From 5700029c65f2218b5fceca77a9140aff6d882aab Mon Sep 17 00:00:00 2001 From: Denys Vlasenko Date: Fri, 12 Jan 2018 14:41:45 +0100 Subject: [PATCH] hush: implement "command -v -V" function old new delta pseudo_exec_argv 231 374 +143 if_command_vV_print_and_exit - 127 +127 builtin_set 267 273 +6 ------------------------------------------------------------------------------ (add/remove: 1/0 grow/shrink: 2/0 up/down: 276/0) Total: 276 bytes Signed-off-by: Denys Vlasenko --- shell/hush.c | 115 +++++++++++++++++++++++++++++++++++++-------------- 1 file changed, 84 insertions(+), 31 deletions(-) diff --git a/shell/hush.c b/shell/hush.c index 93779ba1e..196bdbe97 100644 --- a/shell/hush.c +++ b/shell/hush.c @@ -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); @@ -7406,30 +7429,58 @@ 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 - * 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) { - exec_builtin(&nommu_save->argv_from_re_execing, x, argv); - } + /* 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 @@ -7437,6 +7488,7 @@ static NOINLINE void pseudo_exec_argv(nommu_save_t *nommu_save, { 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