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/*
* pwd.c
* Implementation of SUSv3 XCU pwd utility
* Copyright © 2007 Rich Felker
* Licensed under the terms of the GNU General Public License, v2 or later
*/
/* NOTE: This implementation assumes PATH_MAX is defined and correct. */
#include <limits.h>
#include <unistd.h>
#include <sys/stat.h>
#include <stdlib.h>
#include <string.h>
#include <errno.h>
static int my_write(int fd, const char *s, size_t l)
{
if (!l) l = strlen(s);
while (l) {
ssize_t n = write(fd, s, l);
if (n<0) return -1;
s += n; l -= n;
}
return 0;
}
static void my_perror(char *prog, char *msg)
{
char *err = strerror(errno);
write(2, prog, strlen(prog));
write(2, ": ", 2);
write(2, msg, strlen(msg));
write(2, ": ", 2);
write(2, err, strlen(err));
write(2, "\n", 1);
}
static int is_rel(const char *s)
{
unsigned dots=0, slash=1;
if (*s++ != '/') return 1;
for (; *s; s++) {
if (*s == '/') {
if (dots-1<2) return 1;
dots=0;
}
else slash=1;
if (slash && *s == '.') dots++;
else dots=slash=0;
}
return dots-1<2;
}
int main(int argc, char *argv[])
{
int i, j;
int p=0;
char buf[PATH_MAX+2];
struct stat st1, st2;
char *pwd;
for (i=1; i<argc && argv[i][0]=='-'; i++)
for (j=1; argv[i][j]; j++) {
switch (argv[i][j]) {
case 'L': p=0; continue;
case 'P': p=1;
case 0: continue;
}
invalid:
errno = EINVAL;
my_perror(argv[0], argv[i]);
return 1;
}
if (i<argc) goto invalid;
if (p || !(pwd=getenv("PWD")) || is_rel(pwd)
|| stat(pwd, &st1) || stat(".", &st2)
|| st1.st_dev != st2.st_dev
|| st1.st_ino != st2.st_ino) {
if (!getcwd(buf, sizeof buf)) {
my_perror(argv[0], "getcwd");
return 1;
}
} else {
/* safe because stat succeeded */
strcpy(buf, pwd);
}
strcat(buf, "\n");
return my_write(1, buf, 0) != 0;
}
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