50b06261b6
Implemented by changing write_map to accept a WMAP_FREE flag. In that case, it doesn't update the datablock (creating indirect zones as necessary) pointer, but it frees the datablock if present. Also it frees the single and double indirect blocks if unused. This makes the implementation of truncate_inode() simpler. truncate_inode() now accepts a truncation length which makes implementing truncate() and ftruncate() simple. This also allowed implementing the F_FREESP fcntl().
541 lines
18 KiB
C
541 lines
18 KiB
C
/* This file contains the procedures for creating, opening, closing, and
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* seeking on files.
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*
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* The entry points into this file are
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* do_creat: perform the CREAT system call
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* do_open: perform the OPEN system call
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* do_mknod: perform the MKNOD system call
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* do_mkdir: perform the MKDIR system call
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* do_close: perform the CLOSE system call
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* do_lseek: perform the LSEEK system call
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*/
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#include "fs.h"
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#include <sys/stat.h>
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#include <fcntl.h>
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#include <string.h>
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#include <unistd.h>
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#include <minix/callnr.h>
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#include <minix/com.h>
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#include "buf.h"
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#include "file.h"
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#include "fproc.h"
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#include "inode.h"
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#include "lock.h"
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#include "param.h"
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#include "super.h"
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#define offset m2_l1
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PRIVATE char mode_map[] = {R_BIT, W_BIT, R_BIT|W_BIT, 0};
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FORWARD _PROTOTYPE( int common_open, (int oflags, mode_t omode) );
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FORWARD _PROTOTYPE( int pipe_open, (struct inode *rip,mode_t bits,int oflags));
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FORWARD _PROTOTYPE( struct inode *new_node, (struct inode **ldirp,
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char *path, mode_t bits, zone_t z0, int opaque, char *string));
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/*===========================================================================*
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* do_creat *
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*===========================================================================*/
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PUBLIC int do_creat()
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{
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/* Perform the creat(name, mode) system call. */
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int r;
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if (fetch_name(m_in.name, m_in.name_length, M3) != OK) return(err_code);
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r = common_open(O_WRONLY | O_CREAT | O_TRUNC, (mode_t) m_in.mode);
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return(r);
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}
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/*===========================================================================*
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* do_open *
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*===========================================================================*/
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PUBLIC int do_open()
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{
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/* Perform the open(name, flags,...) system call. */
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int create_mode = 0; /* is really mode_t but this gives problems */
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int r;
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/* If O_CREAT is set, open has three parameters, otherwise two. */
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if (m_in.mode & O_CREAT) {
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create_mode = m_in.c_mode;
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r = fetch_name(m_in.c_name, m_in.name1_length, M1);
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} else {
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r = fetch_name(m_in.name, m_in.name_length, M3);
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}
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if (r != OK) return(err_code); /* name was bad */
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r = common_open(m_in.mode, create_mode);
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return(r);
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}
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/*===========================================================================*
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* common_open *
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*===========================================================================*/
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PRIVATE int common_open(register int oflags, mode_t omode)
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{
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/* Common code from do_creat and do_open. */
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struct inode *rip, *ldirp;
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int r, b, exist = TRUE;
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dev_t dev;
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mode_t bits;
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off_t pos;
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struct filp *fil_ptr, *filp2;
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/* Remap the bottom two bits of oflags. */
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bits = (mode_t) mode_map[oflags & O_ACCMODE];
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/* See if file descriptor and filp slots are available. */
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if ( (r = get_fd(0, bits, &m_in.fd, &fil_ptr)) != OK) return(r);
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/* If O_CREATE is set, try to make the file. */
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if (oflags & O_CREAT) {
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/* Create a new inode by calling new_node(). */
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omode = I_REGULAR | (omode & ALL_MODES & fp->fp_umask);
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rip = new_node(&ldirp, user_path, omode, NO_ZONE, oflags&O_EXCL, NULL);
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r = err_code;
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put_inode(ldirp);
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if (r == OK) exist = FALSE; /* we just created the file */
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else if (r != EEXIST) return(r); /* other error */
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else exist = !(oflags & O_EXCL); /* file exists, if the O_EXCL
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flag is set this is an error */
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} else {
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/* Scan path name. */
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if ( (rip = eat_path(user_path)) == NIL_INODE) return(err_code);
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}
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/* Claim the file descriptor and filp slot and fill them in. */
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fp->fp_filp[m_in.fd] = fil_ptr;
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fil_ptr->filp_count = 1;
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fil_ptr->filp_ino = rip;
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fil_ptr->filp_flags = oflags;
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/* Only do the normal open code if we didn't just create the file. */
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if (exist) {
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/* Check protections. */
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if ((r = forbidden(rip, bits)) == OK) {
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/* Opening reg. files directories and special files differ. */
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switch (rip->i_mode & I_TYPE) {
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case I_REGULAR:
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/* Truncate regular file if O_TRUNC. */
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if (oflags & O_TRUNC) {
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if ((r = forbidden(rip, W_BIT)) !=OK) break;
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truncate_inode(rip, 0);
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wipe_inode(rip);
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/* Send the inode from the inode cache to the
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* block cache, so it gets written on the next
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* cache flush.
