X-Git-Url: https://git.subgeniuskitty.com/unix-history/.git/blobdiff_plain/34b028a5452f2064ae5d50fa06a1de34fa12cc98..ae59e04cb5f746d72d5e3e8c84dad7862c9b50e7:/usr/src/lib/libc/gen/getcwd.c diff --git a/usr/src/lib/libc/gen/getcwd.c b/usr/src/lib/libc/gen/getcwd.c index 448fb84bf0..681fb1bb03 100644 --- a/usr/src/lib/libc/gen/getcwd.c +++ b/usr/src/lib/libc/gen/getcwd.c @@ -1,107 +1,202 @@ -/* @(#)getcwd.c 4.7 (Berkeley) %G% */ - /* - * getwd() returns the pathname of the current working directory. On error - * an error message is copied to pathname and null pointer is returned. + * 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 5.11 (Berkeley) %G%"; +#endif /* LIBC_SCCS and not lint */ + #include #include -#include - -#define CURDIR "." -#define GETWDERR(s) strcpy(pathname, (s)); -#define PARENTDIR ".." -#define PATHSEP "/" -#define ROOTDIR "/" +#include +#include +#include +#include +#include +#include -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 *prepend(); /* prepend dirname to pathname */ - dev_t rdev; /* root device number */ - DIR *dirp; /* directory stream */ - ino_t rino; /* root inode number */ - struct direct *dir; /* directory entry struct */ - struct stat d ,dd; /* file status struct */ - - pathsize = 0; - *pnptr = '\0'; - stat(ROOTDIR, &d); - rdev = d.st_dev; - rino = d.st_ino; - for (;;) { - stat(CURDIR, &d); - if (d.st_ino == rino && d.st_dev == rdev) - break; /* reached root directory */ - if ((dirp = opendir(PARENTDIR)) == NULL) { - GETWDERR("getwd: can't open .."); - goto fail; + 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); } - if (chdir(PARENTDIR) < 0) { - GETWDERR("getwd: can't chdir to .."); - goto fail; + ept = pt + size; + } else { + if (!(pt = (char *)malloc(ptsize = 1024 - 4))) + return((char *)NULL); + ept = pt + ptsize; + } + 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, &dd); - if (d.st_dev == dd.st_dev) { - if (d.st_ino == dd.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 .."); - goto fail; - } - } while (dir->d_ino != d.st_ino); } else - do { - if((dir = readdir(dirp)) == NULL) { - closedir(dirp); - GETWDERR("getwd: read error in .."); - goto fail; + 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; } - stat(dir->d_name, &dd); - } while(dd.st_ino != d.st_ino || dd.st_dev != d.st_dev); - closedir(dirp); - pnptr = prepend(PATHSEP, prepend(dir->d_name, pnptr)); - } - if (*pnptr == '\0') /* current dir == root dir */ - strcpy(pathname, ROOTDIR); - else { - strcpy(pathname, pnptr); - if (chdir(pnptr) < 0) { - GETWDERR("getwd: can't change back to ."); - return (NULL); + 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; } - } - return (pathname); + if (!first) + *--bpt = '/'; + bpt -= dp->d_namlen; + bcopy(dp->d_name, bpt, dp->d_namlen); + (void)closedir(dir); -fail: - chdir(prepend(CURDIR, pnptr)); - return (NULL); -} + /* Truncate any file name. */ + *bup = '\0'; + } -/* - * 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); }