kallsyms: remove usage of memmem and _GNU_SOURCE from scripts/kallsyms.c

The only in-kernel user of "memmem" is scripts/kallsyms.c and it only
uses it to find tokens that are 2 bytes in size. It is trivial to
replace it with a simple function that finds 2-byte tokens.

This should help users from systems that don't have the memmem GNU
extension available.

Signed-off-by: Paulo Marques <pmarques@grupopie.com>
Signed-off-by: Sam Ravnborg <sam@ravnborg.org>

1 files changed, 13 insertions, 4 deletions

diff --git a/scripts/kallsyms.c b/scripts/kallsyms.c
index 8b809b264d1..caf4c86c3d0 100644
--- a/scripts/kallsyms.c
+++ b/scripts/kallsyms.c
@@ -24,8 +24,6 @@
  *
  */
 
-#define _GNU_SOURCE
-
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
@@ -378,6 +376,17 @@ static void build_initial_tok_table(void)
         table_cnt = pos;
 }
 
+static void *find_token(unsigned char *str, int len, unsigned char *token)
+{
+        int i;
+
+        for (i = 0; i < len - 1; i++) {
+                if (str[i] == token[0] && str[i+1] == token[1])
+                        return &str[i];
+        }
+        return NULL;
+}
+
 /* replace a given token in all the valid symbols. Use the sampled symbols
  * to update the counts */
 static void compress_symbols(unsigned char *str, int idx)
@@ -391,7 +400,7 @@ static void compress_symbols(unsigned char *str, int idx)
                 p1 = table[i].sym;
 
                 /* find the token on the symbol */
-                p2 = memmem(p1, len, str, 2);
+                p2 = find_token(p1, len, str);
                 if (!p2) continue;
 
                 /* decrease the counts for this symbol's tokens */
@@ -410,7 +419,7 @@ static void compress_symbols(unsigned char *str, int idx)
                         if (size < 2) break;
 
                         /* find the token on the symbol */
-                        p2 = memmem(p1, size, str, 2);
+                        p2 = find_token(p1, size, str);
 
                 } while (p2);