Introduce compiled_regex, eliminate make_regfree_cleanup

This patch replaces compile_rx_or_error and make_regfree_cleanup with
a class that wraps a regex_t.

gdb/ChangeLog:
2017-06-07  Pedro Alves  <palves@redhat.com>

	* Makefile.in (SFILES): Add gdb_regex.c.
	(COMMON_OBS): Add gdb_regex.o.
	* ada-lang.c (ada_add_standard_exceptions)
	(ada_add_exceptions_from_frame, name_matches_regex)
	(ada_add_global_exceptions, ada_exceptions_list_1): Change regex
	parameter type to compiled_regex.  Adjust.
	(ada_exceptions_list): Use compiled_regex.
	* break-catch-throw.c (exception_catchpoint::pattern): Now a
	std::unique_ptr<compiled_regex>.
	(exception_catchpoint::~exception_catchpoint): Remove regfree
	call.
	(check_status_exception_catchpoint): Adjust to use compiled_regex.
	(handle_gnu_v3_exceptions): Adjust to use compiled_regex.
	* breakpoint.c (solib_catchpoint::compiled): Now a
	std::unique_ptr<compiled_regex>.
	(solib_catchpoint::~solib_catchpoint): Remove regfree call.
	(check_status_catch_solib): Adjust to use compiled_regex.
	(add_solib_catchpoint): Adjust to use compiled_regex.
	* cli/cli-cmds.c (apropos_command): Use compiled_regex.
	* cli/cli-decode.c (apropos_cmd): Change regex parameter to
	compiled_regex reference.  Adjust to use it.
	* cli/cli-decode.h: Remove struct re_pattern_buffer forward
	declaration.  Include "gdb_regex.h".
	(apropos_cmd): Change regex parameter to compiled_regex reference.
	* gdb_regex.c: New file.
	* gdb_regex.h (make_regfree_cleanup, get_regcomp_error): Delete
	declarations.
	(class compiled_regex): New.
	* linux-tdep.c: Include "common/gdb_optional.h".
	(struct mapping_regexes): New, factored out from
	mapping_is_anonymous_p, and adjusted to use compiled_regex.
	(mapping_is_anonymous_p): Use mapping_regexes wrapped in a
	gdb::optional and remove cleanups.  Adjust to compiled_regex.
	* probe.c: Include "common/gdb_optional.h".
	(collect_probes): Use compiled_regex and gdb::optional and remove
	cleanups.
	* skip.c: Include "common/gdb_optional.h".
	(skiplist_entry::compiled_function_regexp): Now a
	gdb::optional<compiled_regex>.
	(skiplist_entry::compiled_function_regexp_is_valid): Delete field.
	(free_skiplist_entry): Remove regfree call.
	(compile_skip_regexp, skip_rfunction_p): Adjust to use
	compiled_regex and gdb::optional.
	* symtab.c: Include "common/gdb_optional.h".
	(search_symbols): Use compiled_regex and gdb::optional.
	* utils.c (do_regfree_cleanup, make_regfree_cleanup)
	(get_regcomp_error, compile_rx_or_error): Delete.  Some bits moved
	to gdb_regex.c.

1 files changed, 44 insertions, 41 deletions

diff --git a/gdb/linux-tdep.c b/gdb/linux-tdep.c
index 016aadf..1afa8d7 100644
--- a/gdb/linux-tdep.c
+++ b/gdb/linux-tdep.c
@@ -38,6 +38,7 @@
 #include "gdbcmd.h"
 #include "gdb_regex.h"
 #include "common/enum-flags.h"
+#include "common/gdb_optional.h"
 
