WebSVN – HelenOS – Diff – /trunk/uspace/srv/fs/fat/fat_ops.c

 /*
  * Copyright (c) 2008 Jakub Jermar
  * All rights reserved.
+ *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
+ *
  * - Redistributions of source code must retain the above copyright
  *   notice, this list of conditions and the following disclaimer.
  * - Redistributions in binary form must reproduce the above copyright
  *   notice, this list of conditions and the following disclaimer in the
  *   documentation and/or other materials provided with the distribution.
  * - The name of the author may not be used to endorse or promote products
  *   derived from this software without specific prior written permission.
+ *
  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
  * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  */
 /** @addtogroup fs
  * @{
  */
 /**
  * @file    fat_ops.c
  * @brief   Implementation of VFS operations for the FAT file system server.
  */
 #include "fat.h"
 #include "fat_dentry.h"
 #include "fat_fat.h"
 #include "../../vfs/vfs.h"
 #include <libfs.h>
 #include <ipc/ipc.h>
 #include <ipc/services.h>
 #include <ipc/devmap.h>
 #include <async.h>
 #include <errno.h>
 #include <string.h>
 #include <byteorder.h>
 #include <libadt/hash_table.h>
 #include <libadt/list.h>
 #include <assert.h>
 #include <futex.h>
 #include <sys/mman.h>
 #include <align.h>
-#define BS_BLOCK        0
-#define BS_SIZE         512
 /** Futex protecting the list of cached free FAT nodes. */
 static futex_t ffn_futex = FUTEX_INITIALIZER;
 /** List of cached free FAT nodes. */
 static LIST_INITIALIZE(ffn_head);
-#define min(a, b)       ((a) < (b) ? (a) : (b))
 static int dev_phone = -1;      /* FIXME */
 static void *dev_buffer = NULL;     /* FIXME */
-/* TODO move somewhere else */
-typedef struct {
-    void *data;
-    size_t size;
-    bool dirty;
-} block_t;
-static block_t *block_get(dev_handle_t dev_handle, off_t offset, size_t bs)
+block_t *block_get(dev_handle_t dev_handle, off_t offset, size_t bs)
+{
     /* FIXME */
     block_t *b;
     off_t bufpos = 0;
     size_t buflen = 0;
     off_t pos = offset * bs;
     assert(dev_phone != -1);
     assert(dev_buffer);
     b = malloc(sizeof(block_t));
     if (!b)
         return NULL;
     b->data = malloc(bs);
     if (!b->data) {
         free(b);
         return NULL;
+    }
     b->size = bs;
     if (!libfs_blockread(dev_phone, dev_buffer, &bufpos, &buflen, &pos,
         b->data, bs, bs)) {
         free(b->data);
         free(b);
         return NULL;
+    }
     return b;
+}
-static void block_put(block_t *block)
+void block_put(block_t *block)
+{
     /* FIXME */
     free(block->data);
     free(block);
+}
-#define FAT1        0
-#define FAT_BS(b)       ((fat_bs_t *)((b)->data))
-#define FAT_CLST_RES0   0x0000
-#define FAT_CLST_RES1   0x0001
-#define FAT_CLST_FIRST  0x0002
-#define FAT_CLST_BAD    0xfff7
-#define FAT_CLST_LAST1  0xfff8
-#define FAT_CLST_LAST8  0xffff
-/* internally used to mark root directory's parent */
-#define FAT_CLST_ROOTPAR    FAT_CLST_RES0
-/* internally used to mark root directory */
-#define FAT_CLST_ROOT       FAT_CLST_RES1
-#define fat_block_get(np, off) \
-    _fat_block_get((np)->idx->dev_handle, (np)->firstc, (off))
-static block_t *
-_fat_block_get(dev_handle_t dev_handle, fat_cluster_t firstc, off_t offset)
-{
-    block_t *bb;
-    block_t *b;
-    unsigned bps;
-    unsigned spc;
-    unsigned rscnt;     /* block address of the first FAT */
-    unsigned fatcnt;
-    unsigned rde;
-    unsigned rds;       /* root directory size */