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*/
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rw_inode(rip, WRITING);
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}
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break;
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case I_DIRECTORY:
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/* Directories may be read but not written. */
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r = (bits & W_BIT ? EISDIR : OK);
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break;
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case I_CHAR_SPECIAL:
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case I_BLOCK_SPECIAL:
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/* Invoke the driver for special processing. */
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dev = (dev_t) rip->i_zone[0];
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r = dev_open(dev, who, bits | (oflags & ~O_ACCMODE));
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break;
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case I_NAMED_PIPE:
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oflags |= O_APPEND; /* force append mode */
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fil_ptr->filp_flags = oflags;
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r = pipe_open(rip, bits, oflags);
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if (r != ENXIO) {
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/* See if someone else is doing a rd or wt on
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* the FIFO. If so, use its filp entry so the
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* file position will be automatically shared.
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*/
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b = (bits & R_BIT ? R_BIT : W_BIT);
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fil_ptr->filp_count = 0; /* don't find self */
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if ((filp2 = find_filp(rip, b)) != NIL_FILP) {
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/* Co-reader or writer found. Use it.*/
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fp->fp_filp[m_in.fd] = filp2;
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filp2->filp_count++;
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filp2->filp_ino = rip;
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filp2->filp_flags = oflags;
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/* i_count was incremented incorrectly
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* by eatpath above, not knowing that
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* we were going to use an existing
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* filp entry. Correct this error.
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*/
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rip->i_count--;
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} else {
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/* Nobody else found. Restore filp. */
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fil_ptr->filp_count = 1;
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if (b == R_BIT)
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pos = rip->i_zone[V2_NR_DZONES+0];
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else
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pos = rip->i_zone[V2_NR_DZONES+1];
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fil_ptr->filp_pos = pos;
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}
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}
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break;
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}
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}
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}
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/* If error, release inode. */
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if (r != OK) {
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if (r == SUSPEND) return(r); /* Oops, just suspended */
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fp->fp_filp[m_in.fd] = NIL_FILP;
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fil_ptr->filp_count= 0;
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put_inode(rip);
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return(r);
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}
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return(m_in.fd);
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}
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/*===========================================================================*
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* new_node *
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*===========================================================================*/
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PRIVATE struct inode *new_node(struct inode **ldirp,
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char *path, mode_t bits, zone_t z0, int opaque, char *parsed)
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{
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/* New_node() is called by common_open(), do_mknod(), and do_mkdir().
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* In all cases it allocates a new inode, makes a directory entry for it on
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* the path 'path', and initializes it. It returns a pointer to the inode if
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* it can do this; otherwise it returns NIL_INODE. It always sets 'err_code'
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* to an appropriate value (OK or an error code).
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*
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* The parsed path rest is returned in 'parsed' if parsed is nonzero. It
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* has to hold at least NAME_MAX bytes.
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*/
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register struct inode *rip;
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register int r;
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char string[NAME_MAX];
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*ldirp = parse_path(path, string, opaque ? LAST_DIR : LAST_DIR_EATSYM)
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;
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if (*ldirp == NIL_INODE) return(NIL_INODE);
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/* The final directory is accessible. Get final component of the path. */
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rip = advance(ldirp, string);
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if (S_ISDIR(bits) &&
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(*ldirp)->i_nlinks >= ((*ldirp)->i_sp->s_version == V1 ?
