patch-1.3.60 linux/fs/fat/misc.c

• Lines: 554
• Date: Wed Feb 7 09:39:28 1996
• Orig file: v1.3.59/linux/fs/fat/misc.c
• Orig date: Thu Jan 1 02:00:00 1970

diff -u --recursive --new-file v1.3.59/linux/fs/fat/misc.c linux/fs/fat/misc.c
@@ -0,0 +1,553 @@
+/*
+ *  linux/fs/msdos/misc.c
+ *
+ *  Written 1992,1993 by Werner Almesberger
+ */
+
+#include <linux/fs.h>
+#include <linux/msdos_fs.h>
+#include <linux/sched.h>
+#include <linux/kernel.h>
+#include <linux/errno.h>
+#include <linux/string.h>
+#include <linux/stat.h>
+
+#include "msbuffer.h"
+
+#define PRINTK(x)
+#define Printk(x)	printk x
+
+/* Well-known binary file extensions - of course there are many more */
+
+static char bin_extensions[] =
+  "EXE" "COM" "BIN" "APP" "SYS" "DRV" "OVL" "OVR" "OBJ" "LIB" "DLL" "PIF" /* program code */
+  "ARC" "ZIP" "LHA" "LZH" "ZOO" "TAR" "Z  " "ARJ"	/* common archivers */
+  "TZ " "TAZ" "TZP" "TPZ"		/* abbreviations of tar.Z and tar.zip */
+  "GZ " "TGZ" "DEB"			/* .gz, .tar.gz and Debian packages   */
+  "GIF" "BMP" "TIF" "GL " "JPG" "PCX"	/* graphics */
+  "TFM" "VF " "GF " "PK " "PXL" "DVI";	/* TeX */
+
+
+/*
+ * fat_fs_panic reports a severe file system problem and sets the file system
+ * read-only. The file system can be made writable again by remounting it.
+ */
+
+void fat_fs_panic(struct super_block *s,const char *msg)
+{
+	int not_ro;
+
+	not_ro = !(s->s_flags & MS_RDONLY);
+	if (not_ro) s->s_flags |= MS_RDONLY;
+	printk("Filesystem panic (dev %s, ", kdevname(s->s_dev));
+	printk("mounted on %s:%ld)\n  %s\n", /* note: kdevname returns & static char[] */
+	       kdevname(s->s_covered->i_dev), s->s_covered->i_ino, msg);
+	if (not_ro)
+		printk("  File system has been set read-only\n");
+}
+
+
+/*
+ * is_binary selects optional text conversion based on the conversion mode and
+ * the extension part of the file name.
+ */
+
+int is_binary(char conversion,char *extension)
+{
+	char *walk;
+
+	switch (conversion) {
+		case 'b':
+			return 1;
+		case 't':
+			return 0;
+		case 'a':
+			for (walk = bin_extensions; *walk; walk += 3)
+				if (!strncmp(extension,walk,3)) return 1;
+			return 0;
+		default:
+			printk("Invalid conversion mode - defaulting to "
+			    "binary.\n");
+			return 1;
+	}
+}
+
+
+/* File creation lock. This is system-wide to avoid deadlocks in rename. */
+/* (rename might deadlock before detecting cross-FS moves.) */
+
+static struct wait_queue *creation_wait = NULL;
+static creation_lock = 0;
+
+
+void fat_lock_creation(void)
+{
+	while (creation_lock) sleep_on(&creation_wait);
+	creation_lock = 1;
+}
+
+
+void fat_unlock_creation(void)
+{
+	creation_lock = 0;
+	wake_up(&creation_wait);
+}
+
+
+void lock_fat(struct super_block *sb)
+{
+	while (MSDOS_SB(sb)->fat_lock) sleep_on(&MSDOS_SB(sb)->fat_wait);
+	MSDOS_SB(sb)->fat_lock = 1;
+}
+
+
+void unlock_fat(struct super_block *sb)
+{
+	MSDOS_SB(sb)->fat_lock = 0;
+	wake_up(&MSDOS_SB(sb)->fat_wait);
+}
+
+
+/*
+ * fat_add_cluster tries to allocate a new cluster and adds it to the file
+ * represented by inode. The cluster is zero-initialized.
