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#include "stddef.h" // for NULL
#include <errno.h> // for errno, ENAMETOOLONG, ENOENT
#include <limits.h> // for PATH_MAX
#include <stdio.h> // for snprintf
#include <stdlib.h> // for getenv
#include <string.h> // for strchr, strlen, strstr
#include <unistd.h> // for execv, execvp
extern char **environ;
int execvp(const char *file, char *const argv[])
{
if (*file == '\0') {
errno = ENOENT;
return -1;
}
if (strchr(file, '/') != NULL) {
return execv(file, argv);
} else {
char *ptr;
char *path = getenv("PATH");
if (path == NULL || *path == '\0') {
path = "/bin";
}
do {
char buf[PATH_MAX];
ptr = strchr(path, ':');
if (ptr == NULL) {
if (snprintf(buf, PATH_MAX, "%s/%s", path, file) >= PATH_MAX) {
errno = ENAMETOOLONG;
return -1;
}
/* Validate path doesn't contain dangerous
* characters */
if (strstr(buf, "..") == NULL && strchr(buf, '\0') == buf + strlen(buf)) {
execv(buf, argv);
}
break;
}
if (snprintf(buf, PATH_MAX, "%.*s/%s", (int)(ptr - path), path, file) >= PATH_MAX) {
errno = ENAMETOOLONG;
return -1;
}
/* Validate path doesn't contain dangerous characters */
if (strstr(buf, "..") == NULL && strchr(buf, '\0') == buf + strlen(buf)) {
execv(buf, argv);
}
path = ptr + 1;
} while (*ptr != '\0');
errno = ENOENT;
return -1;
}
return 0;
}
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