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CHAR_MAX : SHRT_MAX)) {
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/* New entry is a directory, alas we can't give it a ".." */
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put_inode(rip);
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err_code = EMLINK;
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return(NIL_INODE);
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}
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if ( rip == NIL_INODE && err_code == ENOENT) {
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/* Last path component does not exist. Make new directory entry. */
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if ( (rip = alloc_inode((*ldirp)->i_dev, bits)) == NIL_INODE) {
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/* Can't creat new inode: out of inodes. */
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return(NIL_INODE);
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}
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/* Force inode to the disk before making directory entry to make
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* the system more robust in the face of a crash: an inode with
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* no directory entry is much better than the opposite.
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*/
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rip->i_nlinks++;
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rip->i_zone[0] = z0; /* major/minor device numbers */
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rw_inode(rip, WRITING); /* force inode to disk now */
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/* New inode acquired. Try to make directory entry. */
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if ((r = search_dir(*ldirp, string, &rip->i_num,ENTER)) != OK) {
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rip->i_nlinks--; /* pity, have to free disk inode */
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rip->i_dirt = DIRTY; /* dirty inodes are written out */
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put_inode(rip); /* this call frees the inode */
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err_code = r;
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return(NIL_INODE);
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}
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} else {
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/* Either last component exists, or there is some problem. */
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if (rip != NIL_INODE)
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r = EEXIST;
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else
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r = err_code;
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}
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if(parsed) { /* Give the caller the parsed string if requested. */
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strncpy(parsed, string, NAME_MAX-1);
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parsed[NAME_MAX-1] = '\0';
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}
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/* The caller has to return the directory inode (*ldirp). */
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err_code = r;
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return(rip);
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}
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/*===========================================================================*
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* pipe_open *
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*===========================================================================*/
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PRIVATE int pipe_open(register struct inode *rip, register mode_t bits,
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register int oflags)
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{
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/* This function is called from common_open. It checks if
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* there is at least one reader/writer pair for the pipe, if not
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* it suspends the caller, otherwise it revives all other blocked
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* processes hanging on the pipe.
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*/
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rip->i_pipe = I_PIPE;
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if (find_filp(rip, bits & W_BIT ? R_BIT : W_BIT) == NIL_FILP) {
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if (oflags & O_NONBLOCK) {
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if (bits & W_BIT) return(ENXIO);
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} else {
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suspend(XPOPEN); /* suspend caller */
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return(SUSPEND);
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}
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} else if (susp_count > 0) {/* revive blocked processes */
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release(rip, OPEN, susp_count);
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release(rip, CREAT, susp_count);
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}
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return(OK);
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}
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/*===========================================================================*
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* do_mknod *
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*===========================================================================*/
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PUBLIC int do_mknod()
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{
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/* Perform the mknod(name, mode, addr) system call. */
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register mode_t bits, mode_bits;
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struct inode *ip, *ldirp;
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/* Only the super_user may make nodes other than fifos. */
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mode_bits = (mode_t) m_in.mk_mode; /* mode of the inode */
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if (!super_user && ((mode_bits & I_TYPE) != I_NAMED_PIPE)) return(EPERM);
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if (fetch_name(m_in.name1, m_in.name1_length, M1) != OK) return(err_code);
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bits = (mode_bits & I_TYPE) | (mode_bits & ALL_MODES & fp->fp_umask);
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ip = new_node(&ldirp, user_path, bits, (zone_t) m_in.mk_z0, TRUE, NULL);
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put_inode(ip);
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put_inode(ldirp);
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return(err_code);
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}
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/*===========================================================================*
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* do_mkdir *
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*===========================================================================*/
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PUBLIC int do_mkdir()
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{
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/* Perform the mkdir(name, mode) system call. */
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int r1, r2; /* status codes */
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ino_t dot, dotdot; /* inode numbers for . and .. */
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mode_t bits; /* mode bits for the new inode */
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char string[NAME_MAX]; /* last component of the new dir's path name */
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struct inode *rip, *ldirp;
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if (fetch_name(m_in.name1, m_in.name1_length, M1) != OK) return(err_code);
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/* Next make the inode. If that fails, return error code. */
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bits = I_DIRECTORY | (m_in.mode & RWX_MODES & fp->fp_umask);
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rip = new_node(&ldirp, user_path, bits, (zone_t) 0, TRUE, string);
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if (rip == NIL_INODE || err_code == EEXIST) {
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put_inode(rip); /* can't make dir: it already exists */
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put_inode(ldirp);
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return(err_code);
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}
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/* Get the inode numbers for . and .. to enter in the directory. */
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dotdot = ldirp->i_num; /* parent's inode number */
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dot = rip->i_num; /* inode number of the new dir itself */
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/* Now make dir entries for . and .. unless the disk is completely full. */
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/* Use dot1 and dot2, so the mode of the directory isn't important. */
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rip->i_mode = bits; /* set mode */
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r1 = search_dir(rip, dot1, &dot, ENTER); /* enter . in the new dir */
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r2 = search_dir(rip, dot2, &dotdot, ENTER); /* enter .. in the new dir */
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/* If both . and .. were successfully entered, increment the link counts. */
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if (r1 == OK && r2 == OK) {
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/* Normal case. It was possible to enter . and .. in the new dir. */
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rip->i_nlinks++; /* this accounts for . */
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ldirp->i_nlinks++; /* this accounts for .. */
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ldirp->i_dirt = DIRTY; /* mark parent's inode as dirty */
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} else {
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/* It was not possible to enter . or .. probably disk was full -
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* links counts haven't been touched.
