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

  * @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 <libblock.h>
 #include <ipc/ipc.h>
 #include <ipc/services.h>
 #include <ipc/devmap.h>
 #include <async.h>
 #include <errno.h>
 #include <libadt/hash_table.h>
 #include <libadt/list.h>
 #include <assert.h>
 #include <futex.h>
 #include <sys/mman.h>
-#define BS_BLOCK        0
+#include <align.h>
-#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 FAT_NAME_LEN        8
-#define FAT_EXT_LEN     3
-#define FAT_PAD         ' '
-#define FAT_DENTRY_UNUSED   0x00
-#define FAT_DENTRY_E5_ESC   0x05
-#define FAT_DENTRY_DOT      0x2e
-#define FAT_DENTRY_ERASED   0xe5
-#define min(a, b)       ((a) < (b) ? (a) : (b))
-static void dentry_name_canonify(fat_dentry_t *d, char *buf)
-{
-    int i;
-    for (i = 0; i < FAT_NAME_LEN; i++) {
-        if (d->name[i] == FAT_PAD)
-            break;
-        if (d->name[i] == FAT_DENTRY_E5_ESC)
-            *buf++ = 0xe5;
-        else
-            *buf++ = d->name[i];
-    }
-    if (d->ext[0] != FAT_PAD)
-        *buf++ = '.';
-    for (i = 0; i < FAT_EXT_LEN; i++) {
-        if (d->ext[i] == FAT_PAD) {
-            *buf = '\0';
-            return;
-        }
-        if (d->ext[i] == FAT_DENTRY_E5_ESC)
-            *buf++ = 0xe5;
-        else
-            *buf++ = d->ext[i];
-    }
-    *buf = '\0';
-}
-static int dev_phone = -1;      /* FIXME */
-static void *dev_buffer = NULL;     /* FIXME */
-/* TODO move somewhere else */
-typedef struct {
-    void *data;
-    size_t size;
-} block_t;
-static 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)
-{
-    /* FIXME */
-    free(block->data);
-    free(block);
-}
-#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;
     node->lnkcnt = 0;
     node->refcnt = 0;
     node->dirty = false;
+}
-static uint16_t fat_bps_get(dev_handle_t dev_handle)
+static void fat_node_sync(fat_node_t *node)
+{
-    block_t *bb;
+    block_t *b;
+    fat_bs_t *bs;
+    fat_dentry_t *d;
     uint16_t bps;
+    unsigned dps;
-    bb = block_get(dev_handle, BS_BLOCK, BS_SIZE);
-    assert(bb != NULL);
+    assert(node->dirty);
-    bps = uint16_t_le2host(FAT_BS(bb)->bps);
-    block_put(bb);
+    bs = block_bb_get(node->idx->dev_handle);
-    return bps;
+    bps = uint16_t_le2host(bs->bps);
+    dps = bps / sizeof(fat_dentry_t);
-}
+    /* Read the block that contains the dentry of interest. */
+    b = _fat_block_get(bs, node->idx->dev_handle, node->idx->pfc,
+        (node->idx->pdi * sizeof(fat_dentry_t)) / bps);
-typedef enum {
-    FAT_DENTRY_SKIP,
-    FAT_DENTRY_LAST,
-    FAT_DENTRY_VALID
-} fat_dentry_clsf_t;
+    d = ((fat_dentry_t *)b->data) + (node->idx->pdi % dps);
-static fat_dentry_clsf_t fat_classify_dentry(fat_dentry_t *d)
+    d->firstc = host2uint16_t_le(node->firstc);
-{
-    if (d->attr & FAT_ATTR_VOLLABEL) {
+    if (node->type == FAT_FILE)
-        /* volume label entry */
-        return FAT_DENTRY_SKIP;
-    }
-    if (d->name[0] == FAT_DENTRY_ERASED) {
+        d->size = host2uint32_t_le(node->size);
-        /* not-currently-used entry */
+    /* TODO: update other fields? (e.g time fields, attr field) */
-        return FAT_DENTRY_SKIP;
-    }
-    if (d->name[0] == FAT_DENTRY_UNUSED) {
-        /* never used entry */
+    b->dirty = true;        /* need to sync block */
-        return FAT_DENTRY_LAST;
-    }
-    if (d->name[0] == FAT_DENTRY_DOT) {
-        /*
-         * Most likely '.' or '..'.
