[PATCH] open: Normalize tricky .file names

[Eric Blake]

Otherwise, we can run into:
$ touch "*#1*"
$ ./run poke
(poke) .mem #0
The current IOS is now `*#0*'.
(poke) .file "*#1*"
The current IOS is now `*#1*'.
(poke) .mem #1
Buffer *#1* already opened.  Use `.ios #N' to switch.

* src/ios-dev.h (struct ios_dev_if): Replace handler_p with
handler_noramlize callback.
* src/ios.c (ios_open): Store normalized name per ios.
* src/ios-dev-file.c (ios_dev_file_handler_p): Rename...
(ios_dev_file_handler_normalize): ...and prepend ./ to risky
relative file names.
* src/ios-dev-mem.c (ios_dev_mem_handler_p): Rename...
(ios_dev_mem_handler_normalize): ...to this.
(ios_dev_mem_open, ios_dev_mem_close): Drop unused handler member.
* testsuite/poke.cmd/file-relative.pk: New test.
---
 ChangeLog                           | 14 ++++++++++++++
 src/ios-dev-file.c                  | 23 ++++++++++++++++++-----
 src/ios-dev-mem.c                   | 12 +++++-------
 src/ios-dev.h                       |  6 +++---
 src/ios.c                           |  4 ++--
 testsuite/poke.cmd/file-relative.pk |  7 +++++++
 6 files changed, 49 insertions(+), 17 deletions(-)
 create mode 100644 testsuite/poke.cmd/file-relative.pk

diff --git a/ChangeLog b/ChangeLog
index f8581455..52005806 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,17 @@
+2020-02-26  Eric Blake  <address@hidden>
+
+       open: Normalize tricky .file names.
+       * src/ios-dev.h (struct ios_dev_if): Replace handler_p with
+       handler_noramlize callback.
+       * src/ios.c (ios_open): Store normalized name per ios.
+       * src/ios-dev-file.c (ios_dev_file_handler_p): Rename...
+       (ios_dev_file_handler_normalize): ...and prepend ./ to risky
+       relative file names.
+       * src/ios-dev-mem.c (ios_dev_mem_handler_p): Rename...
+       (ios_dev_mem_handler_normalize): ...to this.
+       (ios_dev_mem_open, ios_dev_mem_close): Drop unused handler member.
+       * testsuite/poke.cmd/file-relative.pk: New test.
+
 2020-02-26  Eric Blake  <address@hidden>

        * src/ios.c (ios_close): Avoid side-effect inside assert.
diff --git a/src/ios-dev-file.c b/src/ios-dev-file.c
index 4003cf9c..31e833a5 100644
--- a/src/ios-dev-file.c
+++ b/src/ios-dev-file.c
@@ -42,11 +42,24 @@ struct ios_dev_file
   uint64_t flags;
 };

-static int
-ios_dev_file_handler_p (const char *handler)
+static char *
+ios_dev_file_handler_normalize (const char *handler)
 {
-  /* This backend is special, in the sense it accepts any handler.  */
-  return 1;
+  /* This backend is special, in the sense it accepts any handler.
+     However, we want to ensure that the ios name is unambiguous from
+     other ios devices, by prepending ./ to relative names that might
+     otherwise be confusing.  */
+  static const char safe[] =
+    "abcdefghijklmnopqrstuvwxyz"
+    "ABCDEFGHIJKLMNOPQRSTUVWXYZ"
+    "0123456789/+_-";
+  char *ret;
+
+  if (handler[0] == '/' || strspn (handler, safe) == strlen (handler))
+    return xstrdup (handler);
+  if (asprintf (&ret, "./%s", handler) == -1)
+    assert (0);
+  return ret;
 }

 static void *
@@ -184,7 +197,7 @@ ios_dev_file_size (void *iod)

 struct ios_dev_if ios_dev_file =
   {
-   .handler_p = ios_dev_file_handler_p,
+   .handler_normalize = ios_dev_file_handler_normalize,
    .open = ios_dev_file_open,
    .close = ios_dev_file_close,
    .tell = ios_dev_file_tell,
diff --git a/src/ios-dev-mem.c b/src/ios-dev-mem.c
index 098a327f..52033c96 100644
--- a/src/ios-dev-mem.c
+++ b/src/ios-dev-mem.c
@@ -28,7 +28,6 @@

