| Message ID | 20210228234718.1208376-3-seanga2@gmail.com |
|---|---|
| State | Deferred |
| Delegated to: | Tom Rini |
| Headers | show |
| Series | cmd: Add support for command substitution | expand |
Am 1. März 2021 00:47:15 MEZ schrieb Sean Anderson <seanga2@gmail.com>: >The traditional way to grab the output from a shell script is to use >command substitution. Unfortunately, we don't really have the concept >of >pipes in U-Boot (at least not without console recording). Even if we >did, >stdout is severely polluted by informational printfs. > >Instead of redirecting stdout, instead use a special global variable. >This >lets commands set a result without having to modify the function >signature >of every command, and everything that calls commands. This is a bit of >a >hack, but seemed like the least-invasive of all options. > >Currently, the value of cmd_result is printed if it is set. This makes >sense for things like echo, where you can do something like > > => echo a b c d e > a b c d e > => var=c > => echo a $(echo b $var d) e > a b c d e > >but it makes less sense for some other commands > >All callers of cmd_process must > 1. Print cmd_result (unless it is being "redirected") > 2. free() cmd_result > 3. set cmd_result to NULL >Calling cmd_process with a non-NULL value in cmd_result is a bug. I don't understand what you are changing from the lines above. Before extending the hush shell we should write a man-page in doc/usage/ describing what it actually does. Building in new gimmicks without documentation does not make any sense to me. Best regards Heinrich > >Signed-off-by: Sean Anderson <seanga2@gmail.com> >--- > > common/cli_hush.c | 39 ++++++++++++++++++++++++++++--- > common/cli_simple.c | 8 ++++++- > common/command.c | 3 +++ > include/asm-generic/global_data.h | 4 ++++ > 4 files changed, 50 insertions(+), 4 deletions(-) > >diff --git a/common/cli_hush.c b/common/cli_hush.c >index 83329763c6..8fed7eb14e 100644 >--- a/common/cli_hush.c >+++ b/common/cli_hush.c >@@ -475,6 +475,8 @@ static char *make_string(char **inp, int *nonnull); >static int handle_dollar(o_string *dest, struct p_context *ctx, struct >in_str *input); > #ifndef __U_BOOT__ >static int parse_string(o_string *dest, struct p_context *ctx, const >char *src); >+#else >+static void update_ifs_map(void); > #endif >static int parse_stream(o_string *dest, struct p_context *ctx, struct >in_str *input0, int end_trigger); > /* setup: */ >@@ -1673,6 +1675,10 @@ static int run_pipe_real(struct pipe *pi) > "'run' command\n", child->argv[i]); > return -1; > } >+ if (gd->cmd_result) >+ puts(gd->cmd_result); >+ free(gd->cmd_result); >+ gd->cmd_result = NULL; > /* Process the command */ > return cmd_process(flag, child->argc - i, child->argv + i, > &flag_repeat, NULL); >@@ -2683,6 +2689,7 @@ FILE *generate_stream_from_list(struct pipe >*head) > #endif > return pf; > } >+#endif /* __U_BOOT__ */ > > /* this version hacked for testing purposes */ > /* return code is exit status of the process that is run. */ >@@ -2691,7 +2698,11 @@ static int process_command_subs(o_string *dest, >struct p_context *ctx, struct in > int retcode; > o_string result=NULL_O_STRING; > struct p_context inner; >+#ifdef __U_BOOT__ >+ int list_retcode; >+#else > FILE *p; >+#endif > struct in_str pipe_str; > initialize_context(&inner); > >@@ -2702,13 +2713,21 @@ static int process_command_subs(o_string *dest, >struct p_context *ctx, struct in > done_pipe(&inner, PIPE_SEQ); > b_free(&result); > >+#ifdef __U_BOOT__ >+ list_retcode = run_list_real(inner.list_head); >+ setup_string_in_str(&pipe_str, gd->cmd_result ?: ""); >+ /* Restore the original map as best we can */ >+ update_ifs_map(); >+#else > p=generate_stream_from_list(inner.list_head); > if (p==NULL) return 1; > mark_open(fileno(p)); > setup_file_in_str(&pipe_str, p); >+#endif > > /* now send results of command back into original context */ > retcode = parse_stream(dest, ctx, &pipe_str, '\0'); >+#ifndef __U_BOOT__ > /* XXX In case of a syntax error, should we try to kill the child? > * That would be tough to do right, so just read until EOF. */ > if (retcode == 1) { >@@ -2723,12 +2742,18 @@ static int process_command_subs(o_string *dest, >struct p_context *ctx, struct in > * to the KISS philosophy of this program. */ > mark_closed(fileno(p)); > retcode=pclose(p); >+#else >+ free(gd->cmd_result); >+ gd->cmd_result = NULL; >+ retcode = list_retcode; >+#endif > free_pipe_list(inner.list_head,0); > debug_printf("pclosed, retcode=%d\n",retcode); > /* XXX this process fails to trim a single trailing newline */ > return retcode; > } > >+#ifndef __U_BOOT__ > static int parse_group(o_string *dest, struct p_context *ctx, > struct in_str *input, int ch) > { >@@ -2896,11 +2921,11 @@ static int handle_dollar(o_string *dest, struct >p_context *ctx, struct in_str *i > } > b_addchr(dest, SPECIAL_VAR_SYMBOL); > break; >-#ifndef __U_BOOT__ > case '(': > b_getch(input); > process_command_subs(dest, ctx, input, ')'); > break; >+#ifndef __U_BOOT__ > case '*': > sep[0]=ifs[0]; > for (i=1; i<global_argc; i++) { >@@ -3165,7 +3190,7 @@ static void update_ifs_map(void) > mapset(subst, 3); /* never flow through */ > } > mapset((uchar *)"\\$'\"", 3); /* never flow through */ >- mapset((uchar *)";&|#", 1); /* flow through if quoted */ >+ mapset((uchar *)";&|()#", 1); /* flow through if quoted */ > #endif > mapset(ifs, 2); /* also flow through if quoted */ > } >@@ -3185,7 +3210,8 @@ static int parse_stream_outer(struct in_str *inp, >int flag) > ctx.type = flag; > initialize_context(&ctx); > update_ifs_map(); >- if (!(flag & FLAG_PARSE_SEMICOLON) || (flag & FLAG_REPARSING)) >mapset((uchar *)";$&|", 0); >+ if (!(flag & FLAG_PARSE_SEMICOLON) || (flag & FLAG_REPARSING)) >+ mapset((uchar *)";$&|()", 0); > inp->promptmode=1; > rcode = parse_stream(&temp, &ctx, inp, > flag & FLAG_CONT_ON_NEWLINE ? -1 : '\n'); >@@ -3205,6 +3231,13 @@ static int parse_stream_outer(struct in_str >*inp, int flag) > run_list(ctx.list_head); > #else > code = run_list(ctx.list_head); >+ >+ if (!(flag & FLAG_REPARSING) && gd->cmd_result) { >+ puts(gd->cmd_result); >+ free(gd->cmd_result); >+ gd->cmd_result = NULL; >+ } >+ > if (code == -2) { /* exit */ > b_free(&temp); > code = 0; >diff --git a/common/cli_simple.c b/common/cli_simple.c >index e80ba488a5..5df30d964f 100644 >--- a/common/cli_simple.c >+++ b/common/cli_simple.c >@@ -15,14 +15,16 @@ > #include <console.h> > #include <env.h> > #include <log.h> >+#include <malloc.h> > #include <linux/ctype.h> > >+DECLARE_GLOBAL_DATA_PTR; >+ > #define DEBUG_PARSER 0 /* set to 1 to debug */ > > #define debug_parser(fmt, args...) \ > debug_cond(DEBUG_PARSER, fmt, ##args) > >- > int