"env grep" - add support for regular expression matches

When CONFIG_REGEX is enabled, the new option "-e" becomes available
which causes regular expression matches to be used.  This allows for
example things like these:

- print all MAC addresses:

	=> env grep -e eth.*addr
	eth1addr=00:10:ec:80:c5:15
	ethaddr=00:10:ec:00:c5:15

- print all variables that have at least 2 colons in their value:

	=> env grep -v -e :.*:
	addip=setenv bootargs ${bootargs} ip=${ipaddr}:${serverip}:${gatewayip}:${netmask}:${hostname}:${netdev}:off
	panic=1
	eth1addr=00:10:ec:80:c5:15
	ethaddr=00:10:ec:00:c5:15
	ver=U-Boot 2013.04-rc1-00289-g497746b-dirty (Mar 22 2013 - 12:50:25)

etc.

Signed-off-by: Wolfgang Denk <wd@denx.de>

3 files changed, 52 insertions, 11 deletions

diff --git a/common/cmd_nvedit.c b/common/cmd_nvedit.c
index 9158b96224..f8dc38e89a 100644
--- a/common/cmd_nvedit.c
+++ b/common/cmd_nvedit.c
@@ -165,12 +165,13 @@ static int do_env_grep(cmd_tbl_t *cmdtp, int flag,
 		       int argc, char * const argv[])
 {
 	char *res = NULL;
-	int len, grep_flags;
+	int len, grep_how, grep_what;
 
 	if (argc < 2)
 		return CMD_RET_USAGE;
 
-	grep_flags = H_MATCH_BOTH;
+	grep_how  = H_MATCH_SUBSTR;	/* default: substring search	*/
+	grep_what = H_MATCH_BOTH;	/* default: grep names and values */
 
 	while (argc > 1 && **(argv + 1) == '-') {
 		char *arg = *++argv;
@@ -178,14 +179,19 @@ static int do_env_grep(cmd_tbl_t *cmdtp, int flag,
 		--argc;
 		while (*++arg) {
 			switch (*arg) {
+#ifdef CONFIG_REGEX
+			case 'e':		/* use regex matching */
+				grep_how  = H_MATCH_REGEX;
+				break;
+#endif
 			case 'n':		/* grep for name */
-				grep_flags = H_MATCH_KEY;
+				grep_what = H_MATCH_KEY;
 				break;
 			case 'v':		/* grep for value */
-				grep_flags = H_MATCH_DATA;
+				grep_what = H_MATCH_DATA;
 				break;
 			case 'b':		/* grep for both */
-				grep_flags = H_MATCH_BOTH;
+				grep_what = H_MATCH_BOTH;
 				break;
 			case '-':
 				goto DONE;
@@ -197,7 +203,7 @@ static int do_env_grep(cmd_tbl_t *cmdtp, int flag,
 
 DONE:
 	len = hexport_r(&env_htab, '\n',
-			flag | grep_flags | H_MATCH_SUBSTR,
+			flag | grep_what | grep_how,
 			&res, 0, argc, argv);
 
