/*
- * Copyright (c) 1980 Regents of the University of California.
- * All rights reserved. The Berkeley software License Agreement
- * specifies the terms and conditions for redistribution.
+ * Copyright (c) 1989, 1991 The Regents of the University of California.
+ * All rights reserved.
+ *
+ * %sccs.include.redist.c%
*/
#if defined(LIBC_SCCS) && !defined(lint)
-static char sccsid[] = "@(#)getcwd.c 5.2 (Berkeley) %G%";
-#endif LIBC_SCCS and not lint
+static char sccsid[] = "@(#)getcwd.c 5.11 (Berkeley) %G%";
+#endif /* LIBC_SCCS and not lint */
-/*
- * getwd() returns the pathname of the current working directory. On error
- * an error message is copied to pathname and null pointer is returned.
- */
#include <sys/param.h>
#include <sys/stat.h>
-#include <sys/dir.h>
+#include <errno.h>
+#include <dirent.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <unistd.h>
-#define GETWDERR(s) strcpy(pathname, (s));
-
-char *strcpy();
-static int pathsize; /* pathname length */
+#define ISDOT(dp) \
+ (dp->d_name[0] == '.' && (dp->d_name[1] == '\0' || \
+ dp->d_name[1] == '.' && dp->d_name[2] == '\0'))
char *
-getwd(pathname)
- char *pathname;
+getcwd(pt, size)
+ char *pt;
+ size_t size;
{
- char pathbuf[MAXPATHLEN]; /* temporary pathname buffer */
- char *pnptr = &pathbuf[(sizeof pathbuf)-1]; /* pathname pointer */
- char curdir[MAXPATHLEN]; /* current directory buffer */
- char *dptr = curdir; /* directory pointer */
- char *prepend(); /* prepend dirname to pathname */
- dev_t cdev, rdev; /* current & root device number */
- ino_t cino, rino; /* current & root inode number */
- DIR *dirp; /* directory stream */
- struct direct *dir; /* directory entry struct */
- struct stat d, dd; /* file status struct */
-
- pathsize = 0;
- *pnptr = '\0';
- if (stat("/", &d) < 0) {
- GETWDERR("getwd: can't stat /");
- return (NULL);
- }
- rdev = d.st_dev;
- rino = d.st_ino;
- strcpy(dptr, "./");
- dptr += 2;
- if (stat(curdir, &d) < 0) {
- GETWDERR("getwd: can't stat .");
- return (NULL);
+ register struct dirent *dp;
+ register DIR *dir;
+ register dev_t dev;
+ register ino_t ino;
+ register int first;
+ register char *bpt, *bup;
+ struct stat s;
+ dev_t root_dev;
+ ino_t root_ino;
+ size_t ptsize, upsize;
+ int save_errno;
+ char *ept, *eup, *up;
+
+ /*
+ * If no buffer specified by the user, allocate one as necessary.
+ * If a buffer is specified, the size has to be non-zero. The path
+ * is built from the end of the buffer backwards.
+ */
+ if (pt) {
+ ptsize = 0;
+ if (!size) {
+ errno = EINVAL;
+ return((char *)NULL);
+ }
+ ept = pt + size;
+ } else {
+ if (!(pt = (char *)malloc(ptsize = 1024 - 4)))
+ return((char *)NULL);
+ ept = pt + ptsize;
}
- for (;;) {
- if (d.st_ino == rino && d.st_dev == rdev)
- break; /* reached root directory */
- cino = d.st_ino;
- cdev = d.st_dev;
- strcpy(dptr, "../");
- dptr += 3;
- if ((dirp = opendir(curdir)) == NULL) {
- GETWDERR("getwd: can't open ..");
- return (NULL);
+ bpt = ept - 1;
+ *bpt = '\0';
+
+ /*
+ * Allocate bytes (1024 - malloc space) for the string of "../"'s.
+ * Should always be enough (it's 340 levels). If it's not, allocate
+ * as necessary. Special * case the first stat, it's ".", not "..".
+ */
+ if (!(up = (char *)malloc(upsize = 1024 - 4)))
+ goto err;
+ eup = up + MAXPATHLEN;
+ bup = up;
+ up[0] = '.';
+ up[1] = '\0';
+
+ /* Save root values, so know when to stop. */
+ if (stat("/", &s))
+ goto err;
+ root_dev = s.st_dev;
+ root_ino = s.st_ino;
+
+ errno = 0; /* XXX readdir has no error return. */
+
+ for (first = 1;; first = 0) {
+ /* Stat the current level. */
+ if (lstat(up, &s))
+ goto err;
+
+ /* Save current node values. */
+ ino = s.st_ino;
+ dev = s.st_dev;
+
+ /* Check for reaching root. */
+ if (root_dev == dev && root_ino == ino) {
+ *--bpt = '/';
+ /*
+ * It's unclear that it's a requirement to copy the
+ * path to the beginning of the buffer, but it's always
+ * been that way and stuff would probably break.
