Rewrite filesystem code (WIP)

This patch redoes the filesystem code from the FAT driver up to the
clipboard code in onplay.c.

Not every aspect of this is finished therefore it is still "WIP". I
don't wish to do too much at once (haha!). What is left to do is get
dircache back in the sim and find an implementation for the dircache
indicies in the tagcache and playlist code or do something else that
has the same benefit. Leaving these out for now does not make anything
unusable. All the basics are done.

Phone app code should probably get vetted (and app path handling
just plain rewritten as environment expansions); the SDL app and
Android run well.

Main things addressed:
1) Thread safety: There is none right now in the trunk code. Most of
what currently works is luck when multiple threads are involved or
multiple descriptors to the same file are open.

2) POSIX compliance: Many of the functions behave nothing like their
counterparts on a host system. This leads to inconsistent code or very
different behavior from native to hosted. One huge offender was
rename(). Going point by point would fill a book.

3) Actual running RAM usage: Many targets will use less RAM and less
stack space (some more RAM because I upped the number of cache buffers
for large memory). There's very little memory lying fallow in rarely-used
areas (see 'Key core changes' below). Also, all targets may open the same
number of directory streams whereas before those with less than 8MB RAM
were limited to 8, not 12 implying those targets will save slightly
less.

4) Performance: The test_disk plugin shows markedly improved performance,
particularly in the area of (uncached) directory scanning, due partly to
more optimal directory reading and to a better sector cache algorithm.
Uncached times tend to be better while there is a bit of a slowdown in
dircache due to it being a bit heavier of an implementation. It's not
noticeable by a human as far as I can say.

Key core changes:
1) Files and directories share core code and data structures.

2) The filesystem code knows which descriptors refer to same file.
This ensures that changes from one stream are appropriately reflected
in every open descriptor for that file (fileobj_mgr.c).

3) File and directory cache buffers are borrowed from the main sector
cache. This means that when they are not in use by a file, they are not
wasted, but used for the cache. Most of the time, only a few of them
are needed. It also means that adding more file and directory handles
is less expensive. All one must do in ensure a large enough cache to
borrow from.

4) Relative path components are supported and the namespace is unified.
It does not support full relative paths to an implied current directory;
what is does support is use of "." and "..". Adding the former would
not be very difficult. The namespace is unified in the sense that
volumes may be specified several times along with relative parts, e.g.:
"/<0>/foo/../../<1>/bar" :<=> "/<1>/bar".

5) Stack usage is down due to sharing of data, static allocation and
less duplication of strings on the stack. This requires more
serialization than I would like but since the number of threads is
limited to a low number, the tradoff in favor of the stack seems
reasonable.

6) Separates and heirarchicalizes (sic) the SIM and APP filesystem
code. SIM path and volume handling is just like the target. Some
aspects of the APP file code get more straightforward (e.g. no path
hashing is needed).

Dircache:
Deserves its own section. Dircache is new but pays homage to the old.
The old one was not compatible and so it, since it got redone, does
all the stuff it always should have done such as:

1) It may be update and used at any time during the build process.
No longer has one to wait for it to finish building to do basic file
management (create, remove, rename, etc.).

2) It does not need to be either fully scanned or completely disabled;
it can be incomplete (i.e. overfilled, missing paths), still be
of benefit and be correct.

3) Handles mounting and dismounting of individual volumes which means
a full rebuild is not needed just because you pop a new SD card in the
slot. Now, because it reuses its freed entry data, may rebuild only
that volume.

4) Much more fundamental to the file code. When it is built, it is
the keeper of the master file list whether enabled or not ("disabled"
is just a state of the cache). Its must always to ready to be started
and bind all streams opened prior to being enabled.

5) Maintains any short filenames in OEM format which means that it does
not need to be rebuilt when changing the default codepage.

Miscellaneous Compatibility:
1) Update any other code that would otherwise not work such as the
hotswap mounting code in various card drivers.

2) File management: Clipboard needed updating because of the behavioral
changes. Still needs a little more work on some finer points.

