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#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <errno.h>
#include <limits.h>
int execvp(const char *file, char *const argv[])
{
const char *p, *z, *path = getenv("PATH");
size_t l, k;
errno = ENOENT;
if (!*file) return -1;
if (strchr(file, '/'))
return execv(file, argv);
if (!path) path = "/usr/local/bin:/bin:/usr/bin";
k = strnlen(file, NAME_MAX+1);
if (k > NAME_MAX) {
errno = ENAMETOOLONG;
return -1;
}
l = strnlen(path, PATH_MAX-1)+1;
for(p=path; ; p=z) {
char b[l+k+1];
z = strchr(p, ':');
if (!z) z = p+strlen(p);
if (z-p >= l) {
if (!*z++) break;
continue;
}
memcpy(b, p, z-p);
b[z-p] = '/';
memcpy(b+(z-p)+(z>p), file, k+1);
execv(b, argv);
if (errno != ENOENT) return -1;
if (!*z++) break;
}
return -1;
}
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