+ */
+
+int fat_add_cluster(struct inode *inode)
+{
+	struct super_block *sb = inode->i_sb;
+	int count,nr,limit,last,curr,sector,last_sector,file_cluster;
+	struct buffer_head *bh;
+	int cluster_size = MSDOS_SB(inode->i_sb)->cluster_size;
+
+	if (inode->i_ino == MSDOS_ROOT_INO) return -ENOSPC;
+	if (!MSDOS_SB(inode->i_sb)->free_clusters) return -ENOSPC;
+	lock_fat(inode->i_sb);
+	limit = MSDOS_SB(inode->i_sb)->clusters;
+	nr = limit; /* to keep GCC happy */
+	for (count = 0; count < limit; count++) {
+		nr = ((count+MSDOS_SB(inode->i_sb)->prev_free) % limit)+2;
+		if (fat_access(inode->i_sb,nr,-1) == 0) break;
+	}
+	PRINTK (("cnt = %d --",count));
+#ifdef DEBUG
+printk("free cluster: %d\n",nr);
+#endif
+	MSDOS_SB(inode->i_sb)->prev_free = (count+MSDOS_SB(inode->i_sb)->
+	    prev_free+1) % limit;
+	if (count >= limit) {
+		MSDOS_SB(inode->i_sb)->free_clusters = 0;
+		unlock_fat(inode->i_sb);
+		return -ENOSPC;
+	}
+	fat_access(inode->i_sb,nr,MSDOS_SB(inode->i_sb)->fat_bits == 12 ?
+	    0xff8 : 0xfff8);
+	if (MSDOS_SB(inode->i_sb)->free_clusters != -1)
+		MSDOS_SB(inode->i_sb)->free_clusters--;
+	unlock_fat(inode->i_sb);
+#ifdef DEBUG
+printk("set to %x\n",fat_access(inode->i_sb,nr,-1));
+#endif
+	last = 0;
+	/* We must locate the last cluster of the file to add this
+	   new one (nr) to the end of the link list (the FAT).
+	   
+	   Here file_cluster will be the number of the last cluster of the
+	   file (before we add nr).
+	   
+	   last is the corresponding cluster number on the disk. We will
+	   use last to plug the nr cluster. We will use file_cluster to
+	   update the cache.
+	*/
+	file_cluster = 0;
+	if ((curr = MSDOS_I(inode)->i_start) != 0) {
+		cache_lookup(inode,INT_MAX,&last,&curr);
+		file_cluster = last;
+		while (curr && curr != -1){
+			PRINTK (("."));
+			file_cluster++;
+			if (!(curr = fat_access(inode->i_sb,
+			    last = curr,-1))) {
+				fat_fs_panic(inode->i_sb,"File without EOF");
+				return -ENOSPC;
+			}
+		}
+		PRINTK ((" --  "));
+	}
+#ifdef DEBUG
+printk("last = %d\n",last);
+#endif
+	if (last) fat_access(inode->i_sb,last,nr);
+	else {
+		MSDOS_I(inode)->i_start = nr;
+		inode->i_dirt = 1;
+	}
+#ifdef DEBUG
+if (last) printk("next set to %d\n",fat_access(inode->i_sb,last,-1));
+#endif
+	sector = MSDOS_SB(inode->i_sb)->data_start+(nr-2)*cluster_size;
+	last_sector = sector + cluster_size;
+	for ( ; sector < last_sector; sector++) {
+		#ifdef DEBUG
+			printk("zeroing sector %d\n",sector);
+		#endif
+		if (!(bh = getblk(inode->i_dev,sector,SECTOR_SIZE)))
+			printk("getblk failed\n");
+		else {
+			memset(bh->b_data,0,SECTOR_SIZE);
+			fat_set_uptodate(sb,bh,1);
+			mark_buffer_dirty(bh, 1);
+			brelse(bh);
+		}
+	}
+	if (file_cluster != inode->i_blocks/cluster_size){
+		printk ("file_cluster badly computed!!! %d <> %ld\n"
+			,file_cluster,inode->i_blocks/cluster_size);
+	}else{
+		cache_add(inode,file_cluster,nr);
+	}
+	inode->i_blocks += cluster_size;
+	if (S_ISDIR(inode->i_mode)) {
+		if (inode->i_size & (SECTOR_SIZE-1)) {
+			fat_fs_panic(inode->i_sb,"Odd directory size");
+			inode->i_size = (inode->i_size+SECTOR_SIZE) &
+			    ~(SECTOR_SIZE-1);
+		}
+		inode->i_size += SECTOR_SIZE*cluster_size;
+#ifdef DEBUG
+printk("size is %d now (%x)\n",inode->i_size,inode);
+#endif
+		inode->i_dirt = 1;
+	}