-         * It cannot occur in a regular file name.
-         */
-        return FAT_DENTRY_SKIP;
-    }
-    return FAT_DENTRY_VALID;
+    block_put(b);
+}
-static void fat_node_sync(fat_node_t *node)
+static fat_node_t *fat_node_get_new(void)
+{
+    fat_node_t *nodep;
+    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);
-    /* TODO */
+    } 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);
+    return nodep;
+}
 /** 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_bs_t *bs;
     fat_dentry_t *d;
     fat_node_t *nodep = NULL;
     unsigned bps;
+    unsigned spc;
     unsigned dps;
     if (idxp->nodep) {
         /*
          * We are lucky.
      * 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);
+    nodep = fat_node_get_new();
-        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)
+    if (!nodep)
-            return NULL;
+        return NULL;
-    }
-    fat_node_initialize(nodep);
-    bps = fat_bps_get(idxp->dev_handle);
+    bs = block_bb_get(idxp->dev_handle);
+    bps = uint16_t_le2host(bs->bps);
+    spc = bs->spc;
     dps = bps / sizeof(fat_dentry_t);
     /* Read the block that contains the dentry of interest. */
-    b = _fat_block_get(idxp->dev_handle, idxp->pfc,
+    b = _fat_block_get(bs, 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) {
         /*
          * 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,
+        nodep->size = bps * spc * fat_clusters_get(bs, idxp->dev_handle,
             uint16_t_le2host(d->firstc));
     } else {
         nodep->type = FAT_FILE;
         nodep->size = uint32_t_le2host(d->size);
+    }
         futex_up(&ffn_futex);
+    }
     futex_up(&nodep->lock);
+}
-static void *fat_create(int flags)
+static void *fat_create(dev_handle_t dev_handle, int flags)
+{
     return NULL;    /* not supported at the moment */
+}
 static int fat_destroy(void *node)
     return ENOTSUP; /* not supported at the moment */
+}
 static void *fat_match(void *prnt, const char *component)
+{
+    fat_bs_t *bs;
     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);
+    bs = block_bb_get(parentp->idx->dev_handle);
+    bps = uint16_t_le2host(bs->bps);
     dps = bps / sizeof(fat_dentry_t);
-    blocks = parentp->size / bps + (parentp->size % bps != 0);
+    blocks = parentp->size / bps;
     for (i = 0; i < blocks; i++) {
-        unsigned dentries;
-        b = fat_block_get(parentp, i);
+        b = fat_block_get(bs, parentp, i);
-        dentries = (i == blocks - 1) ?
-            parentp->size % sizeof(fat_dentry_t) :
-            dps;
-        for (j = 0; j < dentries; j++) {
+        for (j = 0; j < dps; j++) {
             d = ((fat_dentry_t *)b->data) + j;
             switch (fat_classify_dentry(d)) {
             case FAT_DENTRY_SKIP:
                 continue;
             case FAT_DENTRY_LAST:
                 return node;
+            }
+        }
         block_put(b);
+    }
     futex_up(&parentp->idx->lock);
     return NULL;
+}
 static fs_index_t fat_index_get(void *node)
     return ((fat_node_t *)node)->lnkcnt;
+}
 static bool fat_has_children(void *node)
+{
+    fat_bs_t *bs;
     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);
+    bs = block_bb_get(nodep->idx->dev_handle);
+    bps = uint16_t_le2host(bs->bps);
     dps = bps / sizeof(fat_dentry_t);
-    blocks = nodep->size / bps + (nodep->size % bps != 0);
+    blocks = nodep->size / bps;
     for (i = 0; i < blocks; i++) {
-        unsigned dentries;
         fat_dentry_t *d;
-        b = fat_block_get(nodep, i);
+        b = fat_block_get(bs, nodep, i);
-        dentries = (i == blocks - 1) ?
