Implementations of common Unix command-line utilities written in C.
unix-tools / pwd.c
| 1 | #define _POSIX_C_SOURCE 200809L |
| 2 | #include <unistd.h> |
| 3 | #include <errno.h> |
| 4 | #include <stdint.h> |
| 5 | #include <stdio.h> |
| 6 | #include <stdlib.h> |
| 7 | |
| 8 | int |
| 9 | main(int argc, char **argv) |
| 10 | { |
| 11 | size_t size = 128; |
| 12 | char *path; |
| 13 | if (argc != 1) { fprintf(stderr, "usage: %s\n", argv[0]); return 1; } |
| 14 | for (;;) { |
| 15 | path = malloc(size); |
| 16 | if (path == NULL) { perror("pwd: malloc"); return 1; } |
| 17 | if (getcwd(path, size) != NULL) break; |
| 18 | { |
| 19 | int saved = errno; |
| 20 | free(path); |
| 21 | errno = saved; |
| 22 | } |
| 23 | if (errno != ERANGE) { perror("pwd: getcwd"); return 1; } |
| 24 | if (size > SIZE_MAX / 2) { fprintf(stderr, "pwd: path too long\n"); return 1; } |
| 25 | size *= 2; |
| 26 | } |
| 27 | if (puts(path) == EOF || fflush(stdout) == EOF) { |
| 28 | perror("pwd: stdout"); free(path); return 1; |
| 29 | } |
| 30 | free(path); |
| 31 | return 0; |
| 32 | } |