On 08/12/2011 08:01 PM, Dhaval Giani wrote:
> On Fri, Aug 12, 2011 at 4:04 AM, Jan Safranek <jsafr...@redhat.com> wrote:
>> Anyway, any other suggestion? YY_FATAL_ERROR *must* stop other
>> processing, otherwise we get sigsegv, which is IMHO worse than exit().
>>
>
> Unfortunately, I cannot think of something better right now. Propagate
> some error which will stop all sort of processing?
The macro does not know if the function where it's used shold return void or int
or whatever. What about setjmp/longjmp voodoo?
---- 8< ----
The error macro should stop all processing, otherwise some NULL pointers might
get dereferenced (e.g. lex.c:1323). It uses setjmp/longjmp to return from
depths of the bison/lex routines. As obvious consequence, all memory allocated
in the parsers is lost and is never freed. Still, it should be better than
exit() I proposed before.
Signed-off-by: Jan Safranek <jsafr...@redhat.com>
---
src/config.c | 12 +++++++++++-
src/lex.l | 7 ++++++-
src/libcgroup-internal.h | 6 ++++++
3 files changed, 23 insertions(+), 2 deletions(-)
diff --git a/src/config.c b/src/config.c
index fc4901f..c7135aa 100644
--- a/src/config.c
+++ b/src/config.c
@@ -743,6 +743,7 @@ int cgroup_config_load_config(const char *pathname)
int namespace_enabled = 0;
int mount_enabled = 0;
yyin = fopen(pathname, "re");
+ int ret;
if (!yyin) {
cgroup_dbg("Failed to open file %s\n", pathname);
@@ -756,7 +757,16 @@ int cgroup_config_load_config(const char *pathname)
init_cgroup_table(config_cgroup_table, MAX_CGROUPS);
- if (yyparse() != 0) {
+ /*
+ * Parser calls longjmp() on really fatal error (like out-of-memory).
+ */
+ ret = setjmp(parser_error_env);
+ if (!ret)
+ ret = yyparse();
+ if (ret) {
+ /*
+ * Either yyparse failed or longjmp() was called.
+ */
cgroup_dbg("Failed to parse file %s\n", pathname);
fclose(yyin);
free(config_cgroup_table);
diff --git a/src/lex.l b/src/lex.l
index 8a99bbc..7a00015 100644
--- a/src/lex.l
+++ b/src/lex.l
@@ -17,8 +17,13 @@
#include <libcgroup-internal.h>
#include "parse.h"
int line_no = 1;
+jmp_buf parser_error_env;
-#define YY_FATAL_ERROR(msg) fprintf(stderr, "%s\n", msg)
+#define YY_FATAL_ERROR(msg) \
+ do { \
+ fprintf(stderr, "%s\n", msg); \
+ longjmp(parser_error_env, 1); \
+ } while(0);
%}
%option nounput noinput
diff --git a/src/libcgroup-internal.h b/src/libcgroup-internal.h
index de437e1..7d683f4 100644
--- a/src/libcgroup-internal.h
+++ b/src/libcgroup-internal.h
@@ -25,6 +25,7 @@ __BEGIN_DECLS
#include <pthread.h>
#include <sys/stat.h>
#include <sys/types.h>
+#include <setjmp.h>
/* Maximum number of mount points/controllers */
#define MAX_MNT_ELEMENTS 8
@@ -185,6 +186,11 @@ struct cgroup_dictionary_iterator {
*/
extern __thread int last_errno;
+/**
+ * 'Exception handler' for lex parser.
+ */
+extern jmp_buf parser_error_env;
+
/* Internal API */
char *cg_build_path(const char *name, char *path, const char *type);
int cgroup_get_uid_gid_from_procfs(pid_t pid, uid_t *euid, gid_t *egid);
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