/**************************************************************************** * fs_fat32util.c * * Copyright (C) 2007 Gregory Nutt. All rights reserved. * Author: Gregory Nutt * * Redistribution and use in source and binary forms, with or without * modification, are permitted provided that the following conditions * are met: * * 1. Redistributions of source code must retain the above copyright * notice, this list of conditions and the following disclaimer. * 2. 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. * 3. Neither the name Gregory Nutt nor the names of its contributors may be * used to endorse or promote products derived from this software * without specific prior written permission. * * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS * "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 * COPYRIGHT OWNER OR CONTRIBUTORS 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. * ****************************************************************************/ /**************************************************************************** * Included Files ****************************************************************************/ #include #include #include #include #include #include #include #include #include #include #include "fs_internal.h" #include "fs_fat32.h" #if CONFIG_FS_FAT /**************************************************************************** * Definitions ****************************************************************************/ /**************************************************************************** * Private Types ****************************************************************************/ /**************************************************************************** * Private Function Prototypes ****************************************************************************/ /**************************************************************************** * Private Variables ****************************************************************************/ /**************************************************************************** * Public Variables ****************************************************************************/ /**************************************************************************** * Private Functions ****************************************************************************/ /**************************************************************************** * Name: fat_fscacheflush * * Desciption: Flush any dirty sectors as necessary * ****************************************************************************/ static int fat_fscacheflush(struct fat_mountpt_s *fs) { int ret; /* Check if the fs_buffer is dirty. In this case, we will write back the * contents of fs_buffer. */ if (fs->fs_dirty) { /* Write the dirty sector */ ret = fat_hwwrite(fs, fs->fs_buffer, fs->fs_currentsector, 1); if (ret < 0) { return ret; } /* Does the sector lie in the FAT region? */ if (fs->fs_currentsector < fs->fs_fatbase + fs->fs_fatsize) { /* Yes, then make the change in the FAT copy as well */ int i; for (i = fs->fs_fatnumfats; i >= 2; i--) { fs->fs_currentsector += fs->fs_fatsize; ret = fat_hwwrite(fs, fs->fs_buffer, fs->fs_currentsector, 1); if (ret < 0) { return ret; } } } /* No longer dirty */ fs->fs_dirty = FALSE; } return OK; } /**************************************************************************** * Name: fat_fscacheread * * Desciption: Read the specified sector into the sector cache, flushing any * existing dirty sectors as necessary. * ****************************************************************************/ static int fat_fscacheread(struct fat_mountpt_s *fs, size_t sector) { int ret; /* fs->fs_currentsector holds the current sector that is buffered in * fs->fs_buffer. If the