header structs is sorted in increasing order of error numbers.
+  Negative error numbers are allowed. Overlap of error numbers is not allowed.
+  Not registered error numbers will be translated to "Unknown error %d.".
+*/
+static struct my_err_head
+{
+  struct my_err_head    *meh_next;      /* chain link */
+  const char            **meh_errmsgs;  /* error messages array */
+  int                   meh_first;      /* error number matching array slot 0 */
+  int                   meh_last;       /* error number matching last slot */
+} my_errmsgs_globerrs = {NULL, globerrs, EE_ERROR_FIRST, EE_ERROR_LAST};
+static struct my_err_head *my_errmsgs_list= &my_errmsgs_globerrs;
+
+/*
    Error message to user
 
    SYNOPSIS
@@ -42,30 +63,42 @@ char NEAR errbuff[NRERRBUFFS][ERRMSGSIZE];
        nr	Errno
        MyFlags	Flags
        ...	variable list
-   NOTE
-    The following subset of printf format is supported:
-    "%[0-9.-]*l?[sdu]", where all length flags are parsed but ignored.
 
-    Additionally "%.*s" is supported and "%.*[ud]" is correctly parsed but
-    the length value is ignored.
+  RETURN
+    What (*error_handler_hook)() returns:
+    0   OK
 */
 
 int my_error(int nr, myf MyFlags, ...)
 {
   const char *format;
+  struct my_err_head *meh_p;
   va_list args;
   char ebuff[ERRMSGSIZE + 20];
   DBUG_ENTER("my_error");
 
   DBUG_PRINT("my", ("nr: %d  MyFlags: %d  errno: %d", nr, MyFlags, errno));
 
-  if (nr / ERRMOD == GLOB && my_errmsg[GLOB] == 0)
-    init_glob_errs();
-  format= my_errmsg[nr / ERRMOD][nr % ERRMOD];
+  /* Search for the error messages array, which could contain the message. */
+  for (meh_p= my_errmsgs_list; meh_p; meh_p= meh_p->meh_next)
+    if (nr <= meh_p->meh_last)
+      break;
 
-  va_start(args,MyFlags);
-  (void) my_vsnprintf (ebuff, sizeof(ebuff), format, args);
-  va_end(args);
+#ifdef SHARED_LIBRARY
+  if ((meh_p == &my_errmsgs_globerrs) && ! globerrs[0])
+    init_glob_errs();
+#endif
+
+  /* get the error message string. Default, if NULL or empty string (""). */
+  if (! (format= (meh_p && (nr >= meh_p->meh_first)) ?
+         meh_p->meh_errmsgs[nr - meh_p->meh_first] : NULL) || ! *format)
+    (void) my_snprintf (ebuff, sizeof(ebuff), "Unknown error %d", nr);
+  else
+  {
+    va_start(args,MyFlags);
+    (void) my_vsnprintf (ebuff, sizeof(ebuff), format, args);
+    va_end(args);
+  }
   DBUG_RETURN((*error_handler_hook)(nr, ebuff, MyFlags));
 }
 
@@ -108,3 +141,109 @@ int my_message(uint error, const char *str, register myf MyFlags)
 {
   return (*error_handler_hook)(error, str, MyFlags);
 }
+
+
+/*
+  Register error messages for use with my_error().
+
+  SYNOPSIS
+    my_error_register()
+    errmsgs                     array of pointers to error messages
+    first                       error number of first message in the array
+    last                        error number of last message in the array
+
+  DESCRIPTION
+    The pointer array is expected to contain addresses to NUL-terminated
+    C character strings. The array contains (last - first + 1) pointers.
+    NULL pointers and empty strings ("") are allowed. These will be mapped to
+    "Unknown error" when my_error() is called with a matching error number.
+    This function registers the error numbers 'first' to 'last'.
+    No overlapping with previously registered error numbers is allowed.
+
+  RETURN
+    0           OK
+    != 0        Error
+*/
+
+int my_error_register(const char **errmsgs, int first, int last)
+{
+  struct my_err_head *meh_p;
+  struct my_err_head **search_meh_pp;
+
+  /* Allocate a new header structure. */
+  if (! (meh_p= (struct my_err_head*) my_malloc(sizeof(struct my_err_head),
+                                                MYF(MY_WME))))
+    return 1;
+  meh_p->meh_errmsgs= errmsgs;
+  meh_p->meh_first= first;
+  meh_p->meh_last= last;
+
+  /* Search for the right position in the list. */
+  for (search_meh_pp= &my_errmsgs_list;
+       *search_meh_pp;
+       search_meh_pp= &(*search_meh_pp)->meh_next)
+  {
+    if ((*search_meh_pp)->meh_last > first)
+      break;
+  }
+
+  /* Error numbers must be unique. No overlapping is allowed. */
+  if (*search_meh_pp && ((*search_meh_pp)->meh_first <= last))
+    return 1;
+
+  /* Insert header into the chain. */
+  meh_p->meh_next= *search_meh_pp;
+  *search_meh_pp= meh_p;
+  return 0;
+}
+
+
+/*
+  Unregister formerly registered error messages.
+
+  SYNOPSIS
+    my_error_unregister()
+    first                       error number of first message
+    last                        error number of last message
+
+  DESCRIPTION
+    This function unregisters the error numbers 'first' to 'last'.
+    These must have been previously registered by my_error_register().
+    'first' and 'last' must exactly match the registration.
+    If a matching registration is present, the header is removed from the
+    list and the pointer to the error messages pointers array is returned.
+    Otherwise, NULL is returned.
+
+  RETURN
+    non-NULL    OK, returns address of error messages pointers array.
+    NULL        Error, no such number range registered.
+*/
+
+const char **my_error_unregister(int first, int last)
+{
+  struct my_err_head    *meh_p;
+  struct my_err_head    **search_meh_pp;
+  const char            **errmsgs;
+
+  /* Search for the registration in the list. */
+  for (search_meh_pp= &my_errmsgs_list;
+       *search_meh_pp;
+       search_meh_pp= &(*search_meh_pp)->meh_next)
+  {
+    if (((*search_meh_pp)->meh_first == first) &&
+        ((*search_meh_pp)->meh_last == last))
+      break;
+  }
+  if (! *search_meh_pp)
+    return NULL;
+
+  /* Remove header from the chain. */
+  meh_p= *search_meh_pp;
+  *search_meh_pp= meh_p->meh_next;
+
+  /* Save the return value and free the header. */
+  errmsgs= meh_p->meh_errmsgs;
+  my_free((gptr) meh_p, MYF(0));
+  
+  return errmsgs;
+}