[PATCH 2/5] cmd: Add support for (limited) command substitution
Heinrich Schuchardt
xypron.glpk at gmx.de
Mon Mar 1 00:59:53 CET 2021
Am 1. März 2021 00:47:15 MEZ schrieb Sean Anderson <seanga2 at 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 at 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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