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hush: fix a bug where we don't properly handle f() { a=A; b=B; }; a= f

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function                                             old     new   delta
unset_local_var                                       20     274    +254
leave_var_nest_level                                   -      98     +98
set_vars_and_save_old                                128     164     +36
enter_var_nest_level                                   -      32     +32
builtin_local                                         46      50      +4
pseudo_exec_argv                                     554     544     -10
redirect_and_varexp_helper                            77      64     -13
run_pipe                                            1890    1641    -249
unset_local_var_len                                  267       -    -267
------------------------------------------------------------------------------
(add/remove: 2/1 grow/shrink: 3/3 up/down: 424/-539)         Total: -115 bytes

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
This commit is contained in:
Denys Vlasenko 2018-04-05 00:51:55 +02:00
parent 332e4115c9
commit d358b0b65d
5 changed files with 93 additions and 82 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

153
shell/hush.c
View File

@ -475,7 +475,6 @@ static const char hush_version_str[] ALIGN1 = "HUSH_VERSION="BB_VER;
*/ */
#if !BB_MMU #if !BB_MMU
typedef struct nommu_save_t { typedef struct nommu_save_t {
char **new_env;
struct variable *old_vars; struct variable *old_vars;
char **argv; char **argv;
char **argv_from_re_execing; char **argv_from_re_execing;
@ -2176,10 +2175,16 @@ static int set_local_var(char *str, unsigned flags)
*eq_sign = '='; *eq_sign = '=';
} }
if (cur->var_nest_level < local_lvl) { if (cur->var_nest_level < local_lvl) {
/* New variable is declared as local, /* New variable is local ("local VAR=VAL" or
* "VAR=VAL cmd")
* and existing one is global, or local * and existing one is global, or local
* from enclosing function. * on a lower level that new one.
* Remove and save old one: */ * Remove and save old one:
*/
debug_printf_env("shadowing %s'%s'/%u by '%s'/%u\n",
cur->flg_export ? "exported " : "",
cur->varstr, cur->var_nest_level, str, local_lvl
);
*cur_pp = cur->next; *cur_pp = cur->next;
cur->next = *G.shadowed_vars_pp; cur->next = *G.shadowed_vars_pp;
*G.shadowed_vars_pp = cur; *G.shadowed_vars_pp = cur;
@ -2197,6 +2202,7 @@ static int set_local_var(char *str, unsigned flags)
} }
if (strcmp(cur->varstr + name_len, eq_sign + 1) == 0) { if (strcmp(cur->varstr + name_len, eq_sign + 1) == 0) {
debug_printf_env("assignement '%s' does not change anything\n", str);
free_and_exp: free_and_exp:
free(str); free(str);
goto exp; goto exp;
@ -2204,6 +2210,7 @@ static int set_local_var(char *str, unsigned flags)
if (cur->max_len != 0) { if (cur->max_len != 0) {
if (cur->max_len >= strlen(str)) { if (cur->max_len >= strlen(str)) {
/* This one is from startup env, reuse space */ /* This one is from startup env, reuse space */
debug_printf_env("reusing startup env for '%s'\n", str);
strcpy(cur->varstr, str); strcpy(cur->varstr, str);
goto free_and_exp; goto free_and_exp;
} }
@ -2221,7 +2228,7 @@ static int set_local_var(char *str, unsigned flags)
goto set_str_and_exp; goto set_str_and_exp;
} }
/* Not found - create new variable struct */ /* Not found or shadowed - create new variable struct */
cur = xzalloc(sizeof(*cur)); cur = xzalloc(sizeof(*cur));
cur->var_nest_level = local_lvl; cur->var_nest_level = local_lvl;
cur->next = *cur_pp; cur->next = *cur_pp;