requested sector is the same as this sector, then * we do nothing. Otherwise, we will have to read the new sector. */ if (fs->fs_currentsector != sector) { /* We will need to read the new sector. First, flush the cached * sector if it is dirty. */ ret = fat_fscacheflush(fs); if (ret < 0) { return ret; } /* Then read the specified sector into the cache */ ret = fat_hwread(fs, fs->fs_buffer, sector, 1); if (ret < 0) { return ret; } /* Update the cached sector number */ fs->fs_currentsector = sector; } return OK; } /**************************************************************************** * Name: fat_path2dirname * * Desciption: Convert a user filename into a properly formatted FAT * (short) filname as it would appear in a directory entry. Here are the * rules for the 11 byte name in the directory: * * The first byte: * - 0xe5 = The directory is free * - 0x00 = This directory and all following directories are free * - 0x05 = Really 0xe5 * - 0x20 = May NOT be ' ' * * Any bytes * 0x00-0x1f = (except for 0x00 and 0x05 in the first byte) * 0x22 = '"' * 0x2a-0x2c = '*', '+', ',' * 0x2e-0x2f = '.', '/' * 0x3a-0x3f = ':', ';', '<', '=', '>', '?' * 0x5b-0x5d = '[', '\\', ;]' * 0x7c = '|' * * Upper case characters are not allowed in directory names (without some * poorly documented operatgions on the NTRes directory byte). Lower case * codes may represent different characters in other character sets ("DOS * code pages". The logic below does not, at present, support any other * character sets. * ****************************************************************************/ static inline int fat_path2dirname(const char **path, struct fat_dirinfo_s *dirinfo, char *terminator) { #ifdef CONFIG_FAT_LCNAMES unsigned int ntlcenable = FATNTRES_LCNAME | FATNTRES_LCEXT; unsigned int ntlcfound = 0; #endif const char *node = *path; int endndx; ubyte ch; int ndx = 0; /* Initialized the name with all spaces */ memset(dirinfo->fd_name, ' ', 8+3); /* Loop until the name is successfully parsed or an error occurs */ endndx = 8; for (;;) { /* Get the next byte from the path */ ch = *node++; /* Check if this the last byte in this node of the name */ if ((ch == '\0' || ch == '/') && ndx != 0 ) { /* Return the accumulated NT flags and the terminating character */ #ifdef CONFIG_FAT_LCNAMES dirinfo->fd_ntflags = ntlcfound & ntlcenable; #endif *terminator = ch; *path = node; return OK; } /* Accept only the printable character set. Note the first byte * of the name could be 0x05 meaning that is it 0xe5, but this is * not a printable character in this character in either case. */ else if (!isgraph(ch)) { goto errout; } /* Check for transition from name to extension */ else if (ch == '.') { /* Starting the extension */ ndx = 8; endndx = 11; continue; } /* Reject printable characters forbidden by FAT */ else if (ch == '"' || (ch >= '*' && ch <= ',') || ch == '.' || ch == '/' || (ch >= ':' && ch <= '?') || (ch >= '[' && ch <= ']') || (ch == '|')) { goto errout; } /* Check for upper case charaters */ #ifdef CONFIG_FAT_LCNAMES else if (isupper(ch)) { /* Some or all of the characters in the name or extension * are upper case. Force all of the characters to be interpreted * as upper case. */ if ( endndx == 8) { /* Clear lower case name bit in mask*/ ntlcenable &= FATNTRES_LCNAME; } else { /* Clear lower case extension in mask */ ntlcenable &= FATNTRES_LCNAME; } } #endif /* Check for lower case characters */ else if (islower(ch)) { /* Convert the character to upper case */ ch = toupper(ch); /* Some or all of the characters in the name or extension * are lower case. They can be interpreted as lower case if * only if all of the characters in the name or extension are * lower case. */ #ifdef CONFIG_FAT_LCNAMES if ( endndx == 8) { /* Set lower case name bit */ ntlcfound |= FATNTRES_LCNAME; } else { /* Set lower case extension bit */ ntlcfound |= FATNTRES_LCNAME; } #endif } /* Check if the file name exceeds the size permitted (without * long file name support */ if (ndx >= endndx) { goto errout; } /* Save next character in the accumulated name */ dirinfo->fd_name[ndx++] = ch; } errout: return -EINVAL; } /**************************************************************************** * Name: fat_dirname2path * * Desciption: Convert a filename in a raw directory entry into a user * filename. This is essentially the inverse operation of that performed * by fat_path2dirname. See that function for more details. * ****************************************************************************/ static inline int fat_dirname2path(char *path, struct fat_dirinfo_s *dirinfo) { const unsigned char *direntry = dirinfo->fd_entry; int ch; int ndx; /* Check if we will be doing upper to lower case conversions */ #ifdef CONFIG_FAT_LCNAMES dirinfo->fd_ntflags = DIR_GETNTRES(direntry); #endif /* Get the 8-byte filename */ for (ndx = 0; ndx < 8; ndx++) { /* Get the next filename character from the directory entry */ ch = direntry[ndx]; /* Any space (or ndx==8) terminates the filename */ if (ch == ' ') { break; } /* In this version, we never write 0xe5 in the directoryfilenames * (because we do not handle any character sets where 0xe5 is valid * in a filaname), but we could encounted this in a filesystem * written by some other system */ if (ndx == 0 && ch == DIR0_E5) { ch = 0xe5; } /* Check if we should perform upper to lower case conversion * of the (whole) filename. */ #ifdef CONFIG_FAT_LCNAMES if (dirinfo->fd_ntflags & FATNTRES_LCNAME && isupper(ch)) { ch = tolower(ch); } #endif /* Copy the next character into the filename */ *path++ = ch; } /* Check if there is an extension */ if (direntry[8] != ' ') { /* Yes, output the dot before the extension */ *path++ = '.'; /* Then output the (up to) 3 character extension */ for (ndx = 8; ndx < 11; ndx++) { /* Get the next extensions character from the directory entry */ ch = dirinfo->fd_name[ndx]; /* Any space (or ndx==11) terminates the extension */ if (ch == ' ') { break; } /* Check if we should perform upper to lower case conversion * of the (whole) filename. */ #ifdef CONFIG_FAT_LCNAMES if (ntflags & FATNTRES_LCEXT && isupper(ch)) { ch = tolower(ch); } #endif /* Copy the next character into the filename */ *path++ = ch; } } /* Put a null terminator at the end of the filename */ *path = '\0'; return OK; } /**************************************************************************** * Name: fat_checkfsinfo * * Desciption: Read the FAT32 FSINFO sector * ****************************************************************************/ static int fat_checkfsinfo(struct fat_mountpt_s *fs) { /* Verify that this is, indeed, an FSINFO sector */ if (FSI_GETLEADSIG(fs->fs_buffer) == 0x41615252 && FSI_GETSTRUCTSIG(fs->fs_buffer) == 0x61417272 && FSI_GETTRAILSIG(fs->fs_buffer) == 0xaa550000) { fs->fs_fsinextfree = FSI_GETFREECOUNT(fs->fs_buffer); fs->fs_fsifreecount = FSI_GETNXTFREE(fs->fs_buffer); return OK; } return -ENODEV; } /**************************************************************************** * Name: fat_checkbootrecord * * Desciption: Read a sector and verify that it is a a FAT boot record. * ****************************************************************************/ static int fat_checkbootrecord(struct fat_mountpt_s *fs) { uint32 ndatasectors; uint32 fatsize; uint16 rootdirsectors = 0; boolean notfat32 = FALSE; /* Verify the MBR signature at offset 510 in the sector (true even * if the sector size is greater than 512. All FAT file systems have * this signature. On a FAT32 volume, the RootEntCount , FatSz16, and * FatSz32 values should always be zero. The FAT sector size should * match the reported hardware sector size. */ if (MBR_GETSIGNATURE(fs->fs_buffer) != 0xaa55 || MBR_GETBYTESPERSEC(fs->fs_buffer) != fs->fs_hwsectorsize) { return -ENODEV; } /* Verify the FAT32 file system type. The determination of the file * system type is based on the number of clusters on the volume: FAT12 * volume has < 4085 cluseter, a FAT16 volume has fewer than 65,525 * clusters, and any larger is FAT32. * * Get the number of 32-bit directory entries in root directory (zero * for FAT32. */ fs->fs_rootentcnt = MBR_GETROOTENTCNT(fs->fs_buffer); if (fs->fs_rootentcnt != 0) { notfat32 = TRUE; /* Must be zero for FAT32 */ rootdirsectors = (32 * fs->fs_rootentcnt + fs->fs_hwsectorsize - 1) / fs->fs_hwsectorsize; } /* Determine the number of sectors in a FAT. */ fs->fs_fatsize = MBR_GETFATSZ16(fs->fs_buffer); /* Should be zero */ if (fs->fs_fatsize) { notfat32 = TRUE; /* Must be zero for FAT32 */ } else { fs->fs_fatsize = MBR_GETFATSZ32(fs->fs_buffer); } if (!fs->fs_fatsize || fs->fs_fatsize >= fs->fs_hwnsectors) { return -ENODEV; } /* Get the total number of sectors on the volume. */ fs->fs_fattotsec = MBR_GETTOTSEC16(fs->fs_buffer); /* Should be zero */ if (fs->fs_fattotsec) { notfat32 = TRUE; /* Must be zero for FAT32 */ } else { fs->fs_fattotsec = MBR_GETTOTSEC32(fs->fs_buffer); } if (!fs->fs_fattotsec || fs->fs_fattotsec > fs->fs_hwnsectors) { return -ENODEV; } /* Get the total number of reserved sectors */ fs->fs_fatresvdseccount = MBR_GETRESVDSECCOUNT(fs->fs_buffer); if (fs->fs_fatresvdseccount > fs->fs_hwnsectors) { return -ENODEV; } /* Get the number of FATs. This is probably two but could have other values */ fs->fs_fatnumfats = MBR_GETNUMFATS(fs->fs_buffer); fatsize = fs->fs_fatnumfats * fs->fs_fatsize; /* Get the total number of data sectors */ ndatasectors = fs->fs_fattotsec - fs->fs_fatresvdseccount - fatsize - rootdirsectors; if (ndatasectors > fs->fs_hwnsectors) { return -ENODEV; } /* Get the sectors per cluster */ fs->fs_fatsecperclus = MBR_GETSECPERCLUS(fs->fs_buffer); /* Calculate the number of clusters */ fs->fs_nclusters = ndatasectors / fs->fs_fatsecperclus; /* Finally, the test: */ if (fs->fs_nclusters < 4085) { fs->fs_fsinfo = 0; fs->fs_type = FSTYPE_FAT12; } else if (fs->fs_nclusters < 65525) { fs->fs_fsinfo = 0; fs->fs_type = FSTYPE_FAT16; } else if (!notfat32) { fs->fs_fsinfo = fs->fs_fatbase + MBR_GETFSINFO(fs->fs_buffer); fs->fs_type = FSTYPE_FAT32; } else { return -ENODEV; } /* We have what appears to be a valid FAT filesystem! Save a few more things * from the boot record that we will need later. */ fs->fs_fatbase += fs->fs_fatresvdseccount; if (fs->fs_type == FSTYPE_FAT32) { fs->fs_rootbase = MBR_GETROOTCLUS(fs->fs_buffer); } else { fs->fs_rootbase = fs->fs_fatbase + fatsize; } fs->fs_database = fs->fs_fatbase + fatsize + fs->fs_rootentcnt / DIRSEC_NDIRS(fs); fs->fs_fsifreecount = 0xffffffff; return OK; } /**************************************************************************** * Public Functions ****************************************************************************/ /**************************************************************************** * Name: fat_getuint16 ****************************************************************************/ uint16 fat_getuint16(ubyte *ptr) { #ifdef CONFIG_ARCH_BIGENDIAN /* The bytes always have to be swapped if the target is big-endian */ return ((uint16)ptr[0] << 8) | ptr[1]; #else /* Byte-by-byte transfer is still necessary if the address is un-aligned */ return ((uint16)ptr[1] << 8) | ptr[0]; #endif } /**************************************************************************** * Name: fat_getuint32 ****************************************************************************/ uint32 fat_getuint32(ubyte *ptr) { #ifdef CONFIG_ARCH_BIGENDIAN /* The bytes