 	if (len > 0) {
@@ -1153,8 +1159,12 @@ static char env_help_text[] =
 	"env flags - print variables that have non-default flags\n"
 #endif
 #if defined(CONFIG_CMD_GREPENV)
+#ifdef CONFIG_REGEX
+	"env grep [-e] [-n | -v | -b] string [...] - search environment\n"
+#else
 	"env grep [-n | -v | -b] string [...] - search environment\n"
 #endif
+#endif
 #if defined(CONFIG_CMD_IMPORTENV)
 	"env import [-d] [-t | -b | -c] addr [size] - import environment\n"
 #endif
@@ -1200,8 +1210,15 @@ U_BOOT_CMD_COMPLETE(
 U_BOOT_CMD_COMPLETE(
 	grepenv, CONFIG_SYS_MAXARGS, 0,  do_env_grep,
 	"search environment variables",
+#ifdef CONFIG_REGEX
+	"[-e] [-n | -v | -b] string ...\n"
+#else
 	"[-n | -v | -b] string ...\n"
+#endif
 	"    - list environment name=value pairs matching 'string'\n"
+#ifdef CONFIG_REGEX
+	"      \"-e\": enable regular expressions;\n"
+#endif
 	"      \"-n\": search variable names; \"-v\": search values;\n"
 	"      \"-b\": search both names and values (default)",
 	var_complete
diff --git a/include/search.h b/include/search.h
index d06a2017a5..d9ac8dfa07 100644
--- a/include/search.h
+++ b/include/search.h
@@ -129,7 +129,8 @@ extern int hwalk_r(struct hsearch_data *__htab, int (*callback)(ENTRY *));
 #define H_MATCH_DATA	(1 << 5) /* search/grep data = variable values	     */
 #define H_MATCH_BOTH	(H_MATCH_KEY | H_MATCH_DATA) /* search/grep both     */
 #define H_MATCH_IDENT	(1 << 6) /* search for indentical strings	     */
-#define H_MATCH_SUBSTR  (1 << 7) /* search for substring matches	     */
-#define H_MATCH_METHOD	(H_MATCH_IDENT | H_MATCH_SUBSTR)
+#define H_MATCH_SUBSTR	(1 << 7) /* search for substring matches	     */
+#define H_MATCH_REGEX	(1 << 8) /* search for regular expression matches    */
+#define H_MATCH_METHOD	(H_MATCH_IDENT | H_MATCH_SUBSTR | H_MATCH_REGEX)
 
 #endif /* search.h */
diff --git a/lib/hashtable.c b/lib/hashtable.c
index 1703941a5a..6050dd0829 100644
--- a/lib/hashtable.c
+++ b/lib/hashtable.c
@@ -57,6 +57,7 @@
 #include <env_callback.h>
 #include <env_flags.h>
 #include <search.h>
+#include <slre.h>
 
 /*
  * [Aho,Sethi,Ullman] Compilers: Principles, Techniques and Tools, 1986
@@ -540,7 +541,7 @@ static int cmpkey(const void *p1, const void *p2)
 	return (strcmp(e1->key, e2->key));
 }
 
-static int match_string(int flag, const char *str, const char *pat)
+static int match_string(int flag, const char *str, const char *pat, void *priv)
 {
 	switch (flag & H_MATCH_METHOD) {
 	case H_MATCH_IDENT:
@@ -551,6 +552,17 @@ static int match_string(int flag, const char *str, const char *pat)
 		if (strstr(str, pat))
 			return 1;
 		break;
+#ifdef CONFIG_REGEX
+	case H_MATCH_REGEX:
+		{
+			struct slre *slrep = (struct slre *)priv;
+			struct cap caps[slrep->num_caps + 2];
+
+			if (slre_match(slrep, str, strlen(str), caps))
+				return 1;
+		}
+		break;
+#endif
 	default:
 		printf("## ERROR: unsupported match method: 0x%02x\n",
 			flag & H_MATCH_METHOD);
@@ -563,14 +575,25 @@ static int match_entry(ENTRY *ep, int flag,
 		 int argc, char * const argv[])
 {
 	int arg;
+	void *priv = NULL;
 
 	for (arg = 1; arg < argc; ++arg) {
+#ifdef CONFIG_REGEX
+		struct slre slre;
+
+		if (slre_compile(&slre, argv[arg]) == 0) {
+			printf("Error compiling regex: %s\n", slre.err_str);
+			return 0;
+		}
+
+		priv = (void *)&slre;
+#endif
 		if (flag & H_MATCH_KEY) {
-			if (match_string(flag, ep->key, argv[arg]))
+			if (match_string(flag, ep->key, argv[arg], priv))
 				return 1;
 		}
 		if (flag & H_MATCH_DATA) {
-			if (match_string(flag, ep->data, argv[arg]))
+			if (match_string(flag, ep->data, argv[arg], priv))
 				return 1;
 		}
 	}