-            nodep->size % sizeof(fat_dentry_t) :
-            dps;
-        for (j = 0; j < dentries; j++) {
+        for (j = 0; j < dps; j++) {
             d = ((fat_dentry_t *)b->data) + j;
             switch (fat_classify_dentry(d)) {
             case FAT_DENTRY_SKIP:
                 continue;
             case FAT_DENTRY_LAST:
 };
 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;
+    fat_bs_t *bs;
     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.
+    /* initialize libblock */
-     */
-    dev_buffer = mmap(NULL, BS_SIZE, PROTO_READ | PROTO_WRITE,
-        MAP_ANONYMOUS | MAP_PRIVATE, 0, 0);
+    rc = block_init(dev_handle, BS_SIZE);
-    if (!dev_buffer) {
+    if (rc != EOK) {
-        ipc_answer_0(rid, ENOMEM);
+        ipc_answer_0(rid, rc);
-        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,
+    /* prepare the boot block */
-        AS_AREA_READ | AS_AREA_WRITE);
+    rc = block_bb_read(dev_handle, BS_BLOCK * BS_SIZE, BS_SIZE);
     if (rc != EOK) {
-            munmap(dev_buffer, BS_SIZE);
+        block_fini(dev_handle);
         ipc_answer_0(rid, rc);
         return;
+    }
+    /* get the buffer with the boot sector */
+    bs = block_bb_get(dev_handle);
     /* Read the number of root directory entries. */
-    bb = block_get(dev_handle, BS_BLOCK, BS_SIZE);
-    bps = uint16_t_le2host(FAT_BS(bb)->bps);
+    bps = uint16_t_le2host(bs->bps);
-    rde = uint16_t_le2host(FAT_BS(bb)->root_ent_max);
+    rde = uint16_t_le2host(bs->root_ent_max);
-    block_put(bb);
     if (bps != BS_SIZE) {
-        munmap(dev_buffer, BS_SIZE);
+        block_fini(dev_handle);
         ipc_answer_0(rid, ENOTSUP);
         return;
+    }
+    /* Initialize the block cache */
+    rc = block_cache_init(dev_handle, bps, 0 /* XXX */);
+    if (rc != EOK) {
+        block_fini(dev_handle);
+        ipc_answer_0(rid, rc);
+        return;
+    }
     rc = fat_idx_init_by_dev_handle(dev_handle);
     if (rc != EOK) {
-            munmap(dev_buffer, BS_SIZE);
+        block_fini(dev_handle);
         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);
+        block_fini(dev_handle);
         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);
+        block_fini(dev_handle);
         free(rootp);
         fat_idx_fini_by_dev_handle(dev_handle);
         ipc_answer_0(rid, ENOMEM);
         return;
+    }
+{
     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);
+    fat_bs_t *bs;
-    uint16_t bps = fat_bps_get(dev_handle);
+    uint16_t bps;
     size_t bytes;
     block_t *b;
     if (!nodep) {
         ipc_answer_0(rid, ENOENT);
         ipc_answer_0(callid, EINVAL);
         ipc_answer_0(rid, EINVAL);
         return;
+    }
+    bs = block_bb_get(dev_handle);
+    bps = uint16_t_le2host(bs->bps);
     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.
