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Update the ".." entry when a directory is moved to a new parent #99

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85 changes: 83 additions & 2 deletions common/src/fx_directory_rename.c
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -51,6 +51,8 @@
/* If found, the rename request is valid and the directory will be */
/* changed to the new name. Otherwise, if the directory is not found, */
/* the appropriate error code is returned to the caller. */
/* If the directory is moved under a different parent, the ".." */
/* entry inside the directory is updated to name the new parent. */
/* */
/* INPUT */
/* */
Expand All @@ -64,6 +66,7 @@
/* */
/* CALLS */
/* */
/* _fx_directory_entry_read Read entries from directory */
/* _fx_directory_entry_write Write the new directory entry */
/* _fx_directory_free_search Search for a free directory */
/* entry */
Expand All @@ -90,6 +93,7 @@ FX_DIR_ENTRY new_dir_entry;
FX_DIR_ENTRY search_directory;
CHAR *new_name_ptr;
ULONG i;
ULONG parent_cluster;
CHAR *work_ptr;
CHAR alpha, beta;
#ifdef FX_RENAME_PATH_INHERIT
Expand Down Expand Up @@ -451,20 +455,97 @@ UINT j;
/* Now wipe out the old directory entry. */
status = _fx_directory_entry_write(media_ptr, &old_dir_entry);

/* Determine if the write was successful. */
if (status != FX_SUCCESS)
{

#ifdef FX_ENABLE_FAULT_TOLERANT
/* Check for a bad status. */
FX_FAULT_TOLERANT_TRANSACTION_FAIL(media_ptr);
#endif /* FX_ENABLE_FAULT_TOLERANT */

/* Release media protection. */
FX_UNPROTECT

/* Return the error code. */
return(status);
}

/* The renamed directory itself contains a ".." entry, which stores
the starting cluster of its parent directory. If the rename moved
the directory under a different parent, that stored cluster is
stale now: ".." inside the renamed directory would still lead to
the old parent and, once the old parent's cluster is reused, to an
unrelated place. Update it in place. */

/* Determine the starting cluster of the new parent directory.
An empty name in the search directory marks the root
directory - the name is the only root indication, the other
fields keep earlier values in that case. A ".." entry stores
its parent's starting cluster; when the parent is the root
directory, it stores cluster 0. */
if (search_directory.fx_dir_entry_name[0])
{

/* New parent is a sub-directory. */
parent_cluster = search_directory.fx_dir_entry_cluster;
}
else
{

/* New parent is the root directory. */
parent_cluster = 0;
}

/* old_dir_entry is no longer needed and still holds the starting
cluster of the renamed directory - reuse it to address that
directory as the one to read from. Ensure the cluster chain is
walked from the start. */
old_dir_entry.fx_dir_entry_last_search_cluster = 0;

/* Read the second directory entry of the renamed directory - its
".." entry, created together with the directory. new_dir_entry
is no longer needed either and serves as the destination. */
i = 1;
status = _fx_directory_entry_read(media_ptr, &old_dir_entry, &i, &new_dir_entry);

/* Update the entry only if it is the ".." entry the FAT format
places at this position - on a non-conformant media the rename
result is left as it is - and only if the stored cluster does
not match the new parent already. A rename inside one parent
ends here without an additional write. */
if ((status == FX_SUCCESS) &&
(new_dir_entry.fx_dir_entry_name[0] == '.') &&
(new_dir_entry.fx_dir_entry_name[1] == '.') &&
(new_dir_entry.fx_dir_entry_name[2] == 0) &&
(new_dir_entry.fx_dir_entry_cluster != parent_cluster))
{

/* Update the stored parent cluster. Everything else of the
entry - its position included - stays untouched: the first
two entries of a directory are a format invariant other
services rely on. */
new_dir_entry.fx_dir_entry_cluster = parent_cluster;

/* Write the updated ".." entry back. */
status = _fx_directory_entry_write(media_ptr, &new_dir_entry);
}

/* Determine if the ".." update was successful. */
if (status != FX_SUCCESS)
{

#ifdef FX_ENABLE_FAULT_TOLERANT
FX_FAULT_TOLERANT_TRANSACTION_FAIL(media_ptr);
#endif /* FX_ENABLE_FAULT_TOLERANT */

