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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/beam/erl_bif_os.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/beam/erl_bif_os.c')
-rw-r--r--erts/emulator/beam/erl_bif_os.c199
1 files changed, 52 insertions, 147 deletions
diff --git a/erts/emulator/beam/erl_bif_os.c b/erts/emulator/beam/erl_bif_os.c
index 910325a2f4..ce2b27409b 100644
--- a/erts/emulator/beam/erl_bif_os.c
+++ b/erts/emulator/beam/erl_bif_os.c
@@ -36,8 +36,7 @@
#include "big.h"
#include "dist.h"
#include "erl_version.h"
-
-static int check_env_name(char *name);
+#include "erl_osenv.h"
/*
* Return the pid for the Erlang process in the host OS.
@@ -67,148 +66,78 @@ BIF_RETTYPE os_getpid_0(BIF_ALIST_0)
BIF_RET(buf_to_intlist(&hp, pid_string, n, NIL));
}
-BIF_RETTYPE os_getenv_0(BIF_ALIST_0)
+static void os_getenv_foreach(Process *process, Eterm *result, Eterm key, Eterm value)
{
- GETENV_STATE state;
- char *cp;
- Eterm* hp;
- Eterm ret;
- Eterm str;
+ Eterm kvp_term, *hp;
- init_getenv_state(&state);
+ hp = HAlloc(process, 5);
+ kvp_term = TUPLE2(hp, key, value);
+ hp += 3;
- ret = NIL;
- while ((cp = getenv_string(&state)) != NULL) {
- str = erts_convert_native_to_filename(BIF_P,(byte *)cp);
- hp = HAlloc(BIF_P, 2);
- ret = CONS(hp, str, ret);
- }
+ (*result) = CONS(hp, kvp_term, (*result));
+}
- fini_getenv_state(&state);
+BIF_RETTYPE os_list_env_vars_0(BIF_ALIST_0)
+{
+ const erts_osenv_t *global_env;
+ Eterm result = NIL;
+
+ global_env = erts_sys_rlock_global_osenv();
+ erts_osenv_foreach_term(global_env, BIF_P, &result, (void*)&os_getenv_foreach);
+ erts_sys_runlock_global_osenv();
- return ret;
+ return result;
}
-#define STATIC_BUF_SIZE 1024
-BIF_RETTYPE os_getenv_1(BIF_ALIST_1)
+BIF_RETTYPE os_get_env_var_1(BIF_ALIST_1)
{
- Process* p = BIF_P;
- Eterm str;
- Sint len;
- int res;
- char *key_str, *val;
- char buf[STATIC_BUF_SIZE];
- size_t val_size = sizeof(buf);
-
- key_str = erts_convert_filename_to_native(BIF_ARG_1,buf,STATIC_BUF_SIZE,
- ERTS_ALC_T_TMP,1,0,&len);
-
- if (!check_env_name(key_str)) {
- if (key_str && key_str != &buf[0])
- erts_free(ERTS_ALC_T_TMP, key_str);
- BIF_ERROR(p, BADARG);
- }
+ const erts_osenv_t *global_env;
+ Eterm out_term;
+ int error;
- if (key_str != &buf[0])
- val = &buf[0];
- else {
- /* len includes zero byte */
- val_size -= len;
- val = &buf[len];
- }
- res = erts_sys_getenv(key_str, val, &val_size);
-
- if (res < 0) {
- no_var:
- str = am_false;
- } else {
- if (res > 0) {
- val = erts_alloc(ERTS_ALC_T_TMP, val_size);
- while (1) {
- res = erts_sys_getenv(key_str, val, &val_size);
- if (res == 0)
- break;
- else if (res < 0)
- goto no_var;
- else
- val = erts_realloc(ERTS_ALC_T_TMP, val, val_size);
- }
- }
- str = erts_convert_native_to_filename(p,(byte *)val);
- }
- if (key_str != &buf[0])
- erts_free(ERTS_ALC_T_TMP, key_str);
- if (val < &buf[0] || &buf[sizeof(buf)-1] < val)
- erts_free(ERTS_ALC_T_TMP, val);
- BIF_RET(str);
+ global_env = erts_sys_rlock_global_osenv();
+ error = erts_osenv_get_term(global_env, BIF_P, BIF_ARG_1, &out_term);
