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hush: implement "command -v -V"

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function                                             old     new   delta
pseudo_exec_argv                                     231     374    +143
if_command_vV_print_and_exit                           -     127    +127
builtin_set                                          267     273      +6
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(add/remove: 1/0 grow/shrink: 2/0 up/down: 276/0)             Total: 276 bytes

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
This commit is contained in:
Denys Vlasenko 2018-01-12 14:41:45 +01:00
parent cca7c611f2
commit 5700029c65
1 changed files with 84 additions and 31 deletions
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103
shell/hush.c
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@ -47,18 +47,13 @@
* follow IFS rules more precisely, including update semantics
* tilde expansion
* aliases
* builtins mandated by standards we don't support:
* [un]alias, command, fc:
* command -v CMD: print "/path/to/CMD"
* prints "CMD" for builtins
* prints "alias ALIAS='EXPANSION'" for aliases
* prints nothing and sets $? to 1 if not found
* command -V CMD: print "CMD is /path/CMD|a shell builtin|etc"
* command [-p] CMD: run CMD, even if a function CMD also exists
* (can use this to override standalone shell as well)
* -p: use default $PATH
* "command" missing features:
* command -p CMD: run CMD using default $PATH
* (can use this to override standalone shell as well?)
* command BLTIN: disables special-ness (e.g. errors do not abort)
* NB: so far, only naked "command CMD" is implemented.
* command -V CMD1 CMD2 CMD3 (multiple args) (not in standard)
* builtins mandated by standards we don't support:
* [un]alias, fc:
* fc -l[nr] [BEG] [END]: list range of commands in history
* fc [-e EDITOR] [BEG] [END]: edit/rerun range of commands
* fc -s [PAT=REP] [CMD]: rerun CMD, replacing PAT with REP
@ -7337,6 +7332,30 @@ static void dump_cmd_in_x_mode(char **argv)
# define dump_cmd_in_x_mode(argv) ((void)0)
#endif
#if ENABLE_HUSH_COMMAND
static void if_command_vV_print_and_exit(char opt_vV, char *cmd, const char *explanation)
{
char *to_free;
if (!opt_vV)
return;
to_free = NULL;
if (!explanation) {
char *path = getenv("PATH");
explanation = to_free = find_executable(cmd, &path); /* path == NULL is ok */
if (opt_vV != 'V')
cmd = to_free; /* -v PROG prints "/path/to/PROG" */
}
if (explanation)
printf((opt_vV == 'V') ? "%s is %s\n" : "%s\n", cmd, explanation);
free(to_free);
fflush_all();
_exit(explanation == NULL); /* exit 1 if PROG was not found */
}
#else
# define if_command_vV_print_and_exit(a,b,c) ((void)0)
#endif
#if BB_MMU
#define pseudo_exec_argv(nommu_save, argv, assignment_cnt, argv_expanded) \
pseudo_exec_argv(argv, assignment_cnt, argv_expanded)
@ -7357,7 +7376,11 @@ static NOINLINE void pseudo_exec_argv(nommu_save_t *nommu_save,
char **argv, int assignment_cnt,
char **argv_expanded)
{
const struct built_in_command *x;
char **new_env;
#if ENABLE_HUSH_COMMAND
char opt_vV = 0;
#endif
new_env = expand_assignments(argv, assignment_cnt);
dump_cmd_in_x_mode(new_env);
@ -7406,37 +7429,66 @@ static NOINLINE void pseudo_exec_argv(nommu_save_t *nommu_save,
}
#endif
#if ENABLE_HUSH_COMMAND
/* "command BAR": run BAR without looking it up among functions
* "command -v BAR": print "BAR" or "/path/to/BAR"; or exit 1
* "command -V BAR": print "BAR is {a function,a shell builtin,/path/to/BAR}"
*/
while (strcmp(argv[0], "command") == 0 && argv[1]) {
char *p;
argv++;
p = *argv;
if (p[0] != '-' || !p[1])
continue; /* bash allows "command command command [-OPT] BAR" */
for (;;) {
p++;
switch (*p) {
case '\0':
argv++;
p = *argv;
if (p[0] != '-' || !p[1])
goto after_opts;
continue; /* next arg is also -opts, process it too */
case 'v':
case 'V':
opt_vV = *p;
continue;
default:
bb_error_msg_and_die("%s: %s: invalid option", "command", argv[0]);
}
}
}
after_opts:
# if ENABLE_HUSH_FUNCTIONS
if (opt_vV && find_function(argv[0]))
if_command_vV_print_and_exit(opt_vV, argv[0], "a function");
# endif
#endif
/* Check if the command matches any of the builtins.
* Depending on context, this might be redundant. But it's
* easier to waste a few CPU cycles than it is to figure out
* if this is one of those cases.
*/
{
const struct built_in_command *x;
#if ENABLE_HUSH_COMMAND
/* This loop effectively makes "command BAR" run BAR without
* looking it up among functions.
*/
while (strcmp(argv[0], "command") == 0 && argv[1])
argv++;
//TODO: implement -Vvp and "disable dying if BAR is a builtin" behavior
#endif
/* On NOMMU, it is more expensive to re-execute shell
/* Why "BB_MMU ? :" difference in logic? -
* On NOMMU, it is more expensive to re-execute shell
* just in order to run echo or test builtin.
* It's better to skip it here and run corresponding
* non-builtin later. */
x = BB_MMU ? find_builtin(argv[0]) : find_builtin1(argv[0]);
if (x) {
if_command_vV_print_and_exit(opt_vV, argv[0], "a shell builtin");
exec_builtin(&nommu_save->argv_from_re_execing, x, argv);
}
}
#if ENABLE_FEATURE_SH_STANDALONE
/* Check if the command matches any busybox applets */
{
int a = find_applet_by_name(argv[0]);
if (a >= 0) {
if_command_vV_print_and_exit(opt_vV, argv[0], "an applet");
# if BB_MMU /* see above why on NOMMU it is not allowed */
if (APPLET_IS_NOEXEC(a)) {
/* Do not leak open fds from opened script files etc.
@ -7466,6 +7518,7 @@ static NOINLINE void pseudo_exec_argv(nommu_save_t *nommu_save,
#if ENABLE_FEATURE_SH_STANDALONE || BB_MMU
skip:
#endif
if_command_vV_print_and_exit(opt_vV, argv[0], NULL);
execvp_or_die(argv);
}
@ -9895,7 +9948,7 @@ static int FAST_FUNC builtin_set(char **argv)
/* Nothing known, so abort */
error:
bb_error_msg("set: %s: invalid option", arg);
bb_error_msg("%s: %s: invalid option", "set", arg);
return EXIT_FAILURE;
}
#endif