From patchwork Mon May 14 16:37:40 2018 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Herbert Xu X-Patchwork-Id: 10398887 X-Patchwork-Delegate: herbert@gondor.apana.org.au Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork.web.codeaurora.org (Postfix) with ESMTP id 01ED86038F for ; Mon, 14 May 2018 16:37:45 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id E032C2836F for ; Mon, 14 May 2018 16:37:44 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id D4603283B0; Mon, 14 May 2018 16:37:44 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-7.9 required=2.0 tests=BAYES_00, MAILING_LIST_MULTI, RCVD_IN_DNSWL_HI autolearn=ham version=3.3.1 Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 27FAA2836F for ; Mon, 14 May 2018 16:37:44 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752691AbeENQhn (ORCPT ); Mon, 14 May 2018 12:37:43 -0400 Received: from orcrist.hmeau.com ([104.223.48.154]:45262 "EHLO deadmen.hmeau.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752423AbeENQhn (ORCPT ); Mon, 14 May 2018 12:37:43 -0400 Received: from gondobar.mordor.me.apana.org.au ([192.168.128.4] helo=gondobar) by deadmen.hmeau.com with esmtps (Exim 4.89 #2 (Debian)) id 1fIGTl-0007N9-Mh; Tue, 15 May 2018 00:37:41 +0800 Received: from herbert by gondobar with local (Exim 4.89) (envelope-from ) id 1fIGTk-0008Rm-E0; Tue, 15 May 2018 00:37:40 +0800 Date: Tue, 15 May 2018 00:37:40 +0800 From: Herbert Xu To: DASH Mailing List Subject: exec: Do not allocate stack string in padvance Message-ID: <20180514163740.kxlo7t74kl5dlinz@gondor.apana.org.au> MIME-Version: 1.0 Content-Disposition: inline User-Agent: NeoMutt/20170113 (1.7.2) Sender: dash-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: dash@vger.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP Many callers of padvance immediately free the allocated string so this patch moves the stalloc call to the caller. Instead of returning the allocated string, padvance now returns the length to allocate (this may be longer than the actual string length, even including the NUL). For the case where we would previously return NULL, we now return -1. Signed-off-by: Herbert Xu diff --git a/src/cd.c b/src/cd.c index a4e024d..7cc8d6f 100644 --- a/src/cd.c +++ b/src/cd.c @@ -98,6 +98,7 @@ cdcmd(int argc, char **argv) char c; struct stat statb; int flags; + int len; flags = cdopt(); dest = *argptr; @@ -127,9 +128,10 @@ dotdot: if (!*dest) dest = "."; path = bltinlookup("CDPATH"); - while (path) { - c = *path; - p = padvance(&path, dest); + while (p = path, (len = padvance(&path, dest)) >= 0) { + c = *p; + p = stalloc(len); + if (stat(p, &statb) >= 0 && S_ISDIR(statb.st_mode)) { if (c && c != ':') flags |= CD_PRINT; diff --git a/src/exec.c b/src/exec.c index 3c0c3b6..9257830 100644 --- a/src/exec.c +++ b/src/exec.c @@ -118,13 +118,13 @@ shellexec(char **argv, const char *path, int idx) e = errno; } else { e = ENOENT; - while ((cmdname = padvance(&path, argv[0])) != NULL) { + while (padvance(&path, argv[0]) >= 0) { + cmdname = stackblock(); if (--idx < 0 && pathopt == NULL) { tryexec(cmdname, argv, envp); if (errno != ENOENT && errno != ENOTDIR) e = errno; } - stunalloc(cmdname); } } @@ -182,8 +182,7 @@ repeat: const char *pathopt; -char * -padvance(const char **path, const char *name) +int padvance(const char **path, const char *name) { const char *p; char *q; @@ -191,7 +190,7 @@ padvance(const char **path, const char *name) size_t len; if (*path == NULL) - return NULL; + return -1; start = *path; for (p = start ; *p && *p != ':' && *p != '%' ; p++); len = p - start + strlen(name) + 2; /* "2" is for '/' and '\0' */ @@ -211,7 +210,7 @@ padvance(const char **path, const char *name) *path = p + 1; else *path = NULL; - return stalloc(len); + return len; } @@ -266,9 +265,9 @@ printentry(struct tblentry *cmdp) idx = cmdp->param.index; path = pathval(); do { - name = padvance(&path, cmdp->cmdname); - stunalloc(name); + padvance(&path, cmdp->cmdname); } while (--idx >= 0); + name = stackblock(); out1str(name); out1fmt(snlfmt, cmdp->rehash ? "*" : nullstr); } @@ -291,6 +290,7 @@ find_command(char *name, struct cmdentry *entry, int act, const char *path) int e; int updatetbl; struct builtincmd *bcmd; + int len; /* If name contains a slash, don't use PATH or hash table */ if (strchr(name, '/') != NULL) { @@ -362,8 +362,8 @@ find_command(char *name, struct cmdentry *entry, int act, const char *path) e = ENOENT; idx = -1; loop: - while ((fullname = padvance(&path, name)) != NULL) { - stunalloc(fullname); + while ((len = padvance(&path, name)) >= 0) { + fullname = stackblock(); idx++; if (pathopt) { if (prefix(pathopt, "builtin")) { @@ -398,7 +398,7 @@ loop: if (!S_ISREG(statb.st_mode)) continue; if (pathopt) { /* this is a %func directory */ - stalloc(strlen(fullname) + 1); + stalloc(len); readcmdfile(fullname); if ((cmdp = cmdlookup(name, 0)) == NULL || cmdp->cmdtype != CMDFUNCTION) @@ -789,9 +789,9 @@ describe_command(out, command, path, verbose) p = command; } else { do { - p = padvance(&path, command); - stunalloc(p); + padvance(&path, command); } while (--j >= 0); + p = stackblock(); } if (verbose) { outfmt( diff --git a/src/exec.h b/src/exec.h index 9ccb305..e241b74 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__)); -char *padvance(const char **, const char *); +int padvance(const char **, const char *); int hashcmd(int, char **); void find_command(char *, struct cmdentry *, int, const char *); struct builtincmd *find_builtin(const char *); diff --git a/src/mail.c b/src/mail.c index 02e07f7..7f9e49d 100644 --- a/src/mail.c +++ b/src/mail.c @@ -77,9 +77,12 @@ chkmail(void) setstackmark(&smark); mpath = mpathset() ? mpathval() : mailval(); for (mtp = mailtime; mtp < mailtime + MAXMBOXES; mtp++) { - p = padvance(&mpath, nullstr); - if (p == NULL) + int len; + + len = padvance(&mpath, nullstr); + if (!len) break; + p = stackblock(); if (*p == '\0') continue; for (q = p ; *q ; q++); diff --git a/src/main.c b/src/main.c index fcd3e7d..80f9e79 100644 --- a/src/main.c +++ b/src/main.c @@ -290,20 +290,18 @@ find_dot_file(char *basename) char *fullname; const char *path = pathval(); struct stat statb; + int len; /* don't try this for absolute or relative paths */ if (strchr(basename, '/')) return basename; - while ((fullname = padvance(&path, basename)) != NULL) { + while ((len = padvance(&path, basename)) >= 0) { + fullname = stackblock(); if ((stat(fullname, &statb) == 0) && S_ISREG(statb.st_mode)) { - /* - * Don't bother freeing here, since it will - * be freed by the caller. - */ - return fullname; + /* This will be freed by the caller. */ + return stalloc(len); } - stunalloc(fullname); } /* not found in the PATH */