-    unsigned sf;
-    unsigned ssa;       /* size of the system area */
-    unsigned clusters;
-    fat_cluster_t clst = firstc;
-    unsigned i;
-    bb = block_get(dev_handle, BS_BLOCK, BS_SIZE);
-    bps = uint16_t_le2host(FAT_BS(bb)->bps);
-    spc = FAT_BS(bb)->spc;
-    rscnt = uint16_t_le2host(FAT_BS(bb)->rscnt);
-    fatcnt = FAT_BS(bb)->fatcnt;
-    rde = uint16_t_le2host(FAT_BS(bb)->root_ent_max);
-    sf = uint16_t_le2host(FAT_BS(bb)->sec_per_fat);
-    block_put(bb);
-    rds = (sizeof(fat_dentry_t) * rde) / bps;
-    rds += ((sizeof(fat_dentry_t) * rde) % bps != 0);
-    ssa = rscnt + fatcnt * sf + rds;
-    if (firstc == FAT_CLST_ROOT) {
-        /* root directory special case */
-        assert(offset < rds);
-        b = block_get(dev_handle, rscnt + fatcnt * sf + offset, bps);
-        return b;
-    }
-    clusters = offset / spc;
-    for (i = 0; i < clusters; i++) {
-        unsigned fsec;  /* sector offset relative to FAT1 */
-        unsigned fidx;  /* FAT1 entry index */
-        assert(clst >= FAT_CLST_FIRST && clst < FAT_CLST_BAD);
-        fsec = (clst * sizeof(fat_cluster_t)) / bps;
-        fidx = clst % (bps / sizeof(fat_cluster_t));
-        /* read FAT1 */
-        b = block_get(dev_handle, rscnt + fsec, bps);
-        clst = uint16_t_le2host(((fat_cluster_t *)b->data)[fidx]);
-        assert(clst != FAT_CLST_BAD);
-        assert(clst < FAT_CLST_LAST1);
-        block_put(b);
-    }
-    b = block_get(dev_handle, ssa + (clst - FAT_CLST_FIRST) * spc +
-        offset % spc, bps);
-    return b;
-}
-/** Return number of blocks allocated to a file.
- *
- * @param dev_handle    Device handle of the device with the file.
- * @param firstc    First cluster of the file.
- *
- * @return      Number of blocks allocated to the file.
- */
-static uint16_t
-_fat_blcks_get(dev_handle_t dev_handle, fat_cluster_t firstc)
-{
-    block_t *bb;
-    block_t *b;
-    unsigned bps;
-    unsigned spc;
-    unsigned rscnt;     /* block address of the first FAT */
-    unsigned clusters = 0;
-    fat_cluster_t clst = firstc;
-    bb = block_get(dev_handle, BS_BLOCK, BS_SIZE);
-    bps = uint16_t_le2host(FAT_BS(bb)->bps);
-    spc = FAT_BS(bb)->spc;
-    rscnt = uint16_t_le2host(FAT_BS(bb)->rscnt);
-    block_put(bb);
-    if (firstc == FAT_CLST_RES0) {
-        /* No space allocated to the file. */
-        return 0;
-    }
-    while (clst < FAT_CLST_LAST1) {
-        unsigned fsec;  /* sector offset relative to FAT1 */
-        unsigned fidx;  /* FAT1 entry index */
-        assert(clst >= FAT_CLST_FIRST);
-        fsec = (clst * sizeof(fat_cluster_t)) / bps;
-        fidx = clst % (bps / sizeof(fat_cluster_t));
-        /* read FAT1 */
-        b = block_get(dev_handle, rscnt + fsec, bps);
-        clst = uint16_t_le2host(((fat_cluster_t *)b->data)[fidx]);
-        assert(clst != FAT_CLST_BAD);
-        block_put(b);
-        clusters++;
-    }
-    return clusters * spc;
-}
 static void fat_node_initialize(fat_node_t *node)
+{
     futex_initialize(&node->lock, 1);
     node->idx = NULL;
     node->type = 0;
     link_initialize(&node->ffn_link);
     node->size = 0;
     node->lnkcnt = 0;
     node->refcnt = 0;
     node->dirty = false;
+}
-static uint16_t fat_bps_get(dev_handle_t dev_handle)
-{
-    block_t *bb;
-    uint16_t bps;
-    bb = block_get(dev_handle, BS_BLOCK, BS_SIZE);
-    assert(bb != NULL);
-    bps = uint16_t_le2host(FAT_BS(bb)->bps);
-    block_put(bb);
-    return bps;
-}
 static void fat_node_sync(fat_node_t *node)
+{
     /* TODO */
+}
 /** Internal version of fat_node_get().
