From a068bf7aa310e8d36ae11c2aec47af1446a18827 Mon Sep 17 00:00:00 2001 From: Herbert Xu Date: Sat, 19 May 2018 02:39:50 +0800 Subject: 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 --- src/cd.c | 2 +- src/exec.c | 133 +++++++++++++++++++++++++++++++++++++------------------------ src/exec.h | 7 +++- src/mail.c | 2 +- src/main.c | 3 +- 5 files changed, 92 insertions(+), 55 deletions(-) (limited to 'src') diff --git a/src/cd.c b/src/cd.c index 610a4fa..b6742af 100644 --- a/src/cd.c +++ b/src/cd.c @@ -128,7 +128,7 @@ dotdot: if (!*dest) dest = "."; path = bltinlookup("CDPATH"); - while (p = path, (len = padvance(&path, dest)) >= 0) { + while (p = path, (len = padvance_magic(&path, dest, 0)) >= 0) { c = *p; p = stalloc(len); diff --git a/src/exec.c b/src/exec.c index 04ee2ba..8948754 100644 --- a/src/exec.c +++ b/src/exec.c @@ -92,7 +92,7 @@ STATIC int builtinloc = -1; /* index in path of %builtin, or -1 */ STATIC void tryexec(char *, char **, char **); STATIC void printentry(struct tblentry *); -STATIC void clearcmdentry(int); +STATIC void clearcmdentry(void); STATIC struct tblentry *cmdlookup(const char *, int); STATIC void delete_cmd_entry(void); STATIC void addcmdentry(char *, struct cmdentry *); @@ -168,7 +168,27 @@ repeat: } } +static const char *legal_pathopt(const char *opt, const char *term, int magic) +{ + switch (magic) { + case 0: + opt = NULL; + break; + case 1: + opt = prefix(opt, "builtin") ?: prefix(opt, "func"); + break; + + default: + opt += strcspn(opt, term); + break; + } + + if (opt && *opt == '%') + opt++; + + return opt; +} /* * Do a path search. The variable path (passed by reference) should be @@ -178,39 +198,64 @@ repeat: * a percent sign) appears in the path entry then the global variable * pathopt will be set to point to it; otherwise pathopt will be set to * NULL. + * + * If magic is 0 then pathopt recognition will be disabled. If magic is + * 1 we shall recognise %builtin/%func. Otherwise we shall accept any + * pathopt. */ const char *pathopt; -int padvance(const char **path, const char *name) +int padvance_magic(const char **path, const char *name, int magic) { + const char *term = "%:"; + const char *lpathopt; const char *p; char *q; const char *start; + size_t qlen; size_t len; if (*path == NULL) return -1; + + lpathopt = NULL; start = *path; - for (p = start ; *p && *p != ':' && *p != '%' ; p++); - len = p - start + strlen(name) + 2; /* "2" is for '/' and '\0' */ - q = growstackto(len); - if (p != start) { - memcpy(q, start, p - start); - q += p - start; - *q++ = '/'; + + if (*start == '%' && (p = legal_pathopt(start + 1, term, magic))) { + lpathopt = start + 1; + start = p; + term = ":"; } - strcpy(q, name); - pathopt = NULL; + + len = strcspn(start, term); + p = start + len; + if (*p == '%') { - pathopt = ++p; - while (*p && *p != ':') p++; + size_t extra = strchrnul(p, ':') - p; + + if (legal_pathopt(p + 1, term, magic)) + lpathopt = p + 1; + else + len += extra; + + p += extra; + } + + pathopt = lpathopt; + *path = *p == ':' ? p + 1 : NULL; + + /* "2" is for '/' and '\0' */ + qlen = len + strlen(name) + 2; + q = growstackto(qlen); + + if (likely(len)) { + q = mempcpy(q, start, len); + *q++ = '/'; } - if (*p == ':') - *path = p + 1; - else - *path = NULL; - return len; + strcpy(q, name); + + return qlen; } @@ -228,7 +273,7 @@ hashcmd(int