+ erts_sys_runlock_global_osenv();
+
+ if (error == 0) {
+ return am_false;
+ } else if (error < 0) {
+ BIF_ERROR(BIF_P, BADARG);
+ }
+
+ return out_term;
}
-BIF_RETTYPE os_putenv_2(BIF_ALIST_2)
+BIF_RETTYPE os_set_env_var_2(BIF_ALIST_2)
{
- char def_buf_key[STATIC_BUF_SIZE];
- char def_buf_value[STATIC_BUF_SIZE];
- char *key_buf = NULL, *value_buf = NULL;
-
- key_buf = erts_convert_filename_to_native(BIF_ARG_1,def_buf_key,
- STATIC_BUF_SIZE,
- ERTS_ALC_T_TMP,0,0,NULL);
- if (!check_env_name(key_buf))
- goto badarg;
-
- value_buf = erts_convert_filename_to_native(BIF_ARG_2,def_buf_value,
- STATIC_BUF_SIZE,
- ERTS_ALC_T_TMP,1,0,
- NULL);
- if (!value_buf)
- goto badarg;
-
- if (erts_sys_putenv(key_buf, value_buf)) {
- if (key_buf != def_buf_key) {
- erts_free(ERTS_ALC_T_TMP, key_buf);
- }
- if (value_buf != def_buf_value) {
- erts_free(ERTS_ALC_T_TMP, value_buf);
- }
- BIF_ERROR(BIF_P, BADARG);
- }
- if (key_buf != def_buf_key) {
- erts_free(ERTS_ALC_T_TMP, key_buf);
- }
- if (value_buf != def_buf_value) {
- erts_free(ERTS_ALC_T_TMP, value_buf);
+ erts_osenv_t *global_env;
+ int error;
+
+ global_env = erts_sys_rwlock_global_osenv();
+ error = erts_osenv_put_term(global_env, BIF_ARG_1, BIF_ARG_2);
+ erts_sys_rwunlock_global_osenv();
+
+ if (error < 0) {
+ BIF_ERROR(BIF_P, BADARG);
}
- BIF_RET(am_true);
-badarg:
- if (key_buf && key_buf != def_buf_key)
- erts_free(ERTS_ALC_T_TMP, key_buf);
- if (value_buf && value_buf != def_buf_value)
- erts_free(ERTS_ALC_T_TMP, value_buf);
- BIF_ERROR(BIF_P, BADARG);
+ BIF_RET(am_true);
}
-BIF_RETTYPE os_unsetenv_1(BIF_ALIST_1)
+BIF_RETTYPE os_unset_env_var_1(BIF_ALIST_1)
{
- char *key_buf;
- char buf[STATIC_BUF_SIZE];
+ erts_osenv_t *global_env;
+ int error;
- key_buf = erts_convert_filename_to_native(BIF_ARG_1,buf,STATIC_BUF_SIZE,
- ERTS_ALC_T_TMP,0,0,NULL);
- if (!check_env_name(key_buf))
- goto badarg;
+ global_env = erts_sys_rwlock_global_osenv();
+ error = erts_osenv_unset_term(global_env, BIF_ARG_1);
+ erts_sys_rwunlock_global_osenv();
- if (erts_sys_unsetenv(key_buf))
- goto badarg;
-
- if (key_buf != buf) {
- erts_free(ERTS_ALC_T_TMP, key_buf);
+ if (error < 0) {
+ BIF_ERROR(BIF_P, BADARG);
}
- BIF_RET(am_true);
-badarg:
- if (key_buf && key_buf != buf)
- erts_free(ERTS_ALC_T_TMP, key_buf);
- BIF_ERROR(BIF_P, BADARG);
+ BIF_RET(am_true);
}
BIF_RETTYPE os_set_signal_2(BIF_ALIST_2) {
@@ -224,27 +153,3 @@ BIF_RETTYPE os_set_signal_2(BIF_ALIST_2) {
error:
BIF_ERROR(BIF_P, BADARG);
}
-
-static int
-check_env_name(char *raw_name)
-{
- byte *c = (byte *) raw_name;
- int encoding;
-
- if (!c)
- return 0;
-
- encoding = erts_get_native_filename_encoding();
-
- if (erts_raw_env_char_is_7bit_ascii_char('\0', c, encoding))
- return 0; /* Do not allow empty name... */
-
- /* Verify no '=' characters in variable name... */
- do {
- if (erts_raw_env_char_is_7bit_ascii_char('=', c, encoding))
- return 0;
- c = erts_raw_env_next_char(c, encoding);
- } while (!erts_raw_env_char_is_7bit_ascii_char('\0', c, encoding));
-
- return 1; /* Seems ok... */
-}