/* $NetBSD: exec.c,v 1.34 2002/11/24 22:35:39 christos Exp $ */ /*- * Copyright (c) 1991, 1993 * The Regents of the University of California. All rights reserved. * * This code is derived from software contributed to Berkeley by * Kenneth Almquist. * * Redistribution and use in source and binary forms, with or without * modification, are permitted provided that the following conditions * are met: * 1. Redistributions of source code must retain the above copyright * notice, this list of conditions and the following disclaimer. * 2. Redistributions in binary form must reproduce the above copyright * notice, this list of conditions and the following disclaimer in the * documentation and/or other materials provided with the distribution. * 3. All advertising materials mentioning features or use of this software * must display the following acknowledgement: * This product includes software developed by the University of * California, Berkeley and its contributors. * 4. Neither the name of the University nor the names of its contributors * may be used to endorse or promote products derived from this software * without specific prior written permission. * * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF * SUCH DAMAGE. */ #include #ifndef lint #if 0 static char sccsid[] = "@(#)exec.c 8.4 (Berkeley) 6/8/95"; #else __RCSID("$NetBSD: exec.c,v 1.34 2002/11/24 22:35:39 christos Exp $"); #endif #endif /* not lint */ #include #include #include #include #include #include #include #include /* * When commands are first encountered, they are entered in a hash table. * This ensures that a full path search will not have to be done for them * on each invocation. * * We should investigate converting to a linear search, even though that * would make the command name "hash" a misnomer. */ #include "shell.h" #include "main.h" #include "nodes.h" #include "parser.h" #include "redir.h" #include "eval.h" #include "exec.h" #include "builtins.h" #include "var.h" #include "options.h" #include "input.h" #include "output.h" #include "syntax.h" #include "memalloc.h" #include "error.h" #include "init.h" #include "mystring.h" #include "show.h" #include "jobs.h" #include "alias.h" #define CMDTABLESIZE 31 /* should be prime */ #define ARB 1 /* actual size determined at run time */ struct tblentry { struct tblentry *next; /* next entry in hash chain */ union param param; /* definition of builtin function */ short cmdtype; /* index identifying command */ char rehash; /* if set, cd done since entry created */ char cmdname[ARB]; /* name of command */ }; STATIC struct tblentry *cmdtable[CMDTABLESIZE]; STATIC int builtinloc = -1; /* index in path of %builtin, or -1 */ int exerrno = 0; /* Last exec error */ STATIC void tryexec(char *, char **, char **, int); STATIC void execinterp(char **, char **); STATIC void printentry(struct tblentry *, int); STATIC void clearcmdentry(int); STATIC struct tblentry *cmdlookup(const char *, int); STATIC void delete_cmd_entry(void); extern char *const parsekwd[]; /* * Exec a program. Never returns. If you change this routine, you may * have to change the find_command routine as well. */ void shellexec(char **argv, char **envp, const char *path, int idx, int vforked) { char *cmdname; int e; if (strchr(argv[0], '/') != NULL) { tryexec(argv[0], argv, envp, vforked); e = errno; } else { e = ENOENT; while ((cmdname = padvance(&path, argv[0])) != NULL) { if (--idx < 0 && pathopt == NULL) { tryexec(cmdname, argv, envp, vforked); if (errno != ENOENT && errno != ENOTDIR) e = errno; } stunalloc(cmdname); } } /* Map to POSIX errors */ switch (e) { case EACCES: exerrno = 