@ -2250,7 +2257,7 @@ static int set_local_var(char *str, unsigned flags)
/* unsetenv was already done */ /* unsetenv was already done */
} else { } else {
int i; int i;
debug_printf_env("%s: putenv '%s'\n", __func__, cur->varstr); debug_printf_env("%s: putenv '%s'/%u\n", __func__, cur->varstr, cur->var_nest_level);
i = putenv(cur->varstr); i = putenv(cur->varstr);
/* only now we can free old exported malloced string */ /* only now we can free old exported malloced string */
free(free_me); free(free_me);
@ -2313,21 +2320,6 @@ static int unset_local_var(const char *name)
} }
#endif #endif
static void unset_vars(char **strings)
{
char **v;
if (!strings)
return;
v = strings;
while (*v) {
const char *eq = strchrnul(*v, '=');
unset_local_var_len(*v, (int)(eq - *v));
v++;
}
free(strings);
}
#if BASH_HOSTNAME_VAR || ENABLE_FEATURE_SH_MATH || ENABLE_HUSH_READ || ENABLE_HUSH_GETOPTS #if BASH_HOSTNAME_VAR || ENABLE_FEATURE_SH_MATH || ENABLE_HUSH_READ || ENABLE_HUSH_GETOPTS
static void FAST_FUNC set_local_var_from_halves(const char *name, const char *val) static void FAST_FUNC set_local_var_from_halves(const char *name, const char *val)
{ {
@ -2349,15 +2341,20 @@ static void add_vars(struct variable *var)
var->next = G.top_var; var->next = G.top_var;
G.top_var = var; G.top_var = var;
if (var->flg_export) { if (var->flg_export) {
debug_printf_env("%s: restoring exported '%s'\n", __func__, var->varstr); debug_printf_env("%s: restoring exported '%s'/%u\n", __func__, var->varstr, var->var_nest_level);
putenv(var->varstr); putenv(var->varstr);
} else { } else {
debug_printf_env("%s: restoring variable '%s'\n", __func__, var->varstr); debug_printf_env("%s: restoring variable '%s'/%u\n", __func__, var->varstr, var->var_nest_level);
} }
var = next; var = next;
} }
} }
/* We put strings[i] into variable table and possibly putenv them.
* If variable is read only, we can free the strings[i]
* which attempts to overwrite it.
* The strings[] vector itself is freed.
*/
static struct variable *set_vars_and_save_old(char **strings) static struct variable *set_vars_and_save_old(char **strings)
{ {
char **s; char **s;
@ -2365,6 +2362,7 @@ static struct variable *set_vars_and_save_old(char **strings)
if (!strings) if (!strings)
return old; return old;
s = strings; s = strings;
while (*s) { while (*s) {
struct variable *var_p; struct variable *var_p;
@ -2398,11 +2396,15 @@ static struct variable *set_vars_and_save_old(char **strings)
var_p->next = old; var_p->next = old;
old = var_p; old = var_p;
} }
set_local_var(*s, SETFLAG_EXPORT); //bb_error_msg("G.var_nest_level:%d", G.var_nest_level);
set_local_var(*s, (G.var_nest_level << SETFLAG_VARLVL_SHIFT) | SETFLAG_EXPORT);
} else if (HUSH_DEBUG) {
bb_error_msg_and_die("BUG in varexp4");
} }
s++; s++;
next: ; next: ;
} }
free(strings);
return old; return old;
} }
@ -6339,7 +6341,7 @@ static char **expand_strvec_to_strvec_singleword_noglob(char **argv)
#endif #endif
/* Used for expansion of right hand of assignments, /* Used for expansion of right hand of assignments,
* $((...)), heredocs, variable espansion parts. * $((...)), heredocs, variable expansion parts.
* *
* NB: should NOT do globbing! * NB: should NOT do globbing!
* "export v=/bin/c*; env | grep ^v=" outputs "v=/bin/c*" * "export v=/bin/c*; env | grep ^v=" outputs "v=/bin/c*"
@ -7385,6 +7387,7 @@ static void exec_function(char ***to_free,
static void enter_var_nest_level(void) static void enter_var_nest_level(void)
{ {
G.var_nest_level++; G.var_nest_level++;
debug_printf_env("var_nest_level++ %u\n", G.var_nest_level);
/* Try: f() { echo -n .; f; }; f /* Try: f() { echo -n .; f; }; f
