[PATCH v2] ios: track sub IOS devices

[Mohammad-Reza Nabipoor]

In this commit, we keep track of number of sub-devices for each
IO space.  If the user close the super-IOS, it'll become a zombie
IOS: it's dead but the corresponding `struct ios' is not un-allocated
yet.  When user closes the sub-IOS, and if it's the last sub-IOS,
it'll de-allocate the corresponding `struct ios'.

2023-04-19  Mohammad-Reza Nabipoor  <mnabipoor@gnu.org>

        * libpoke/ios.h (ios_inc_sub_dev): New function to track sub
        IO spaces.
        (ios_dec_sub_dev): Likewise.
        (ios_zombie_p): New function.
        * libpoke/ios.c (struct ios): Add new fields `zombie_p` and
        `num_sub_devs'.
        (ios_inc_sub_dev): New function definition.
        (ios_dec_sub_dev): Likewise.
        (ios_zombie_p): Likewise.
        (ios_open): Initialize new fields.
        (ios_close): Instead of deallocating the IOS, it becomes a zombie,
        if there's at least one sub-device that using this IOS.
        * libpoke/ios-dev-sub.c (struct ios_dev_sub): Use `ios' instead of
        ios id.
        (ios_dev_sub_open): Update to track base IOS.
        (ios_dev_sub_close): Likewise.
        (ios_dev_sub_pread): Use base IOS directly instead of searching
        using id.
        (ios_dev_sub_pwrite): Likewise.
        * testsuite/poke.pkl/open-sub-19.pk: New test.
        * testusite/poke.pkl/open-sub-20.pk: Likewise.
        * testsuite/Makefile.am (EXTRA_DIST): Update.
---
 ChangeLog                         | 25 +++++++++++++++++++++++++
 libpoke/ios-dev-sub.c             | 26 ++++++++++++++------------
 libpoke/ios.c                     | 31 ++++++++++++++++++++++++++++++-
 libpoke/ios.h                     | 10 ++++++++++
 testsuite/Makefile.am             |  2 ++
 testsuite/poke.pkl/open-sub-19.pk | 18 ++++++++++++++++++
 testsuite/poke.pkl/open-sub-20.pk | 20 ++++++++++++++++++++
 7 files changed, 119 insertions(+), 13 deletions(-)
 create mode 100644 testsuite/poke.pkl/open-sub-19.pk
 create mode 100644 testsuite/poke.pkl/open-sub-20.pk

diff --git a/ChangeLog b/ChangeLog
index 1f790dc8..e9af4895 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,28 @@
+2023-04-19  Mohammad-Reza Nabipoor  <mnabipoor@gnu.org>
+
+       * libpoke/ios.h (ios_inc_sub_dev): New function to track sub
+       IO spaces.
+       (ios_dec_sub_dev): Likewise.
+       (ios_zombie_p): New function.
+       * libpoke/ios.c (struct ios): Add new fields `zombie_p` and
+       `num_sub_devs'.
+       (ios_inc_sub_dev): New function definition.
+       (ios_dec_sub_dev): Likewise.
+       (ios_zombie_p): Likewise.
+       (ios_open): Initialize new fields.
+       (ios_close): Instead of deallocating the IOS, it becomes a zombie,
+       if there's at least one sub-device that using this IOS.
+       * libpoke/ios-dev-sub.c (struct ios_dev_sub): Use `ios' instead of
+       ios id.
+       (ios_dev_sub_open): Update to track base IOS.
+       (ios_dev_sub_close): Likewise.
+       (ios_dev_sub_pread): Use base IOS directly instead of searching
+       using id.
+       (ios_dev_sub_pwrite): Likewise.
+       * testsuite/poke.pkl/open-sub-19.pk: New test.
+       * testusite/poke.pkl/open-sub-20.pk: Likewise.
+       * testsuite/Makefile.am (EXTRA_DIST): Update.
+
 2023-04-17  Jose E. Marchesi  <jemarch@gnu.org>
 
        * NEWS: Add entries for 3.1.
diff --git a/libpoke/ios-dev-sub.c b/libpoke/ios-dev-sub.c
index 64872cee..2a7f363e 100644
--- a/libpoke/ios-dev-sub.c
+++ b/libpoke/ios-dev-sub.c
@@ -32,7 +32,7 @@
 
 struct ios_dev_sub
 {
-  int base_ios_id;
+  ios base_ios;
   ios_dev_off base;
   ios_dev_off size;
   char *name;
@@ -76,6 +76,7 @@ ios_dev_sub_open (const char *handler, uint64_t flags, int 
*error, void *data)
   struct ios_dev_sub *sub = malloc (sizeof (struct ios_dev_sub));
   const char *p;
   char *end;
+  int base_ios_id;
   int explicit_flags_p = (flags != 0);
 
   if (sub == NULL)
@@ -86,6 +87,7 @@ ios_dev_sub_open (const char *handler, uint64_t flags, int 
*error, void *data)
     }
 
   sub->name = NULL; /* To ease error management below.  */
+  sub->base_ios = NULL;
 