+ *
  * @param idxp      Locked index structure.
  */
 static void *fat_node_get_core(fat_idx_t *idxp)
+{
     block_t *b;
     fat_dentry_t *d;
     fat_node_t *nodep = NULL;
     unsigned bps;
     unsigned dps;
     if (idxp->nodep) {
         /*
          * We are lucky.
          * The node is already instantiated in memory.
          */
         futex_down(&idxp->nodep->lock);
         if (!idxp->nodep->refcnt++)
             list_remove(&idxp->nodep->ffn_link);
         futex_up(&idxp->nodep->lock);
         return idxp->nodep;
+    }
     /*
      * We must instantiate the node from the file system.
      */
     assert(idxp->pfc);
     futex_down(&ffn_futex);
     if (!list_empty(&ffn_head)) {
         /* Try to use a cached free node structure. */
         fat_idx_t *idxp_tmp;
         nodep = list_get_instance(ffn_head.next, fat_node_t, ffn_link);
         if (futex_trydown(&nodep->lock) == ESYNCH_WOULD_BLOCK)
             goto skip_cache;
         idxp_tmp = nodep->idx;
         if (futex_trydown(&idxp_tmp->lock) == ESYNCH_WOULD_BLOCK) {
             futex_up(&nodep->lock);
             goto skip_cache;
+        }
         list_remove(&nodep->ffn_link);
         futex_up(&ffn_futex);
         if (nodep->dirty)
             fat_node_sync(nodep);
         idxp_tmp->nodep = NULL;
         futex_up(&nodep->lock);
         futex_up(&idxp_tmp->lock);
     } else {
 skip_cache:
         /* Try to allocate a new node structure. */
         futex_up(&ffn_futex);
         nodep = (fat_node_t *)malloc(sizeof(fat_node_t));
         if (!nodep)
             return NULL;
+    }
     fat_node_initialize(nodep);
     bps = fat_bps_get(idxp->dev_handle);
     dps = bps / sizeof(fat_dentry_t);
     /* Read the block that contains the dentry of interest. */
     b = _fat_block_get(idxp->dev_handle, idxp->pfc,
         (idxp->pdi * sizeof(fat_dentry_t)) / bps);
     assert(b);
     d = ((fat_dentry_t *)b->data) + (idxp->pdi % dps);
     if (d->attr & FAT_ATTR_SUBDIR) {
         /*
          * The only directory which does not have this bit set is the
          * root directory itself. The root directory node is handled
          * and initialized elsewhere.
          */
         nodep->type = FAT_DIRECTORY;
         /*
          * Unfortunately, the 'size' field of the FAT dentry is not
          * defined for the directory entry type. We must determine the
          * size of the directory by walking the FAT.
          */
         nodep->size = bps * _fat_blcks_get(idxp->dev_handle,
             uint16_t_le2host(d->firstc));
     } else {
         nodep->type = FAT_FILE;
         nodep->size = uint32_t_le2host(d->size);
+    }
     nodep->firstc = uint16_t_le2host(d->firstc);
     nodep->lnkcnt = 1;
     nodep->refcnt = 1;
     block_put(b);
     /* Link the idx structure with the node structure. */
     nodep->idx = idxp;
     idxp->nodep = nodep;
     return nodep;
+}
 /** Instantiate a FAT in-core node. */
 static void *fat_node_get(dev_handle_t dev_handle, fs_index_t index)
+{
     void *node;
     fat_idx_t *idxp;
     idxp = fat_idx_get_by_index(dev_handle, index);
     if (!idxp)
         return NULL;
     /* idxp->lock held */
     node = fat_node_get_core(idxp);
     futex_up(&idxp->lock);
     return node;
+}
 static void fat_node_put(void *node)
+{
     fat_node_t *nodep = (fat_node_t *)node;
     futex_down(&nodep->lock);
     if (!--nodep->refcnt) {
         futex_down(&ffn_futex);
         list_append(&nodep->ffn_link, &ffn_head);
         futex_up(&ffn_futex);
+    }
     futex_up(&nodep->lock);
+}
 static void *fat_create(int flags)
+{
     return NULL;    /* not supported at the moment */