+	return 0;
+}
+
+
+/* Linear day numbers of the respective 1sts in non-leap years. */
+
+static int day_n[] = { 0,31,59,90,120,151,181,212,243,273,304,334,0,0,0,0 };
+		  /* JanFebMarApr May Jun Jul Aug Sep Oct Nov Dec */
+
+
+extern struct timezone sys_tz;
+
+
+/* Convert a MS-DOS time/date pair to a UNIX date (seconds since 1 1 70). */
+
+int date_dos2unix(unsigned short time,unsigned short date)
+{
+	int month,year,secs;
+
+	month = ((date >> 5) & 15)-1;
+	year = date >> 9;
+	secs = (time & 31)*2+60*((time >> 5) & 63)+(time >> 11)*3600+86400*
+	    ((date & 31)-1+day_n[month]+(year/4)+year*365-((year & 3) == 0 &&
+	    month < 2 ? 1 : 0)+3653);
+			/* days since 1.1.70 plus 80's leap day */
+	secs += sys_tz.tz_minuteswest*60;
+	return secs;
+}
+
+
+/* Convert linear UNIX date to a MS-DOS time/date pair. */
+
+void fat_date_unix2dos(int unix_date,unsigned short *time,
+    unsigned short *date)
+{
+	int day,year,nl_day,month;
+
+	unix_date -= sys_tz.tz_minuteswest*60;
+	*time = (unix_date % 60)/2+(((unix_date/60) % 60) << 5)+
+	    (((unix_date/3600) % 24) << 11);
+	day = unix_date/86400-3652;
+	year = day/365;
+	if ((year+3)/4+365*year > day) year--;
+	day -= (year+3)/4+365*year;
+	if (day == 59 && !(year & 3)) {
+		nl_day = day;
+		month = 2;
+	}
+	else {
+		nl_day = (year & 3) || day <= 59 ? day : day-1;
+		for (month = 0; month < 12; month++)
+			if (day_n[month] > nl_day) break;
+	}
+	*date = nl_day-day_n[month-1]+1+(month << 5)+(year << 9);
+}
+
+
+/* Returns the inode number of the directory entry at offset pos. If bh is
+   non-NULL, it is brelse'd before. Pos is incremented. The buffer header is
+   returned in bh. */
+
+int fat_get_entry(struct inode *dir, loff_t *pos,struct buffer_head **bh,
+    struct msdos_dir_entry **de)
+{
+	struct super_block *sb = dir->i_sb;
+	int sector,offset;
+
+	while (1) {
+		offset = *pos;
+		PRINTK (("get_entry offset %d\n",offset));
+		if ((sector = fat_smap(dir,offset >> SECTOR_BITS)) == -1)
+			return -1;
+		PRINTK (("get_entry sector %d %p\n",sector,*bh));
+		if (!sector)
+			return -1; /* beyond EOF */
+		*pos += sizeof(struct msdos_dir_entry);
+		if (*bh)
+			brelse(*bh);
+		PRINTK (("get_entry sector apres brelse\n"));
+		if (!(*bh = bread(dir->i_dev,sector,SECTOR_SIZE))) {
+			printk("Directory sread (sector %d) failed\n",sector);
+			continue;
+		}
+		PRINTK (("get_entry apres sread\n"));
+		*de = (struct msdos_dir_entry *) ((*bh)->b_data+(offset &
+		    (SECTOR_SIZE-1)));
+		return (sector << MSDOS_DPS_BITS)+((offset & (SECTOR_SIZE-1)) >>
+		    MSDOS_DIR_BITS);
+	}
+}
+
+
+/*
+ * Now an ugly part: this set of directory scan routines works on clusters
+ * rather than on inodes and sectors. They are necessary to locate the '..'
+ * directory "inode". raw_scan_sector operates in four modes:
+ *
+ * name     number   ino      action
+ * -------- -------- -------- -------------------------------------------------
+ * non-NULL -        X        Find an entry with that name
+ * NULL     non-NULL non-NULL Find an entry whose data starts at *number
+ * NULL     non-NULL NULL     Count subdirectories in *number. (*)
+ * NULL     NULL     non-NULL Find an empty entry
+ *
+ * (*) The return code should be ignored. It DOES NOT indicate success or
+ *     failure. *number has to be initialized to zero.
