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authorDenys Vlasenko2016-10-26 22:29:11 +0200
committerDenys Vlasenko2016-10-26 22:29:11 +0200
commit65a8b859a9a3f2bb4a62c15ca1f4d01288593734 (patch)
tree11965425b70a8cb6f40a7ad1d4d64e730be313bb
parent0e081d01a8ae37df11af612eb65d858c1c0f28be (diff)
downloadbusybox-65a8b859a9a3f2bb4a62c15ca1f4d01288593734.zip
busybox-65a8b859a9a3f2bb4a62c15ca1f4d01288593734.tar.gz
ash: optimize tryexec(): avoid one allocation
There was a bug in tryexec which bbox had fixed in 2003. dash had a smaller fix in 2007. Copy it. It is smaller, although it is also more quirky (requires argv[-1] to exist). Upstream commit 1: Date: Mon, 15 Oct 2007 20:24:28 +0800 [EXEC] Fixed execing of scripts with no hash-bang The function tryexec used the original name instead of the path found through PATH search. This patch fixes that. Test case: trap 'rm -f $TMP' EXIT TMP=$(tempfile -s nosuchthing) cat <<- EOF > $TMP echo OK EOF chmod u+x $TMP cd / PATH=${TMP%/*} ${TMP##*/} Old result: /bin/sh: Can't open filelgY4Fanosuchthing New result: OK Upstream commit 2: Date: Sun, 23 Dec 2007 11:02:26 +0800 [EVAL] Fix bad pointer arithmetic in evalcommand dash dies on sparc with a SIGBUS due to an arithmetic error introduced with commit 03b4958, this patch fixes it. Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au> function old new delta evalcommand 1261 1264 +3 dotcmd 321 319 -2 tryexec 115 64 -51 ------------------------------------------------------------------------------ (add/remove: 0/0 grow/shrink: 1/2 up/down: 3/-53) Total: -50 bytes Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
-rw-r--r--shell/ash.c31
1 files changed, 11 insertions, 20 deletions
diff --git a/shell/ash.c b/shell/ash.c
index 8bf02e6..133b2d4 100644
--- a/shell/ash.c
+++ b/shell/ash.c
@@ -7467,13 +7467,7 @@ tryexec(IF_FEATURE_SH_STANDALONE(int applet_no,) char *cmd, char **argv, char **
#else
execve(cmd, argv, envp);
#endif
- if (cmd == (char*) bb_busybox_exec_path) {
- /* We already visited ENOEXEC branch below, don't do it again */
-//TODO: try execve(initial_argv0_of_shell, argv, envp) before giving up?
- free(argv);
- return;
- }
- if (errno == ENOEXEC) {
+ if (cmd != (char*) bb_busybox_exec_path && errno == ENOEXEC) {
/* Run "cmd" as a shell script:
* http://pubs.opengroup.org/onlinepubs/9699919799/utilities/V3_chap02.html
* "If the execve() function fails with ENOEXEC, the shell
@@ -7490,19 +7484,13 @@ tryexec(IF_FEATURE_SH_STANDALONE(int applet_no,) char *cmd, char **argv, char **
* message and exit code 126. For one, this prevents attempts
* to interpret foreign ELF binaries as shell scripts.
*/
- char **ap;
- char **new;
-
- for (ap = argv; *ap; ap++)
- continue;
- new = ckmalloc((ap - argv + 2) * sizeof(new[0]));
- new[0] = (char*) "ash";
- new[1] = cmd;
- ap = new + 2;
- while ((*ap++ = *++argv) != NULL)
- continue;
+ argv[0] = cmd;
cmd = (char*) bb_busybox_exec_path;
- argv = new;
+ /* NB: this is only possible because all callers of shellexec()
+ * ensure that the argv[-1] slot exists!
+ */
+ argv--;
+ argv[0] = (char*) "ash";
goto repeat;
}
}
@@ -7510,6 +7498,7 @@ tryexec(IF_FEATURE_SH_STANDALONE(int applet_no,) char *cmd, char **argv, char **
/*
* Exec a program. Never returns. If you change this routine, you may
* have to change the find_command routine as well.
+ * argv[-1] must exist and be writable! See tryexec() for why.
*/
static void shellexec(char **, const char *, int) NORETURN;
static void
@@ -9415,7 +9404,9 @@ evalcommand(union node *cmd, int flags)
argc++;
}
- argv = nargv = stalloc(sizeof(char *) * (argc + 1));
+ /* Reserve one extra spot at the front for shellexec. */
+ nargv = stalloc(sizeof(char *) * (argc + 2));
+ argv = ++nargv;
for (sp = arglist.list; sp; sp = sp->next) {
TRACE(("evalcommand arg: %s\n", sp->text));
*nargv++ = sp->text;