use readdir_r instead of readdir for reentrancy

Signed-off-by: Harsh Prateek Bora <harsh@linux.vnet.ibm.com>
Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>

fsdev/file-op-9p.h

@@ -78,7 +78,7 @@ typedef struct FileOperations
     int (*open2)(FsContext *, const char *, int, FsCred *);
     void (*rewinddir)(FsContext *, DIR *);
     off_t (*telldir)(FsContext *, DIR *);
-    struct dirent *(*readdir)(FsContext *, DIR *);
+    int (*readdir_r)(FsContext *, DIR *, struct dirent *, struct dirent **);
     void (*seekdir)(FsContext *, DIR *, off_t);
     ssize_t (*preadv)(FsContext *, int, const struct iovec *, int, off_t);
     ssize_t (*pwritev)(FsContext *, int, const struct iovec *, int, off_t);

hw/9pfs/codir.c

@@ -17,16 +17,16 @@
 #include "qemu-coroutine.h"
 #include "virtio-9p-coth.h"
 
-int v9fs_co_readdir(V9fsState *s, V9fsFidState *fidp, struct dirent **dent)
+int v9fs_co_readdir_r(V9fsState *s, V9fsFidState *fidp, struct dirent *dent,
+                      struct dirent **result)
 {
     int err;
 
     v9fs_co_run_in_worker(
         {
             errno = 0;
-            /*FIXME!! need to switch to readdir_r */
+            err = s->ops->readdir_r(&s->ctx, fidp->fs.dir, dent, result);
-            *dent = s->ops->readdir(&s->ctx, fidp->fs.dir);
+            if (!*result && errno) {
-            if (!*dent && errno) {
                 err = -errno;
             } else {
                 err = 0;

hw/9pfs/virtio-9p-coth.h

@@ -57,8 +57,8 @@ typedef struct V9fsThPool {
 extern void co_run_in_worker_bh(void *);
 extern int v9fs_init_worker_threads(void);
 extern int v9fs_co_readlink(V9fsState *, V9fsString *, V9fsString *);
-extern int v9fs_co_readdir(V9fsState *, V9fsFidState *,
+extern int v9fs_co_readdir_r(V9fsState *, V9fsFidState *,
-                           struct dirent **);
+                           struct dirent *, struct dirent **result);
 extern off_t v9fs_co_telldir(V9fsState *, V9fsFidState *);
 extern void v9fs_co_seekdir(V9fsState *, V9fsFidState *, off_t);
 extern void v9fs_co_rewinddir(V9fsState *, V9fsFidState *);

hw/9pfs/virtio-9p-local.c

@@ -165,9 +165,10 @@ static off_t local_telldir(FsContext *ctx, DIR *dir)
     return telldir(dir);
 }
 
-static struct dirent *local_readdir(FsContext *ctx, DIR *dir)
+static int local_readdir_r(FsContext *ctx, DIR *dir, struct dirent *entry,
+                         struct dirent **result)
 {
-    return readdir(dir);
+    return readdir_r(dir, entry, result);
 }
 
 static void local_seekdir(FsContext *ctx, DIR *dir, off_t off)
@@ -532,7 +533,7 @@ FileOperations local_ops = {
     .opendir = local_opendir,
     .rewinddir = local_rewinddir,
     .telldir = local_telldir,
-    .readdir = local_readdir,
+    .readdir_r = local_readdir_r,
     .seekdir = local_seekdir,
     .preadv = local_preadv,
     .pwritev = local_pwritev,

hw/9pfs/virtio-9p.c

@@ -1495,17 +1495,20 @@ static int v9fs_do_readdir_with_stat(V9fsState *s, V9fsPDU *pdu,
     int32_t count = 0;
     struct stat stbuf;
     off_t saved_dir_pos;
-    struct dirent *dent;
+    struct dirent *dent, *result;
 
     /* save the directory position */
     saved_dir_pos = v9fs_co_telldir(s, fidp);
     if (saved_dir_pos < 0) {
         return saved_dir_pos;
     }
+
+    dent = g_malloc(sizeof(struct dirent));
+
     while (1) {
         v9fs_string_init(&name);
-        err = v9fs_co_readdir(s, fidp, &dent);
+        err = v9fs_co_readdir_r(s, fidp, dent, &result);
-        if (err || !dent) {
+        if (err || !result) {
             break;
         }
         v9fs_string_sprintf(&name, "%s/%s", fidp->path.data, dent->d_name);
@@ -1524,6 +1527,7 @@ static int v9fs_do_readdir_with_stat(V9fsState *s, V9fsPDU *pdu,
             v9fs_co_seekdir(s, fidp, saved_dir_pos);
             v9fs_stat_free(&v9stat);
             v9fs_string_free(&name);
+            g_free(dent);
             return count;
         }
         count += len;
@@ -1532,6 +1536,7 @@ static int v9fs_do_readdir_with_stat(V9fsState *s, V9fsPDU *pdu,
         saved_dir_pos = dent->d_off;
     }
 out:
+    g_free(dent);
     v9fs_string_free(&name);
     if (err < 0) {
         return err;
@@ -1628,16 +1633,19 @@ static int v9fs_do_readdir(V9fsState *s, V9fsPDU *pdu,
     int len, err = 0;
     int32_t count = 0;
     off_t saved_dir_pos;
-    struct dirent *dent;
+    struct dirent *dent, *result;
 
     /* save the directory position */
     saved_dir_pos = v9fs_co_telldir(s, fidp);
     if (saved_dir_pos < 0) {
         return saved_dir_pos;
     }
+
+    dent = g_malloc(sizeof(struct dirent));
+
     while (1) {
-        err = v9fs_co_readdir(s, fidp, &dent);
+        err = v9fs_co_readdir_r(s, fidp, dent, &result);
-        if (err || !dent) {
+        if (err || !result) {
             break;
         }
         v9fs_string_init(&name);
@@ -1646,6 +1654,7 @@ static int v9fs_do_readdir(V9fsState *s, V9fsPDU *pdu,
             /* Ran out of buffer. Set dir back to old position and return */
             v9fs_co_seekdir(s, fidp, saved_dir_pos);
             v9fs_string_free(&name);
+            g_free(dent);
             return count;
         }
         /*
@@ -1667,6 +1676,7 @@ static int v9fs_do_readdir(V9fsState *s, V9fsPDU *pdu,
         v9fs_string_free(&name);
         saved_dir_pos = dent->d_off;
     }
+    g_free(dent);
     if (err < 0) {
         return err;
     }