always have to be swapped if the target is big-endian */ return ((uint32)fat_getuint16(&ptr[0]) << 16) | fat_getuint16(&ptr[2]); #else /* Byte-by-byte transfer is still necessary if the address is un-aligned */ return ((uint32)fat_getuint16(&ptr[2]) << 16) | fat_getuint16(&ptr[0]); #endif } /**************************************************************************** * Name: fat_putuint16 ****************************************************************************/ void fat_putuint16(ubyte *ptr, uint16 value16) { ubyte *val = (ubyte*)&value16; #ifdef CONFIG_ARCH_BIGENDIAN /* The bytes always have to be swapped if the target is big-endian */ ptr[0] = val[1]; ptr[1] = val[0]; #else /* Byte-by-byte transfer is still necessary if the address is un-aligned */ ptr[0] = val[0]; ptr[1] = val[1]; #endif } /**************************************************************************** * Name: fat_putuint32 ****************************************************************************/ void fat_putuint32(ubyte *ptr, uint32 value32) { uint16 *val = (uint16*)&value32; #ifdef CONFIG_ARCH_BIGENDIAN /* The bytes always have to be swapped if the target is big-endian */ fat_putuint16(&ptr[0], val[2]); fat_putuint16(&ptr[2], val[0]); #else /* Byte-by-byte transfer is still necessary if the address is un-aligned */ fat_putuint16(&ptr[0], val[0]); fat_putuint16(&ptr[2], val[2]); #endif } /**************************************************************************** * Name: fat_semtake ****************************************************************************/ void fat_semtake(struct fat_mountpt_s *fs) { /* Take the semaphore (perhaps waiting) */ while (sem_wait(&fs->fs_sem) != 0) { /* The only case that an error should occur here is if * the wait was awakened by a signal. */ ASSERT(*get_errno_ptr() == EINTR); } } /**************************************************************************** * Name: fat_semgive ****************************************************************************/ void fat_semgive(struct fat_mountpt_s *fs) { sem_post(&fs->fs_sem); } /**************************************************************************** * Name: fat_mount * * Desciption: This function is called only when the mountpoint is first * established. It initializes the mountpoint structure and verifies * that a valid FAT32 filesystem is provided by the block driver. * * The caller should hold the mountpoint semaphore * ****************************************************************************/ int fat_mount(struct fat_mountpt_s *fs, boolean writeable) { FAR struct inode *inode; struct geometry geo; int ret; /* Assume that the mount is successful */ fs->fs_mounted = TRUE; /* Check if there is media available */ inode = fs->fs_blkdriver; if (!inode || !inode->u.i_bops || !inode->u.i_bops->geometry || inode->u.i_bops->geometry(inode, &geo) != OK || !geo.geo_available) { ret = -ENODEV; goto errout; } /* Make sure that that the media is write-able (if write access is needed) */ if (writeable && !geo.geo_writeenabled) { ret = -EACCES; goto errout; } /* Save the hardware geometry */ fs->fs_hwsectorsize = geo.geo_sectorsize; fs->fs_hwnsectors = geo.geo_nsectors; /* Allocate a buffer to hold one hardware sector */ fs->fs_buffer = (ubyte*)malloc(fs->fs_hwsectorsize); if (!fs->fs_buffer) { ret = -ENOMEM; goto errout; } /* Search FAT boot record on the drive. First check at sector zero. This * could be either the boot record or a partition that refers to the boot * record. * * First read sector zero. This will be the first access to the drive and a * likely failure point. */ fs->fs_fatbase = 0; ret = fat_hwread(fs, fs->fs_buffer, 0, 1); if (ret < 0) { goto errout_with_buffer; } if (fat_checkbootrecord(fs) != OK) { /* The contents of sector 0 is not a boot record. It could be a * partition, however. Assume it is a partition and get the offset * into the partition table. This table is at offset MBR_TABLE and is * indexed by 16x the partition number. Here we support only * parition 0. */ ubyte *partition = &fs->fs_buffer[MBR_TABLE + 0]; /* Check if the partition exists and, if so, get the bootsector for that * partition and see if we can find the boot record there. */ if (partition[4]) { /* There appears to be a partition, get the sector number of the * partition (LBA) */ fs->fs_fatbase = MBR_GETPARTSECTOR(&partition[8]); /* Read the new candidate boot sector */ ret = fat_hwread(fs, fs->fs_buffer, fs->fs_fatbase, 1); if (ret < 0) { goto errout_with_buffer; } /* Check if this is a boot record */ if (fat_checkbootrecord(fs) != OK) { goto errout_with_buffer; } } } /* We have what appears to be a valid FAT filesystem! Now read the * FSINFO sector (FAT32 only) */ if (fs->fs_type == FSTYPE_FAT32) { ret = fat_checkfsinfo(fs); if (ret != OK) { goto errout_with_buffer; } } /* We did it! */ dbg("FAT%d:\n", fs->fs_type == 0 ? 12 : fs->fs_type == 1 ? 16 : 32); dbg("\tHW sector size: %d\n", fs->fs_hwsectorsize); dbg("\t sectors: %d\n", fs->fs_hwnsectors); dbg("\tFAT reserved: %d\n", fs->fs_fatresvdseccount); dbg("\t sectors: %d\n", fs->fs_fattotsec); dbg("\t start sector: %d\n", fs->fs_fatbase); dbg("\t root sector: %d\n", fs->fs_rootbase); dbg("\t root entries: %d\n", fs->fs_rootentcnt); dbg("\t data sector: %d\n", fs->fs_database); dbg("\t FSINFO sector: %d\n", fs->fs_fsinfo); dbg("\t Num FATs: %d\n", fs->fs_fatnumfats); dbg("\t FAT size: %d\n", fs->fs_fatsize); dbg("\t sectors/cluster: %d\n", fs->fs_fatsecperclus); dbg("\t max clusters: %d\n", fs->fs_nclusters); dbg("\tFSI free count %d\n", fs->fs_fsifreecount); dbg("\t next free %d\n", fs->fs_fsinextfree); return OK; errout_with_buffer: free(fs->fs_buffer); fs->fs_buffer = 0; errout: fs->fs_mounted = FALSE; return ret; } /**************************************************************************** * Name: fat_checkmount * * Desciption: Check if the mountpoint is still valid. * * The caller should hold the mountpoint semaphore * ****************************************************************************/ int fat_checkmount(struct fat_mountpt_s *fs) { /* If the fs_mounted flag is FALSE, then we have already handled the loss * of the mount. */ if (fs && fs->fs_mounted) { struct fat_file_s *file; /* We still think the mount is healthy. Check an see if this is * still the case */ if (fs->fs_blkdriver) { struct inode *inode = fs->fs_blkdriver; if (inode && inode->u.i_bops && inode->u.i_bops->geometry) { struct geometry geo; int errcode = inode->u.i_bops->geometry(inode, &geo); if (errcode == OK && geo.geo_available && !geo.geo_mediachanged) { return OK; } } } /* If we get here, the mount is NOT healthy */ fs->fs_mounted = FALSE; /* Make sure that this is flagged in every opened file */ for (file = fs->fs_head; file; file = file->ff_next) { file->ff_open = FALSE; } } return -ENODEV; } /**************************************************************************** * Name: fat_hwread * * Desciption: Read the specified sector into the sector buffer * ****************************************************************************/ int fat_hwread(struct fat_mountpt_s *fs, ubyte *buffer, size_t sector, unsigned int nsectors) { int ret = -ENODEV; if (fs && fs->fs_blkdriver ) { struct inode *inode = fs->fs_blkdriver; if (inode && inode->u.i_bops && inode->u.i_bops->read) { ssize_t nSectorsRead = inode->u.i_bops->read(inode, buffer, sector, nsectors); if (nSectorsRead == nsectors) { ret = OK; } else if (nSectorsRead < 0) { ret = nSectorsRead; } } } return ret; } /**************************************************************************** * Name: fat_hwwrite * * Desciption: Write the