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authorJohn Högberg <[email protected]>2017-11-22 13:19:57 +0100
committerJohn Högberg <[email protected]>2018-01-03 08:14:28 +0100
commitc2d70945dce9cb09d5d7120d6e9ddf7faac8d230 (patch)
tree3cfbaca9af7b6a32871e669a39027ce987c846da /erts/emulator/sys/unix/sys.c
parentbe9f93b14e0fb9ff09db36abde62ae8099bf5bd0 (diff)
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Replace the libc environment with a thread-safe emulation
putenv(3) and friends aren't thread-safe regardless of how you slice it; a global lock around all environment operations (like before) keeps things safe as far as our own operations go, but we have absolutely no control over what libc or a library dragged in by a driver/NIF does -- they're free to call getenv(3) or putenv(3) without honoring our lock. This commit solves this by setting up an "emulated" environment which can't be touched without going through our interfaces. Third-party libraries can still shoot themselves in the foot but benign uses of os:putenv/2 will no longer risk crashing the emulator.
Diffstat (limited to 'erts/emulator/sys/unix/sys.c')
-rw-r--r--erts/emulator/sys/unix/sys.c127
1 files changed, 4 insertions, 123 deletions
diff --git a/erts/emulator/sys/unix/sys.c b/erts/emulator/sys/unix/sys.c
index 6315135151..189ca083d7 100644
--- a/erts/emulator/sys/unix/sys.c
+++ b/erts/emulator/sys/unix/sys.c
@@ -62,9 +62,6 @@
#include "erl_mseg.h"
-extern char **environ;
-erts_rwmtx_t environ_rwmtx;
-
#define MAX_VSIZE 16 /* Max number of entries allowed in an I/O
* vector sock_sendv().
*/
@@ -77,7 +74,7 @@ erts_rwmtx_t environ_rwmtx;
#include "erl_check_io.h"
#include "erl_cpu_topology.h"
-
+#include "erl_osenv.h"
extern int driver_interrupt(int, int);
extern void do_break(void);
@@ -454,10 +451,10 @@ prepare_crash_dump(int secs)
close(crashdump_companion_cube_fd);
envsz = sizeof(env);
- i = erts_sys_getenv__("ERL_CRASH_DUMP_NICE", env, &envsz);
+ i = erts_sys_explicit_8bit_getenv("ERL_CRASH_DUMP_NICE", env, &envsz);
if (i >= 0) {
int nice_val;
- nice_val = i != 0 ? 0 : atoi(env);
+ nice_val = i != 1 ? 0 : atoi(env);
if (nice_val > 39) {
nice_val = 39;
}
@@ -749,34 +746,6 @@ void os_version(int *pMajor, int *pMinor, int *pBuild) {
*pBuild = get_number(&release); /* Pointer to build number. */
}
-void init_getenv_state(GETENV_STATE *state)
-{
- erts_rwmtx_rlock(&environ_rwmtx);
- *state = NULL;
-}
-
-char *getenv_string(GETENV_STATE *state0)
-{
- char **state = (char **) *state0;
- char *cp;
-
- ERTS_LC_ASSERT(erts_lc_rwmtx_is_rlocked(&environ_rwmtx));
-
- if (state == NULL)
- state = environ;
-
- cp = *state++;
- *state0 = (GETENV_STATE) state;
-
- return cp;
-}
-
-void fini_getenv_state(GETENV_STATE *state)
-{
- *state = NULL;
- erts_rwmtx_runlock(&environ_rwmtx);
-}
-
void erts_do_break_handling(void)
{
struct termios temp_mode;
@@ -830,90 +799,6 @@ void sys_get_pid(char *buffer, size_t buffer_size){
erts_snprintf(buffer, buffer_size, "%lu",(unsigned long) p);
}
-int
-erts_sys_putenv_raw(char *key, char *value) {
- return erts_sys_putenv(key, value);
-}
-int
-erts_sys_putenv(char *key, char *value)
-{
- int res;
- char *env;
- Uint need = strlen(key) + strlen(value) + 2;
-
-#ifdef HAVE_COPYING_PUTENV
- env = erts_alloc(ERTS_ALC_T_TMP, need);
-#else
- env = erts_alloc(ERTS_ALC_T_PUTENV_STR, need);
- erts_atomic_add_nob(&sys_misc_mem_sz, need);
-#endif
- strcpy(env,key);
- strcat(env,"=");
- strcat(env,value);
- erts_rwmtx_rwlock(&environ_rwmtx);
- res = putenv(env);
- erts_rwmtx_rwunlock(&environ_rwmtx);
-#ifdef HAVE_COPYING_PUTENV
- erts_free(ERTS_ALC_T_TMP, env);
-#endif
- return res;
-}
-
-int
-erts_sys_getenv__(char *key, char *value, size_t *size)
-{
- int res;
- char *orig_value = getenv(key);
- if (!orig_value)
- res = -1;
- else {
- size_t len = sys_strlen(orig_value);
- if (len >= *size) {
- *size = len + 1;
- res = 1;
- }
- else {
- *size = len;
- sys_memcpy((void *) value, (void *) orig_value, len+1);
- res = 0;
- }
- }
- return res;
-}
-
-int
-erts_sys_getenv_raw(char *key, char *value, size_t *size) {
- return erts_sys_getenv(key, value, size);
-}
-
-/*
- * erts_sys_getenv
- * returns:
- * -1, if environment key is not set with a value
- * 0, if environment key is set and value fits into buffer size
- * 1, if environment key is set but does not fit into buffer size
- * size is set with the needed buffer size value
- */
-
-int
-erts_sys_getenv(char *key, char *value, size_t *size)
-{
- int res;
- erts_rwmtx_rlock(&environ_rwmtx);
- res = erts_sys_getenv__(key, value, size);
- erts_rwmtx_runlock(&environ_rwmtx);
- return res;
-}
-
-int
-erts_sys_unsetenv(char *key)
-{
- int res;
- erts_rwmtx_rwlock(&environ_rwmtx);
- res = unsetenv(key);
- erts_rwmtx_rwunlock(&environ_rwmtx);
- return res;
-}
void sys_init_io(void) { }
void erts_sys_alloc_init(void) { }
@@ -1260,14 +1145,9 @@ erts_sys_main_thread(void)
}
}
-
void
erl_sys_args(int* argc, char** argv)
{
-
- erts_rwmtx_init(&environ_rwmtx, "environ", NIL,
- ERTS_LOCK_FLAGS_PROPERTY_STATIC | ERTS_LOCK_FLAGS_CATEGORY_GENERIC);
-
ASSERT(argc && argv);
max_files = erts_check_io_max_files();
@@ -1275,4 +1155,5 @@ erl_sys_args(int* argc, char** argv)
init_smp_sig_notify();
init_smp_sig_suspend();
+ erts_sys_env_init();
}