          */
+        if (pos >= nodep->size) {
+            /* reading beyond the EOF */
+            bytes = 0;
+            (void) ipc_data_read_finalize(callid, NULL, 0);
+        } else {
-        bytes = min(len, bps - pos % bps);
+            bytes = min(len, bps - pos % bps);
+            bytes = min(bytes, nodep->size - pos);
-        b = fat_block_get(nodep, pos / bps);
+            b = fat_block_get(bs, nodep, pos / bps);
-        (void) ipc_data_read_finalize(callid, b->data + pos % bps,
+            (void) ipc_data_read_finalize(callid, b->data + pos % bps,
-            bytes);
+                bytes);
-        block_put(b);
+            block_put(b);
+        }
     } else {
         unsigned bnum;
         off_t spos = pos;
         char name[FAT_NAME_LEN + 1 + FAT_EXT_LEN + 1];
         fat_dentry_t *d;
          */
         bnum = (pos * sizeof(fat_dentry_t)) / bps;
         while (bnum < nodep->size / bps) {
             off_t o;
-            b = fat_block_get(nodep, bnum);
+            b = fat_block_get(bs, 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)) {
     fat_node_put(nodep);
     ipc_answer_1(rid, EOK, (ipcarg_t)bytes);
+}
+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);
+    fat_bs_t *bs;
+    size_t bytes;
+    block_t *b;
+    uint16_t bps;
+    unsigned spc;
+    unsigned bpc;       /* bytes per cluster */
+    off_t boundary;
+    if (!nodep) {
+        ipc_answer_0(rid, ENOENT);
+        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;
+    }
+    bs = block_bb_get(dev_handle);
+    bps = uint16_t_le2host(bs->bps);
+    spc = bs->spc;
+    bpc = bps * spc;
+    /*
+     * 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);
+    boundary = ROUND_UP(nodep->size, bpc);
+    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(bs, nodep, FAT_CLST_RES0, pos);
+        b = fat_block_get(bs, 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 */
+        }
+        ipc_answer_2(rid, EOK, bytes, nodep->size);
+        fat_node_put(nodep);
+        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, bpc) - boundary) / bpc;
+        /* create an independent chain of nclsts clusters in all FATs */
+        status = fat_alloc_clusters(bs, 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(bs, nodep, mcl, pos);
+        b = _fat_block_get(bs, 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(bs, nodep, mcl);
+        nodep->size = pos + bytes;
+        nodep->dirty = true;        /* need to sync node */
+        ipc_answer_2(rid, EOK, bytes, nodep->size);
+        fat_node_put(nodep);
+        return;
+    }
+}
+void fat_truncate(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);
+    size_t size = (off_t)IPC_GET_ARG3(*request);
+    fat_node_t *nodep = (fat_node_t *)fat_node_get(dev_handle, index);
+    fat_bs_t *bs;
+    uint16_t bps;
+    uint8_t spc;
+    unsigned bpc;   /* bytes per cluster */
+    int rc;
+    if (!nodep) {
+        ipc_answer_0(rid, ENOENT);
+        return;
+    }
+    bs = block_bb_get(dev_handle);
+    bps = uint16_t_le2host(bs->bps);
+    spc = bs->spc;
+    bpc = bps * spc;
+    if (nodep->size == size) {
+        rc = EOK;
+    } else if (nodep->size < size) {
+        /*
+         * The standard says we have the freedom to grow the node.
+         * For now, we simply return an error.
+         */
+        rc = EINVAL;
+    } else if (ROUND_UP(nodep->size, bpc) == ROUND_UP(size, bpc)) {
+        /*
+         * The node will be shrunk, but no clusters will be deallocated.
+         */
+        nodep->size = size;
+        nodep->dirty = true;        /* need to sync node */
+        rc = EOK;
+    } else {
+        /*
+         * The node will be shrunk, clusters will be deallocated.
+         */
+        if (size == 0) {
+            fat_chop_clusters(bs, nodep, FAT_CLST_RES0);
+        } else {
+            fat_cluster_t lastc;
+            (void) fat_cluster_walk(bs, dev_handle, nodep->firstc,
+                &lastc, (size - 1) / bpc);
+            fat_chop_clusters(bs, nodep, lastc);
+        }
+        nodep->size = size;
+        nodep->dirty = true;        /* need to sync node */
+        rc = EOK;
+    }
+    fat_node_put(nodep);
+    ipc_answer_0(rid, rc);
+    return;
+}
 /**
  * @}
  */

Subversion Repositories HelenOS

(root)//branches/sparc/uspace/srv/fs/fat/fat_ops.c – Rev 3397 → 3593