[OE-core][dunfell 08/28] psuedo: Add tracking of linked files for fds

Steve Sakoman
2020-12-03T15:09:00Z

Where files are link()'d and one is unlink()'d, pseudo's fd mappings
can become confused. Add a patch to try and improve this for the common
usecases we see.

Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>
(cherry picked from commit 9ce621fa2099608ca0ccbb8420b31d71cdd7b00e)
Signed-off-by: Steve Sakoman <steve@sakoman.com>
---
.../pseudo/files/track_link_fds.patch | 155 ++++++++++++++++++
meta/recipes-devtools/pseudo/pseudo_git.bb | 1 +
2 files changed, 156 insertions(+)
create mode 100644 meta/recipes-devtools/pseudo/files/track_link_fds.patch

diff --git a/meta/recipes-devtools/pseudo/files/track_link_fds.patch b/meta/recipes-devtools/pseudo/files/track_link_fds.patch
new file mode 100644
index 0000000000..a3a9eb3f23
--- /dev/null
+++ b/meta/recipes-devtools/pseudo/files/track_link_fds.patch
@@ -0,0 +1,155 @@
+Consider what happens if a program does:
+
+fd = fopen("A")
+link("A", "B")
+unlink("A")
+fchown(fd)
+
+Assuming we can't use the database, in order to handle this correctly,
+we need to change the open fd to point at B when A us unlinked.
+
+Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>
+Upstream-Status: Pending
+
+Index: git/ports/unix/guts/linkat.c
+===================================================================
+--- git.orig/ports/unix/guts/linkat.c
++++ git/ports/unix/guts/linkat.c
+@@ -116,6 +116,7 @@
+ * if the thing linked is a symlink.
+ */
+ pseudo_client_op(OP_LINK, 0, -1, -1, newpath, &buf);
++ pseudo_client_linked_paths(oldpath, newpath);
+
+ errno = save_errno;
+
+Index: git/pseudo_client.c
+===================================================================
+--- git.orig/pseudo_client.c
++++ git/pseudo_client.c
+@@ -70,6 +70,8 @@ int pseudo_umask = 022;
+
+ static char **fd_paths = NULL;
+ static int nfds = 0;
++static char **linked_fd_paths = NULL;
++static int linked_nfds = 0;
+ static const char **passwd_paths = NULL;
+ static int npasswd_paths = 0;
+ #ifdef PSEUDO_PROFILING
+@@ -889,39 +891,70 @@ fd_path(int fd) {
+ }
+
+ static void
+-pseudo_client_path(int fd, const char *path) {
++pseudo_client_path_set(int fd, const char *path, char ***patharray, int *len) {
+ if (fd < 0)
+ return;
+
+- if (fd >= nfds) {
++ if (fd >= *len) {
+ int i;
+ pseudo_debug(PDBGF_CLIENT, "expanding fds from %d to %d\n",
+- nfds, fd + 1);
+- fd_paths = realloc(fd_paths, (fd + 1) * sizeof(char *));
+- for (i = nfds; i < fd + 1; ++i)
+- fd_paths[i] = 0;
+- nfds = fd + 1;
++ *len, fd + 1);
++ (*patharray) = realloc((*patharray), (fd + 1) * sizeof(char *));
++ for (i = *len; i < fd + 1; ++i)
++ (*patharray)[i] = 0;
++ *len = fd + 1;
+ } else {
+- if (fd_paths[fd]) {
++ if ((*patharray)[fd]) {
+ pseudo_debug(PDBGF_CLIENT, "reopening fd %d [%s] -- didn't see close\n",
+- fd, fd_paths[fd]);
++ fd, (*patharray)[fd]);
+ }
+ /* yes, it is safe to free null pointers. yay for C89 */
+- free(fd_paths[fd]);
+- fd_paths[fd] = 0;
++ free((*patharray)[fd]);
++ (*patharray)[fd] = 0;
+ }
+ if (path) {
+- fd_paths[fd] = strdup(path);
++ (*patharray)[fd] = strdup(path);
++ }
++}
++
++static void
++pseudo_client_path(int fd, const char *path) {
++ pseudo_client_path_set(fd, path, &fd_paths, &nfds);
++}
++
++void
++pseudo_client_linked_paths(const char *oldpath, const char *newpath) {
++ int fd;
++ for (fd = 3; fd < nfds; ++fd) {
++ if (fd_paths[fd] && !strcmp(oldpath, fd_paths[fd])) {
++ pseudo_client_path_set(fd, newpath, &linked_fd_paths, &linked_nfds);
++ }
+ }
+ }
+
+ static void
++pseudo_client_unlinked_path(const char *path) {
++ int fd;
++ for (fd = 0; fd < linked_nfds; ++fd) {
++ if (linked_fd_paths[fd] && fd_paths[fd] && !strcmp(path, fd_paths[fd])) {
++ pseudo_client_path(fd, linked_fd_paths[fd]);
++ }
++ }
++}
++
++
++static void
+ pseudo_client_close(int fd) {
+ if (fd < 0 || fd >= nfds)
+ return;
+
+ free(fd_paths[fd]);
+ fd_paths[fd] = 0;
++
++ if (fd < linked_nfds) {
++ free(linked_fd_paths[fd]);
++ linked_fd_paths[fd] = 0;
++ }
+ }
+
+ /* spawn server */
+@@ -1860,6 +1893,12 @@ pseudo_client_op(pseudo_op_t op, int acc
+ dirfd);
+ pseudo_client_path(dirfd, fd_path(fd));
+ break;
++ case OP_UNLINK:
++ case OP_DID_UNLINK:
++ if (path)
++ pseudo_client_unlinked_path(path);
++ do_request = 1;
++ break;
+ /* operations for which we should use the magic uid/gid */
+ case OP_CHMOD:
+ case OP_CREAT:
+@@ -1882,8 +1921,6 @@ pseudo_client_op(pseudo_op_t op, int acc
+ case OP_LINK:
+ case OP_RENAME:
+ case OP_STAT:
+- case OP_UNLINK:
+- case OP_DID_UNLINK:
+ case OP_CANCEL_UNLINK:
+ case OP_MAY_UNLINK:
+ case OP_GET_XATTR:
+Index: git/pseudo_client.h
+===================================================================
+--- git.orig/pseudo_client.h
++++ git/pseudo_client.h
+@@ -9,6 +9,7 @@
+ extern pseudo_msg_t *pseudo_client_op(pseudo_op_t op, int access, int fd, int dirfd, const char *path, const PSEUDO_STATBUF *buf, ...);
+ extern int pseudo_client_ignore_path(const char *path);
+ extern int pseudo_client_ignore_fd(int fd);
++extern void pseudo_client_linked_paths(const char *oldpath, const char *newpath);
+ #if PSEUDO_STATBUF_64
+ #define base_lstat real_lstat64
+ #define base_fstat real_fstat64
diff --git a/meta/recipes-devtools/pseudo/pseudo_git.bb b/meta/recipes-devtools/pseudo/pseudo_git.bb
index 56c9b4e232..a5e79ec9a5 100644
--- a/meta/recipes-devtools/pseudo/pseudo_git.bb
+++ b/meta/recipes-devtools/pseudo/pseudo_git.bb
@@ -5,6 +5,7 @@ SRC_URI = "git://git.yoctoproject.org/pseudo;branch=oe-core \
file://delete_mismatches.patch \
file://add_ignore_paths.patch \
file://abort_on_mismatch.patch \
+ file://track_link_fds.patch \
file://fallback-passwd \
file://fallback-group \
"
--
2.17.1