[U-Boot] [PATCH v2] common: command: Add support for $ auto-completion

[Boris Brezillon]

Add the dollar_complete() function to auto-complete arguments starting
with a '$' and use it in the cmd_auto_complete() path such that all
args starting with a $ can be auto-completed based on the available env
vars.

Signed-off-by: Boris Brezillon <boris.brezillon at bootlin.com>
---
Changes in v2:
- Call dollar_complete() from cmd_auto_complete() to provide $
  auto-completion to everyone (suggested by Wolfgang)
---
 common/command.c | 33 ++++++++++++++++++++++++++------
 env/common.c     | 50 +++++++++++++++++++++++++++++++++++++++++++++---
 include/common.h |  3 ++-
 3 files changed, 76 insertions(+), 10 deletions(-)

diff --git a/common/command.c b/common/command.c
index 19f0534a76ea..0a93322814a6 100644
--- a/common/command.c
+++ b/common/command.c
@@ -143,22 +143,38 @@ int cmd_usage(const cmd_tbl_t *cmdtp)
 
 #ifdef CONFIG_AUTO_COMPLETE
 
+static char env_complete_buf[512];
+
 int var_complete(int argc, char * const argv[], char last_char, int maxv, char *cmdv[])
 {
-	static char tmp_buf[512];
 	int space;
 
 	space = last_char == '\0' || isblank(last_char);
 
 	if (space && argc == 1)
-		return env_complete("", maxv, cmdv, sizeof(tmp_buf), tmp_buf);
+		return env_complete("", maxv, cmdv, sizeof(env_complete_buf),
+				    env_complete_buf, false);
 
 	if (!space && argc == 2)
-		return env_complete(argv[1], maxv, cmdv, sizeof(tmp_buf), tmp_buf);
+		return env_complete(argv[1], maxv, cmdv,
+				    sizeof(env_complete_buf),
+				    env_complete_buf, false);
 
 	return 0;
 }
 
+static int dollar_complete(int argc, char * const argv[], char last_char,
+			   int maxv, char *cmdv[])
+{
+	/* Make sure the last argument starts with a $. */
+	if (argc < 1 || argv[argc - 1][0] != '$' ||
+	    last_char == '\0' || isblank(last_char))
+		return 0;
+
+	return env_complete(argv[argc - 1], maxv, cmdv, sizeof(env_complete_buf),
+			    env_complete_buf, true);
+}
+
 /*************************************************************************************/
 
 int complete_subcmdv(cmd_tbl_t *cmdtp, int count, int argc,
@@ -357,9 +373,14 @@ int cmd_auto_complete(const char *const prompt, char *buf, int *np, int *colp)
 	/* separate into argv */
 	argc = make_argv(tmp_buf, sizeof(argv)/sizeof(argv[0]), argv);
 
-	/* do the completion and return the possible completions */
-	i = complete_cmdv(argc, argv, last_char,
-			  sizeof(cmdv) / sizeof(cmdv[0]), cmdv);
+	/* first try a $ completion */
+	i = dollar_complete(argc, argv, last_char,
+			    sizeof(cmdv) / sizeof(cmdv[0]), cmdv);
+	if (!i) {
+		/* do the completion and return the possible completions */
+		i = complete_cmdv(argc, argv, last_char,
+				  sizeof(cmdv) / sizeof(cmdv[0]), cmdv);
+	}
 
 	/* no match; bell and out */
 	if (i == 0) {
diff --git a/env/common.c b/env/common.c
index 3317cef35522..aa9a097bced0 100644
--- a/env/common.c
+++ b/env/common.c
@@ -241,31 +241,75 @@ void env_relocate(void)
 }
 
 #if defined(CONFIG_AUTO_COMPLETE) && !defined(CONFIG_SPL_BUILD)
-int env_complete(char *var, int maxv, char *cmdv[], int bufsz, char *buf)
+int env_complete(char *var, int maxv, char *cmdv[], int bufsz, char *buf,
+		 bool dollar_comp)
 {
 	ENTRY *match;
 	int found, idx;
 
+	if (dollar_comp) {
+		/*
+		 * When doing $ completion, the first character should
+		 * obviously be a '$'.
+		 */
+		if (var[0] != '$')
+			return 0;
+
+		var++;
+
+		/*
+		 * The second one, if present, should be a '{', as some
+		 * configuration of the u-boot shell expand ${var} but not
+		 * $var.
+		 */
+		if (var[0] == '{')
+			var++;
+		else if (var[0] != '\0')
+			return 0;
+	}
+
 	idx = 0;
 	found = 0;
 	cmdv[0] = NULL;
 
+
 	while ((idx = hmatch_r(var, idx, &match, &env_htab))) {
 		int vallen = strlen(match->key) + 1;
 
-		if (found >= maxv - 2 || bufsz < vallen)
+		if (found >= maxv - 2 ||
+		    bufsz < vallen + (dollar_comp ? 3 : 0))
 			break;
 
 		cmdv[found++] = buf;
+
+		/* Add the '${' prefix to each var when doing $ completion. */
+		if (dollar_comp) {
+			strcpy(buf, "${");
+			buf += 2;
+			bufsz -= 3;
+		}
+
 		memcpy(buf, match->key, vallen);
 		buf += vallen;
 		bufsz -= vallen;
+
+		if (dollar_comp) {
+			/*
+			 * This one is a bit odd: vallen already contains the
+			 * '\0' character but we need to add the '}' suffix,
+			 * hence the buf - 1 here. strcpy() will add the '\0'
+			 * character just after '}'. buf is then incremented
+			 * to account for the extra '}' we just added.
+			 */
+			strcpy(buf - 1, "}");
+			buf++;
+		}
 	}
 
 	qsort(cmdv, found, sizeof(cmdv[0]), strcmp_compar);
 
 	if (idx)
-		cmdv[found++] = "...";
+		cmdv[found++] = dollar_comp ? "${...}" : "...";
 
 	cmdv[found] = NULL;
 	return found;
diff --git a/include/common.h b/include/common.h
index 8b561370326f..2c776adc5fe0 100644
--- a/include/common.h
+++ b/include/common.h
@@ -237,7 +237,8 @@ static inline int env_set_addr(const char *varname, const void *addr)
 }
 
 #ifdef CONFIG_AUTO_COMPLETE
-int env_complete(char *var, int maxv, char *cmdv[], int maxsz, char *buf);
+int env_complete(char *var, int maxv, char *cmdv[], int maxsz, char *buf,
+		 bool dollar_comp);
 #endif
 int get_env_id (void);
 
-- 
2.17.1