Maxim Pugachev wrote:
> In a case when the shell name is not specified (i.e. just "#!" without
> a path), don't run the heavy logic that checks shell, simply return
> ENOENT.
I'm not sure whether this is a reasonable thing to do. Someone with more
kernel API experience will have to comment.
> Also, as a tiny improvement: avoid a loop when calculating shell's
> args length.
It seems like there's a simpler solution to this: strlen. Also, the
assignment that follows the for loop seems dead, as we know *cp will be
NUL.
The below diff makes that change, removes the useless if condition you
noticed, and bumps a few variable initializations into the declaration
block.
Index: sys/kern/exec_script.c
===================================================================
RCS file: /cvs/src/sys/kern/exec_script.c,v
retrieving revision 1.37
diff -u -p -r1.37 exec_script.c
--- sys/kern/exec_script.c 31 Dec 2015 18:55:33 -0000 1.37
+++ sys/kern/exec_script.c 10 Jan 2016 01:41:55 -0000
@@ -67,9 +67,9 @@
int
exec_script_makecmds(struct proc *p, struct exec_package *epp)
{
- int error, hdrlinelen, shellnamelen, shellarglen;
+ int error, hdrlinelen, shellnamelen, shellarglen = 0;
char *hdrstr = epp->ep_hdr;
- char *cp, *shellname, *shellarg, *oldpnbuf;
+ char *cp, *shellname = NULL, *shellarg = NULL, *oldpnbuf;
char **shellargp = NULL, **tmpsap;
struct vnode *scriptvp;
uid_t script_uid = -1;
@@ -110,10 +110,6 @@ exec_script_makecmds(struct proc *p, str
if (cp >= hdrstr + hdrlinelen)
return ENOEXEC;
- shellname = NULL;
- shellarg = NULL;
- shellarglen = 0;
-
/* strip spaces before the shell name */
for (cp = hdrstr + EXEC_SCRIPT_MAGICLEN; *cp == ' ' || *cp == '\t';
cp++)
@@ -122,8 +118,6 @@ exec_script_makecmds(struct proc *p, str
/* collect the shell name; remember its length for later */
shellname = cp;
shellnamelen = 0;
- if (*cp == '\0')
- goto check_shell;
for ( /* cp = cp */ ; *cp != '\0' && *cp != ' ' && *cp != '\t'; cp++)
shellnamelen++;
if (*cp == '\0')
@@ -142,9 +136,8 @@ exec_script_makecmds(struct proc *p, str
* behaviour.
*/
shellarg = cp;
- for ( /* cp = cp */ ; *cp != '\0'; cp++)
- shellarglen++;
- *cp++ = '\0';
+ shellarglen = strlen(shellarg);
+ cp += shellarglen + 1;
check_shell:
/*