+}
 static int fat_destroy(void *node)
+{
     return ENOTSUP; /* not supported at the moment */
+}
 static bool fat_link(void *prnt, void *chld, const char *name)
+{
     return false;   /* not supported at the moment */
+}
 static int fat_unlink(void *prnt, void *chld)
+{
     return ENOTSUP; /* not supported at the moment */
+}
 static void *fat_match(void *prnt, const char *component)
+{
     fat_node_t *parentp = (fat_node_t *)prnt;
     char name[FAT_NAME_LEN + 1 + FAT_EXT_LEN + 1];
     unsigned i, j;
     unsigned bps;       /* bytes per sector */
     unsigned dps;       /* dentries per sector */
     unsigned blocks;
     fat_dentry_t *d;
     block_t *b;
     futex_down(&parentp->idx->lock);
     bps = fat_bps_get(parentp->idx->dev_handle);
     dps = bps / sizeof(fat_dentry_t);
     blocks = parentp->size / bps + (parentp->size % bps != 0);
     for (i = 0; i < blocks; i++) {
         unsigned dentries;
         b = fat_block_get(parentp, i);
         dentries = (i == blocks - 1) ?
             parentp->size % sizeof(fat_dentry_t) :
             dps;
         for (j = 0; j < dentries; j++) {
             d = ((fat_dentry_t *)b->data) + j;
             switch (fat_classify_dentry(d)) {
             case FAT_DENTRY_SKIP:
                 continue;
             case FAT_DENTRY_LAST:
                 block_put(b);
                 futex_up(&parentp->idx->lock);
                 return NULL;
             default:
             case FAT_DENTRY_VALID:
                 dentry_name_canonify(d, name);
                 break;
+            }
             if (stricmp(name, component) == 0) {
                 /* hit */
                 void *node;
                 /*
                  * Assume tree hierarchy for locking.  We
                  * already have the parent and now we are going
                  * to lock the child.  Never lock in the oposite
                  * order.
                  */
                 fat_idx_t *idx = fat_idx_get_by_pos(
                     parentp->idx->dev_handle, parentp->firstc,
                     i * dps + j);
                 futex_up(&parentp->idx->lock);
                 if (!idx) {
                     /*
                      * Can happen if memory is low or if we
                      * run out of 32-bit indices.
                      */
                     block_put(b);
                     return NULL;
+                }
                 node = fat_node_get_core(idx);
                 futex_up(&idx->lock);
                 block_put(b);
                 return node;
+            }
+        }
         block_put(b);
+    }
     futex_up(&parentp->idx->lock);
     return NULL;
+}
 static fs_index_t fat_index_get(void *node)
+{
     fat_node_t *fnodep = (fat_node_t *)node;
     if (!fnodep)
         return 0;
     return fnodep->idx->index;
+}
 static size_t fat_size_get(void *node)
+{
     return ((fat_node_t *)node)->size;
+}
 static unsigned fat_lnkcnt_get(void *node)
+{
     return ((fat_node_t *)node)->lnkcnt;
+}
 static bool fat_has_children(void *node)
+{
     fat_node_t *nodep = (fat_node_t *)node;
     unsigned bps;
     unsigned dps;
     unsigned blocks;
     block_t *b;
     unsigned i, j;
     if (nodep->type != FAT_DIRECTORY)
         return false;
     futex_down(&nodep->idx->lock);
     bps = fat_bps_get(nodep->idx->dev_handle);
     dps = bps / sizeof(fat_dentry_t);
     blocks = nodep->size / bps + (nodep->size % bps != 0);
     for (i = 0; i < blocks; i++) {
         unsigned dentries;
         fat_dentry_t *d;
         b = fat_block_get(nodep, i);
         dentries = (i == blocks - 1) ?