+ *
+ * - = not used, X = a value is returned unless NULL
+ *
+ * If res_bh is non-NULL, the buffer is not deallocated but returned to the
+ * caller on success. res_de is set accordingly.
+ *
+ * If cont is non-zero, raw_found continues with the entry after the one
+ * res_bh/res_de point to.
+ */
+
+
+#define RSS_NAME /* search for name */ \
+    done = !strncmp(data[entry].name,name,MSDOS_NAME) && \
+     !(data[entry].attr & ATTR_VOLUME);
+
+#define RSS_START /* search for start cluster */ \
+    done = !IS_FREE(data[entry].name) && CF_LE_W(data[entry].start) == *number;
+
+#define RSS_FREE /* search for free entry */ \
+    { \
+	done = IS_FREE(data[entry].name); \
+	if (done) { \
+	    inode = iget(sb,sector*MSDOS_DPS+entry); \
+	    if (inode) { \
+	    /* Directory slots of busy deleted files aren't available yet. */ \
+		done = !MSDOS_I(inode)->i_busy; \
+		iput(inode); \
+	    } \
+	} \
+    }
+
+#define RSS_COUNT /* count subdirectories */ \
+    { \
+	done = 0; \
+	if (!IS_FREE(data[entry].name) && (data[entry].attr & ATTR_DIR)) \
+	    (*number)++; \
+    }
+
+static int raw_scan_sector(struct super_block *sb,int sector,const char *name,
+    int *number,int *ino,struct buffer_head **res_bh,
+    struct msdos_dir_entry **res_de,char scantype)
+{
+	struct buffer_head *bh;
+	struct msdos_dir_entry *data;
+	struct inode *inode;
+	int entry,start,done;
+
+	if (!(bh = bread(sb->s_dev,sector,SECTOR_SIZE))) return -EIO;
+	data = (struct msdos_dir_entry *) bh->b_data;
+	for (entry = 0; entry < MSDOS_DPS; entry++) {
+/* RSS_COUNT:  if (data[entry].name == name) done=true else done=false. */
+		if (name) {
+			RSS_NAME
+			if (done && scantype) {   /* scantype != SCAN_ANY */
+				done = (data[entry].attr & ATTR_HIDDEN)
+					? (scantype==SCAN_HID)
+					: (scantype==SCAN_NOTHID);
+			}
+		} else {
+			if (!ino) RSS_COUNT
+			else {
+				if (number) RSS_START
+				else RSS_FREE
+			}
+		}
+		if (done) {
+			if (ino) *ino = sector*MSDOS_DPS+entry;
+			start = CF_LE_W(data[entry].start);
+			if (!res_bh) brelse(bh);
+			else {
+				*res_bh = bh;
+				*res_de = &data[entry];
+			}
+			return start;
+		}
+	}
+	brelse(bh);
+	return -ENOENT;
+}
+
+
+/*
+ * raw_scan_root performs raw_scan_sector on the root directory until the
+ * requested entry is found or the end of the directory is reached.
+ */
+
+static int raw_scan_root(struct super_block *sb,const char *name,int *number,int *ino,
+    struct buffer_head **res_bh,struct msdos_dir_entry **res_de,char scantype)
+{
+	int count,cluster;
+
+	for (count = 0; count < MSDOS_SB(sb)->dir_entries/MSDOS_DPS; count++) {
+		if ((cluster = raw_scan_sector(sb,MSDOS_SB(sb)->dir_start+count,
+		    name,number,ino,res_bh,res_de,scantype)) >= 0) return cluster;
+	}
+	return -ENOENT;
+}
+
+
+/*
+ * raw_scan_nonroot performs raw_scan_sector on a non-root directory until the
+ * requested entry is found or the end of the directory is reached.