   /* Flags: only IOS_F_READ and IOS_F_WRITE are allowed.  */
   sub->flags = explicit_flags_p ? flags : IOS_F_READ | IOS_F_WRITE;
@@ -104,7 +106,7 @@ ios_dev_sub_open (const char *handler, uint64_t flags, int 
*error, void *data)
   p = handler + 6;
 
   /* Parse the Id of the base IOS.  This is an integer.  */
-  sub->base_ios_id = strtol (p, &end, 0);
+  base_ios_id = strtol (p, &end, 0);
   if (*p != '\0' && *end == '/')
     /* Valid integer found.  */;
   else
@@ -146,7 +148,7 @@ ios_dev_sub_open (const char *handler, uint64_t flags, int 
*error, void *data)
     uint64_t iflags;
 
     /* The referred IOS should exist.  */
-    base_ios = ios_search_by_id (sub->base_ios_id);
+    base_ios = ios_search_by_id (base_ios_id);
     if (base_ios == NULL)
       goto error;
 
@@ -170,6 +172,8 @@ ios_dev_sub_open (const char *handler, uint64_t flags, int 
*error, void *data)
         free (sub);
         return NULL;
       }
+    sub->base_ios = base_ios;
+    ios_inc_sub_dev (base_ios);
   }
 
   if (error)
@@ -189,6 +193,9 @@ ios_dev_sub_close (void *iod)
 {
   struct ios_dev_sub *sub = iod;
 
+  assert (sub->base_ios != NULL);
+
+  ios_dec_sub_dev (sub->base_ios);
   free (sub->name);
   free (sub);
   return IOD_OK;
@@ -201,18 +208,13 @@ ios_dev_sub_get_flags (void *iod)
   return sub->flags;
 }
 
-/* XXX search_by_id to get the base IOS in pread and pwrite is slow as
-   shit.  It would be good to cache the IOS at open time, but then we
-   have to make ios.c aware of subios so it will mark all sub-ios of a
-   given IOS when the later is closed.  */
-
 static int
 ios_dev_sub_pread (void *iod, void *buf, size_t count, ios_dev_off offset)
 {
   struct ios_dev_sub *sub = iod;
-  ios ios = ios_search_by_id (sub->base_ios_id);
+  ios ios = sub->base_ios;
 
-  if (ios == NULL || !(sub->flags & IOS_F_READ))
+  if (ios_zombie_p (ios) || !(sub->flags & IOS_F_READ))
     return IOD_ERROR;
 
   if (offset >= sub->size)
@@ -228,9 +230,9 @@ ios_dev_sub_pwrite (void *iod, const void *buf, size_t 
count,
                     ios_dev_off offset)
 {
   struct ios_dev_sub *sub = iod;
-  ios ios = ios_search_by_id (sub->base_ios_id);
+  ios ios = sub->base_ios;
 
-  if (ios == NULL || !(sub->flags & IOS_F_WRITE))
+  if (ios_zombie_p (ios) || !(sub->flags & IOS_F_WRITE))
     return IOD_ERROR;
 
   /* Sub-range IOS dot accept writes past the end of the IOS.  */
diff --git a/libpoke/ios.c b/libpoke/ios.c
index 93da34c5..b5a893b3 100644
--- a/libpoke/ios.c
+++ b/libpoke/ios.c
@@ -70,6 +70,8 @@
 struct ios
 {
   int id;
+  int zombie_p;
+  int num_sub_devs;
   char *handler;
   void *dev;
   struct ios_dev_if *dev_if;
@@ -146,6 +148,8 @@ ios_open (const char *handler, uint64_t flags, int set_cur)
   if (!io)
     return IOS_ENOMEM;
 
+  io->zombie_p = 0;
+  io->num_sub_devs = 0;
   io->handler = NULL;
   io->next = NULL;
   io->bias = 0;
@@ -245,7 +249,10 @@ ios_close (ios io)
   if (ios_next_id == io->id + 1)
     --ios_next_id;
 
-  free (io);
+  if (io->num_sub_devs == 0)
+    free (io);
+  else
+    io->zombie_p = 1;
 
   return IOD_ERROR_TO_IOS_ERROR (ret);
 }
@@ -274,6 +281,13 @@ ios_set_cur (ios io)
   cur_io = io;
 }
 