cli_simple_parse_line(char *line, char *argv[]) > { > int nargs = 0; >@@ -257,6 +259,10 @@ int cli_simple_run_command(const char *cmd, int >flag) > > if (cmd_process(flag, argc, argv, &repeatable, NULL)) > rc = -1; >+ if (gd->cmd_result) >+ puts(gd->cmd_result); >+ free(gd->cmd_result); >+ gd->cmd_result = NULL; > > /* Did the user stop this? */ > if (had_ctrlc()) >diff --git a/common/command.c b/common/command.c >index 3fe6791eda..952a8f00eb 100644 >--- a/common/command.c >+++ b/common/command.c >@@ -588,6 +588,9 @@ enum command_ret_t cmd_process(int flag, int argc, >char *const argv[], > enum command_ret_t rc = CMD_RET_SUCCESS; > struct cmd_tbl *cmdtp; > >+ /* Clear previous result */ >+ assert(!gd->cmd_result); >+ > #if defined(CONFIG_SYS_XTRACE) > char *xtrace; > >diff --git a/include/asm-generic/global_data.h >b/include/asm-generic/global_data.h >index b6a9991fc9..85262d9566 100644 >--- a/include/asm-generic/global_data.h >+++ b/include/asm-generic/global_data.h >@@ -453,6 +453,10 @@ struct global_data { > */ > char *smbios_version; > #endif >+ /** >+ * @cmd_result: Result of the current command >+ */ >+ char *cmd_result; > }; > > /**
On 2/28/21 6:59 PM, Heinrich Schuchardt wrote: > Am 1. März 2021 00:47:15 MEZ schrieb Sean Anderson <seanga2@gmail.com>: >> The traditional way to grab the output from a shell script is to use >> command substitution. Unfortunately, we don't really have the concept >> of >> pipes in U-Boot (at least not without console recording). Even if we >> did, >> stdout is severely polluted by informational printfs. >> >> Instead of redirecting stdout, instead use a special global variable. >> This >> lets commands set a result without having to modify the function >> signature >> of every command, and everything that calls commands. This is a bit of >> a >> hack, but seemed like the least-invasive of all options. >> >> Currently, the value of cmd_result is printed if it is set. This makes >> sense for things like echo, where you can do something like >> >> => echo a b c d e >> a b c d e >> => var=c >> => echo a $(echo b $var d) e >> a b c d e >> >> but it makes less sense for some other commands >> >> All callers of cmd_process must >> 1. Print cmd_result (unless it is being "redirected") >> 2. free() cmd_result >> 3. set cmd_result to NULL >> Calling cmd_process with a non-NULL value in cmd_result is a bug. > > I don't understand what you are changing from the lines above. > => echo a $(echo b $var d) e This is a syntax error at the moment, and this series makes it work. > > Before extending the hush shell we should write a man-page in doc/usage/ describing what it actually does. What would it be named? Is there an existing section of the documentation which documents the standard and non-standard features of hush? > > Building in new gimmicks without documentation does not make any sense to me. Yes, this should likely be better-documented. However, I'm not sure that this approach is the best one, so I wanted to get some feedback before writing out documentation. I suppose this makes this an RFC series. --Sean > > Best regards > > Heinrich > > >> >> Signed-off-by: Sean Anderson <seanga2@gmail.com> >> --- >> >> common/cli_hush.c | 39 ++++++++++++++++++++++++++++--- >> common/cli_simple.c | 8 ++++++- >> common/command.c | 3 +++ >> include/asm-generic/global_data.h | 4 ++++ >> 4 files changed, 50 insertions(+), 4 deletions(-) >> >> diff --git a/common/cli_hush.c b/common/cli_hush.c >> index 83329763c6..8fed7eb14e 100644 >> --- a/common/cli_hush.c >> +++ b/common/cli_hush.c >> @@ -475,6 +475,8 @@ static char *make_string(char **inp, int *nonnull); >> static int handle_dollar(o_string *dest, struct p_context *ctx, struct >> in_str *input); >> #ifndef __U_BOOT__ >> static int parse_string(o_string *dest, struct p_context *ctx, const >> char *src); >> +#else >> +static void update_ifs_map(void); >> #endif >> static int parse_stream(o_string *dest, struct p_context *ctx, struct >> in_str *input0, int end_trigger); >> /* setup: */ >> @@ -1673,6 +1675,10 @@ static int run_pipe_real(struct pipe *pi) >> "'run' command\n", child->argv[i]); >> return -1; >> } >> + if (gd->cmd_result) >> + puts(gd->cmd_result); >> + free(gd->cmd_result); >> + gd->cmd_result = NULL; >> /* Process the command */ >> return cmd_process(flag, child->argc - i, child->argv + i, >> &flag_repeat, NULL); >> @@ -2683,6 +2689,7 @@ FILE *generate_stream_from_list(struct pipe >> *head) >> #endif >> return pf; >> } >> +#endif /* __U_BOOT__ */ >> >> /* this version hacked for testing purposes */ >> /* return code is exit status of the process that is run. */ >> @@ -2691,7 +2698,11 @@ static int process_command_subs(o_string *dest, >> struct p_context *ctx, struct in >> int retcode; >> o_string result=NULL_O_STRING; >> struct p_context inner; >> +#ifdef __U_BOOT__ >> + int list_retcode; >> +#else >> FILE *p; >> +#endif >> struct in_str pipe_str; >> initialize_context(&inner); >> >> @@ -2702,13 +2713,21 @@ static int process_command_subs(o_string *dest, >> struct p_context *ctx, struct in >> done_pipe(&inner, PIPE_SEQ); >> b_free(&result); >> >> +#ifdef __U_BOOT__ >> + list_retcode = run_list_real(inner.list_head); >> + setup_string_in_str(&pipe_str, gd->cmd_result ?: ""); >> + /* Restore the original map as best we can */ >> + update_ifs_map(); >> +#else >> p=generate_stream_from_list(inner.list_head); >> if (p==NULL) return 1; >> mark_open(fileno(p)); >> setup_file_in_str(&pipe_str, p); >> +#endif >> >> /* now send results of command back into original context */ >> retcode = parse_stream(dest, ctx, &pipe_str, '\0'); >> +#ifndef __U_BOOT__ >> /* XXX In case of a syntax error, should we try to kill the child? >> * That would be tough to do right, so just read until EOF. */ >> if (retcode == 1) { >> @@ -2723,12 +2742,18 @@ static int process_command_subs(o_string *dest, >> struct p_context *ctx, struct in >> * to the KISS philosophy of this program. */ >> mark_closed(fileno(p)); >> retcode=pclose(p); >> +#else >> + free(gd->cmd_result); >> + gd->cmd_result = NULL; >> + retcode = list_retcode; >> +#endif >> free_pipe_list(inner.list_head,0); >> debug_printf("pclosed, retcode=%d\n",retcode); >> /* XXX this process fails to trim a single trailing newline */ >> return retcode; >> } >> >> +#ifndef __U_BOOT__ >> static int parse_group(o_string *dest, struct p_context *ctx, >> struct in_str *input, int ch) >> { >> @@ -2896,11 +2921,11 @@ static int handle_dollar(o_string *dest, struct >> p_context *ctx, struct in_str *i >> } >> b_addchr(dest, SPECIAL_VAR_SYMBOL); >> break; >> -#ifndef __U_BOOT__ >> case '(': >> b_getch(input); >> process_command_subs(dest, ctx, input, ')'); >> break; >> +#ifndef __U_BOOT__ >> case '*': >> sep[0]=ifs[0]; >> for (i=1; i<global_argc; i++) { >> @@ -3165,7 +3190,7 @@ static void update_ifs_map(void) >> mapset(subst, 3); /* never flow through */ >> } >> mapset((uchar *)"\\$'\"", 3); /* never flow through */ >> - mapset((uchar *)";&|#", 1); /* flow through if quoted */ >> + mapset((uchar *)";&|()#", 1); /* flow through if quoted */ >> #endif >> mapset(ifs, 2); /* also flow through if quoted */ >> } >> @@ -3185,7 +3210,8 @@ static int parse_stream_outer(struct in_str *inp, >> int flag) >> ctx.type = flag; >> initialize_context(&ctx); >> update_ifs_map(); >> - if (!(flag & FLAG_PARSE_SEMICOLON) || (flag & FLAG_REPARSING)) >> mapset((uchar *)";$&|", 0); >> + if (!(flag & FLAG_PARSE_SEMICOLON) || (flag & FLAG_REPARSING)) >> + mapset((uchar *)";$&|()", 0); >> inp->promptmode=1; >> rcode = parse_stream(&temp, &ctx, inp, >> flag & FLAG_CONT_ON_NEWLINE ? -1 : '\n'); >> @@ -3205,6 +3231,13 @@ static int parse_stream_outer(struct in_str >> *inp, int flag) >> run_list(ctx.list_head); >> #else >> code = run_list(ctx.list_head); >> + >> + if (!(flag & FLAG_REPARSING) && gd->cmd_result) { >> + puts(gd->cmd_result); >> + free(gd->cmd_result); >> + gd->cmd_result = NULL; >> + } >> + >> if (code == -2) { /* exit */ >> b_free(&temp); >> code = 0; >> diff --git a/common/cli_simple.c b/common/cli_simple.c >> index e80ba488a5..5df30d964f 100644 >> --- a/common/cli_simple.c >> +++ b/common/cli_simple.c >> @@ -15,14 +15,16 @@ >> #include <console.h> >> #include <env.h> >> #include <log.h> >> +#include <malloc.h> >> #include <linux/ctype.h> >> >> +DECLARE_GLOBAL_DATA_PTR; >> + >> #define DEBUG_PARSER 0 /* set to 1 to debug */ >> >> #define debug_parser(fmt, args...) \ >> debug_cond(DEBUG_PARSER, fmt, ##args) >> >> - >> int cli_simple_parse_line(char *line, char *argv[]) >> { >> int nargs = 0; >> @@ -257,6 +259,10 @@ int cli_simple_run_command(const char *cmd, int >> flag) >> >> if (cmd_process(flag, argc, argv, &repeatable, NULL)) >> rc = -1; >> + if (gd->cmd_result) >> + puts(gd->cmd_result); >> + free(gd->cmd_result); >> + gd->cmd_result = NULL; >> >> /* Did the user stop this? */ >> if (had_ctrlc()) >> diff --git a/common/command.c b/common/command.c >> index 3fe6791eda..952a8f00eb 100644 >> --- a/common/command.c >> +++ b/common/command.c >> @@ -588,6 +588,9 @@ enum command_ret_t cmd_process(int flag, int argc, >> char *const argv[], >> enum command_ret_t rc = CMD_RET_SUCCESS; >> struct cmd_tbl *cmdtp; >> >> + /* Clear previous result */ >> + assert(!gd->cmd_result); >> + >> #if defined(CONFIG_SYS_XTRACE) >> char *xtrace; >> >> diff --git a/include/asm-generic/global_data.h >> b/include/asm-generic/global_data.h >> index b6a9991fc9..85262d9566 100644 >> --- a/include/asm-generic/global_data.h >> +++ b/include/asm-generic/global_data.h >> @@ -453,6 +453,10 @@ struct global_data { >> */ >> char *smbios_version; >> #endif >> + /** >> + * @cmd_result: Result of the current command >> + */ >> + char *cmd_result; >> }; >> >> /** >
