From f435f0412aa4ca631aa178d10ed33008e34f37cb Mon Sep 17 00:00:00 2001
From: Rob Landley <rob@landley.net>
Date: Wed, 10 Feb 2016 21:05:22 -0600
Subject: Factor out strnstr() since posix hasn't got it, and add a config
 option for the deeply sad passwd heuristics that don't even check numbers and
 punctuation.

---
 lib/lib.c         | 11 +++++++++++
 lib/lib.h         |  1 +
 toys/lsb/passwd.c | 22 ++++++++++++++--------
 toys/posix/grep.c |  9 ++-------
 4 files changed, 28 insertions(+), 15 deletions(-)

diff --git a/lib/lib.c b/lib/lib.c
index 6559030c..681d4d23 100644
--- a/lib/lib.c
+++ b/lib/lib.c
@@ -1033,3 +1033,14 @@ char *next_printf(char *s, char **start)
 
   return 0;
 }
+
+// Posix inexplicably hasn't got this, so find str in line.
+char *strnstr(char *line, char *str)
+{
+  long len = strlen(str);
+  char *s;
+
+  for (s = line; *s; s++) if (!strncasecmp(s, str, len)) break;
+
+  return *s ? s : 0;
+}
diff --git a/lib/lib.h b/lib/lib.h
index 2714ad3d..dac3b67f 100644
--- a/lib/lib.h
+++ b/lib/lib.h
@@ -199,6 +199,7 @@ int qstrcmp(const void *a, const void *b);
 void create_uuid(char *uuid);
 char *show_uuid(char *uuid);
 char *next_printf(char *s, char **start);
+char *strnstr(char *line, char *str);
 
 #define HR_SPACE 1 // Space between number and units
 #define HR_B     2 // Use "B" for single byte units
diff --git a/toys/lsb/passwd.c b/toys/lsb/passwd.c
index ca98f2ef..687d4c09 100644
--- a/toys/lsb/passwd.c
+++ b/toys/lsb/passwd.c
@@ -20,6 +20,16 @@ config PASSWD
     -d		Set password to ''
     -l		Lock (disable) account
     -u		Unlock (enable) account
+
+config PASSWD_SAD
+  bool "Add sad password checking heuristics"
+  default n
+  depends on PASSWD
+  help
+    Password changes are checked to make sure they don't include the entire
+    username (but not a subset of it), and the entire previous password
+    (but changing password1, password2, password3 is fine). This heuristic
+    accepts "aaaaaa" as a password.
 */
 
 #define FOR_passwd
@@ -29,16 +39,13 @@ GLOBALS(
   char *algo;
 )
 
-#ifndef _GNU_SOURCE
-char *strcasestr(const char *haystack, const char *needle);
-#endif
-
 static int str_check(char *s, char *p)
 {
-  if (strcasestr(s, p) || strcasestr(p, s)) return 1;
+  if (strnstr(s, p) || strnstr(p, s)) return 1;
   return 0;
 }
 
+// Insane heuristic won't find password1 password2 password3...?
 static void strength_check(char *newp, char *oldp, char *user)
 {
   char *msg = NULL;
@@ -81,7 +88,7 @@ static char *new_password(char *oldp, char *user)
     return NULL; //may be due to Ctrl-C
 
   newp = xstrdup(toybuf);
-  strength_check(newp, oldp, user);
+  if (CFG_PASSWD_SAD) strength_check(newp, oldp, user);
   if (read_password(toybuf, sizeof(toybuf), "Retype password:")) {
     free(newp);
     return NULL; //may be due to Ctrl-C
@@ -114,8 +121,7 @@ void passwd_main(void)
 
   pw = xgetpwnam(name);
 
-  if (myuid && (myuid != pw->pw_uid))
-    error_exit("You need to be root to change '%s' password\n", name);
+  if (myuid && (myuid != pw->pw_uid)) error_exit("Not root");
 
   pass = pw->pw_passwd;
   if (pw->pw_passwd[0] == 'x') {
diff --git a/toys/posix/grep.c b/toys/posix/grep.c
index c5d626aa..2ca02d2c 100644
--- a/toys/posix/grep.c
+++ b/toys/posix/grep.c
@@ -125,13 +125,8 @@ static void do_grep(int fd, char *name)
             fseek.arg = s = line;
             break;
           }
-          if (toys.optflags & FLAG_i) {
-            long ll = strlen(seek->arg);;
-
-            // Alas, posix hasn't got strcasestr()
-            for (s = line; *s; s++) if (!strncasecmp(s, seek->arg, ll)) break;
-            if (!*s) s = 0;
-          } else s = strstr(line, seek->arg);
+          if (toys.optflags & FLAG_i) s = strnstr(line, seek->arg);
+          else s = strstr(line, seek->arg);
           if (s) break;
         }
 
-- 
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