             nodep->size % sizeof(fat_dentry_t) :
             dps;
         for (j = 0; j < dentries; j++) {
             d = ((fat_dentry_t *)b->data) + j;
             switch (fat_classify_dentry(d)) {
             case FAT_DENTRY_SKIP:
                 continue;
             case FAT_DENTRY_LAST:
                 block_put(b);
                 futex_up(&nodep->idx->lock);
                 return false;
             default:
             case FAT_DENTRY_VALID:
                 block_put(b);
                 futex_up(&nodep->idx->lock);
                 return true;
+            }
             block_put(b);
             futex_up(&nodep->idx->lock);
             return true;
+        }
         block_put(b);
+    }
     futex_up(&nodep->idx->lock);
     return false;
+}
 static void *fat_root_get(dev_handle_t dev_handle)
+{
     return fat_node_get(dev_handle, 0);
+}
 static char fat_plb_get_char(unsigned pos)
+{
     return fat_reg.plb_ro[pos % PLB_SIZE];
+}
 static bool fat_is_directory(void *node)
+{
     return ((fat_node_t *)node)->type == FAT_DIRECTORY;
+}
 static bool fat_is_file(void *node)
+{
     return ((fat_node_t *)node)->type == FAT_FILE;
+}
 /** libfs operations */
 libfs_ops_t fat_libfs_ops = {
     .match = fat_match,
     .node_get = fat_node_get,
     .node_put = fat_node_put,
     .create = fat_create,
     .destroy = fat_destroy,
     .link = fat_link,
     .unlink = fat_unlink,
     .index_get = fat_index_get,
     .size_get = fat_size_get,
     .lnkcnt_get = fat_lnkcnt_get,
     .has_children = fat_has_children,
     .root_get = fat_root_get,
     .plb_get_char = fat_plb_get_char,
     .is_directory = fat_is_directory,
     .is_file = fat_is_file
 };
 void fat_mounted(ipc_callid_t rid, ipc_call_t *request)
+{
     dev_handle_t dev_handle = (dev_handle_t) IPC_GET_ARG1(*request);
     block_t *bb;
     uint16_t bps;
     uint16_t rde;
     int rc;
     /*
      * For now, we don't bother to remember dev_handle, dev_phone or
      * dev_buffer in some data structure. We use global variables because we
      * know there will be at most one mount on this file system.
      * Of course, this is a huge TODO item.
      */
     dev_buffer = mmap(NULL, BS_SIZE, PROTO_READ | PROTO_WRITE,
         MAP_ANONYMOUS | MAP_PRIVATE, 0, 0);
     if (!dev_buffer) {
         ipc_answer_0(rid, ENOMEM);
         return;
+    }
     dev_phone = ipc_connect_me_to(PHONE_NS, SERVICE_DEVMAP,
         DEVMAP_CONNECT_TO_DEVICE, dev_handle);
     if (dev_phone < 0) {
         munmap(dev_buffer, BS_SIZE);
         ipc_answer_0(rid, dev_phone);
         return;
+    }
     rc = ipc_share_out_start(dev_phone, dev_buffer,
         AS_AREA_READ | AS_AREA_WRITE);
     if (rc != EOK) {
             munmap(dev_buffer, BS_SIZE);
         ipc_answer_0(rid, rc);
         return;
+    }
     /* Read the number of root directory entries. */
     bb = block_get(dev_handle, BS_BLOCK, BS_SIZE);
     bps = uint16_t_le2host(FAT_BS(bb)->bps);
     rde = uint16_t_le2host(FAT_BS(bb)->root_ent_max);
     block_put(bb);
     if (bps != BS_SIZE) {
         munmap(dev_buffer, BS_SIZE);
         ipc_answer_0(rid, ENOTSUP);
         return;
+    }
     rc = fat_idx_init_by_dev_handle(dev_handle);
     if (rc != EOK) {
             munmap(dev_buffer, BS_SIZE);
         ipc_answer_0(rid, rc);
         return;
+    }
     /* Initialize the root node. */
     fat_node_t *rootp = (fat_node_t *)malloc(sizeof(fat_node_t));
     if (!rootp) {
             munmap(dev_buffer, BS_SIZE);
         fat_idx_fini_by_dev_handle(dev_handle);
         ipc_answer_0(rid, ENOMEM);
         return;
+    }
     fat_node_initialize(rootp);
     fat_idx_t *ridxp = fat_idx_get_by_pos(dev_handle, FAT_CLST_ROOTPAR, 0);
     if (!ridxp) {
             munmap(dev_buffer, BS_SIZE);