+ */
+ (void)bcopy(bpt, pt, ept - bpt);
+ free(up);
+ return(pt);
}
- fstat(dirp->dd_fd, &d);
- if (cdev == d.st_dev) {
- if (cino == d.st_ino) {
- /* reached root directory */
- closedir(dirp);
- break;
+
+ /*
+ * Build pointer to the parent directory, allocating memory
+ * as necessary. Max length is 3 for "../", the largest
+ * possible component name, plus a trailing NULL.
+ */
+ if (bup + 3 + MAXNAMLEN + 1 >= eup) {
+ if (!(up = (char *)realloc(up, upsize *= 2)))
+ goto err;
+ eup = up + upsize;
+ }
+ *bup++ = '.';
+ *bup++ = '.';
+ *bup = '\0';
+
+ /* Open and stat parent directory. */
+ if (!(dir = opendir(up)) || fstat(dirfd(dir), &s))
+ goto err;
+
+ /* Add trailing slash for next directory. */
+ *bup++ = '/';
+
+ /*
+ * If it's a mount point, have to stat each element because
+ * the inode number in the directory is for the entry in the
+ * parent directory, not the inode number of the mounted file.
+ */
+ save_errno = 0;
+ if (s.st_dev == dev) {
+ for (;;) {
+ if (!(dp = readdir(dir)))
+ goto notfound;
+ if (dp->d_fileno == ino)
+ break;
}
- do {
- if ((dir = readdir(dirp)) == NULL) {
- closedir(dirp);
- GETWDERR("getwd: read error in ..");
- return (NULL);
- }
- } while (dir->d_ino != cino);
} else
- do {
- if ((dir = readdir(dirp)) == NULL) {
- closedir(dirp);
- GETWDERR("getwd: read error in ..");
- return (NULL);
+ for (;;) {
+ if (!(dp = readdir(dir)))
+ goto notfound;
+ if (ISDOT(dp))
+ continue;
+ bcopy(dp->d_name, bup, dp->d_namlen + 1);
+
+ /* Save the first error for later. */
+ if (lstat(up, &s)) {
+ if (!save_errno)
+ save_errno = errno;
+ errno = 0;
+ continue;
}
- strcpy(dptr, dir->d_name);
- lstat(curdir, &dd);
- } while(dd.st_ino != cino || dd.st_dev != cdev);
- closedir(dirp);
- pnptr = prepend("/", prepend(dir->d_name, pnptr));
+ if (s.st_dev == dev && s.st_ino == ino)
+ break;
+ }
+
+ /*
+ * Check for length of the current name, preceding slash,
+ * leading slash.
+ */
+ if (bpt - pt <= dp->d_namlen + (first ? 1 : 2)) {
+ size_t len, off;
+
+ if (!ptsize) {
+ errno = ERANGE;
+ goto err;
+ }
+ off = bpt - pt;
+ len = ept - bpt;
+ if (!(pt = (char *)realloc(pt, ptsize *= 2)))
+ goto err;
+ bpt = pt + off;
+ ept = pt + ptsize;
+ (void)bcopy(bpt, ept - len, len);
+ bpt = ept - len;
+ }
+ if (!first)
+ *--bpt = '/';
+ bpt -= dp->d_namlen;
+ bcopy(dp->d_name, bpt, dp->d_namlen);
+ (void)closedir(dir);
+
+ /* Truncate any file name. */
+ *bup = '\0';
}
- if (*pnptr == '\0') /* current dir == root dir */
- strcpy(pathname, "/");
- else
- strcpy(pathname, pnptr);
- return (pathname);
-}
-/*
- * prepend() tacks a directory name onto the front of a pathname.
- */
-static char *
-prepend(dirname, pathname)
- register char *dirname;
- register char *pathname;
-{
- register int i; /* directory name size counter */
-
- for (i = 0; *dirname != '\0'; i++, dirname++)
- continue;
- if ((pathsize += i) < MAXPATHLEN)
- while (i-- > 0)
- *--pathname = *--dirname;
- return (pathname);
+notfound:
+ /*
+ * If readdir set errno, use it, not any saved error; otherwise,
+ * didn't find the current directory in its parent directory, set
+ * errno to ENOENT.
+ */
+ if (!errno)
+ errno = save_errno ? save_errno : ENOENT;
+ /* FALLTHROUGH */
+err:
+ if (ptsize)
+ free(pt);
+ free(up);
+ return((char *)NULL);
}