/* Release media protection. */
FX_UNPROTECT

/* Return the bad status. */
/* Return the error code. */
return(status);
}

#ifdef FX_ENABLE_FAULT_TOLERANT
/* End transaction. */
status = _fx_fault_tolerant_transaction_end(media_ptr);
#endif /* FX_ENABLE_FAULT_TOLERANT */
Expand Down
225 changes: 225 additions & 0 deletions test/regression_test/filex_directory_rename_test.c
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -15,6 +15,7 @@
#include "tx_api.h"
#endif
#include "fx_api.h"
#include "fx_directory.h"
#include "fx_ram_driver_test.h"
#include "fx_fault_tolerant.h"
#include "fx_utility.h"
Expand All @@ -35,6 +36,7 @@
static TX_THREAD ftest_0;
#endif
static FX_MEDIA ram_disk;
static FX_FILE probe_file;
static CHAR max_name[FX_MAX_LONG_NAME_LEN + 2];
static CHAR max_newname[FX_MAX_LONG_NAME_LEN + 1];

Expand All @@ -55,6 +57,9 @@ static UCHAR fault_tolerant_buffer[FAULT_TOLERANT_SIZE];

void filex_directory_rename_application_define(void *first_unused_memory);
static void ftest_0_entry(ULONG thread_input);
static UINT dot_dot_probe(CHAR *marker_path);
static UINT directory_cluster_read(CHAR *directory_path, ULONG *cluster_ptr);
static UINT dot_dot_cluster_read(CHAR *directory_path, ULONG *cluster_ptr);

VOID _fx_ram_driver(FX_MEDIA *media_ptr);
void test_control_return(UINT status);
Expand Down Expand Up @@ -102,13 +107,102 @@ void filex_directory_rename_application_define(void *first_unused_memory)



/* Open and close the file at marker_path - a path that contains a ".."
component - to report where ".." currently leads. */
static UINT dot_dot_probe(CHAR *marker_path)
{

UINT status;

status = fx_file_open(&ram_disk, &probe_file, marker_path, FX_OPEN_FOR_READ);
if (status == FX_SUCCESS)
{
fx_file_close(&probe_file);
}

return(status);
}


/* Return the starting cluster of the directory at directory_path. */
static UINT directory_cluster_read(CHAR *directory_path, ULONG *cluster_ptr)
{

UINT status;
FX_DIR_ENTRY dir_entry;

/* The directory's own entry carries its starting cluster. */
dir_entry.fx_dir_entry_name = ram_disk.fx_media_name_buffer + FX_MAX_LONG_NAME_LEN;
dir_entry.fx_dir_entry_short_name[0] = 0;
status = _fx_directory_search(&ram_disk, directory_path, &dir_entry, FX_NULL, FX_NULL);

/* Return the cluster only on success. */
if (status == FX_SUCCESS)
{
*cluster_ptr = dir_entry.fx_dir_entry_cluster;
}

return(status);
}


/* Read the ".." entry - entry 1 - of the directory at directory_path and
return the parent starting cluster stored in it. Verifies that the
entry actually reads back as "..". */
static UINT dot_dot_cluster_read(CHAR *directory_path, ULONG *cluster_ptr)
{

UINT status;
ULONG entry_index;
FX_DIR_ENTRY dir_entry;
FX_DIR_ENTRY dot_dot_entry;

/* Find the directory itself first. */
dir_entry.fx_dir_entry_name = ram_disk.fx_media_name_buffer + FX_MAX_LONG_NAME_LEN;
dir_entry.fx_dir_entry_short_name[0] = 0;
status = _fx_directory_search(&ram_disk, directory_path, &dir_entry, FX_NULL, FX_NULL);
if (status != FX_SUCCESS)
{
return(status);
}