diff --git a/common/cli_hush.c b/common/cli_hush.c index 83329763c6..8fed7eb14e 100644 --- a/common/cli_hush.c +++ b/common/cli_hush.c @@ -475,6 +475,8 @@ static char *make_string(char **inp, int *nonnull); static int handle_dollar(o_string *dest, struct p_context *ctx, struct in_str *input); #ifndef __U_BOOT__ static int parse_string(o_string *dest, struct p_context *ctx, const char *src); +#else +static void update_ifs_map(void); #endif static int parse_stream(o_string *dest, struct p_context *ctx, struct in_str *input0, int end_trigger); /* setup: */ @@ -1673,6 +1675,10 @@ static int run_pipe_real(struct pipe *pi) "'run' command\n", child->argv[i]); return -1; } + if (gd->cmd_result) + puts(gd->cmd_result); + free(gd->cmd_result); + gd->cmd_result = NULL; /* Process the command */ return cmd_process(flag, child->argc - i, child->argv + i, &flag_repeat, NULL); @@ -2683,6 +2689,7 @@ FILE *generate_stream_from_list(struct pipe *head) #endif return pf; } +#endif /* __U_BOOT__ */ /* this version hacked for testing purposes */ /* return code is exit status of the process that is run. */ @@ -2691,7 +2698,11 @@ static int process_command_subs(o_string *dest, struct p_context *ctx, struct in int retcode; o_string result=NULL_O_STRING; struct p_context inner; +#ifdef __U_BOOT__ + int list_retcode; +#else FILE *p; +#endif struct in_str pipe_str; initialize_context(&inner); @@ -2702,13 +2713,21 @@ static int process_command_subs(o_string *dest, struct p_context *ctx, struct in done_pipe(&inner, PIPE_SEQ); b_free(&result); +#ifdef __U_BOOT__ + list_retcode = run_list_real(inner.list_head); + setup_string_in_str(&pipe_str, gd->cmd_result ?: ""); + /* Restore the original map as best we can */ + update_ifs_map(); +#else p=generate_stream_from_list(inner.list_head); if (p==NULL) return 1; mark_open(fileno(p)); setup_file_in_str(&pipe_str, p); +#endif /* now send results of command back into original context */ retcode = parse_stream(dest, ctx, &pipe_str, '\0'); +#ifndef __U_BOOT__ /* XXX In case of a syntax error, should we try to kill the child? * That would be tough to do right, so just read until EOF. */ if (retcode == 1) { @@ -2723,12 +2742,18 @@ static int process_command_subs(o_string *dest, struct p_context *ctx, struct in * to the KISS philosophy of this program. */ mark_closed(fileno(p)); retcode=pclose(p); +#else + free(gd->cmd_result); + gd->cmd_result = NULL; + retcode = list_retcode; +#endif free_pipe_list(inner.list_head,0); debug_printf("pclosed, retcode=%d\n",retcode); /* XXX this process fails to trim a single trailing newline */ return retcode; } +#ifndef __U_BOOT__ static int parse_group(o_string *dest, struct p_context *ctx, struct in_str *input, int ch) { @@ -2896,11 +2921,11 @@ static int handle_dollar(o_string *dest, struct p_context *ctx, struct in_str *i } b_addchr(dest, SPECIAL_VAR_SYMBOL); break; -#ifndef __U_BOOT__ case '(': b_getch(input); process_command_subs(dest, ctx, input, ')'); break; +#ifndef __U_BOOT__ case '*': sep[0]=ifs[0]; for (i=1; i<global_argc; i++) { @@ -3165,7 +3190,7 @@ static void update_ifs_map(void) mapset(subst, 3); /* never flow through */ } mapset((uchar *)"\\$'\"", 3); /* never flow through */ - mapset((uchar *)";&|#", 1); /* flow through if quoted */ + mapset((uchar *)";&|()#", 1); /* flow through if quoted */ #endif mapset(ifs, 2); /* also flow through if quoted */ } @@ -3185,7 +3210,8 @@ static int parse_stream_outer(struct in_str *inp, int flag) ctx.type = flag; initialize_context(&ctx); update_ifs_map(); - if (!(flag & FLAG_PARSE_SEMICOLON) || (flag & FLAG_REPARSING)) mapset((uchar *)";$&|", 0); + if (!