         free(rootp);
         fat_idx_fini_by_dev_handle(dev_handle);
         ipc_answer_0(rid, ENOMEM);
         return;
+    }
     assert(ridxp->index == 0);
     /* ridxp->lock held */
     rootp->type = FAT_DIRECTORY;
     rootp->firstc = FAT_CLST_ROOT;
     rootp->refcnt = 1;
     rootp->lnkcnt = 0;  /* FS root is not linked */
     rootp->size = rde * sizeof(fat_dentry_t);
     rootp->idx = ridxp;
     ridxp->nodep = rootp;
     futex_up(&ridxp->lock);
     ipc_answer_3(rid, EOK, ridxp->index, rootp->size, rootp->lnkcnt);
+}
 void fat_mount(ipc_callid_t rid, ipc_call_t *request)
+{
     ipc_answer_0(rid, ENOTSUP);
+}
 void fat_lookup(ipc_callid_t rid, ipc_call_t *request)
+{
     libfs_lookup(&fat_libfs_ops, fat_reg.fs_handle, rid, request);
+}
 void fat_read(ipc_callid_t rid, ipc_call_t *request)
+{
     dev_handle_t dev_handle = (dev_handle_t)IPC_GET_ARG1(*request);
     fs_index_t index = (fs_index_t)IPC_GET_ARG2(*request);
     off_t pos = (off_t)IPC_GET_ARG3(*request);
     fat_node_t *nodep = (fat_node_t *)fat_node_get(dev_handle, index);
     uint16_t bps = fat_bps_get(dev_handle);
     size_t bytes;
     block_t *b;
     if (!nodep) {
         ipc_answer_0(rid, ENOENT);
         return;
+    }
     ipc_callid_t callid;
     size_t len;
     if (!ipc_data_read_receive(&callid, &len)) {
         fat_node_put(nodep);
         ipc_answer_0(callid, EINVAL);
         ipc_answer_0(rid, EINVAL);
         return;
+    }
     if (nodep->type == FAT_FILE) {
         /*
          * Our strategy for regular file reads is to read one block at
          * most and make use of the possibility to return less data than
          * requested. This keeps the code very simple.
          */
         bytes = min(len, bps - pos % bps);
         b = fat_block_get(nodep, pos / bps);
         (void) ipc_data_read_finalize(callid, b->data + pos % bps,
             bytes);
         block_put(b);
     } else {
         unsigned bnum;
         off_t spos = pos;
         char name[FAT_NAME_LEN + 1 + FAT_EXT_LEN + 1];
         fat_dentry_t *d;
         assert(nodep->type == FAT_DIRECTORY);
         assert(nodep->size % bps == 0);
         assert(bps % sizeof(fat_dentry_t) == 0);
         /*
          * Our strategy for readdir() is to use the position pointer as
          * an index into the array of all dentries. On entry, it points
          * to the first unread dentry. If we skip any dentries, we bump
          * the position pointer accordingly.
          */
         bnum = (pos * sizeof(fat_dentry_t)) / bps;
         while (bnum < nodep->size / bps) {
             off_t o;
             b = fat_block_get(nodep, bnum);
             for (o = pos % (bps / sizeof(fat_dentry_t));
                 o < bps / sizeof(fat_dentry_t);
                 o++, pos++) {
                 d = ((fat_dentry_t *)b->data) + o;
                 switch (fat_classify_dentry(d)) {
                 case FAT_DENTRY_SKIP:
                     continue;
                 case FAT_DENTRY_LAST:
                     block_put(b);
                     goto miss;
                 default:
                 case FAT_DENTRY_VALID:
                     dentry_name_canonify(d, name);
                     block_put(b);
                     goto hit;
+                }
+            }
             block_put(b);
             bnum++;
+        }
 miss:
         fat_node_put(nodep);
         ipc_answer_0(callid, ENOENT);
         ipc_answer_1(rid, ENOENT, 0);
         return;
 hit:
         (void) ipc_data_read_finalize(callid, name, strlen(name) + 1);
         bytes = (pos - spos) + 1;
+    }
     fat_node_put(nodep);
     ipc_answer_1(rid, EOK, (ipcarg_t)bytes);
+}
-/** Fill the gap between EOF and a new file position.
- *
- * @param nodep     FAT node with the gap.