126; break; case ENOENT: exerrno = 127; break; default: exerrno = 2; break; } TRACE(("shellexec failed for %s, errno %d, vforked %d, suppressint %d\n", argv[0], e, vforked, suppressint )); exerror(EXEXEC, "%s: %s", argv[0], errmsg(e, E_EXEC)); /* NOTREACHED */ } STATIC void tryexec(char *cmd, char **argv, char **envp, int vforked) { int e; #ifndef BSD char *p; #endif #ifdef SYSV do { execve(cmd, argv, envp); } while (errno == EINTR); #else execve(cmd, argv, envp); #endif e = errno; if (e == ENOEXEC) { if (vforked) { /* We are currently vfork(2)ed, so raise an * exception, and evalcommand will try again * with a normal fork(2). */ exraise(EXSHELLPROC); } initshellproc(); setinputfile(cmd, 0); commandname = arg0 = savestr(argv[0]); #ifndef BSD pgetc(); pungetc(); /* fill up input buffer */ p = parsenextc; if (parsenleft > 2 && p[0] == '#' && p[1] == '!') { argv[0] = cmd; execinterp(argv, envp); } #endif setparam(argv + 1); exraise(EXSHELLPROC); } errno = e; } #ifndef BSD /* * Execute an interpreter introduced by "#!", for systems where this * feature has not been built into the kernel. If the interpreter is * the shell, return (effectively ignoring the "#!"). If the execution * of the interpreter fails, exit. * * This code peeks inside the input buffer in order to avoid actually * reading any input. It would benefit from a rewrite. */ #define NEWARGS 5 STATIC void execinterp(char **argv, char **envp) { int n; char *inp; char *outp; char c; char *p; char **ap; char *newargs[NEWARGS]; int i; char **ap2; char **new; n = parsenleft - 2; inp = parsenextc + 2; ap = newargs; for (;;) { while (--n >= 0 && (*inp == ' ' || *inp == '\t')) inp++; if (n < 0) goto bad; if ((c = *inp++) == '\n') break; if (ap == &newargs[NEWARGS]) bad: error("Bad #! line"); STARTSTACKSTR(outp); do { STPUTC(c, outp); } while (--n >= 0 && (c = *inp++) != ' ' && c != '\t' && c != '\n'); STPUTC('\0', outp); n++, inp--; *ap++ = grabstackstr(outp); } if (ap == newargs + 1) { /* if no args, maybe no exec is needed */ p = newargs[0]; for (;;) { if (equal(p, "sh") || equal(p, "ash")) { return; } while (*p != '/') { if (*p == '\0') goto break2; p++; } p++; } break2:; } i = (char *)ap - (char *)newargs; /* size in bytes */ if (i == 0) error("Bad #! line"); for (ap2 = argv ; *ap2++ != NULL ; ); new = ckmalloc(i + ((char *)ap2 - (char *)argv)); ap = newargs, ap2 = new; while ((i -= sizeof (char **)) >= 0) *ap2++ = *ap++; ap = argv; while (*ap2++ = *ap++); shellexec(new, envp, pathval(), 0); /* NOTREACHED */ } #endif /* * Do a path search. The variable path (passed by reference) should be * set to the start of the path before the first call; padvance will update * this value as it proceeds. Successive calls to padvance will return * the possible path expansions in sequence. If an option (indicated by * 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. */ const char *pathopt; char * padvance(const char **path, const char *name) { const char *p; char *q; const char *start; int len; if (*path == NULL) return NULL; start = *path; for (p = start ; *p && *p != ':' && *p != '%' ; p++); len = p - start + strlen(name) + 2; /* "2" is for '/' and '\0' */ while (stackblocksize() < len) growstackblock(); q = stackblock(); if (p != start) { memcpy(q, start, p - start); q += p - start; *q++ = '/'; } strcpy(q, name); pathopt = NULL; if (*p == '%') { pathopt = ++p; while (*p && *p != ':') p++; } if (*p == ':') *path = p + 1; else *path = NULL; return stalloc(len); } /*** Command hashing code ***/ int hashcmd(int argc, char **argv) { struct tblentry **pp; struct tblentry *cmdp; int c; int verbose; struct cmdentry