161 lines
3.4 KiB
C
161 lines
3.4 KiB
C
/* This file contains file writing system call handlers.
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*
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* The entry points into this file are:
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* do_write perform the WRITE file system call
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* do_ftrunc perform the FTRUNC file system call
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*
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* Created:
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* April 2009 (D.C. van Moolenbroek)
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*/
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#include "inc.h"
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static int write_file(struct inode *ino, u64_t *posp, size_t *countp,
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cp_grant_id_t *grantp);
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/*===========================================================================*
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* write_file *
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*===========================================================================*/
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static int write_file(struct inode *ino, u64_t *posp, size_t *countp,
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cp_grant_id_t *grantp)
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{
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/* Write data or zeroes to a file, depending on whether a valid pointer to
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* a data grant was provided.
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*/
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u64_t pos;
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size_t count, size;
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vir_bytes off;
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char *ptr;
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int r, chunk;
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assert(!IS_DIR(ino));
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if ((r = get_handle(ino)) != OK)
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return r;
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pos = *posp;
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count = *countp;
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assert(count > 0);
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/* Use the buffer from below to eliminate extra copying. */
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size = sffs_table->t_writebuf(&ptr);
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off = 0;
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while (count > 0) {
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chunk = MIN(count, size);
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if (grantp != NULL) {
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r = sys_safecopyfrom(m_in.m_source, *grantp,
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off, (vir_bytes) ptr, chunk);
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if (r != OK)
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break;
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} else {
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/* Do this every time. We don't know what happens below. */
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memset(ptr, 0, chunk);
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}
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if ((r = sffs_table->t_write(ino->i_file, ptr, chunk, pos)) <= 0)
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break;
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count -= r;
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off += r;
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pos += r;
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}
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if (r < 0)
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return r;
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*posp = pos;
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*countp = off;
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return OK;
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}
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/*===========================================================================*
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* do_write *
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*===========================================================================*/
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int do_write(void)
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{
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/* Write data to a file.
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*/
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struct inode *ino;
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off_t pos;
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size_t count;
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cp_grant_id_t grant;
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int r;
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if (state.s_read_only)
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return EROFS;
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if ((ino = find_inode(m_in.m_vfs_fs_readwrite.inode)) == NULL)
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return EINVAL;
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if (IS_DIR(ino)) return EISDIR;
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pos = m_in.m_vfs_fs_readwrite.seek_pos;
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count = m_in.m_vfs_fs_readwrite.nbytes;
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grant = m_in.m_vfs_fs_readwrite.grant;
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if (count == 0) return EINVAL;
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if ((r = write_file(ino, &pos, &count, &grant)) != OK)
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return r;
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m_out.m_fs_vfs_readwrite.seek_pos = pos;
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m_out.m_fs_vfs_readwrite.nbytes = count;
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return OK;
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}
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/*===========================================================================*
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* do_ftrunc *
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*===========================================================================*/
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int do_ftrunc(void)
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{
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/* Change file size or create file holes.
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*/
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char path[PATH_MAX];
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struct inode *ino;
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struct sffs_attr attr;
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u64_t start, end, delta;
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size_t count;
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int r;
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if (state.s_read_only)
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return EROFS;
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if ((ino = find_inode(m_in.m_vfs_fs_ftrunc.inode)) == NULL)
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return EINVAL;
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if (IS_DIR(ino)) return EISDIR;
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start = m_in.m_vfs_fs_ftrunc.trc_start;
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end = m_in.m_vfs_fs_ftrunc.trc_end;
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if (end == 0) {
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/* Truncate or expand the file. */
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if ((r = verify_inode(ino, path, NULL)) != OK)
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return r;
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attr.a_mask = SFFS_ATTR_SIZE;
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attr.a_size = start;
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r = sffs_table->t_setattr(path, &attr);
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} else {
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/* Write zeroes to the file. We can't create holes. */
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if (end <= start) return EINVAL;
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delta = end - start;
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if (ex64hi(delta) != 0) return EINVAL;
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count = ex64lo(delta);
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r = write_file(ino, &start, &count, NULL);
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}
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return r;
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}
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