On 2/28/21 6:59 PM, Heinrich Schuchardt wrote:
Am 1. März 2021 00:47:15 MEZ schrieb Sean Anderson <sean...@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 <sean...@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;
};

/**



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