* struct variable::var_nest_level is uint16_t, * struct variable::var_nest_level is uint16_t,
@ -7408,17 +7411,22 @@ static void leave_var_nest_level(void)
continue; continue;
} }
/* Unexport */ /* Unexport */
if (cur->flg_export) if (cur->flg_export) {
debug_printf_env("unexporting nested '%s'/%u\n", cur->varstr, cur->var_nest_level);
bb_unsetenv(cur->varstr); bb_unsetenv(cur->varstr);
}
/* Remove from global list */ /* Remove from global list */
*cur_pp = cur->next; *cur_pp = cur->next;
/* Free */ /* Free */
if (!cur->max_len) if (!cur->max_len) {
debug_printf_env("freeing nested '%s'/%u\n", cur->varstr, cur->var_nest_level);
free(cur->varstr); free(cur->varstr);
}
free(cur); free(cur);
} }
G.var_nest_level--; G.var_nest_level--;
debug_printf_env("var_nest_level-- %u\n", G.var_nest_level);
if (HUSH_DEBUG && (int)G.var_nest_level < 0) if (HUSH_DEBUG && (int)G.var_nest_level < 0)
bb_error_msg_and_die("BUG: nesting underflow"); bb_error_msg_and_die("BUG: nesting underflow");
} }
@ -7431,11 +7439,12 @@ static int run_function(const struct function *funcp, char **argv)
save_and_replace_G_args(&sv, argv); save_and_replace_G_args(&sv, argv);
/* "we are in function, ok to use return" */ /* "We are in function, ok to use return" */
sv_flg = G_flag_return_in_progress; sv_flg = G_flag_return_in_progress;
G_flag_return_in_progress = -1; G_flag_return_in_progress = -1;
enter_var_nest_level(); /* Make "local" variables properly shadow previous ones */
IF_HUSH_LOCAL(enter_var_nest_level();)
IF_HUSH_LOCAL(G.func_nest_level++;) IF_HUSH_LOCAL(G.func_nest_level++;)
/* On MMU, funcp->body is always non-NULL */ /* On MMU, funcp->body is always non-NULL */
@ -7451,7 +7460,7 @@ static int run_function(const struct function *funcp, char **argv)
} }
IF_HUSH_LOCAL(G.func_nest_level--;) IF_HUSH_LOCAL(G.func_nest_level--;)
leave_var_nest_level(); IF_HUSH_LOCAL(leave_var_nest_level();)
G_flag_return_in_progress = sv_flg; G_flag_return_in_progress = sv_flg;
@ -7608,11 +7617,9 @@ static NOINLINE void pseudo_exec_argv(nommu_save_t *nommu_save,
#if BB_MMU #if BB_MMU
set_vars_and_save_old(new_env); set_vars_and_save_old(new_env);
free(new_env); /* optional */ /* we can destroy set_vars_and_save_old's return value,
/* we can also destroy set_vars_and_save_old's return value,
* to save memory */ * to save memory */
#else #else
nommu_save->new_env = new_env;
nommu_save->old_vars = set_vars_and_save_old(new_env); nommu_save->old_vars = set_vars_and_save_old(new_env);
#endif #endif
@ -8174,10 +8181,10 @@ static int checkjobs_and_fg_shell(struct pipe *fg_pipe)
* subshell: ( list ) [&] * subshell: ( list ) [&]
*/ */
#if !ENABLE_HUSH_MODE_X #if !ENABLE_HUSH_MODE_X
#define redirect_and_varexp_helper(new_env_p, old_vars_p, command, squirrel, argv_expanded) \ #define redirect_and_varexp_helper(old_vars_p, command, squirrel, argv_expanded) \
redirect_and_varexp_helper(new_env_p, old_vars_p, command, squirrel) redirect_and_varexp_helper(old_vars_p, command, squirrel)
#endif #endif
static int redirect_and_varexp_helper(char ***new_env_p, static int redirect_and_varexp_helper(
struct variable **old_vars_p, struct variable **old_vars_p,
struct command *command, struct command *command,
struct squirrel **sqp, struct squirrel **sqp,
@ -8190,11 +8197,10 @@ static int redirect_and_varexp_helper(char ***new_env_p,
int rcode = setup_redirects(command, sqp); int rcode = setup_redirects(command, sqp);
if (rcode == 0) { if (rcode == 0) {
char **new_env = expand_assignments(command->argv, command->assignment_cnt); char **new_env = expand_assignments(command->argv, command->assignment_cnt);
