92 lines
2.6 KiB
C
92 lines
2.6 KiB
C
/*
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* Copyright (c) 2013
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* The President and Fellows of Harvard College.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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* 3. Neither the name of the University nor the names of its contributors
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* may be used to endorse or promote products derived from this software
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* without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE UNIVERSITY AND CONTRIBUTORS ``AS IS'' AND
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE UNIVERSITY OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*/
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#include <stdio.h>
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#include <stdlib.h>
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#include <string.h>
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#include <unistd.h>
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#include <errno.h>
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#include <limits.h>
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/*
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* POSIX C function: exec a program on the search path. Tries
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* execv() repeatedly until one of the choices works.
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*/
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int
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execvp(const char *prog, char *const *args)
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{
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const char *searchpath, *s, *t;
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char progpath[PATH_MAX];
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size_t len;
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if (strchr(prog, '/') != NULL) {
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execv(prog, args);
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return -1;
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}
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searchpath = getenv("PATH");
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if (searchpath == NULL) {
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errno = ENOENT;
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return -1;
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}
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for (s = searchpath; s != NULL; s = t) {
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t = strchr(s, ':');
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if (t != NULL) {
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len = t - s;
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/* advance past the colon */
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t++;
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}
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else {
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len = strlen(s);
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}
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if (len == 0) {
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continue;
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}
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if (len >= sizeof(progpath)) {
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continue;
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}
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memcpy(progpath, s, len);
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snprintf(progpath + len, sizeof(progpath) - len, "/%s", prog);
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execv(progpath, args);
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switch (errno) {
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case ENOENT:
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case ENOTDIR:
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case ENOEXEC:
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/* routine errors, try next dir */
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break;
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default:
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/* oops, let's fail */
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return -1;
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}
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}
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errno = ENOENT;
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return -1;
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}
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