Re: [RFA] set/unset/show substitute-path commands (take 2)

[Joel Brobecker <brobecker@adacore.com>]

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Hello,

Sorry for the delay, got side-tracked on something else...

Here is take 3 of the substitute-path feature. I corrected something
that I forgot, namely use FILENAME_CMP to do comparisons rather than
strcmp. I also implemented Andrew's two suggestions.

2006-07-19  Joel Brobecker  <brobecker@adacore.com>

        * source.c: #include gdb_assert.h.
        (substitute_path_rule): New struct.
        (substitute_path_rules): New static global variable.
        (substitute_path_rule_matches): New function.
        (get_substitute_path_rule): New function.
        (rewrite_source_path): New function.
        (find_and_open_source): Add source path rewriting support.
        (strip_trailing_directory_separator): New function.
        (make_cleanup_argv): New function.
        (find_substitute_path_rule): New function.
        (add_substitute_path_rule): New function.
        (delete_substitute_path_rule): New function.
        (show_substitute_path_command): New function.
        (unset_substitute_path_command): New function.
        (set_substitute_path_command): New function.
        (_initialize_source): Add new substitute-path commands.
        * Makefile.in (source.o): Add dependency on gdb_assert.h.

Tested on x86-linux.

> 2006-07-14  Joel Brobecker  <brobecker@adacore.com>
> 
>         * gdb.base/subst.exp: New testcase.

I adjusted the testcase according to the modifications in the code.
I also tried to add a test that would verify that the substitution
correctly takes place, but as expected, I'm having some trouble
doing that. Here is what I did:

        * gdb.base/subst.exp
        * gdb.base/subst.c
        * gdb.base/subst.dir/subst.c

The version of subst.c in subst.dir is a modified version of subst.c.
I built the subst executable using gdb.base/subst.c, as usual. And then
tried to add a substitution rule as follow:

        (gdb) set substitute-path '${srcdir}/${subdir}' '${srcdir}/${subdir}/subst.dir'

But the problem is that ${srcdir} is not string equal to what compiler
put in the debugging information. As far as I can tell from the testcase
output, ${srcdir} is something like ../../gdb/testsuite. I don't see how
to reliably get the source path in a way that would be identical to what
the compiler sets.

Perhaps this is telling us that, instead of just FILENAME_CMP, we should
use something more sophisticated like xfullpath to check for path equality.
But I'm very reluctant to even suggest that, because performance would
probably become horrendous on large applications where lots and lots of
files are used.

Any suggestion on how to setup this test?

Again, documentation will be supplied as soon as this patch gets in.

Thanks,
-- 
Joel

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Index: source.c
===================================================================
RCS file: /cvs/src/src/gdb/source.c,v
retrieving revision 1.75
diff -u -p -r1.75 source.c
--- source.c	15 May 2006 15:50:13 -0000	1.75
+++ source.c	19 Jul 2006 17:54:48 -0000
@@ -29,6 +29,7 @@
 #include "gdbcmd.h"
 #include "frame.h"
 #include "value.h"
+#include "gdb_assert.h"
 
 #include <sys/types.h>
 #include "gdb_string.h"
@@ -73,6 +74,17 @@ static void show_directories (char *, in
 
 char *source_path;
 
+/* Support for source path substitution commands.  */
+
+struct substitute_path_rule
+{
+  char *from;
+  char *to;
+  struct substitute_path_rule *next;
+};
+
+static struct substitute_path_rule *substitute_path_rules = NULL;
+
 /* Symtab of default file for listing lines of.  */
 
 static struct symtab *current_source_symtab;
@@ -828,6 +840,85 @@ source_full_path_of (char *filename, cha
   return 1;
 }
 