/* Read its second directory entry - the ".." entry. */
dir_entry.fx_dir_entry_last_search_cluster = 0;
dot_dot_entry.fx_dir_entry_name = ram_disk.fx_media_name_buffer + FX_MAX_LONG_NAME_LEN * 2;
dot_dot_entry.fx_dir_entry_short_name[0] = 0;
entry_index = 1;
status = _fx_directory_entry_read(&ram_disk, &dir_entry, &entry_index, &dot_dot_entry);
if (status != FX_SUCCESS)
{
return(status);
}

/* Anything other than ".." at this position is a failure. */
if ((dot_dot_entry.fx_dir_entry_name[0] != '.') ||
(dot_dot_entry.fx_dir_entry_name[1] != '.') ||
(dot_dot_entry.fx_dir_entry_name[2] != 0))
{
return(FX_INVALID_STATE);
}

*cluster_ptr = dot_dot_entry.fx_dir_entry_cluster;

return(FX_SUCCESS);
}


/* Define the test threads. */

static void ftest_0_entry(ULONG thread_input)
{

UINT status;
UINT i;
ULONG parent_cluster;
ULONG dot_dot_cluster;
#ifndef FX_MEDIA_STATISTICS_DISABLE
ULONG entry_writes_before;
#endif

FX_PARAMETER_NOT_USED(thread_input);

Expand Down Expand Up @@ -296,6 +390,137 @@ static void ftest_0_entry(ULONG thread_input)
status = fx_media_close(&ram_disk);
return_if_fail( status == FX_SUCCESS);

/* Format the media again: the checks below build their own fixture
and must not disturb - or depend on - the directory layout the
error-injection steps above are calibrated against. */
status = fx_media_format(&ram_disk,
_fx_ram_driver, // Driver entry
ram_disk_memory, // RAM disk memory pointer
cache_buffer, // Media buffer pointer
CACHE_SIZE, // Media buffer size
"MY_RAM_DISK", // Volume Name
1, // Number of FATs
128, // Directory Entries
0, // Hidden sectors

#ifdef FX_ENABLE_FAULT_TOLERANT
4096 * 8, // Total sectors
256, // Sector size
8, // Sectors per cluster
#else
4096, // Total sectors
128, // Sector size
1, // Sectors per cluster
#endif

1, // Heads
1); // Sectors per track
status += fx_media_open(&ram_disk, "RAM DISK", _fx_ram_driver, ram_disk_memory, cache_buffer, CACHE_SIZE);
return_if_fail( status == FX_SUCCESS);

#ifdef FX_ENABLE_FAULT_TOLERANT
status = fx_fault_tolerant_enable(&ram_disk, fault_tolerant_buffer, FAULT_TOLERANT_SIZE);
return_if_fail( status == FX_SUCCESS);
#endif

/* Moving a directory to a different parent has to update the ".."
entry inside the moved directory: it stores the starting cluster
of the parent directory - cluster 0 when the parent is the root
directory. Exercise every parent transition and verify both the
path resolution through ".." and the on-media entry itself. */
status = fx_directory_create(&ram_disk, "/DOTA");
status += fx_directory_create(&ram_disk, "/DOTB");
status += fx_file_create(&ram_disk, "/MARKR.TXT");
status += fx_file_create(&ram_disk, "/DOTA/MARKA.TXT");
status += fx_file_create(&ram_disk, "/DOTB/MARKB.TXT");
status += fx_directory_create(&ram_disk, "/DOTA/SUB");
return_if_fail( status == FX_SUCCESS);

/* The probe itself has to work before anything is moved: ".." of a
new directory leads to the parent it was created in. */
status = dot_dot_probe("/DOTA/SUB/../MARKA.TXT");
return_if_fail( status == FX_SUCCESS);
status = dot_dot_probe("/DOTA/SUB/../MARKB.TXT");
return_if_fail( status == FX_NOT_FOUND);

/* Move the directory to a different parent directory. Exactly one
directory entry write - the ".." update - is added to the two
parent entry writes. */
#ifndef FX_MEDIA_STATISTICS_DISABLE
entry_writes_before = ram_disk.fx_media_directory_entry_writes;
#endif
status = fx_directory_rename(&ram_disk, "/DOTA/SUB", "/DOTB/SUB");
return_if_fail( status == FX_SUCCESS);
#ifndef FX_MEDIA_STATISTICS_DISABLE
return_if_fail( (ram_disk.fx_media_directory_entry_writes - entry_writes_before) == 3);
#endif

