diff --git a/src/os/linux/vm/os_linux.cpp b/src/os/linux/vm/os_linux.cpp index a3975d89892351baf5a8aa26805f06cd4d492e6a..19d87fe7fde301f95ed3395efe064f44da3484fc 100644 --- a/src/os/linux/vm/os_linux.cpp +++ b/src/os/linux/vm/os_linux.cpp @@ -2648,45 +2648,39 @@ bool os::uncommit_memory(char* addr, size_t size) { // writing thread stacks don't use growable mappings (i.e. those // creeated with MAP_GROWSDOWN), and aren't marked "[stack]", so this // only applies to the main thread. -static bool -get_stack_bounds(uintptr_t *bottom, uintptr_t *top) -{ - FILE *f = fopen("/proc/self/maps", "r"); - if (f == NULL) - return false; - while (!feof(f)) { - size_t dummy; - char *str = NULL; - ssize_t len = getline(&str, &dummy, f); - if (len == -1) { - fclose(f); - return false; - } +static +bool get_stack_bounds(uintptr_t *bottom, uintptr_t *top) { - if (len > 0 && str[len-1] == '\n') { - str[len-1] = 0; - len--; - } + char buf[128]; + int fd, sz; + + if ((fd = ::open("/proc/self/maps", O_RDONLY)) < 0) { + return false; + } - static const char *stack_str = "[stack]"; - if (len > (ssize_t)strlen(stack_str) - && (strcmp(str + len - strlen(stack_str), stack_str) == 0)) { - if (sscanf(str, "%" SCNxPTR "-%" SCNxPTR, bottom, top) == 2) { - uintptr_t sp = (uintptr_t)__builtin_frame_address(0); - if (sp >= *bottom && sp <= *top) { - free(str); - fclose(f); - return true; + const char kw[] = "[stack]"; + const int kwlen = sizeof(kw)-1; + + // Address part of /proc/self/maps couldn't be more than 128 bytes + while ((sz = os::get_line_chars(fd, buf, sizeof(buf))) > 0) { + if (sz > kwlen && ::memcmp(buf+sz-kwlen, kw, kwlen) == 0) { + // Extract addresses + if (sscanf(buf, "%" SCNxPTR "-%" SCNxPTR, bottom, top) == 2) { + uintptr_t sp = (uintptr_t) __builtin_frame_address(0); + if (sp >= *bottom && sp <= *top) { + ::close(fd); + return true; + } } - } - } - free(str); + } } - fclose(f); + + ::close(fd); return false; } + // If the (growable) stack mapping already extends beyond the point // where we're going to put our guard pages, truncate the mapping at // that point by munmap()ping it. This ensures that when we later diff --git a/src/share/vm/runtime/os.cpp b/src/share/vm/runtime/os.cpp index cf949071bc9715d7c6ab0ab74a705812b061e46a..0f84de3d1a2daa143717067a1e256cdc1b519611 100644 --- a/src/share/vm/runtime/os.cpp +++ b/src/share/vm/runtime/os.cpp @@ -1291,3 +1291,41 @@ bool os::is_server_class_machine() { } return result; } + +// Read file line by line, if line is longer than bsize, +// skip rest of line. +int os::get_line_chars(int fd, char* buf, const size_t bsize){ + size_t sz, i = 0; + + // read until EOF, EOL or buf is full + while ((sz = (int) read(fd, &buf[i], 1)) == 1 && i < (bsize-1) && buf[i] != '\n') { + ++i; + } + + if (buf[i] == '\n') { + // EOL reached so ignore EOL character and return + + buf[i] = 0; + return (int) i; + } + + buf[i+1] = 0; + + if (sz != 1) { + // EOF reached. if we read chars before EOF return them and + // return EOF on next call otherwise return EOF + + return (i == 0) ? -1 : (int) i; + } + + // line is longer than size of buf, skip to EOL + int ch; + while (read(fd, &ch, 1) == 1 && ch != '\n') { + // Do nothing + } + + // return initial part of line that fits in buf. + // If we reached EOF, it will be returned on next call. + + return (int) i; +} diff --git a/src/share/vm/runtime/os.hpp b/src/share/vm/runtime/os.hpp index b9b9d0c05ae20a4e7cff8825722dce06405d1254..13a266ea8fac8c3bd222efcc15e06964dfcd5024 100644 --- a/src/share/vm/runtime/os.hpp +++ b/src/share/vm/runtime/os.hpp @@ -658,6 +658,10 @@ class os: AllStatic { // Hook for os specific jvm options that we don't want to abort on seeing static bool obsolete_option(const JavaVMOption *option); + // Read file line by line. If line is longer than bsize, + // rest of line is skipped. Returns number of bytes read or -1 on EOF + static int get_line_chars(int fd, char *buf, const size_t bsize); + // Platform dependent stuff #ifdef TARGET_OS_FAMILY_linux # include "os_linux.hpp"