+/* Return non-zero if RULE matches PATH, that is if the rule can be
+   applied to PATH.  */
+
+static int
+substitute_path_rule_matches (const struct substitute_path_rule *rule,
+                              const char *path)
+{
+  const int from_len = strlen (rule->from);
+  const int path_len = strlen (path);
+  char *path_start;
+
+  if (path_len < from_len)
+    return 0;
+
+  /* The substitution rules are anchored at the start of the path,
+     so the path should start with rule->from.  There is no filename
+     comparison routine, so we need to extract the first FROM_LEN
+     characters from PATH first and use that to do the comparison.  */
+
+  path_start = alloca (from_len + 1);
+  strncpy (path_start, path, from_len);
+  path_start[from_len] = '\0';
+
+  if (FILENAME_CMP (path_start, rule->from) != 0)
+    return 0;
+
+  /* Make sure that the region in the path that matches the substitution
+     rule is immediately followed by a directory separator (or the end of
+     string character).  */
+  
+  if (path[from_len] != '\0' && !IS_DIR_SEPARATOR (path[from_len]))
+    return 0;
+
+  return 1;
+}
+
+/* Find the substitute-path rule that applies to PATH and return it.
+   Return NULL if no rule applies.  */
+
+static struct substitute_path_rule *
+get_substitute_path_rule (const char *path)
+{
+  struct substitute_path_rule *rule = substitute_path_rules;
+
+  while (rule != NULL && !substitute_path_rule_matches (rule, path))
+    rule = rule->next;
+
+  return rule;
+}
+
+/* If the user specified a source path substitution rule that applies
+   to PATH, then apply it and return the new path.  This new path must
+   be deallocated afterwards.  
+   
+   Return NULL if no substitution rule was specified by the user,
+   or if no rule applied to the given PATH.  */
+   
+static char *
+rewrite_source_path (const char *path)
+{
+  const struct substitute_path_rule *rule = get_substitute_path_rule (path);
+  char *new_path;
+  int from_len;
+  
+  if (rule == NULL)
+    return NULL;
+
+  from_len = strlen (rule->from);
+
+  /* Compute the rewritten path and return it.  */
+
+  new_path =
+    (char *) xmalloc (strlen (path) + 1 + strlen (rule->to) - from_len);
+  strcpy (new_path, rule->to);
+  strcat (new_path, path + from_len);
+
+  return new_path;
+}
+
 /* This function is capable of finding the absolute path to a
    source file, and opening it, provided you give it an 
    OBJFILE and FILENAME. Both the DIRNAME and FULLNAME are only
@@ -844,7 +935,7 @@ source_full_path_of (char *filename, cha
      FULLNAME is set to the absolute path to the file just opened.
 
    On Failure
-     A non valid file descriptor is returned. ( the return value is negitive ) 
+     An invalid file descriptor is returned. ( the return value is negative ) 
      FULLNAME is set to NULL.  */
 int
 find_and_open_source (struct objfile *objfile,
@@ -857,8 +948,22 @@ find_and_open_source (struct objfile *ob
   int result;
 
   /* Quick way out if we already know its full name */
+
   if (*fullname)
     {
+      {
+        /* The user may have requested that source paths be rewritten
+           according to substitution rules he provided.  If a substitution
+           rule applies to this path, then apply it.  */
+        char *rewritten_fullname = rewrite_source_path (*fullname);
+
+        if (rewritten_fullname != NULL)
+           {
+             xfree (*fullname);
+             *fullname = rewritten_fullname;
+           }
+      }
+
       result = open (*fullname, OPEN_MODE);
       if (result >= 0)
 	return result;
@@ -869,6 +974,17 @@ find_and_open_source (struct objfile *ob
 