+int
+ios_zombie_p (ios io)
+{
+  assert (io);
+  return io->zombie_p;
+}
+
 ios
 ios_search (const char *handler)
 {
@@ -1650,3 +1664,18 @@ ios_register_foreign_iod (struct ios_dev_if *iod_if)
   ios_dev_ifs[0] = iod_if;
   return IOS_OK;
 }
+
+void
+ios_inc_sub_dev (ios io)
+{
+  ++io->num_sub_devs;
+}
+
+void
+ios_dec_sub_dev (ios io)
+{
+  assert (io->num_sub_devs != 0);
+  --io->num_sub_devs;
+  if (io->zombie_p && io->num_sub_devs == 0)
+    free (io);
+}
diff --git a/libpoke/ios.h b/libpoke/ios.h
index b639822d..57bacedc 100644
--- a/libpoke/ios.h
+++ b/libpoke/ios.h
@@ -238,6 +238,8 @@ ios_off ios_get_bias (ios io);
 
 void ios_set_bias (ios io, ios_off bias);
 
+int ios_zobmie_p (ios io);
+
 /* **************** Object read/write API ****************  */
 
 /* An integer with flags is passed to the read/write operations,
@@ -366,4 +368,12 @@ struct ios_dev_if *ios_foreign_iod (void);
 struct ios_dev_if;
 int ios_register_foreign_iod (struct ios_dev_if *iod_if);
 
+/* **************** Sub IO space **************** */
+
+/* Increase the number of sub-devices for IOS.  */
+void ios_inc_sub_dev (ios io);
+
+/* Decrease the number of sub-devices for IOS.  */
+void ios_dec_sub_dev (ios io);
+
 #endif /* ! IOS_H */
diff --git a/testsuite/Makefile.am b/testsuite/Makefile.am
index de4bb752..9a123340 100644
--- a/testsuite/Makefile.am
+++ b/testsuite/Makefile.am
@@ -1951,6 +1951,8 @@ EXTRA_DIST = \
   poke.pkl/open-sub-16.pk \
   poke.pkl/open-sub-17.pk \
   poke.pkl/open-sub-18.pk \
+  poke.pkl/open-sub-19.pk \
+  poke.pkl/open-sub-20.pk \
   poke.pkl/open-sub-2.pk \
   poke.pkl/open-sub-3.pk \
   poke.pkl/open-sub-4.pk \
diff --git a/testsuite/poke.pkl/open-sub-19.pk 
b/testsuite/poke.pkl/open-sub-19.pk
new file mode 100644
index 00000000..20aa2afb
--- /dev/null
+++ b/testsuite/poke.pkl/open-sub-19.pk
@@ -0,0 +1,18 @@
+/* { dg-do run } */
+/* { dg-data {c*} {0x10 0x20 0x30 0x40  0x50 0x60 0x70 0x80   0x90 0xa0 0xb0 
0xc0} foo } */
+
+/* Closing the super-IOS before the sub-IOS.  */
+
+/* { dg-command {.set obase 16} } */
+/* { dg-command {var file = open ("foo")} } */
+/* { dg-command {var sub = opensub (file, 4#B, 6#B)} } */
+/* { dg-command {byte @ sub : 1#B} } */
+/* { dg-output "0x60UB" } */
+/* { dg-command {byte @ file : 5#B} } */
+/* { dg-output "\n0x60UB" } */
+/* { dg-command {close (file)} } */
+/* { dg-command {(byte @ sub : 0#B) ?! E_io} } */
+/* { dg-output "\n0x00000001" } */
+/* { dg-command {close (sub)} } */
+/* { dg-command {(byte @ sub : 0#B) ?! E_no_ios} } */
+/* { dg-output "\n0x00000001" } */
diff --git a/testsuite/poke.pkl/open-sub-20.pk 
b/testsuite/poke.pkl/open-sub-20.pk
new file mode 100644
index 00000000..0c0f81ef
--- /dev/null
+++ b/testsuite/poke.pkl/open-sub-20.pk
@@ -0,0 +1,20 @@
+/* { dg-do run } */
+/* { dg-data {c*} {0x10 0x20 0x30 0x40  0x50 0x60 0x70 0x80   0x90 0xa0 0xb0 
0xc0} foo } */
+
+/* Closing the super-IOS before the sub-IOS.  */
+
+/* { dg-command {.set obase 16} } */
+/* { dg-command {var file = open ("foo")} } */
+/* { dg-command {var sub1 = opensub (file, 4#B, 6#B, "")} } */
+/* { dg-command {var sub2 = opensub (sub1, 1#B, 2#B, "")} } */
+/* { dg-command {byte @ sub2 : 0#B = 0xff} } */
+/* { dg-command {byte @ sub1 : 1#B} } */
+/* { dg-output "0xffUB" } */
+/* { dg-command {byte @ file : 5#B} } */
+/* { dg-output "\n0xffUB" } */
+/* { dg-command {close (sub1)} } */
+/* { dg-command {(byte @ sub2 : 0#B) ?! E_io} } */
+/* { dg-output "\n0x00000001" } */
+/* { dg-command {close (sub2)} } */
+/* { dg-command {(byte @ sub2 : 0#B) ?! E_no_ios} } */
+/* { dg-output "\n0x00000001" } */
-- 
2.40.0