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-rw-r--r--src/pwd.c90
1 files changed, 90 insertions, 0 deletions
diff --git a/src/pwd.c b/src/pwd.c
new file mode 100644
index 0000000..8ccd28b
--- /dev/null
+++ b/src/pwd.c
@@ -0,0 +1,90 @@
+/*
+ * 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;
+}