 #include <ctype.h>
 
@@ -493,6 +494,44 @@ decode_vmflags (char *p, struct smaps_vmflags *v)
     }
 }
 
+/* Regexes used by mapping_is_anonymous_p.  Put in a structure because
+   they're initialized lazily.  */
+
+struct mapping_regexes
+{
+  /* Matches "/dev/zero" filenames (with or without the "(deleted)"
+     string in the end).  We know for sure, based on the Linux kernel
+     code, that memory mappings whose associated filename is
+     "/dev/zero" are guaranteed to be MAP_ANONYMOUS.  */
+  compiled_regex dev_zero
+    {"^/dev/zero\\( (deleted)\\)\\?$", REG_NOSUB,
+     _("Could not compile regex to match /dev/zero filename")};
+
+  /* Matches "/SYSV%08x" filenames (with or without the "(deleted)"
+     string in the end).  These filenames refer to shared memory
+     (shmem), and memory mappings associated with them are
+     MAP_ANONYMOUS as well.  */
+  compiled_regex shmem_file
+    {"^/\\?SYSV[0-9a-fA-F]\\{8\\}\\( (deleted)\\)\\?$", REG_NOSUB,
+     _("Could not compile regex to match shmem filenames")};
+
+  /* A heuristic we use to try to mimic the Linux kernel's 'n_link ==
+     0' code, which is responsible to decide if it is dealing with a
+     'MAP_SHARED | MAP_ANONYMOUS' mapping.  In other words, if
+     FILE_DELETED matches, it does not necessarily mean that we are
+     dealing with an anonymous shared mapping.  However, there is no
+     easy way to detect this currently, so this is the best
+     approximation we have.
+
+     As a result, GDB will dump readonly pages of deleted executables
+     when using the default value of coredump_filter (0x33), while the
+     Linux kernel will not dump those pages.  But we can live with
+     that.  */
+  compiled_regex file_deleted
+    {" (deleted)$", REG_NOSUB,
+     _("Could not compile regex to match '<file> (deleted)'")};
+};
+
 /* Return 1 if the memory mapping is anonymous, 0 otherwise.
 
    FILENAME is the name of the file present in the first line of the
@@ -506,52 +545,16 @@ decode_vmflags (char *p, struct smaps_vmflags *v)
 static int
 mapping_is_anonymous_p (const char *filename)
 {
-  static regex_t dev_zero_regex, shmem_file_regex, file_deleted_regex;
+  static gdb::optional<mapping_regexes> regexes;
   static int init_regex_p = 0;
 
   if (!init_regex_p)
     {
-      struct cleanup *c = make_cleanup (null_cleanup, NULL);
-
       /* Let's be pessimistic and assume there will be an error while
 	 compiling the regex'es.  */
       init_regex_p = -1;
 
-      /* DEV_ZERO_REGEX matches "/dev/zero" filenames (with or
-	 without the "(deleted)" string in the end).  We know for
-	 sure, based on the Linux kernel code, that memory mappings
-	 whose associated filename is "/dev/zero" are guaranteed to be
-	 MAP_ANONYMOUS.  */
-      compile_rx_or_error (&dev_zero_regex, "^/dev/zero\\( (deleted)\\)\\?$",
-			   _("Could not compile regex to match /dev/zero "
-			     "filename"));
-      /* SHMEM_FILE_REGEX matches "/SYSV%08x" filenames (with or
-	 without the "(deleted)" string in the end).  These filenames
-	 refer to shared memory (shmem), and memory mappings
-	 associated with them are MAP_ANONYMOUS as well.  */
-      compile_rx_or_error (&shmem_file_regex,
-			   "^/\\?SYSV[0-9a-fA-F]\\{8\\}\\( (deleted)\\)\\?$",
-			   _("Could not compile regex to match shmem "
-			     "filenames"));
-      /* FILE_DELETED_REGEX is a heuristic we use to try to mimic the
-	 Linux kernel's 'n_link == 0' code, which is responsible to
-	 decide if it is dealing with a 'MAP_SHARED | MAP_ANONYMOUS'
-	 mapping.  In other words, if FILE_DELETED_REGEX matches, it
-	 does not necessarily mean that we are dealing with an
-	 anonymous shared mapping.  However, there is no easy way to
-	 detect this currently, so this is the best approximation we
-	 have.
-
-	 As a result, GDB will dump readonly pages of deleted
-	 executables when using the default value of coredump_filter
-	 (0x33), while the Linux kernel will not dump those pages.
-	 But we can live with that.  */
-      compile_rx_or_error (&file_deleted_regex, " (deleted)$",
-			   _("Could not compile regex to match "
-			     "'<file> (deleted)'"));
-      /* We will never release these regexes, so just discard the
-	 cleanups.  */
-      discard_cleanups (c);
+      regexes.emplace ();
 
       /* If we reached this point, then everything succeeded.  */
       init_regex_p = 1;
@@ -573,9 +576,9 @@ mapping_is_anonymous_p (const char *filename)
     }
 
   if (*filename == '\0'
-      || regexec (&dev_zero_regex, filename, 0, NULL, 0) == 0
-      || regexec (&shmem_file_regex, filename, 0, NULL, 0) == 0
-      || regexec (&file_deleted_regex, filename, 0, NULL, 0) == 0)
+      || regexes->dev_zero.exec (filename, 0, NULL, 0) == 0
+      || regexes->shmem_file.exec (filename, 0, NULL, 0) == 0
+      || regexes->file_deleted.exec (filename, 0, NULL, 0) == 0)
     return 1;
 
   return 0;