*new_env_p = new_env;
dump_cmd_in_x_mode(new_env); dump_cmd_in_x_mode(new_env);
dump_cmd_in_x_mode(argv_expanded); dump_cmd_in_x_mode(argv_expanded);
if (old_vars_p) /* this takes ownership of new_env[i] elements, and frees new_env: */
*old_vars_p = set_vars_and_save_old(new_env); *old_vars_p = set_vars_and_save_old(new_env);
} }
return rcode; return rcode;
} }
@ -8284,13 +8290,9 @@ static NOINLINE int run_pipe(struct pipe *pi)
argv = command->argv ? command->argv : (char **) &null_ptr; argv = command->argv ? command->argv : (char **) &null_ptr;
{ {
const struct built_in_command *x; const struct built_in_command *x;
#if ENABLE_HUSH_FUNCTIONS IF_HUSH_FUNCTIONS(const struct function *funcp;)
const struct function *funcp; IF_NOT_HUSH_FUNCTIONS(enum { funcp = 0 };)
#else struct variable *old_vars;
enum { funcp = 0 };
#endif
char **new_env = NULL;
struct variable *old_vars = NULL;
#if ENABLE_HUSH_LINENO_VAR #if ENABLE_HUSH_LINENO_VAR
if (G.lineno_var) if (G.lineno_var)
@ -8303,28 +8305,6 @@ static NOINLINE int run_pipe(struct pipe *pi)
* Try "a=t >file" * Try "a=t >file"
*/ */
G.expand_exitcode = 0; G.expand_exitcode = 0;
#if 0 /* A few cases in testsuite fail with this code. FIXME */
rcode = redirect_and_varexp_helper(&new_env, /*old_vars:*/ NULL, command, &squirrel, /*argv_expanded:*/ NULL);
/* Set shell variables */
if (new_env) {
argv = new_env;
while (*argv) {
if (set_local_var(*argv, /*flag:*/ 0)) {
/* assignment to readonly var / putenv error? */
rcode = 1;
}
argv++;
}
}
/* Redirect error sets $? to 1. Otherwise,
* if evaluating assignment value set $?, retain it.
* Try "false; q=`exit 2`; echo $?" - should print 2: */
if (rcode == 0)
rcode = G.expand_exitcode;
/* Exit, _skipping_ variable restoring code: */
goto clean_up_and_ret0;
#else /* Older, bigger, but more correct code */
rcode = setup_redirects(command, &squirrel); rcode = setup_redirects(command, &squirrel);
restore_redirects(squirrel); restore_redirects(squirrel);
@ -8358,7 +8338,6 @@ static NOINLINE int run_pipe(struct pipe *pi)
debug_leave(); debug_leave();
debug_printf_exec("run_pipe: return %d\n", rcode); debug_printf_exec("run_pipe: return %d\n", rcode);
return rcode; return rcode;
#endif
} }
/* Expand the rest into (possibly) many strings each */ /* Expand the rest into (possibly) many strings each */
@ -8372,6 +8351,7 @@ static NOINLINE int run_pipe(struct pipe *pi)
} }
/* if someone gives us an empty string: `cmd with empty output` */ /* if someone gives us an empty string: `cmd with empty output` */
//TODO: what about: var=EXPR `` >FILE ? will var be set? Will FILE be created?
if (!argv_expanded[0]) { if (!argv_expanded[0]) {
free(argv_expanded); free(argv_expanded);
debug_leave(); debug_leave();
@ -8394,7 +8374,14 @@ static NOINLINE int run_pipe(struct pipe *pi)
goto clean_up_and_ret1; goto clean_up_and_ret1;
} }
} }
rcode = redirect_and_varexp_helper(&new_env, &old_vars, command, &squirrel, argv_expanded);
/* Without bumping var nesting level, this leaks
* exported $a:
* a=b true; env | grep ^a=
*/
enter_var_nest_level();
rcode = redirect_and_varexp_helper(&old_vars, command, &squirrel, argv_expanded);
if (rcode == 0) { if (rcode == 0) {
if (!funcp) { if (!funcp) {
debug_printf_exec(": builtin '%s' '%s'...\n", debug_printf_exec(": builtin '%s' '%s'...\n",
@ -8405,24 +8392,23 @@ static NOINLINE int run_pipe(struct pipe *pi)
} }
#if ENABLE_HUSH_FUNCTIONS #if ENABLE_HUSH_FUNCTIONS
else { else {
# if ENABLE_HUSH_LOCAL struct variable **sv = G.shadowed_vars_pp;
struct variable **sv; /* Make "local" builtins in the called function
sv = G.shadowed_vars_pp; * stash shadowed variables in old_vars list