   if (dirname != NULL)
     {
+      /* If necessary, rewrite the compilation directory name according
+         to the source path substitution rules specified by the user.  */
+
+      char *rewritten_dirname = rewrite_source_path (dirname);
+
+      if (rewritten_dirname != NULL)
+        {
+          make_cleanup (xfree, rewritten_dirname);
+          dirname = rewritten_dirname;
+        }
+      
       /* Replace a path entry of  $cdir  with the compilation directory name */
 #define	cdir_len	5
       /* We cast strstr's result in case an ANSIhole has made it const,
@@ -1587,6 +1703,228 @@ reverse_search_command (char *regex, int
   fclose (stream);
   return;
 }
+
+/* If the last character of PATH is a directory separator, then strip it.  */
+
+static void
+strip_trailing_directory_separator (char *path)
+{
+  const int last = strlen (path) - 1;
+
+  if (last < 0)
+    return;  /* No stripping is needed if PATH is the empty string.  */
+
+  if (IS_DIR_SEPARATOR (path[last]))
+    path[last] = '\0';
+}
+
+/* A convenience function to push ARGV in the cleanup queue.  */
+
+static void
+make_cleanup_argv (char **argv)
+{
+  make_cleanup ((make_cleanup_ftype *) freeargv, argv);
+}
+
+/* Return the path substitution rule that matches FROM.
+   Return NULL if no rule matches.  */
+
+static struct substitute_path_rule *
+find_substitute_path_rule (const char *from)
+{
+  struct substitute_path_rule *rule = substitute_path_rules;
+
+  while (rule != NULL)
+    {
+      if (FILENAME_CMP (rule->from, from) == 0)
+        return rule;
+      rule = rule->next;
+    }
+
+  return NULL;
+}
+
+/* Add a new substitute-path rule at the end of the current list of rules.
+   The new rule will replace FROM into TO.  */
+
+static void
+add_substitute_path_rule (char *from, char *to)
+{
+  struct substitute_path_rule *rule;
+  struct substitute_path_rule *new_rule;
+
+  new_rule = xmalloc (sizeof (struct substitute_path_rule));
+  new_rule->from = xstrdup (from);
+  new_rule->to = xstrdup (to);
+  new_rule->next = NULL;
+
+  /* If the list of rules are empty, then insert the new rule
+     at the head of the list.  */
+
+  if (substitute_path_rules == NULL)
+    {
+      substitute_path_rules = new_rule;
+      return;
+    }
+
+  /* Otherwise, skip to the last rule in our list and then append
+     the new rule.  */
+
+  rule = substitute_path_rules;
+  while (rule->next != NULL)
+    rule = rule->next;
+
+  rule->next = new_rule;
+}
+
+/* Remove the given source path substitution rule from the current list
+   of rules.  The memory allocated for that rule is also deallocated.  */
+
+static void
+delete_substitute_path_rule (struct substitute_path_rule *rule)
+{
+  if (rule == substitute_path_rules)
+    substitute_path_rules = rule->next;
+  else
+    {
+      struct substitute_path_rule *prev = substitute_path_rules;
+
+      while (prev != NULL && prev->next != rule)
+        prev = prev->next;
+
+      gdb_assert (prev != NULL);
+
+      prev->next = rule->next;
+    }
+
+  xfree (rule->from);
+  xfree (rule->to);
+  xfree (rule);
+}
+
+/* Implement the "show substitute-path" command.  */
+
+static void
+show_substitute_path_command (char *args, int from_tty)
+{
+  struct substitute_path_rule *rule = substitute_path_rules;
+  char **argv;
+  char *from = NULL;
+  
+  argv = buildargv (args);
+  make_cleanup_argv (argv);
+
+  /* We expect zero or one argument.  */
+
+  if (argv != NULL && argv[0] != NULL && argv[1] != NULL)
+    error (_("Too many arguments in command"));
+
+  if (argv != NULL && argv[0] != NULL)
+    from = argv[0];
+
+  /* Print the substitution rules.  */
+
+  if (from != NULL)
+    printf_filtered
+      (_("Source path substitution rule matching `%s':\n"), from);
+  else
+    printf_filtered (_("List of all source path substitution rules:\n"));
+
+  while (rule != NULL)
+    {
+      if (from == NULL || FILENAME_CMP (rule->from, from) == 0)
+        printf_filtered ("  `%s' -> `%s'.\n", rule->from, rule->to);
+      rule = rule->next;
+    }
+}
+
+/* Implement the "unset substitute-path" command.  */
+
+static void
+unset_substitute_path_command (char *args, int from_tty)
