diff options
| -rw-r--r-- | lib/lib.c | 143 | ||||
| -rw-r--r-- | lib/lib.h | 2 | ||||
| -rw-r--r-- | lib/llist.c | 4 | ||||
| -rw-r--r-- | toys/other/readlink.c | 18 |
4 files changed, 130 insertions, 37 deletions
@@ -323,37 +323,134 @@ void xstat(char *path, struct stat *st) if(stat(path, st)) perror_exit("Can't stat %s", path); } -// Cannonicalize path, even to file with one or more missing components at end -char *xabspath(char *path, unsigned missing) +// Split a path into linked list of components, tracking head and tail of list. +// Filters out // entries with no contents. +struct string_list **splitpath(char *path, struct string_list **list) { - char *apath, *temp, *slash; - int i=0; + char *new = path; - // If this isn't an absolute path, make it one with cwd. - if (path[0]!='/') { - char *temp=xgetcwd(); - apath = xmsprintf("%s/%s", temp, path); - free(temp); - } else apath = path; - slash = apath+strlen(apath); + *list = 0; + do { + int len; + + if (*path && *path != '/') continue; + len = path-new; + if (len > 0) { + *list = xmalloc(sizeof(struct string_list) + len + 1); + (*list)->next = 0; + strncpy((*list)->str, new, len); + (*list)->str[len] = 0; + list = &(*list)->next; + } + new = path+1; + } while (*path++); - for (;;) { - temp = realpath(apath, NULL); - if (i) *slash = '/'; - if (temp || ++i > missing) break; - while (slash>apath) if (*--slash == '/') break; - *slash=0; + return list; +} + +// Cannonicalize path, even to file with one or more missing components at end. +// if exact, require last path component to exist +char *xabspath(char *path, int exact) +{ + struct string_list *todo, *done = 0; + int try = 9999, dirfd = open("/", 0);; + char buf[4096], *ret; + + // If this isn't an absolute path, start with cwd. + if (*path != '/') { + char *temp = xgetcwd(); + + splitpath(path, splitpath(temp, &todo)); free(temp); + } else splitpath(path, &todo); + + // Iterate through path components + while (todo) { + struct string_list *new = llist_pop(&todo), **tail; + ssize_t len; + + if (!try--) { + errno = ELOOP; + goto error; + } + + // Removable path componenents. + if (!strcmp(new->str, ".") || !strcmp(new->str, "..")) { + if (new->str[1] && done) free(llist_pop(&done)); + free(new); + continue; + } + + // Is this a symlink? + len=readlinkat(dirfd, new->str, buf, 4096); + if (len>4095) goto error; + if (len<1) { + int fd; + + // Not a symlink: add to linked list, move dirfd, fail if error + if ((exact || todo) && errno != EINVAL) goto error; + new->next = done; + done = new; + fd = openat(dirfd, new->str, O_DIRECTORY); + if (fd == -1 && (exact || todo)) goto error; + close(dirfd); + dirfd = fd; + continue; + } + + // If this symlink is to an absolute path, discard existing resolved path + buf[len] = 0; + if (*buf == '/') { + llist_traverse(done, free); + done=0; + close(dirfd); + dirfd = open("/", 0); + } + free(new); + + // prepend components of new path. Note symlink to "/" will leave new NULL + tail = splitpath(buf, &new); + + // symlink to "/" will return null and leave tail alone + if (new) { + *tail = todo; + todo = new; + } } + close(dirfd); - if (i && temp) { - slash = xmsprintf("%s%s", temp, slash); - free(temp); - temp = slash; + // At this point done has the path, in reverse order. Reverse list while + // calculating buffer length. + + try = 2; + while (done) { + struct string_list *temp = llist_pop(&done);; + + if (todo) try++; + try += strlen(temp->str); + temp->next = todo; + todo = temp; + } + + // Assemble return buffer + + ret = xmalloc(try); + *ret = '/'; + ret [try = 1] = 0; + while (todo) { + if (try>1) ret[try++] = '/'; + try = stpcpy(ret+try, todo->str) - ret; + free(llist_pop(&todo)); } - if (path != apath) free(apath); - return temp; + return ret; + +error: + close(dirfd); + llist_traverse(todo, free); + llist_traverse(done, free); + + return NULL; } // Resolve all symlinks, returning malloc() memory. @@ -116,7 +116,7 @@ char *readfile(char *name); char *xreadfile(char *name); char *xgetcwd(void); void xstat(char *path, struct stat *st); -char *xabspath(char *path, unsigned missing); +char *xabspath(char *path, int exact); char *xrealpath(char *path); void xchdir(char *path); void xmkpath(char *path, int mode); diff --git a/lib/llist.c b/lib/llist.c index 9b6c2950..7b41fd08 100644 --- a/lib/llist.c +++ b/lib/llist.c @@ -8,12 +8,14 @@ // Call a function (such as free()) on each element of a linked list. void llist_traverse(void *list, void (*using)(void *data)) { + void *old = list; + while (list) { void *pop = llist_pop(&list); using(pop); // End doubly linked list too. - if (list==pop) break; + if (old == list) break; } } diff --git a/toys/other/readlink.c b/toys/other/readlink.c index b237a510..46855f10 100644 --- a/toys/other/readlink.c +++ b/toys/other/readlink.c @@ -2,7 +2,7 @@ * * Copyright 2007 Rob Landley <rob@landley.net> -USE_READLINK(NEWTOY(readlink, "<1>1femnq[-fem]", TOYFLAG_BIN)) +USE_READLINK(NEWTOY(readlink, "<1>1fenq[-fe]", TOYFLAG_BIN)) config READLINK bool "readlink" @@ -14,9 +14,8 @@ config READLINK Options for producing cannonical paths (all symlinks/./.. resolved): - -e cannonical path to existing file (fail if does not exist) - -f cannonical path to creatable file (fail if directory does not exist) - -m cannonical path + -e cannonical path to existing entry (fail if nothing there) + -f full path (fail if location does not exist) -n no trailing newline -q quiet (no output, just error code) */ @@ -30,14 +29,9 @@ void readlink_main(void) // Calculating full cannonical path? - if (toys.optflags & (FLAG_f|FLAG_e|FLAG_m)) { - unsigned u = 0; - - if (toys.optflags & FLAG_f) u++; - if (toys.optflags & FLAG_m) u=999999999; - - s = xabspath(*toys.optargs, u); - } else s = xreadlink(*toys.optargs); + if (toys.optflags & (FLAG_f|FLAG_e)) + s = xabspath(*toys.optargs, toys.optflags & FLAG_e); + else s = xreadlink(*toys.optargs); if (s) { if (!(toys.optflags & FLAG_q)) |