- * @param mcl       First cluster in an independent cluster chain that will
- *          be later appended to the end of the node's own cluster
- *          chain. If pos is still in the last allocated cluster,
- *          this argument is ignored.
- * @param pos       Position in the last node block.
- */
-static void
-fat_fill_gap(fat_node_t *nodep, fat_cluster_t mcl, off_t pos)
-{
-    uint16_t bps;
-    unsigned spc;
-    block_t *bb, *b;
-    off_t o, boundary;
-    bb = block_get(nodep->idx->dev_handle, BS_BLOCK, BS_SIZE);
-    bps = uint16_t_le2host(FAT_BS(bb)->bps);
-    spc = FAT_BS(bb)->spc;
-    block_put(bb);
-    boundary = ROUND_UP(nodep->size, bps * spc);
-    /* zero out already allocated space */
-    for (o = nodep->size - 1; o < pos && o < boundary;
-        o = ALIGN_DOWN(o + bps, bps)) {
-        b = fat_block_get(nodep, o / bps);
-        memset(b->data + o % bps, 0, bps - o % bps);
-        b->dirty = true;        /* need to sync node */
-        block_put(b);
-    }
-    if (o >= pos)
-        return;
-    /* zero out the initial part of the new cluster chain */
-    for (o = boundary; o < pos; o += bps) {
-        b = _fat_block_get(nodep->idx->dev_handle, mcl,
-            (o - boundary) / bps);
-        memset(b->data, 0, min(bps, pos - o));
-        b->dirty = true;        /* need to sync node */
-        block_put(b);
-    }
-}
-static void
-fat_mark_cluster(dev_handle_t dev_handle, unsigned fatno, fat_cluster_t clst,
-    fat_cluster_t value)
-{
-    /* TODO */
-}
-static void
-fat_alloc_shadow_clusters(dev_handle_t dev_handle, fat_cluster_t *lifo,
-    unsigned nclsts)
-{
-    /* TODO */
-}
-static int
-fat_alloc_clusters(dev_handle_t dev_handle, unsigned nclsts, fat_cluster_t *mcl,
-    fat_cluster_t *lcl)
-{
-    uint16_t bps;
-    uint16_t rscnt;
-    uint16_t sf;
-    block_t *bb, *blk;
-    fat_cluster_t *lifo;    /* stack for storing free cluster numbers */
-    unsigned found = 0; /* top of the free cluster number stack */
-    unsigned b, c, cl;
-    lifo = (fat_cluster_t *) malloc(nclsts * sizeof(fat_cluster_t));
-    if (lifo)
-        return ENOMEM;
-    bb = block_get(dev_handle, BS_BLOCK, BS_SIZE);
-    bps = uint16_t_le2host(FAT_BS(bb)->bps);
-    rscnt = uint16_t_le2host(FAT_BS(bb)->rscnt);
-    sf = uint16_t_le2host(FAT_BS(bb)->sec_per_fat);
-    block_put(bb);
-    /*
-     * Search FAT1 for unused clusters.
-     */
-    for (b = 0, cl = 0; b < sf; blk++) {
-        blk = block_get(dev_handle, rscnt + b, bps);
-        for (c = 0; c < bps / sizeof(fat_cluster_t); c++, cl++) {
-            fat_cluster_t *clst = (fat_cluster_t *)blk->data + c;
-            if (*clst == FAT_CLST_RES0) {
-                /*
-                 * The cluster is free. Put it into our stack
-                 * of found clusters and mark it as non-free.
-                 */
-                lifo[found] = cl;
-                if (found == 0)
-                    *clst = FAT_CLST_LAST1;
-                else
-                    *clst = lifo[found - 1];
-                blk->dirty = true;  /* need to sync block */
-                if (++found == nclsts) {
-                    /* we are almost done */
-                    block_put(blk);
-                    /* update the shadow copies of FAT */
-                    fat_alloc_shadow_clusters(dev_handle,
-                        lifo, nclsts);
-                    *mcl = lifo[found - 1];
-                    *lcl = lifo[0];
-                    free(lifo);
-                    return EOK;
-                }
-            }
-        }
-        block_put(blk);
-    }
-    /*
-     * We could not find enough clusters. Now we need to free the clusters
-     * we have allocated so far.