 struct ios_dev_mem
 {
-  char *handler;
   char *pointer;
   size_t size;
   size_t cur;
@@ -38,10 +37,11 @@ struct ios_dev_mem
 #define MEM_STEP (512 * 8)

 static int
-ios_dev_mem_handler_p (const char *handler)
+ios_dev_mem_handler_normalize (const char *handler)
 {
-  return (handler[0] == '*'
-          && handler[strlen(handler) - 1] == '*');
+  if (handler[0] == '*' && handler[strlen (handler) - 1] == '*')
+    return xstrdup (handler);
+  return NULL;
 }

 static void *
@@ -50,7 +50,6 @@ ios_dev_mem_open (const char *handler, uint64_t flags, int 
*error)
   struct ios_dev_mem *mio;

   mio = xmalloc (sizeof (struct ios_dev_mem));
-  mio->handler = xstrdup (handler);
   mio->pointer = xmalloc (MEM_STEP);
   mio->size = MEM_STEP;
   mio->cur = 0;
@@ -64,7 +63,6 @@ ios_dev_mem_close (void *iod)
 {
   struct ios_dev_mem *mio = iod;

-  free (mio->handler);
   free (mio->pointer);
   free (mio);

@@ -139,7 +137,7 @@ ios_dev_mem_size (void *iod)

 struct ios_dev_if ios_dev_mem =
   {
-   .handler_p = ios_dev_mem_handler_p,
+   .handler_normalize = ios_dev_mem_handler_normalize,
    .open = ios_dev_mem_open,
    .close = ios_dev_mem_close,
    .tell = ios_dev_mem_tell,
diff --git a/src/ios-dev.h b/src/ios-dev.h
index 5bc5a257..1ed63008 100644
--- a/src/ios-dev.h
+++ b/src/ios-dev.h
@@ -47,7 +47,7 @@ typedef uint64_t ios_dev_off;
 struct ios_dev_if
 {
   /* Determine whether the provided HANDLER is recognized as a valid
-     device spec by this backend.  Return 1 if the handler is
-     recognized, 0 otherwise.  */
+     device spec by this backend, and if so, return its normalized
+     form (caller will free).  If not, return NULL.  */

-  int (*handler_p) (const char *handler);
+  char *(*handler_normalize) (const char *handler);

   /* Open a device using the provided HANDLER.  Return the opened
      device, or NULL if there was an error.  In case of invalid flags,
diff --git a/src/ios.c b/src/ios.c
index 4bdc80d6..bb760161 100644
--- a/src/ios.c
+++ b/src/ios.c
@@ -172,14 +172,14 @@ ios_open (const char *handler, uint64_t flags, int 
set_cur)
   io = xmalloc (sizeof (struct ios));
   io->id = ios_next_id++;
   io->next = NULL;
-  io->handler = xstrdup (handler);
   io->bias = 0;

   /* Look for a device interface suitable to operate on the given
      handler.  */
   for (dev_if = ios_dev_ifs; *dev_if; ++dev_if)
     {
-      if ((*dev_if)->handler_p (handler))
+      io->handler = (*dev_if)->handler_normalize (handler);
+      if (io->handler)
         break;
     }

diff --git a/testsuite/poke.cmd/file-relative.pk 
b/testsuite/poke.cmd/file-relative.pk
new file mode 100644
index 00000000..82b3f2aa
--- /dev/null
+++ b/testsuite/poke.cmd/file-relative.pk
@@ -0,0 +1,7 @@
+/* { dg-do run } */
+/* { dg-data {c*} {0x10 0x20 0x30 0x40 0x50 0x60 0x70 0x80} a#b } */
+
+/* { dg-command { .file "a#b" } } */
+/* { dg-command { .info ios } } */
+/* { dg-output "  Id\tMode\tPosition\tName" } */
+/* { dg-output "\n\\* #0\trw\t0x00000000#b\t./a#b" } */
-- 
2.24.1