(flag & FLAG_PARSE_SEMICOLON) || (flag & FLAG_REPARSING)) + mapset((uchar *)";$&|()", 0); inp->promptmode=1; rcode = parse_stream(&temp, &ctx, inp, flag & FLAG_CONT_ON_NEWLINE ? -1 : '\n'); @@ -3205,6 +3231,13 @@ static int parse_stream_outer(struct in_str *inp, int flag) run_list(ctx.list_head); #else code = run_list(ctx.list_head); + + if (!(flag & FLAG_REPARSING) && gd->cmd_result) { + puts(gd->cmd_result); + free(gd->cmd_result); + gd->cmd_result = NULL; + } + if (code == -2) { /* exit */ b_free(&temp); code = 0; diff --git a/common/cli_simple.c b/common/cli_simple.c index e80ba488a5..5df30d964f 100644 --- a/common/cli_simple.c +++ b/common/cli_simple.c @@ -15,14 +15,16 @@ #include <console.h> #include <env.h> #include <log.h> +#include <malloc.h> #include <linux/ctype.h> +DECLARE_GLOBAL_DATA_PTR; + #define DEBUG_PARSER 0 /* set to 1 to debug */ #define debug_parser(fmt, args...) \ debug_cond(DEBUG_PARSER, fmt, ##args) - int cli_simple_parse_line(char *line, char *argv[]) { int nargs = 0; @@ -257,6 +259,10 @@ int cli_simple_run_command(const char *cmd, int flag) if (cmd_process(flag, argc, argv, &repeatable, NULL)) rc = -1; + if (gd->cmd_result) + puts(gd->cmd_result); + free(gd->cmd_result); + gd->cmd_result = NULL; /* Did the user stop this? */ if (had_ctrlc()) diff --git a/common/command.c b/common/command.c index 3fe6791eda..952a8f00eb 100644 --- a/common/command.c +++ b/common/command.c @@ -588,6 +588,9 @@ enum command_ret_t cmd_process(int flag, int argc, char *const argv[], enum command_ret_t rc = CMD_RET_SUCCESS; struct cmd_tbl *cmdtp; + /* Clear previous result */ + assert(!gd->cmd_result); + #if defined(CONFIG_SYS_XTRACE) char *xtrace; diff --git a/include/asm-generic/global_data.h b/include/asm-generic/global_data.h index b6a9991fc9..85262d9566 100644 --- a/include/asm-generic/global_data.h +++ b/include/asm-generic/global_data.h @@ -453,6 +453,10 @@ struct global_data { */ char *smbios_version; #endif + /** + * @cmd_result: Result of the current command + */ + char *cmd_result; }; /**
The traditional way to grab the output from a shell script is to use command substitution. Unfortunately, we don't really have the concept of pipes in U-Boot (at least not without console recording). Even if we did, stdout is severely polluted by informational printfs. Instead of redirecting stdout, instead use a special global variable. This lets commands set a result without having to modify the function signature of every command, and everything that calls commands. This is a bit of a hack, but seemed like the least-invasive of all options. Currently, the value of cmd_result is printed if it is set. This makes sense for things like echo, where you can do something like => echo a b c d e a b c d e => var=c => echo a $(echo b $var d) e a b c d e but it makes less sense for some other commands All callers of cmd_process must 1. Print cmd_result (unless it is being "redirected") 2. free() cmd_result 3. set cmd_result to NULL Calling cmd_process with a non-NULL value in cmd_result is a bug. Signed-off-by: Sean Anderson <seanga2@gmail.com> --- common/cli_hush.c | 39 ++++++++++++++++++++++++++++--- common/cli_simple.c | 8 ++++++- common/command.c | 3 +++ include/asm-generic/global_data.h | 4 ++++ 4 files changed, 50 insertions(+), 4 deletions(-)