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	which.c - sbase - suckless unix tools
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	---
	which.c (1648B)
	---
	1 /* See LICENSE file for copyright and license details. */
	2 #include <sys/stat.h>
	3 #include <sys/types.h>
	4
	5 #include <fcntl.h>
	6 #include <limits.h>
	7 #include <stdio.h>
	8 #include <stdlib.h>
	9 #include <string.h>
	10 #include <unistd.h>
	11
	12 #include "util.h"
	13
	14 static int aflag;
	15
	16 static int
	17 canexec(int fd, const char *name)
	18 {
	19 struct stat st;
	20
	21 if (fstatat(fd, name, &st, 0) < 0 \|\| !S_ISREG(st.st_mode))
	22 return 0;
	23 return faccessat(fd, name, X_OK, AT_EACCESS) == 0;
	24 }
	25
	26 static int
	27 which(const char path, const char name)
	28 {
	29 char ptr, p;
	30 size_t i, len;
	31 int dirfd, found = 0;
	32
	33 if (strchr(name, '/')) {
	34 found = canexec(AT_FDCWD, name);
	35 if (found)
	36 puts(name);
	37 return found;
	38 }
	39
	40 ptr = p = enstrdup(3, path);
	41 len = strlen(p);
	42 for (i = 0; i < len + 1; i++) {
	43 if (ptr[i] != ':' && ptr[i] != '\0')
	44 continue;
	45 ptr[i] = '\0';
	46 if ((dirfd = open(p, O_RDONLY)) >= 0) {
	47 if (canexec(dirfd, name)) {
	48 found = 1;
	49 fputs(p, stdout);
	50 if (i && ptr[i - 1] != '/')
	51 fputc('/', stdout);
	52 puts(name);
	53 }
	54 close(dirfd);
	55 if (!aflag && found)
	56 break;
	57 }
	58 p = ptr + i + 1;
	59 }
	60 free(ptr);
	61
	62 return found;
	63 }
	64
	65 static void
	66 usage(void)
	67 {
	68 eprintf("usage: %s [-a] name ...\n", argv0);
	69 }
	70
	71 int
	72 main(int argc, char *argv[])
	73 {
	74 char *path;
	75 int found = 0, foundall = 1;
	76
	77 ARGBEGIN {
	78 case 'a':
	79 aflag = 1;
	80 break;
	81 default:
	82 usage();
	83 } ARGEND
	84
	85 if (!argc)
	86 usage();
	87
	88 if (!(path = getenv("PATH")))
	89 enprintf(3, "$PATH is not set\n");
	90
	91 for (; *argv; argc--, argv++) {
	92 if (which(path, *argv)) {
	93 found = 1;
	94 } else {
	95 weprintf("%s: not an external command\n", *argv);
	96 foundall = 0;
	97 }
	98 }
	99
	100 return found ? foundall ? 0 : 1 : 2;
	101 }