entry; char *name; verbose = 0; while ((c = nextopt("rv")) != '\0') { if (c == 'r') { clearcmdentry(0); } else if (c == 'v') { verbose++; } } if (*argptr == NULL) { for (pp = cmdtable ; pp < &cmdtable[CMDTABLESIZE] ; pp++) { for (cmdp = *pp ; cmdp ; cmdp = cmdp->next) { printentry(cmdp, verbose); } } return 0; } while ((name = *argptr) != NULL) { if ((cmdp = cmdlookup(name, 0)) != NULL && (cmdp->cmdtype == CMDNORMAL || (cmdp->cmdtype == CMDBUILTIN && builtinloc >= 0))) delete_cmd_entry(); find_command(name, &entry, DO_ERR, pathval()); if (verbose) { if (entry.cmdtype != CMDUNKNOWN) { /* if no error msg */ cmdp = cmdlookup(name, 0); printentry(cmdp, verbose); } flushall(); } argptr++; } return 0; } STATIC void printentry(struct tblentry *cmdp, int verbose) { int idx; const char *path; char *name; switch (cmdp->cmdtype) { case CMDNORMAL: idx = cmdp->param.index; path = pathval(); do { name = padvance(&path, cmdp->cmdname); stunalloc(name); } while (--idx >= 0); out1str(name); break; case CMDSPLBLTIN: out1fmt("special builtin %s", cmdp->cmdname); break; case CMDBUILTIN: out1fmt("builtin %s", cmdp->cmdname); break; case CMDFUNCTION: out1fmt("function %s", cmdp->cmdname); if (verbose) { struct procstat ps; INTOFF; commandtext(&ps, cmdp->param.func); out1c(' '); out1str(ps.cmd); INTON; } break; default: error("internal error: %s cmdtype %d", cmdp->cmdname, cmdp->cmdtype); } if (cmdp->rehash) out1c('*'); out1c('\n'); } /* * Resolve a command name. If you change this routine, you may have to * change the shellexec routine as well. */ void find_command(char *name, struct cmdentry *entry, int act, const char *path) { struct tblentry *cmdp; int idx; int prev; char *fullname; struct stat statb; int e; int (*bltin)(int,char **); /* If name contains a slash, don't use the hash table */ if (strchr(name, '/') != NULL) { if (act & DO_ABS) { while (stat(name, &statb) < 0) { #ifdef SYSV if (errno == EINTR) continue; #endif if (errno != ENOENT && errno != ENOTDIR) e = errno; entry->cmdtype = CMDUNKNOWN; entry->u.index = -1; return; } entry->cmdtype = CMDNORMAL; entry->u.index = -1; return; } entry->cmdtype = CMDNORMAL; entry->u.index = 0; return; } /* If name is in the table, and not invalidated by cd, we're done */ if ((cmdp = cmdlookup(name, 0)) != NULL && cmdp->rehash == 0) goto success; /* If %builtin not in path, check for builtin next */ if (builtinloc < 0 && (bltin = find_builtin(name)) != 0) { INTOFF; cmdp = cmdlookup(name, 1); cmdp->cmdtype = CMDBUILTIN; cmdp->param.bltin = bltin; INTON; goto success; } /* We have to search path. */ prev = -1; /* where to start */ if (cmdp) { /* doing a rehash */ if (cmdp->cmdtype == CMDBUILTIN) prev = builtinloc; else prev = cmdp->param.index; } e = ENOENT; idx = -1; loop: while ((fullname = padvance(&path, name)) != NULL) { stunalloc(fullname); idx++; if (pathopt) { if (prefix("builtin", pathopt)) { if ((bltin = find_builtin(name)) == 0) goto loop; INTOFF; cmdp = cmdlookup(name, 1); cmdp->cmdtype = CMDBUILTIN; cmdp->param.bltin = bltin; INTON; goto success; } else if (prefix("func", pathopt)) { /* handled below */ } else { goto loop; /* ignore unimplemented options */ } } /* if rehash, don't redo absolute path names */ if (fullname[0] == '/' && idx <= prev) { if (idx < prev) goto loop; TRACE(("searchexec \"%s\": no change\n", name)); goto success; } while (stat(fullname, &statb) < 0) { #ifdef SYSV if (errno == EINTR) continue; #endif if (errno != ENOENT && errno != ENOTDIR) e = errno; goto loop; } e = EACCES; /* if we fail, this will be the error */ if (!S_ISREG(statb.st_mode)) goto loop; if (pathopt) { /* this is a %func directory */ stalloc(strlen(fullname) + 1); readcmdfile(fullname); if ((cmdp = cmdlookup(name, 0)) == NULL || cmdp->cmdtype != CMDFUNCTION) error("%s not defined in %s", name, fullname); stunalloc(fullname); goto success; } #ifdef notdef if (statb.st_uid == geteuid()) { if ((statb.st_mode & 0100) == 0) goto loop; } else if (statb.st_gid == getegid()) { if ((statb.st_mode & 010) == 0) goto loop; } else { if ((statb.st_mode & 01) == 0) goto loop; } #endif TRACE(("searchexec \"%s\" returns \"%s\"\n", name, fullname)); INTOFF; cmdp = cmdlookup(name, 1); cmdp->cmdtype = CMDNORMAL; cmdp->param.index = idx; INTON; goto success; } /* We failed. If there was an entry for this command, delete it */ if (cmdp) delete_cmd_entry(); if (act & DO_ERR) outfmt(out2, "%s: %s\n", name, errmsg(e, E_EXEC)); entry->cmdtype = CMDUNKNOWN; return; success: cmdp->rehash = 0; entry->cmdtype = cmdp->cmdtype; entry->u = cmdp->param; } /* * Search the table of builtin commands. */ int (*find_builtin(name))(int, char **) char *name; { const struct builtincmd *bp; for (bp = builtincmd ; bp->name ; bp++) { if (*bp->name == *name && equal(bp->name, name)) return bp->builtin; } return 0; } int (*find_splbltin(name))(int, char **) char *name; { const struct builtincmd *bp; for (bp = splbltincmd ; bp->name ; bp++) { if (*bp->name == *name && equal(bp->name, name)) return bp->builtin; } return 0; } /* * At shell startup put special builtins into hash table. * ensures they are executed first (see posix). * We stop functions being added with the same name * (as they are impossible to call) */ void hash_special_builtins(void) { const struct builtincmd *bp; struct tblentry *cmdp; for (bp = splbltincmd ; bp->name ; bp++) { cmdp = cmdlookup(bp->name, 1); cmdp->cmdtype = CMDSPLBLTIN; cmdp->param.bltin = bp->builtin; } } /* * Called when a cd is done. Marks all commands so the next time they * are executed they will be rehashed. */ void hashcd(void) { struct tblentry **pp; struct tblentry *cmdp; for (pp = cmdtable ; pp < &cmdtable[CMDTABLESIZE] ; pp++) { for (cmdp = *pp ; cmdp ; cmdp = cmdp->next) { if (cmdp->cmdtype == CMDNORMAL || (cmdp->cmdtype == CMDBUILTIN && builtinloc >= 0)) cmdp->rehash = 1; } } } /* * Called before PATH is changed. The argument is the new value of PATH; * pathval() still returns the old value at this point. Called with * interrupts off. */ void changepath(const char *newval) { const char *old, *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("builtin", new + 1)) bltin = idx; if (*new == ':') { idx++; } new++, old++; } if (builtinloc < 0 && bltin >= 0) builtinloc = bltin; /* zap builtins */ if (builtinloc >= 0 && bltin < 0) firstchange = 0; clearcmdentry(firstchange); builtinloc = bltin; } /* * Clear out command entries. The argument specifies the first entry in * PATH which has changed. */ STATIC void clearcmdentry(int firstchange) { struct tblentry **tblp; struct tblentry **pp; struct tblentry *cmdp; INTOFF; 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)) { *pp = cmdp->next; ckfree(cmdp); } else { pp = &cmdp->next; } } } INTON; } /* * Delete all functions. */ #ifdef mkinit MKINIT void deletefuncs(void); MKINIT void hash_special_builtins(void); INIT { hash_special_builtins(); } SHELLPROC { deletefuncs(); } #endif void deletefuncs(void) { struct tblentry **tblp; struct tblentry **pp; struct tblentry *cmdp; INTOFF; for (tblp = cmdtable ; tblp < &cmdtable[CMDTABLESIZE] ; tblp++) { pp = tblp; while ((cmdp = *pp) != NULL) { if (cmdp->cmdtype == CMDFUNCTION) { *pp = cmdp->next; freefunc(cmdp->param.func); ckfree(cmdp); } else { pp = &cmdp->next; } } } INTON; } /* * Locate a command