+ */
+
+static int raw_scan_nonroot(struct super_block *sb,int start,const char *name,
+    int *number,int *ino,struct buffer_head **res_bh,struct msdos_dir_entry
+    **res_de,char scantype)
+{
+	int count,cluster;
+
+#ifdef DEBUG
+	printk("raw_scan_nonroot: start=%d\n",start);
+#endif
+	do {
+		for (count = 0; count < MSDOS_SB(sb)->cluster_size; count++) {
+			if ((cluster = raw_scan_sector(sb,(start-2)*
+			    MSDOS_SB(sb)->cluster_size+MSDOS_SB(sb)->data_start+
+			    count,name,number,ino,res_bh,res_de,scantype)) >= 0)
+				return cluster;
+		}
+		if (!(start = fat_access(sb,start,-1))) {
+			fat_fs_panic(sb,"FAT error");
+			break;
+		}
+#ifdef DEBUG
+	printk("next start: %d\n",start);
+#endif
+	}
+	while (start != -1);
+	return -ENOENT;
+}
+
+
+/*
+ * raw_scan performs raw_scan_sector on any sector.
+ *
+ * NOTE: raw_scan must not be used on a directory that is is the process of
+ *       being created.
+ */
+
+static int raw_scan(struct super_block *sb, int start, const char *name,
+    int *number, int *ino, struct buffer_head **res_bh,
+    struct msdos_dir_entry **res_de, char scantype)
+{
+	if (start) return raw_scan_nonroot
+		(sb,start,name,number,ino,res_bh,res_de,scantype);
+	else return raw_scan_root
+		(sb,name,number,ino,res_bh,res_de,scantype);
+}
+
+
+/*
+ * fat_parent_ino returns the inode number of the parent directory of dir.
+ * File creation has to be deferred while fat_parent_ino is running to
+ * prevent renames.
+ */
+
+int fat_parent_ino(struct inode *dir,int locked)
+{
+	static int zero = 0;
+	int error,curr,prev,nr;
+
+	if (!S_ISDIR(dir->i_mode)) panic("Non-directory fed to m_p_i");
+	if (dir->i_ino == MSDOS_ROOT_INO) return dir->i_ino;
+	if (!locked) fat_lock_creation(); /* prevent renames */
+	if ((curr = raw_scan(dir->i_sb,MSDOS_I(dir)->i_start,MSDOS_DOTDOT,
+	    &zero,NULL,NULL,NULL,SCAN_ANY)) < 0) {
+		if (!locked) fat_unlock_creation();
+		return curr;
+	}
+	if (!curr) nr = MSDOS_ROOT_INO;
+	else {
+		if ((prev = raw_scan(dir->i_sb,curr,MSDOS_DOTDOT,&zero,NULL,
+		    NULL,NULL,SCAN_ANY)) < 0) {
+			if (!locked) fat_unlock_creation();
+			return prev;
+		}
+		if ((error = raw_scan(dir->i_sb,prev,NULL,&curr,&nr,NULL,
+		    NULL,SCAN_ANY)) < 0) {
+			if (!locked) fat_unlock_creation();
+			return error;
+		}
+	}
+	if (!locked) fat_unlock_creation();
+	return nr;
+}
+
+
+/*
+ * fat_subdirs counts the number of sub-directories of dir. It can be run
+ * on directories being created.
+ */
+
+int fat_subdirs(struct inode *dir)
+{
+	int count;
+
+	count = 0;
+	if (dir->i_ino == MSDOS_ROOT_INO)
+		(void) raw_scan_root(dir->i_sb,NULL,&count,NULL,NULL,NULL,SCAN_ANY);
+	else {
+		if (!MSDOS_I(dir)->i_start) return 0; /* in mkdir */
+		else (void) raw_scan_nonroot(dir->i_sb,MSDOS_I(dir)->i_start,
+		    NULL,&count,NULL,NULL,NULL,SCAN_ANY);
+	}
+	return count;
+}
+
+
+/*
+ * Scans a directory for a given file (name points to its formatted name) or
+ * for an empty directory slot (name is NULL). Returns an error code or zero.
+ */
+
+int fat_scan(struct inode *dir,const char *name,struct buffer_head **res_bh,
+    struct msdos_dir_entry **res_de,int *ino, char scantype)
+{
+	int res;
+
+	res = (name)
+		? raw_scan(dir->i_sb,MSDOS_I(dir)->i_start,
+		    name, NULL, ino, res_bh, res_de, scantype)
+		: raw_scan(dir->i_sb,MSDOS_I(dir)->i_start,
+		    NULL, NULL, ino, res_bh, res_de, scantype);
+	return res<0 ? res : 0;
+}