sbase/which.c

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1.6 KiB
C
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/* See LICENSE file for copyright and license details. */
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#include <sys/stat.h>
#include <sys/types.h>
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#include <fcntl.h>
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#include <limits.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include "util.h"
static int aflag;
static int
canexec(int fd, const char *name)
{
struct stat st;
if (fstatat(fd, name, &st, 0) < 0 || !S_ISREG(st.st_mode))
return 0;
return faccessat(fd, name, X_OK, AT_EACCESS) == 0;
}
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static int
which(const char *path, const char *name)
{
char *ptr, *p;
size_t i, len;
int dirfd, found = 0;
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if (strchr(name, '/')) {
found = canexec(AT_FDCWD, name);
if (found)
puts(name);
return found;
}
ptr = p = enstrdup(3, path);
len = strlen(p);
for (i = 0; i < len + 1; i++) {
if (ptr[i] != ':' && ptr[i] != '\0')
continue;
ptr[i] = '\0';
if ((dirfd = open(p, O_RDONLY)) >= 0) {
if (canexec(dirfd, name)) {
found = 1;
fputs(p, stdout);
if (i && ptr[i - 1] != '/')
fputc('/', stdout);
puts(name);
}
close(dirfd);
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if (!aflag && found)
break;
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}
p = ptr + i + 1;
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}
free(ptr);
return found;
}
static void
usage(void)
{
eprintf("usage: %s [-a] name ...\n", argv0);
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}
int
main(int argc, char *argv[])
{
char *path;
int found = 0, foundall = 1;
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ARGBEGIN {
case 'a':
aflag = 1;
break;
default:
usage();
} ARGEND
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if (!argc)
usage();
if (!(path = getenv("PATH")))
enprintf(3, "$PATH is not set\n");
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for (; *argv; argc--, argv++) {
if (which(path, *argv)) {
found = 1;
} else {
weprintf("%s: not an external command\n", *argv);
foundall = 0;
}
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}
return found ? foundall ? 0 : 1 : 2;
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}