*/
G.shadowed_vars_pp = &old_vars; G.shadowed_vars_pp = &old_vars;
# endif
debug_printf_exec(": function '%s' '%s'...\n", debug_printf_exec(": function '%s' '%s'...\n",
funcp->name, argv_expanded[1]); funcp->name, argv_expanded[1]);
rcode = run_function(funcp, argv_expanded) & 0xff; rcode = run_function(funcp, argv_expanded) & 0xff;
# if ENABLE_HUSH_LOCAL
G.shadowed_vars_pp = sv; G.shadowed_vars_pp = sv;
# endif
} }
#endif #endif
} }
clean_up_and_ret: clean_up_and_ret:
unset_vars(new_env); leave_var_nest_level();
add_vars(old_vars); add_vars(old_vars);
/* clean_up_and_ret0: */
restore_redirects(squirrel); restore_redirects(squirrel);
/* /*
* Try "usleep 99999999" + ^C + "echo $?" * Try "usleep 99999999" + ^C + "echo $?"
@ -8453,7 +8439,8 @@ static NOINLINE int run_pipe(struct pipe *pi)
if (ENABLE_FEATURE_SH_NOFORK && NUM_APPLETS > 1) { if (ENABLE_FEATURE_SH_NOFORK && NUM_APPLETS > 1) {
int n = find_applet_by_name(argv_expanded[0]); int n = find_applet_by_name(argv_expanded[0]);
if (n >= 0 && APPLET_IS_NOFORK(n)) { if (n >= 0 && APPLET_IS_NOFORK(n)) {
rcode = redirect_and_varexp_helper(&new_env, &old_vars, command, &squirrel, argv_expanded); enter_var_nest_level();
rcode = redirect_and_varexp_helper(&old_vars, command, &squirrel, argv_expanded);
if (rcode == 0) { if (rcode == 0) {
debug_printf_exec(": run_nofork_applet '%s' '%s'...\n", debug_printf_exec(": run_nofork_applet '%s' '%s'...\n",
argv_expanded[0], argv_expanded[1]); argv_expanded[0], argv_expanded[1]);
@ -8487,7 +8474,6 @@ static NOINLINE int run_pipe(struct pipe *pi)
struct fd_pair pipefds; struct fd_pair pipefds;
#if !BB_MMU #if !BB_MMU
volatile nommu_save_t nommu_save; volatile nommu_save_t nommu_save;
nommu_save.new_env = NULL;
nommu_save.old_vars = NULL; nommu_save.old_vars = NULL;
nommu_save.argv = NULL; nommu_save.argv = NULL;
nommu_save.argv_from_re_execing = NULL; nommu_save.argv_from_re_execing = NULL;
@ -8580,7 +8566,6 @@ static NOINLINE int run_pipe(struct pipe *pi)
/* Clean up after vforked child */ /* Clean up after vforked child */
free(nommu_save.argv); free(nommu_save.argv);
free(nommu_save.argv_from_re_execing); free(nommu_save.argv_from_re_execing);
unset_vars(nommu_save.new_env);
add_vars(nommu_save.old_vars); add_vars(nommu_save.old_vars);
#endif #endif
free(argv_expanded); free(argv_expanded);
@ -10066,7 +10051,11 @@ static int FAST_FUNC builtin_local(char **argv)
return EXIT_FAILURE; /* bash compat */ return EXIT_FAILURE; /* bash compat */
} }
argv++; argv++;
return helper_export_local(argv, G.var_nest_level << SETFLAG_VARLVL_SHIFT); /* Since all builtins run in a nested variable level,
* need to use level - 1 here. Or else the variable will be removed at once
* after builtin returns.
*/
return helper_export_local(argv, (G.var_nest_level - 1) << SETFLAG_VARLVL_SHIFT);
} }
#endif #endif

3
shell/hush_test/hush-vars/var_nested1.right Normal file
View File

@ -0,0 +1,3 @@
Expected:AB Actual:AB
Expected:Ab Actual:Ab
Expected:ab Actual:ab

16
shell/hush_test/hush-vars/var_nested1.tests Executable file
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@ -0,0 +1,16 @@
f() { a=A; b=B; }
a=a
b=b
f
echo Expected:AB Actual:$a$b
a=a
b=b
b= f
echo Expected:Ab Actual:$a$b
a=a
b=b
a= b= f
echo Expected:ab Actual:$a$b

1
shell/hush_test/hush-vars/var_nested2.right Normal file
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@ -0,0 +1 @@
aB

2
shell/hush_test/hush-vars/var_nested2.tests Executable file
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@ -0,0 +1,2 @@
# the bug was easier to trigger in one-liner form
a=a; b=b; f() { a=A; b=B; }; a= f; echo $a$b