/* ".." now leads to the new parent and only to the new parent. */
status = dot_dot_probe("/DOTB/SUB/../MARKB.TXT");
return_if_fail( status == FX_SUCCESS);
status = dot_dot_probe("/DOTB/SUB/../MARKA.TXT");
return_if_fail( status == FX_NOT_FOUND);

/* The on-media ".." entry stores the new parent's starting cluster. */
status = directory_cluster_read("/DOTB", &parent_cluster);
return_if_fail( status == FX_SUCCESS);
status = dot_dot_cluster_read("/DOTB/SUB", &dot_dot_cluster);
return_if_fail( status == FX_SUCCESS);
return_if_fail( (dot_dot_cluster == parent_cluster) && (parent_cluster != 0));

/* Move the directory into the root directory: ".." stores cluster 0
there, per the FAT convention directory create itself writes. */
status = fx_directory_rename(&ram_disk, "/DOTB/SUB", "/SUB");
return_if_fail( status == FX_SUCCESS);
status = dot_dot_probe("/SUB/../MARKR.TXT");
return_if_fail( status == FX_SUCCESS);
status = dot_dot_probe("/SUB/../MARKB.TXT");
return_if_fail( status == FX_NOT_FOUND);
status = dot_dot_cluster_read("/SUB", &dot_dot_cluster);
return_if_fail( (status == FX_SUCCESS) && (dot_dot_cluster == 0));

/* Move the directory back out of the root directory: 0 becomes the
new parent's cluster again. */
status = fx_directory_rename(&ram_disk, "/SUB", "/DOTA/SUB");
return_if_fail( status == FX_SUCCESS);
status = dot_dot_probe("/DOTA/SUB/../MARKA.TXT");
return_if_fail( status == FX_SUCCESS);
status = dot_dot_probe("/DOTA/SUB/../MARKR.TXT");
return_if_fail( status == FX_NOT_FOUND);
status = directory_cluster_read("/DOTA", &parent_cluster);
return_if_fail( status == FX_SUCCESS);
status = dot_dot_cluster_read("/DOTA/SUB", &dot_dot_cluster);
return_if_fail( (status == FX_SUCCESS) && (dot_dot_cluster == parent_cluster) && (parent_cluster != 0));

/* A rename inside one parent does not touch ".." - and adds no third
directory entry write. */
status = fx_directory_create(&ram_disk, "/DOTC");
return_if_fail( status == FX_SUCCESS);
#ifndef FX_MEDIA_STATISTICS_DISABLE
entry_writes_before = ram_disk.fx_media_directory_entry_writes;
#endif
status = fx_directory_rename(&ram_disk, "/DOTC", "/DOTD");
return_if_fail( status == FX_SUCCESS);
#ifndef FX_MEDIA_STATISTICS_DISABLE
return_if_fail( (ram_disk.fx_media_directory_entry_writes - entry_writes_before) == 2);
#endif
status = dot_dot_probe("/DOTD/../MARKR.TXT");
return_if_fail( status == FX_SUCCESS);
status = dot_dot_cluster_read("/DOTD", &dot_dot_cluster);
return_if_fail( (status == FX_SUCCESS) && (dot_dot_cluster == 0));

/* Same inside a sub-directory: ".." keeps the parent's cluster. */
status = fx_directory_rename(&ram_disk, "/DOTA/SUB", "/DOTA/SUB2");
return_if_fail( status == FX_SUCCESS);
status = dot_dot_probe("/DOTA/SUB2/../MARKA.TXT");
return_if_fail( status == FX_SUCCESS);
status = dot_dot_cluster_read("/DOTA/SUB2", &dot_dot_cluster);
return_if_fail( (status == FX_SUCCESS) && (dot_dot_cluster == parent_cluster));

/* Close the media. */
status = fx_media_close(&ram_disk);
return_if_fail( status == FX_SUCCESS);

printf("SUCCESS!\n");
test_control_return(0);
}