-     */
-    while (found--)
-        fat_mark_cluster(dev_handle, FAT1, lifo[found], FAT_CLST_RES0);
-    free(lifo);
-    return ENOSPC;
-}
-static void
-fat_append_clusters(fat_node_t *nodep, fat_cluster_t mcl)
-{
-}
 void fat_write(ipc_callid_t rid, ipc_call_t *request)
+{
     dev_handle_t dev_handle = (dev_handle_t)IPC_GET_ARG1(*request);
     fs_index_t index = (fs_index_t)IPC_GET_ARG2(*request);
     off_t pos = (off_t)IPC_GET_ARG3(*request);
     fat_node_t *nodep = (fat_node_t *)fat_node_get(dev_handle, index);
     size_t bytes;
     block_t *b, *bb;
     uint16_t bps;
     unsigned spc;
     off_t boundary;
     if (!nodep) {
         ipc_answer_0(rid, ENOENT);
         return;
+    }
     /* XXX remove me when you are ready */
+    {
         ipc_answer_0(rid, ENOTSUP);
         fat_node_put(nodep);
         return;
+    }
     ipc_callid_t callid;
     size_t len;
     if (!ipc_data_write_receive(&callid, &len)) {
         fat_node_put(nodep);
         ipc_answer_0(callid, EINVAL);
         ipc_answer_0(rid, EINVAL);
         return;
+    }
     /*
      * In all scenarios, we will attempt to write out only one block worth
      * of data at maximum. There might be some more efficient approaches,
      * but this one greatly simplifies fat_write(). Note that we can afford
      * to do this because the client must be ready to handle the return
      * value signalizing a smaller number of bytes written.
      */
     bytes = min(len, bps - pos % bps);
     bb = block_get(dev_handle, BS_BLOCK, BS_SIZE);
     bps = uint16_t_le2host(FAT_BS(bb)->bps);
     spc = FAT_BS(bb)->spc;
     block_put(bb);
     boundary = ROUND_UP(nodep->size, bps * spc);
     if (pos < boundary) {
         /*
          * This is the easier case - we are either overwriting already
          * existing contents or writing behind the EOF, but still within
          * the limits of the last cluster. The node size may grow to the
          * next block size boundary.
          */
         fat_fill_gap(nodep, FAT_CLST_RES0, pos);
         b = fat_block_get(nodep, pos / bps);
         (void) ipc_data_write_finalize(callid, b->data + pos % bps,
             bytes);
         b->dirty = true;        /* need to sync block */
         block_put(b);
         if (pos + bytes > nodep->size) {
             nodep->size = pos + bytes;
             nodep->dirty = true;    /* need to sync node */
+        }
         fat_node_put(nodep);
         ipc_answer_1(rid, EOK, bytes);
         return;
     } else {
         /*
          * This is the more difficult case. We must allocate new
          * clusters for the node and zero them out.
          */
         int status;
         unsigned nclsts;
         fat_cluster_t mcl, lcl;
         nclsts = (ROUND_UP(pos + bytes, bps * spc) - boundary) /
             bps * spc;
         /* create an independent chain of nclsts clusters in all FATs */
         status = fat_alloc_clusters(dev_handle, nclsts, &mcl, &lcl);
         if (status != EOK) {
             /* could not allocate a chain of nclsts clusters */
             fat_node_put(nodep);
             ipc_answer_0(callid, status);
             ipc_answer_0(rid, status);
             return;
+        }
         /* zero fill any gaps */
         fat_fill_gap(nodep, mcl, pos);
         b = _fat_block_get(dev_handle, lcl, (pos / bps) % spc);
         (void) ipc_data_write_finalize(callid, b->data + pos % bps,
             bytes);
         b->dirty = true;        /* need to sync block */
         block_put(b);
         /*
          * Append the cluster chain starting in mcl to the end of the
          * node's cluster chain.
          */
         fat_append_clusters(nodep, mcl);
         nodep->size = pos + bytes;
         nodep->dirty = true;        /* need to sync node */
         fat_node_put(nodep);
         ipc_answer_1(rid, EOK, bytes);
         return;
+    }
+}
 /**
  * @}
  */

Subversion Repositories HelenOS

(root)/trunk/uspace/srv/fs/fat/fat_ops.c @ 4339 – Rev 3505 → 3506