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*/
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if(search_dir(ldirp, string, (ino_t *) 0, DELETE) != OK)
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panic(__FILE__, "Dir disappeared ", rip->i_num);
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rip->i_nlinks--; /* undo the increment done in new_node() */
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}
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rip->i_dirt = DIRTY; /* either way, i_nlinks has changed */
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put_inode(ldirp); /* return the inode of the parent dir */
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put_inode(rip); /* return the inode of the newly made dir */
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return(err_code); /* new_node() always sets 'err_code' */
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}
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|
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/*===========================================================================*
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* do_close *
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*===========================================================================*/
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PUBLIC int do_close()
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{
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/* Perform the close(fd) system call. */
|
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register struct filp *rfilp;
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register struct inode *rip;
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struct file_lock *flp;
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int rw, mode_word, lock_count;
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dev_t dev;
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/* First locate the inode that belongs to the file descriptor. */
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if ( (rfilp = get_filp(m_in.fd)) == NIL_FILP) return(err_code);
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rip = rfilp->filp_ino; /* 'rip' points to the inode */
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if (rfilp->filp_count - 1 == 0 && rfilp->filp_mode != FILP_CLOSED) {
|
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/* Check to see if the file is special. */
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mode_word = rip->i_mode & I_TYPE;
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if (mode_word == I_CHAR_SPECIAL || mode_word == I_BLOCK_SPECIAL) {
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dev = (dev_t) rip->i_zone[0];
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if (mode_word == I_BLOCK_SPECIAL) {
|
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/* Invalidate cache entries unless special is mounted
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* or ROOT
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*/
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if (!mounted(rip)) {
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(void) do_sync(); /* purge cache */
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invalidate(dev);
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}
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}
|
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/* Do any special processing on device close. */
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dev_close(dev);
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}
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}
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|
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/* If the inode being closed is a pipe, release everyone hanging on it. */
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if (rip->i_pipe == I_PIPE) {
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rw = (rfilp->filp_mode & R_BIT ? WRITE : READ);
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release(rip, rw, NR_PROCS);
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}
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|
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/* If a write has been done, the inode is already marked as DIRTY. */
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if (--rfilp->filp_count == 0) {
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if (rip->i_pipe == I_PIPE && rip->i_count > 1) {
|
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/* Save the file position in the i-node in case needed later.
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|
* The read and write positions are saved separately. The
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* last 3 zones in the i-node are not used for (named) pipes.