in the command hash table. If "add" is nonzero, * add the command to the table if it is not already present. The * variable "lastcmdentry" is set to point to the address of the link * pointing to the entry, so that delete_cmd_entry can delete the * entry. */ struct tblentry **lastcmdentry; STATIC struct tblentry * cmdlookup(const char *name, int add) { int hashval; const char *p; struct tblentry *cmdp; struct tblentry **pp; p = name; hashval = *p << 4; while (*p) hashval += *p++; hashval &= 0x7FFF; pp = &cmdtable[hashval % CMDTABLESIZE]; for (cmdp = *pp ; cmdp ; cmdp = cmdp->next) { if (equal(cmdp->cmdname, name)) break; pp = &cmdp->next; } if (add && cmdp == NULL) { INTOFF; cmdp = *pp = ckmalloc(sizeof (struct tblentry) - ARB + strlen(name) + 1); cmdp->next = NULL; cmdp->cmdtype = CMDUNKNOWN; cmdp->rehash = 0; strcpy(cmdp->cmdname, name); INTON; } lastcmdentry = pp; return cmdp; } /* * Delete the command entry returned on the last lookup. */ STATIC void delete_cmd_entry(void) { struct tblentry *cmdp; INTOFF; cmdp = *lastcmdentry; *lastcmdentry = cmdp->next; ckfree(cmdp); INTON; } #ifdef notdef void getcmdentry(char *name, struct cmdentry *entry) { struct tblentry *cmdp = cmdlookup(name, 0); if (cmdp) { entry->u = cmdp->param; entry->cmdtype = cmdp->cmdtype; } else { entry->cmdtype = CMDUNKNOWN; entry->u.index = 0; } } #endif /* * Add a new command entry, replacing any existing command entry for * the same name - except special builtins. */ void addcmdentry(char *name, struct cmdentry *entry) { struct tblentry *cmdp; INTOFF; cmdp = cmdlookup(name, 1); if (cmdp->cmdtype != CMDSPLBLTIN) { if (cmdp->cmdtype == CMDFUNCTION) { freefunc(cmdp->param.func); } cmdp->cmdtype = entry->cmdtype; cmdp->param = entry->u; } INTON; } /* * Define a shell function. */ void defun(char *name, union node *func) { struct cmdentry entry; INTOFF; entry.cmdtype = CMDFUNCTION; entry.u.func = copyfunc(func); addcmdentry(name, &entry); INTON; } /* * Delete a function if it exists. */ int unsetfunc(char *name) { struct tblentry *cmdp; if ((cmdp = cmdlookup(name, 0)) != NULL && cmdp->cmdtype == CMDFUNCTION) { freefunc(cmdp->param.func); delete_cmd_entry(); return (0); } return (1); } /* * Locate and print what a word is... */ int typecmd(int argc, char **argv) { struct cmdentry entry; struct tblentry *cmdp; char * const *pp; struct alias *ap; int i; int err = 0; for (i = 1; i < argc; i++) { out1str(argv[i]); /* First look at the keywords */ for (pp = parsekwd; *pp; pp++) if (**pp == *argv[i] && equal(*pp, argv[i])) break; if (*pp) { out1str(" is a shell keyword\n"); continue; } /* Then look at the aliases */ if ((ap = lookupalias(argv[i], 1)) != NULL) { out1fmt(" is an alias for %s\n", ap->val); continue; } /* Then check if it is a tracked alias */ if ((cmdp = cmdlookup(argv[i], 0)) != NULL) { entry.cmdtype = cmdp->cmdtype; entry.u = cmdp->param; } else { /* Finally use brute force */ find_command(argv[i], &entry, DO_ABS, pathval()); } switch (entry.cmdtype) { case CMDNORMAL: { if (strchr(argv[i], '/') == NULL) { const char *path = pathval(); char *name; int j = entry.u.index; do { name = padvance(&path, argv[i]); stunalloc(name); } while (--j >= 0); out1fmt(" is%s %s\n", cmdp ? " a tracked alias for" : "", name); } else { if (access(argv[i], X_OK) == 0) out1fmt(" is %s\n", argv[i]); else out1fmt(": %s\n", strerror(errno)); } break; } case CMDFUNCTION: out1str(" is a shell function\n"); break; case CMDBUILTIN: out1str(" is a shell builtin\n"); break; case CMDSPLBLTIN: out1str(" is a special shell builtin\n"); break; default: out1str(": not found\n"); err |= 127; break; } } return err; }