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comparison src/os/linux/vm/os_linux.cpp @ 2469:677234770800

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7017193: Small memory leak in get_stack_bounds os::create_stack_guard_pages Summary: getline() returns -1 but still allocate memory for str Reviewed-by: dcubed, coleenp
author dsamersoff
date Wed, 30 Mar 2011 19:38:07 +0400
parents da091bb67459
children 0654ee04b214 7f3faf7159fd
comparison
equal deleted inserted replaced
2393:74e790c48cd4 2469:677234770800
2646 // 2646 //
2647 // We only need this for stacks that are growable: at the time of 2647 // We only need this for stacks that are growable: at the time of
2648 // writing thread stacks don't use growable mappings (i.e. those 2648 // writing thread stacks don't use growable mappings (i.e. those
2649 // creeated with MAP_GROWSDOWN), and aren't marked "[stack]", so this 2649 // creeated with MAP_GROWSDOWN), and aren't marked "[stack]", so this
2650 // only applies to the main thread. 2650 // only applies to the main thread.
2651 static bool 2651
2652 get_stack_bounds(uintptr_t *bottom, uintptr_t *top) 2652 static
2653 { 2653 bool get_stack_bounds(uintptr_t *bottom, uintptr_t *top) {
2654 FILE *f = fopen("/proc/self/maps", "r"); 2654
2655 if (f == NULL) 2655 char buf[128];
2656 int fd, sz;
2657
2658 if ((fd = ::open("/proc/self/maps", O_RDONLY)) < 0) {
2656 return false; 2659 return false;
2657 2660 }
2658 while (!feof(f)) { 2661
2659 size_t dummy; 2662 const char kw[] = "[stack]";
2660 char *str = NULL; 2663 const int kwlen = sizeof(kw)-1;
2661 ssize_t len = getline(&str, &dummy, f); 2664
2662 if (len == -1) { 2665 // Address part of /proc/self/maps couldn't be more than 128 bytes
2663 fclose(f); 2666 while ((sz = os::get_line_chars(fd, buf, sizeof(buf))) > 0) {
2664 return false; 2667 if (sz > kwlen && ::memcmp(buf+sz-kwlen, kw, kwlen) == 0) {
2665 } 2668 // Extract addresses
2666 2669 if (sscanf(buf, "%" SCNxPTR "-%" SCNxPTR, bottom, top) == 2) {
2667 if (len > 0 && str[len-1] == '\n') { 2670 uintptr_t sp = (uintptr_t) __builtin_frame_address(0);
2668 str[len-1] = 0; 2671 if (sp >= *bottom && sp <= *top) {
2669 len--; 2672 ::close(fd);
2670 } 2673 return true;
2671 2674 }
2672 static const char *stack_str = "[stack]";
2673 if (len > (ssize_t)strlen(stack_str)
2674 && (strcmp(str + len - strlen(stack_str), stack_str) == 0)) {
2675 if (sscanf(str, "%" SCNxPTR "-%" SCNxPTR, bottom, top) == 2) {
2676 uintptr_t sp = (uintptr_t)__builtin_frame_address(0);
2677 if (sp >= *bottom && sp <= *top) {
2678 free(str);
2679 fclose(f);
2680 return true;
2681 } 2675 }
2682 } 2676 }
2683 } 2677 }
2684 free(str); 2678
2685 } 2679 ::close(fd);
2686 fclose(f);
2687 return false; 2680 return false;
2688 } 2681 }
2682
2689 2683
2690 // If the (growable) stack mapping already extends beyond the point 2684 // If the (growable) stack mapping already extends beyond the point
2691 // where we're going to put our guard pages, truncate the mapping at 2685 // where we're going to put our guard pages, truncate the mapping at
2692 // that point by munmap()ping it. This ensures that when we later 2686 // that point by munmap()ping it. This ensures that when we later
2693 // munmap() the guard pages we don't leave a hole in the stack 2687 // munmap() the guard pages we don't leave a hole in the stack