3) Remove now-obsolete functionality such as the mutex's "no preempt"
flag (which was only for the prior FAT driver).

4) struct dirinfo uses time_t rather than raw FAT directory entry
time fields. I plan to follow up on genericizing everything there
(i.e. no FAT attributes).

5) unicode.c needed some redoing so that the file code does not try
try to load codepages during a scan, which is actually a problem with
the current code. The default codepage, if any is required, is now
kept in RAM separarately (bufalloced) from codepages specified to
iso_decode() (which must not be bufalloced because the conversion
may be done by playback threads).

Brings with it some additional reusable core code:
1) Revised file functions: Reusable code that does things such as
safe path concatenation and parsing without buffer limitations or
data duplication. Variants that copy or alter the input path may be
based off these.

To do:
1) Put dircache functionality back in the sim. Treating it internally
as a different kind of file system seems the best approach at this
time.

2) Restore use of dircache indexes in the playlist and database or
something effectively the same. Since the cache doesn't have to be
complete in order to be used, not getting a hit on the cache doesn't
unambiguously say if the path exists or not.

Change-Id: Ia30f3082a136253e3a0eae0784e3091d138915c8
Reviewed-on: http://gerrit.rockbox.org/566
Reviewed-by: Michael Sevakis <jethead71@rockbox.org>
Tested: Michael Sevakis <jethead71@rockbox.org>

1 files changed, 94 insertions, 143 deletions

diff --git a/apps/playlist.c b/apps/playlist.c
index 43aa97790b..db93344ef1 100755
--- a/apps/playlist.c
+++ b/apps/playlist.c
@@ -86,7 +86,7 @@
 #include "screens.h"
 #include "core_alloc.h"
 #include "misc.h"
-#include "filefuncs.h"
+#include "pathfuncs.h"
 #include "button.h"
 #include "filetree.h"
 #include "abrepeat.h"
@@ -107,6 +107,8 @@
 #include "panic.h"
 #include "logdiskf.h"
 
+#undef HAVE_DIRCACHE
+
 #define PLAYLIST_CONTROL_FILE_VERSION 2
 
 /*
@@ -180,8 +182,8 @@ static int get_next_directory(char *dir);
 static int get_next_dir(char *dir, bool is_forward);
 static int get_previous_directory(char *dir);
 static int check_subdir_for_music(char *dir, const char *subdir, bool recurse);
-static int format_track_path(char *dest, char *src, int buf_length, int max,
-                             const char *dir);
+static ssize_t format_track_path(char *dest, char *src, int buf_length,
+                                 const char *dir);
 static void display_playlist_count(int count, const unsigned char *fmt,
                                    bool final);
 static void display_buffer_full(void);
@@ -526,7 +528,7 @@ static int add_indices_to_playlist(struct playlist_info* playlist,
     int result = 0;
     /* get emergency buffer so we don't fail horribly */
     if (!buflen)
-        buffer = __builtin_alloca((buflen = 64));
+        buffer = alloca((buflen = 64));
 
     if(-1 == playlist->fd)
         playlist->fd = open_utf8(playlist->filename, O_RDONLY);
@@ -1429,7 +1431,7 @@ static int get_filename(struct playlist_info* playlist, int index, int seek,
 
     strlcpy(dir_buf, playlist->filename, playlist->dirlen);
 
-    return (format_track_path(buf, tmp_buf, buf_length, max, dir_buf));
+    return format_track_path(buf, tmp_buf, buf_length, dir_buf);
 }
 
 static int get_next_directory(char *dir){
@@ -1629,7 +1631,7 @@ static int get_next_dir(char *dir, bool is_forward)
 static int check_subdir_for_music(char *dir, const char *subdir, bool recurse)
 {
     int result = -1;
-    int dirlen = strlen(dir);
+    size_t dirlen = strlen(dir);
     int num_files = 0;
     int i;
     struct entry *files;
@@ -1637,12 +1639,11 @@ static int check_subdir_for_music(char *dir, const char *subdir, bool recurse)
     bool has_subdir = false;
     struct tree_context* tc = tree_get_context();
 