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*/
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if (rfilp->filp_mode == R_BIT)
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rip->i_zone[V2_NR_DZONES+0] = (zone_t) rfilp->filp_pos;
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else
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rip->i_zone[V2_NR_DZONES+1] = (zone_t) rfilp->filp_pos;
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}
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put_inode(rip);
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}
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fp->fp_cloexec &= ~(1L << m_in.fd); /* turn off close-on-exec bit */
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fp->fp_filp[m_in.fd] = NIL_FILP;
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|
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/* Check to see if the file is locked. If so, release all locks. */
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if (nr_locks == 0) return(OK);
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lock_count = nr_locks; /* save count of locks */
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for (flp = &file_lock[0]; flp < &file_lock[NR_LOCKS]; flp++) {
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if (flp->lock_type == 0) continue; /* slot not in use */
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if (flp->lock_inode == rip && flp->lock_pid == fp->fp_pid) {
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flp->lock_type = 0;
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nr_locks--;
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}
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}
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|
if (nr_locks < lock_count) lock_revive(); /* lock released */
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return(OK);
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}
|
|
|
|
/*===========================================================================*
|
|
* do_lseek *
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|
*===========================================================================*/
|
|
PUBLIC int do_lseek()
|
|
{
|
|
/* Perform the lseek(ls_fd, offset, whence) system call. */
|
|
|
|
register struct filp *rfilp;
|
|
register off_t pos;
|
|
|
|
/* Check to see if the file descriptor is valid. */
|
|
if ( (rfilp = get_filp(m_in.ls_fd)) == NIL_FILP) return(err_code);
|
|
|
|
/* No lseek on pipes. */
|
|
if (rfilp->filp_ino->i_pipe == I_PIPE) return(ESPIPE);
|
|
|
|
/* The value of 'whence' determines the start position to use. */
|
|
switch(m_in.whence) {
|
|
case SEEK_SET: pos = 0; break;
|
|
case SEEK_CUR: pos = rfilp->filp_pos; break;
|
|
case SEEK_END: pos = rfilp->filp_ino->i_size; break;
|
|
default: return(EINVAL);
|
|
}
|
|
|
|
/* Check for overflow. */
|
|
if (((long)m_in.offset > 0) && ((long)(pos + m_in.offset) < (long)pos))
|
|
return(EINVAL);
|
|
if (((long)m_in.offset < 0) && ((long)(pos + m_in.offset) > (long)pos))
|
|
return(EINVAL);
|
|
pos = pos + m_in.offset;
|
|
|
|
if (pos != rfilp->filp_pos)
|
|
rfilp->filp_ino->i_seek = ISEEK; /* inhibit read ahead */
|
|
rfilp->filp_pos = pos;
|
|
m_out.reply_l1 = pos; /* insert the long into the output message */
|
|
return(OK);
|
|
}
|
|
|
|
/*===========================================================================*
|
|
* do_slink *
|
|
*===========================================================================*/
|
|
PUBLIC int do_slink()
|
|
{
|
|
/* Perform the symlink(name1, name2) system call. */
|
|
|
|
register int r; /* error code */
|
|
char string[NAME_MAX]; /* last component of the new dir's path name */
|
|
struct inode *sip; /* inode containing symbolic link */
|
|
struct buf *bp; /* disk buffer for link */
|
|
struct inode *ldirp; /* directory containing link */
|
|
|
|
if (fetch_name(m_in.name2, m_in.name2_length, M1) != OK)
|
|
return(err_code);
|
|
|
|
if (m_in.name1_length <= 1 || m_in.name1_length > _MIN_BLOCK_SIZE+1)
|
|
return(ENAMETOOLONG);
|
|
|
|
/* Create the inode for the symlink. */
|
|
sip = new_node(&ldirp, user_path, (mode_t) (I_SYMBOLIC_LINK | RWX_MODES),
|
|
(zone_t) 0, TRUE, string);
|
|
|
|
/* Allocate a disk block for the contents of the symlink.
|
|
* Copy contents of symlink (the name pointed to) into first disk block.
|
|
*/
|
|
if ((r = err_code) == OK) {
|
|
r = (bp = new_block(sip, (off_t) 0)) == NIL_BUF
|
|
? err_code
|
|
: ( sip->i_size = m_in.name1_length-1,
|
|
sys_vircopy(who, D, (vir_bytes) m_in.name1,
|
|
SELF, D, (vir_bytes) bp->b_data,
|
|
(vir_bytes) m_in.name1_length-1));
|
|
|
|
put_block(bp, DIRECTORY_BLOCK); /* put_block() accepts NIL_BUF. */
|
|
|
|
if (r != OK) {
|
|
sip->i_nlinks = 0;
|
|
if (search_dir(ldirp, string, (ino_t *) 0, DELETE) != OK)
|
|
panic(__FILE__, "Symbolic link vanished", NO_NUM);
|
|
}
|
|
}
|
|
|
|
/* put_inode() accepts NIL_INODE as a noop, so the below are safe. */
|
|
put_inode(sip);
|
|
put_inode(ldirp);
|
|
|
|
return(r);
|
|
}
|
|
|