argc, char **argv) char *name; while ((c = nextopt("r")) != '\0') { - clearcmdentry(0); + clearcmdentry(); return 0; } if (*argptr == NULL) { @@ -363,15 +408,16 @@ find_command(char *name, struct cmdentry *entry, int act, const char *path) idx = -1; loop: while ((len = padvance(&path, name)) >= 0) { + const char *lpathopt = pathopt; + fullname = stackblock(); idx++; - if (pathopt) { - if (prefix(pathopt, "builtin")) { + if (lpathopt) { + if (*lpathopt == 'b') { if (bcmd) goto builtin_success; continue; - } else if (!(act & DO_NOFUNC) && - prefix(pathopt, "func")) { + } else if (!(act & DO_NOFUNC)) { /* handled below */ } else { /* ignore unimplemented options */ @@ -397,7 +443,7 @@ loop: e = EACCES; /* if we fail, this will be the error */ if (!S_ISREG(statb.st_mode)) continue; - if (pathopt) { /* this is a %func directory */ + if (lpathopt) { /* this is a %func directory */ stalloc(len); readcmdfile(fullname); if ((cmdp = cmdlookup(name, 0)) == NULL || @@ -515,39 +561,26 @@ hashcd(void) void changepath(const char *newval) { - const char *old, *new; + const char *new; int idx; - int firstchange; int bltin; - old = pathval(); new = newval; - firstchange = 9999; /* assume no change */ idx = 0; bltin = -1; for (;;) { - if (*old != *new) { - firstchange = idx; - if ((*old == '\0' && *new == ':') - || (*old == ':' && *new == '\0')) - firstchange++; - old = new; /* ignore subsequent differences */ - } - if (*new == '\0') - break; - if (*new == '%' && bltin < 0 && prefix(new + 1, "builtin")) + if (*new == '%' && prefix(new + 1, "builtin")) { bltin = idx; - if (*new == ':') { - idx++; + break; } - new++, old++; + new = strchr(new, ':'); + if (!new) + break; + idx++; + new++; } - if (builtinloc < 0 && bltin >= 0) - builtinloc = bltin; /* zap builtins */ - if (builtinloc >= 0 && bltin < 0) - firstchange = 0; - clearcmdentry(firstchange); builtinloc = bltin; + clearcmdentry(); } @@ -557,7 +590,7 @@ changepath(const char *newval) */ STATIC void -clearcmdentry(int firstchange) +clearcmdentry(void) { struct tblentry **tblp; struct tblentry **pp; @@ -567,10 +600,8 @@ clearcmdentry(int firstchange) for (tblp = cmdtable ; tblp < &cmdtable[CMDTABLESIZE] ; tblp++) { pp = tblp; while ((cmdp = *pp) != NULL) { - if ((cmdp->cmdtype == CMDNORMAL && - cmdp->param.index >= firstchange) - || (cmdp->cmdtype == CMDBUILTIN && - builtinloc >= firstchange)) { + if (cmdp->cmdtype == CMDNORMAL || + (cmdp->cmdtype == CMDBUILTIN && builtinloc > 0)) { *pp = cmdp->next; ckfree(cmdp); } else { 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); +} diff --git a/src/mail.c b/src/mail.c index 7f9e49d..8eacb2d 100644 --- a/src/mail.c +++ b/src/mail.c @@ -79,7 +79,7 @@ chkmail(void) for (mtp = mailtime; mtp < mailtime + MAXMBOXES; mtp++) { int len; - len = padvance(&mpath, nullstr); + len = padvance_magic(&mpath, nullstr, 2); if (!len) break; p = stackblock(); diff --git a/src/main.c b/src/main.c index c87fbd7..e8e4256 100644 --- a/src/main.c +++ b/src/main.c @@ -300,7 +300,8 @@ find_dot_file(char *basename) while ((len = padvance(&path, basename)) >= 0) { fullname = stackblock(); - if ((stat(fullname, &statb) == 0) && S_ISREG(statb.st_mode)) { + if ((!pathopt || *pathopt == 'f') && + !stat(fullname, &statb) && S_ISREG(statb.st_mode)) { /* This will be freed by the caller. */ return stalloc(len); } -- cgit 1.4.1