sbase

suckless unix tools
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which.c (1642B)


      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, 0) == 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)) >= 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 }