-    snprintf(
-        dir + dirlen, MAX_PATH - dirlen,
-        /* only add a trailing slash if we need one */
-        dirlen && dir[dirlen - 1] == '/' ? "%s" : "/%s",
-        subdir
-    );
+    if (path_append(dir + dirlen, PA_SEP_HARD, subdir, MAX_PATH - dirlen) >=
+            MAX_PATH - dirlen)
+    {
+        return 0;
+    }
     
     if (ft_load(tc, dir) < 0)
     {
@@ -1695,7 +1696,7 @@ static int check_subdir_for_music(char *dir, const char *subdir, bool recurse)
         }
         else
         {
-            strcpy(dir, "/");
+            strcpy(dir, PATH_ROOTSTR);
         }
 
         /* we now need to reload our current directory */
@@ -1708,79 +1709,31 @@ static int check_subdir_for_music(char *dir, const char *subdir, bool recurse)
 /*
  * Returns absolute path of track
  */
-static int format_track_path(char *dest, char *src, int buf_length, int max,
-                             const char *dir)
+static ssize_t format_track_path(char *dest, char *src, int buf_length,
+                                 const char *dir)
 {
-    int i = 0;
-    int j;
-    char *temp_ptr;
-
-    /* Look for the end of the string */
-    while((i < max) &&
-          (src[i] != '\n') &&
-          (src[i] != '\r') &&
-          (src[i] != '\0'))
-        i++;
-
-    /* Now work back killing white space */
-    while((i > 0) &&
-          ((src[i-1] == ' ') ||
-          (src[i-1] == '\t')))
-        i--;
+    size_t len;
 
-    /* Zero-terminate the file name */
-    src[i]=0;
+    /* strip whitespace at beginning and end */
+    len = path_trim_whitespace(src, (const char **)&src);
+    src[len] = '\0';
 
     /* replace backslashes with forward slashes */
-    for ( j=0; j<i; j++ )
-        if ( src[j] == '\\' )
-            src[j] = '/';
+    path_correct_separators(src, src);
 
-    if('/' == src[0])
-    {
-        strlcpy(dest, src, buf_length);
-    }
-    else
-    {
-        /* handle dos style drive letter */
-        if (':' == src[1])
-            strlcpy(dest, &src[2], buf_length);
-        else if (!strncmp(src, "../", 3))
-        {
-            /* handle relative paths */
-            i=3;
-            while(!strncmp(&src[i], "../", 3))
-                i += 3;
-            for (j=0; j<i/3; j++) {
-                temp_ptr = strrchr(dir, '/');
-                if (temp_ptr)
-                    *temp_ptr = '\0';
-                else
-                    break;
-            }
-            snprintf(dest, buf_length, "%s/%s", dir, &src[i]);
-        }
-        else if ( '.' == src[0] && '/' == src[1] ) {
-            snprintf(dest, buf_length, "%s/%s", dir, &src[2]);
-        }
-        else {
-            snprintf(dest, buf_length, "%s/%s", dir, src);
-        }
-    }
-#ifdef HAVE_MULTIVOLUME 
+    /* handle DOS style drive letter and parse non-greedily so that:
+     * 1) "c:/foo" becomes "/foo" and the result is absolute
+     * 2) "c:foo becomes "foo" and the result is relative
+     * This is how Windows seems to handle it except drive letters are of no
+     * meaning here. */
+    path_strip_drive(src, (const char **)&src, false);
 
-    char vol_string[VOL_ENUM_POS + 8];
-    snprintf(vol_string, sizeof(vol_string), "/"VOL_NAMES, 1);
+    /* prepends directory only if src is relative */
+    len = path_append(dest, *dir ? dir : PATH_ROOTSTR, src, buf_length);
+    if (len >= (size_t)buf_length)
+        return -1; /* buffer too small */
 
-    /*check if the playlist is on a external card, and correct path if needed */
-    if(strstr(dir, vol_string) && (strstr(dest, vol_string) == NULL)){
-        char temp[buf_length];
-        strlcpy(temp, dest, buf_length);
-        snprintf(dest, buf_length, "%s%s", vol_string, temp);
-    }
-#endif
-
-    return 0;
+    return len;
 }
 
