exec: Stricter pathopt parsing

This patch changes the parsing of pathopt.  First of all only
%builtin and %func (with arbitrary suffixes) will be recognised.
Any other pathopt will be treated as a normal directory.

Furthermore, pathopt can now be specified before the directory,
rather than after it.  In fact, a future version may remove support
for pathopt suffixes.

Wherever the pathopt is placed, an optional % may be placed after
it to terminate the pathopt.

This is so that it is less likely that a genuine directory containing
a % sign is parsed as a pathopt.

Users of padvance outside of exec.c have also been modified:

1) cd(1) will always treat % characters as part of the path.
2) chkmail will continue to accept arbitrary pathopt.
3) find_dot_file will ignore the %builtin pathopt instead of trying
to do a stat in the accompanying directory (which is usually the
current directory).

The patch also removes the clearcmdentry optimisation where we
attempt to only partially flush the table where possible.

Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

1 files changed, 6 insertions, 1 deletions

diff --git a/src/exec.h b/src/exec.h
index e241b74..f394f3f 100644
--- a/src/exec.h
+++ b/src/exec.h
@@ -62,7 +62,7 @@ extern const char *pathopt;	/* set by padvance */
 
 void shellexec(char **, const char *, int)
     __attribute__((__noreturn__));
-int padvance(const char **, const char *);
+int padvance_magic(const char **path, const char *name, int magic);
 int hashcmd(int, char **);
 void find_command(char *, struct cmdentry *, int, const char *);
 struct builtincmd *find_builtin(const char *);
@@ -75,3 +75,8 @@ void defun(union node *);
 void unsetfunc(const char *);
 int typecmd(int, char **);
 int commandcmd(int, char **);
+
+static inline int padvance(const char **path, const char *name)
+{
+	return padvance_magic(path, name, 1);
+}