modpost: expand pattern matching to support substring matches

Currently the match() function supports a leading * to match any
prefix and a trailing * to match any suffix.  However there currently
is not a combination of both that can be used to target matches of
whole families of functions that share a common substring.

Here we expand the *foo and foo* match to also support *foo* with
the goal of targeting compiler generated symbol names that contain
strings like ".constprop." and ".isra."

Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>

scripts/mod/modpost.c

@@ -776,6 +776,7 @@ static const char *sech_name(struct elf_info *elf, Elf_Shdr *sechdr)
  * "foo" will match an exact string equal to "foo"
  * "*foo" will match a string that ends with "foo"
  * "foo*" will match a string that begins with "foo"
+ * "*foo*" will match a string that contains "foo"
  */
 static int match(const char *sym, const char * const pat[])
 {
@@ -784,8 +785,17 @@ static int match(const char *sym, const char * const pat[])
 		p = *pat++;
 		const char *endp = p + strlen(p) - 1;
 
+		/* "*foo*" */
+		if (*p == '*' && *endp == '*') {
+			char *here, *bare = strndup(p + 1, strlen(p) - 2);
+
+			here = strstr(sym, bare);
+			free(bare);
+			if (here != NULL)
+				return 1;
+		}
 		/* "*foo" */
-		if (*p == '*') {
+		else if (*p == '*') {
 			if (strrcmp(sym, p + 1) == 0)
 				return 1;
 		}