 /*
@@ -3113,8 +3066,7 @@ int playlist_insert_playlist(struct playlist_info* playlist, const char *filenam
 {
     int fd;
     int max;
-    char *temp_ptr;
-    const char *dir;
+    char *dir;
     unsigned char *count_str;
     char temp_buf[MAX_PATH+1];
     char trackname[MAX_PATH+1];
@@ -3139,13 +3091,8 @@ int playlist_insert_playlist(struct playlist_info* playlist, const char *filenam
     }
 
     /* we need the directory name for formatting purposes */
-    dir = filename;
-
-    temp_ptr = strrchr(filename+1,'/');
-    if (temp_ptr)
-        *temp_ptr = 0;
-    else
-        dir = "/";
+    size_t dirlen = path_dirname(filename, (const char **)&dir);
+    dir = strmemdupa(dir, dirlen);
 
     if (queue)
         count_str = ID2P(LANG_PLAYLIST_QUEUE_COUNT);
@@ -3183,8 +3130,8 @@ int playlist_insert_playlist(struct playlist_info* playlist, const char *filenam
 
             /* we need to format so that relative paths are correctly
                handled */
-            if (format_track_path(trackname, temp_buf, sizeof(trackname), max,
-                    dir) < 0)
+            if (format_track_path(trackname, temp_buf, sizeof(trackname),
+                                  dir) < 0)
             {
                 result = -1;
                 break;
@@ -3223,9 +3170,6 @@ int playlist_insert_playlist(struct playlist_info* playlist, const char *filenam
 
     close(fd);
 
-    if (temp_ptr)
-        *temp_ptr = '/';
-
     sync_control(playlist, false);
 
     cpu_boost(false);
@@ -3537,9 +3481,9 @@ int playlist_save(struct playlist_info* playlist, char *filename,
     char path[MAX_PATH+1];
     char tmp_buf[MAX_PATH+1];
     int result = 0;
-    bool overwrite_current = false;
     int *seek_buf;
     bool reparse;
+    ssize_t pathlen;
 
     ALIGN_BUFFER(temp_buffer, temp_buffer_size, sizeof(int));
     seek_buf = temp_buffer;
@@ -3557,22 +3501,18 @@ int playlist_save(struct playlist_info* playlist, char *filename,
         return -1;
 
     /* use current working directory as base for pathname */
-    if (format_track_path(path, filename, sizeof(tmp_buf),
-                          strlen(filename)+1, "/") < 0)
+    pathlen = format_track_path(path, filename, sizeof(path), PATH_ROOTSTR);
+    if (pathlen < 0)
+        return -1;
+
+    /* Use temporary pathname and overwrite/rename later */
+    if (strlcat(path, "_temp", sizeof(path)) >= sizeof (path))
         return -1;
 
     /* can ignore volatile here, because core_get_data() is called later */
     char* old_buffer = (char*)playlist->buffer;
     size_t old_buffer_size = playlist->buffer_size;
 
-    if (!strncmp(playlist->filename, path, strlen(path)))
-    {
-        /* Attempting to overwrite current playlist file.
-         * use temporary pathname and overwrite later */
-        strlcat(path, "_temp", sizeof(path));
-        overwrite_current = true;
-    }
-
     if (is_m3u8(path))
     {
         fd = open_utf8(path, O_CREAT|O_WRONLY|O_TRUNC);
@@ -3621,8 +3561,8 @@ int playlist_save(struct playlist_info* playlist, char *filename,
                 break;
             }
 
-            if (overwrite_current && !reparse)
-                seek_buf[count] = lseek(fd, 0, SEEK_CUR);
+            if (!reparse)
+                seek_buf[count] = filesize(fd);
 
             if (fdprintf(fd, "%s\n", tmp_buf) < 0)
             {
@@ -3647,57 +3587,61 @@ int playlist_save(struct playlist_info* playlist, char *filename,
         index = (index+1)%playlist->amount;
     }
 