+{
+  struct substitute_path_rule *rule = substitute_path_rules;
+  char **argv = buildargv (args);
+  char *from = NULL;
+  int rule_found = 0;
+
+  /* This function takes either 0 or 1 argument.  */
+
+  if (argv != NULL && argv[0] != NULL && argv[1] != NULL)
+    error (_("Incorrect usage, too many arguments in command"));
+
+  if (argv != NULL && argv[0] != NULL)
+    from = argv[0];
+
+  /* If the user asked for all the rules to be deleted, ask him
+     to confirm and give him a chance to abort before the action
+     is performed.  */
+
+  if (from == NULL
+      && !query (_("Delete all source path substitution rules? ")))
+    error (_("Canceled"));
+
+  /* Delete the rule matching the argument.  No argument means that
+     all rules should be deleted.  */
+
+  while (rule != NULL)
+    {
+      struct substitute_path_rule *next = rule->next;
+
+      if (from == NULL || FILENAME_CMP (from, rule->from) == 0)
+        {
+          delete_substitute_path_rule (rule);
+          rule_found = 1;
+        }
+
+      rule = next;
+    }
+  
+  /* If the user asked for a specific rule to be deleted but
+     we could not find it, then report an error.  */
+
+  if (from != NULL && !rule_found)
+    error (_("No substitution rule defined for `%s'"), from);
+}
+
+/* Add a new source path substitution rule.  */
+
+static void
+set_substitute_path_command (char *args, int from_tty)
+{
+  char *from_path, *to_path;
+  char **argv;
+  struct substitute_path_rule *rule;
+  
+  argv = buildargv (args);
+  make_cleanup_argv (argv);
+
+  if (argv == NULL || argv[0] == NULL || argv [1] == NULL)
+    error (_("Incorrect usage, too few arguments in command"));
+
+  if (argv[2] != NULL)
+    error (_("Incorrect usage, too many arguments in command"));
+
+  if (*(argv[0]) == '\0')
+    error (_("First argument must be at least one character long"));
+
+  /* Strip any trailing directory separator character in either FROM
+     or TO.  The substitution rule already implicitly contains them.  */
+  strip_trailing_directory_separator (argv[0]);
+  strip_trailing_directory_separator (argv[1]);
+
+  /* If a rule with the same "from" was previously defined, then
+     delete it.  This new rule replaces it.  */
+
+  rule = find_substitute_path_rule (argv[0]);
+  if (rule != NULL)
+    delete_substitute_path_rule (rule);
+      
+  /* Insert the new substitution rule.  */
+
+  add_substitute_path_rule (argv[0], argv[1]);
+}
+
 \f
 void
 _initialize_source (void)
@@ -1666,4 +2004,19 @@ Show number of source lines gdb will lis
 			    NULL,
 			    show_lines_to_list,
 			    &setlist, &showlist);
+
+  add_cmd ("substitute-path", class_files, set_substitute_path_command,
+           _("\
+Add a source path substitution rule.  If a substitution rule was previously\n\
+set, it is overridden."), &setlist);
+
+  add_cmd ("substitute-path", class_files, unset_substitute_path_command,
+           _("\
+Remove the current source path substitution rule.  This has no effect\n\
+if no path substitution rule was previously specified."),
+           &unsetlist);
+
+  add_cmd ("substitute-path", class_files, show_substitute_path_command,
+           _("Show the current source path substitution rule."),
+           &showlist);
 }
Index: Makefile.in
===================================================================
RCS file: /cvs/src/src/gdb/Makefile.in,v
retrieving revision 1.822
diff -u -p -r1.822 Makefile.in
--- Makefile.in	23 Jun 2006 13:01:05 -0000	1.822
+++ Makefile.in	19 Jul 2006 17:54:49 -0000
@@ -2630,7 +2630,8 @@ source.o: source.c $(defs_h) $(symtab_h)
 	$(command_h) $(source_h) $(gdbcmd_h) $(frame_h) $(value_h) \
 	$(gdb_string_h) $(gdb_stat_h) $(gdbcore_h) $(gdb_regex_h) \
 	$(symfile_h) $(objfiles_h) $(annotate_h) $(gdbtypes_h) $(linespec_h) \
-	$(filenames_h) $(completer_h) $(ui_out_h) $(readline_h)
+	$(filenames_h) $(completer_h) $(ui_out_h) $(readline_h) \
+	$(gdb_assert_h)
 sparc64fbsd-nat.o: sparc64fbsd-nat.c $(defs_h) $(regcache_h) $(target_h) \
 	$(fbsd_nat_h) $(sparc64_tdep_h) $(sparc_nat_h) $(bsd_kvm_h)
 sparc64fbsd-tdep.o: sparc64fbsd-tdep.c $(defs_h) $(frame_h) \