/* Copyright (C) 2006 by Paolo Giarrusso - modified from glibc' execvp.c. Original copyright notice follows: Copyright (C) 1991,92,1995-99,2002,2004 Free Software Foundation, Inc. This file is part of the GNU C Library. The GNU C Library is free software; you can redistribute it and/or modify it under the terms of the GNU Lesser General Public License as published by the Free Software Foundation; either version 2.1 of the License, or (at your option) any later version. The GNU C Library is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public License for more details. You should have received a copy of the GNU Lesser General Public License along with the GNU C Library; if not, write to the Free Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA. */ #include <unistd.h> #include <stdbool.h> #include <stdlib.h> #include <string.h> #include <errno.h> #include <limits.h> #ifndef TEST #include "um_malloc.h" #else #include <stdio.h> #define um_kmalloc malloc #endif #include "os.h" /* Execute FILE, searching in the `PATH' environment variable if it contains no slashes, with arguments ARGV and environment from `environ'. */ int execvp_noalloc(char *buf, const char *file, char *const argv[]) { if (*file == '\0') { return -ENOENT; } if (strchr (file, '/') != NULL) { /* Don't search when it contains a slash. */ execv(file, argv); } else { int got_eacces; size_t len, pathlen; char *name, *p; char *path = getenv("PATH"); if (path == NULL) path = ":/bin:/usr/bin"; len = strlen(file) + 1; pathlen = strlen(path); /* Copy the file name at the top. */ name = memcpy(buf + pathlen + 1, file, len); /* And add the slash. */ *--name = '/'; got_eacces = 0; p = path; do { char *startp; path = p; //Let's avoid this GNU extension. //p = strchrnul (path, ':'); p = strchr(path, ':'); if (!p) p = strchr(path, '\0'); if (p == path) /* Two adjacent colons, or a colon at the beginning or the end of `PATH' means to search the current directory. */ startp = name + 1; else startp = memcpy(name - (p - path), path, p - path); /* Try to execute this name. If it works, execv will not return. */ execv(startp, argv); /* if (errno == ENOEXEC) { } */ switch (errno) { case EACCES: /* Record the we got a `Permission denied' error. If we end up finding no executable we can use, we want to diagnose that we did find one but were denied access. */ got_eacces = 1; case ENOENT: case ESTALE: case ENOTDIR: /* Those errors indicate the file is missing or not executable by us, in which case we want to just try the next path directory. */ case ENODEV: case ETIMEDOUT: /* Some strange filesystems like AFS return even stranger error numbers. They cannot reasonably mean anything else so ignore those, too. */ case ENOEXEC: /* We won't go searching for the shell * if it is not executable - the Linux * kernel already handles this enough, * for us. */ break; default: /* Some other error means we found an executable file, but something went wrong executing it; return the error to our caller. */ return -errno; } } while (*p++ != '\0'); /* We tried every element and none of them worked. */ if (got_eacces) /* At least one failure was due to permissions, so report that error. */ return -EACCES; } /* Return the error from the last attempt (probably ENOENT). */ return -errno; } #ifdef TEST int main(int argc, char**argv) { char buf[PATH_MAX]; int ret; argc--; if (!argc) { fprintf(stderr, "Not enough arguments\n"); return 1; } argv++; if (ret = execvp_noalloc(buf, argv[0], argv)) { errno = -ret; perror("execvp_noalloc"); } return 0; } #endif