-    display_playlist_count(count, ID2P(LANG_PLAYLIST_SAVE_COUNT), true);
-
     close(fd);
+    fd = -1;
 
-    if (overwrite_current && result >= 0)
+    display_playlist_count(count, ID2P(LANG_PLAYLIST_SAVE_COUNT), true);
+
+    if (result >= 0)
     {
-        result = -1;
+        strmemcpy(tmp_buf, path, pathlen); /* remove "_temp" */
 
         mutex_lock(playlist->control_mutex);
 
-        /* Replace the current playlist with the new one and update indices */
-        close(playlist->fd);
-        playlist->fd = -1;
-        if (remove(playlist->filename) >= 0)
+        if (!rename(path, tmp_buf))
         {
-            if (rename(path, playlist->filename) >= 0)
+            fd = open_utf8(tmp_buf, O_RDONLY);
+            if (fsamefile(fd, playlist->fd) > 0)
             {
-                playlist->fd = open_utf8(playlist->filename, O_RDONLY);
-                if (playlist->fd >= 0)
+                /* Replace the current playlist with the new one and update
+                   indices */
+                close(playlist->fd);
+                playlist->fd = fd;
+                fd = -1;
+
+                if (!reparse)
                 {
-                    if (!reparse)
+                    index = playlist->first_index;
+                    for (i=0, count=0; i<playlist->amount; i++)
                     {
-                        index = playlist->first_index;
-                        for (i=0, count=0; i<playlist->amount; i++)
+                        if (!(playlist->indices[index] & PLAYLIST_QUEUE_MASK))
                         {
-                            if (!(playlist->indices[index] & PLAYLIST_QUEUE_MASK))
-                            {
-                                playlist->indices[index] = seek_buf[count];
-                                count++;
-                            }
-                            index = (index+1)%playlist->amount;
+                            playlist->indices[index] = seek_buf[count];
+                            count++;
                         }
+                        index = (index+1)%playlist->amount;
                     }
-                    else
-                    {
-                        NOTEF("reparsing current playlist (slow)");
-                        playlist->amount = 0;
-                        add_indices_to_playlist(playlist, temp_buffer, temp_buffer_size);
-                    }
-                    /* we need to recreate control because inserted tracks are
-                       now part of the playlist and shuffle has been
-                       invalidated */
-                    result = recreate_control(playlist);
                 }
-            }
-       }
+                else
+                {
+                    NOTEF("reparsing current playlist (slow)");
+                    playlist->amount = 0;
+                    add_indices_to_playlist(playlist, temp_buffer,
+                                            temp_buffer_size);
+                }
 
-       mutex_unlock(playlist->control_mutex);
+                /* we need to recreate control because inserted tracks are
+                   now part of the playlist and shuffle has been invalidated */
+                result = recreate_control(playlist);
+            }
+        }
 
+        mutex_unlock(playlist->control_mutex);
     }
 
+    if (fd >= 0)
+        close(fd);
+
     cpu_boost(false);
 
 reset_old_buffer:
@@ -3759,8 +3703,12 @@ int playlist_directory_tracksearch(const char* dirname, bool recurse,
             if (recurse)
             {
                 /* recursively add directories */
-                snprintf(buf, sizeof(buf), "%s/%s",
-                            dirname[1]? dirname: "", files[i].name);
+                if (path_append(buf, dirname, files[i].name, sizeof(buf))
+                        >= sizeof(buf))
+                {
+                    continue;
+                }
+
                 result = playlist_directory_tracksearch(buf, recurse,
                     callback, context);
                 if (result < 0)
@@ -3785,8 +3733,11 @@ int playlist_directory_tracksearch(const char* dirname, bool recurse,
         }
         else if ((files[i].attr & FILE_ATTR_MASK) == FILE_ATTR_AUDIO)
         {
-            snprintf(buf, sizeof(buf), "%s/%s",
-                        dirname[1]? dirname: "", files[i].name);
+            if (path_append(buf, dirname, files[i].name, sizeof(buf))
+                    >= sizeof(buf))
+            {
+                continue;
+            }
 
             if (callback(buf, context) != 0)
             {