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unistd/dir: fix resolve_path behavior on trailing slashes #346

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unistd/dir: fix resolve_path behavior on trailing slashes #346

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79 changes: 50 additions & 29 deletions unistd/dir.c
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Original file line number Diff line number Diff line change
Expand Up @@ -173,13 +173,14 @@ static int _resolve_abspath(char *path, char *result, int resolve_last_symlink,
p = strchrnul(node, '/');
const size_t node_len = p - node;

/* skip trailing slashes to properly detect leaf node */
const int is_leaf = (*p == '\0') ? 1 : 0;
while (*p == '/') {
p += 1;
}

const int is_leaf = (*p == '\0') ? 1 : 0;

/* TODO: this is too permissive, because it allows creating files (not just directories)
* with a path that has trailing slashes */
const int is_leaf_after_slashes = (*p == '\0') ? 1 : 0;
/* check for '.' and '..' */
if (node_len == 0) { /* multiple '/' */
continue;
Expand All @@ -202,11 +203,6 @@ static int _resolve_abspath(char *path, char *result, int resolve_last_symlink,
r += node_len;
*r = '\0';

if ((is_leaf != 0) && (resolve_last_symlink == 0)) {
/* WARN: slight inconsistency: we're not checking if the path actually exists in this case (TODO?) */
break;
}

/*
* Number of initial unused `path` bytes that can be used to resolve current node. If link content is
* longer we will not be able to merge it with remaining path and still fit in PATH_MAX buffer
Expand All @@ -217,18 +213,29 @@ static int _resolve_abspath(char *path, char *result, int resolve_last_symlink,
ssize_t symlink_len = _readlink_abs(result, path, readlink_max_len);

if (symlink_len < 0) {
if (errno == EINVAL) { /* not a symlink */
if (symlink_len == -EISDIR) {
continue;
}
else if ((errno == ENOENT) && (is_leaf != 0) && (allow_missing_leaf != 0)) { /* non-esixting leaf */
if (symlink_len == -EINVAL) { /* not a symlink or directory */
if (is_leaf == 0) {
return SET_ERRNO(-ENOTDIR);
}
else {
continue;
}
}
else if ((symlink_len == -ENOENT) && (is_leaf_after_slashes != 0) && (allow_missing_leaf != 0)) { /* non-existing leaf */
break;
}
else {
/* errno set by _readlink_abs */
return -1;
return SET_ERRNO(symlink_len);
}
}

if ((is_leaf != 0) && (resolve_last_symlink == 0)) {
break;
}

if (symlink_len == 0) {
/* NOTE: this case is not defined in POSIX */
/* see: https://lwn.net/Articles/551224/ */
Expand All @@ -247,8 +254,11 @@ static int _resolve_abspath(char *path, char *result, int resolve_last_symlink,
}

/* prepend resolved symlink to remaining unresolved path */
p -= 1;
*p = '/';
if (*p != '\0') {
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p -= 1;
*p = '/';
}

p -= symlink_len;
memmove(p, path, symlink_len);

Expand Down Expand Up @@ -475,21 +485,27 @@ static ssize_t _readlink_abs(const char *path, char *buf, size_t bufsiz)

assert(path && path[0] == '/');

if ((ret = safe_lookup(path, &oid, NULL)) < 0)
return SET_ERRNO(ret);
ret = safe_lookup(path, &oid, NULL);
if (ret < 0) {
return ret;
}

msg.type = mtGetAttr;
memcpy(&msg.i.attr.oid, &oid, sizeof(oid_t));
msg.i.attr.type = atMode;

if ((ret = msgSend(oid.port, &msg)) != EOK)
return SET_ERRNO(ret);
ret = msgSend(oid.port, &msg);
if (ret != EOK) {
return ret;
}

if (msg.o.attr.err != EOK)
return SET_ERRNO(msg.o.attr.err);
if (msg.o.attr.err != EOK) {
return msg.o.attr.err;
}

if (!S_ISLNK(msg.o.attr.val))
return SET_ERRNO(-EINVAL);
if (!S_ISLNK(msg.o.attr.val)) {
return S_ISDIR(msg.o.attr.val) ? -EISDIR : -EINVAL;
}

memset(&msg, 0, sizeof(msg_t));
msg.type = mtRead;
Expand All @@ -499,13 +515,12 @@ static ssize_t _readlink_abs(const char *path, char *buf, size_t bufsiz)
msg.o.size = bufsiz;
msg.o.data = buf;

if ((ret = msgSend(oid.port, &msg)) != EOK)
return SET_ERRNO(ret);

if (msg.o.io.err < 0)
return SET_ERRNO(msg.o.io.err);
ret = msgSend(oid.port, &msg);
if (ret != EOK) {
return ret;
}

/* number of bytes written without terminating NULL byte */
/* number of bytes written without terminating NULL byte or retcode if < 0 */
return msg.o.io.err;
}

Expand All @@ -522,8 +537,14 @@ ssize_t readlink(const char *path, char *buf, size_t bufsiz)
ret = _readlink_abs(canonical, buf, bufsiz);

free(canonical);
if (ret < 0) {
if (ret == -EISDIR) {
ret = -EINVAL;
}

return SET_ERRNO(ret);
}

/* if error - errno set by _readlink_abs() */
return ret;
}

Expand Down
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