sector buffer to the specified sector * ****************************************************************************/ int fat_hwwrite(struct fat_mountpt_s *fs, ubyte *buffer, size_t sector, unsigned int nsectors) { int ret = -ENODEV; if (fs && fs->fs_blkdriver ) { struct inode *inode = fs->fs_blkdriver; if (inode && inode->u.i_bops && inode->u.i_bops->write) { ssize_t nSectorsWritten = inode->u.i_bops->write(inode, buffer, sector, nsectors); if (nSectorsWritten == nsectors) { ret = OK; } else if (nSectorsWritten < 0) { ret = nSectorsWritten; } } } return ret; } /**************************************************************************** * Name: fat_cluster2sector * * Desciption: Convert a cluster number to a start sector number * ****************************************************************************/ ssize_t fat_cluster2sector(struct fat_mountpt_s *fs, uint32 cluster ) { cluster -= 2; if (cluster >= fs->fs_nclusters - 2) { return -EINVAL; } return cluster * fs->fs_fatsecperclus + fs->fs_database; } /**************************************************************************** * Name: fat_getcluster * * Desciption: Get the cluster start sector into the FAT * ****************************************************************************/ ssize_t fat_getcluster(struct fat_mountpt_s *fs, unsigned int clusterno) { /* Verify that the cluster number is within range */ if (clusterno >= 2 && clusterno < fs->fs_nclusters) { /* Okay.. Read the next cluster from the FAT. The way we will do * this depends on the type of FAT filesystm we are dealing with. */ switch (fs->fs_type) { case FSTYPE_FAT12 : { size_t fatsector; unsigned int fatoffset; unsigned int startsector; unsigned int fatindex; /* FAT12 is more complex because it has 12-bits (1.5 bytes) * per FAT entry. Get the offset to the first byte: */ fatoffset = (clusterno * 3) / 2; fatsector = fs->fs_fatbase + SEC_NSECTORS(fs, fatoffset); /* Read the sector at this offset */ if (fat_fscacheread(fs, fatsector) < 0) { /* Read error */ break; } /* Get the first, LS byte of the cluster from the FAT */ fatindex = fatoffset & SEC_NDXMASK(fs); startsector = fs->fs_buffer[fatindex]; /* With FAT12, the second byte of the cluster number may lie in * a different sector than the first byte. */ fatindex++; if (fatindex >= fs->fs_hwsectorsize) { fatsector++; fatindex = 0; if (fat_fscacheread(fs, fatsector) < 0) { /* Read error */ break; } } /* Get the second, MS byte of the cluster for 16-bits. The * does not depend on the endian-ness of the target, but only * on the fact that the byte stream is little-endian. */ startsector |= (unsigned int)fs->fs_buffer[fatindex] << 8; /* Now, pick out the correct 12 bit cluster start sector value */ if ((clusterno & 1) != 0) { /* Odd.. take the MS 12-bits */ startsector >>= 4; } else { /* Even.. take the LS 12-bits */ startsector &= 0x0fff; } return startsector; } case FSTYPE_FAT16 : { unsigned int fatoffset = 2 * clusterno; size_t fatsector = fs->fs_fatbase + SEC_NSECTORS(fs, fatoffset); unsigned int fatindex = fatoffset & SEC_NDXMASK(fs); if (fat_fscacheread(fs, fatsector) < 0) { /* Read error */ break; } return FAT_GETFAT16(fs->fs_buffer, fatindex); } case FSTYPE_FAT32 : { unsigned int fatoffset = 4 * clusterno; size_t fatsector = fs->fs_fatbase + SEC_NSECTORS(fs, fatoffset); unsigned int fatindex = fatoffset & SEC_NDXMASK(fs); if (fat_fscacheread(fs, fatsector) < 0) { /* Read error */ break; } return FAT_GETFAT16(fs->fs_buffer, fatindex) & 0x0fffffff; } default: break; } } /* There is no cluster information, or an error occured */ return (ssize_t)ERROR; } /**************************************************************************** * Name: fat_putcluster * * Desciption: Write a new cluster start sector into the FAT * ****************************************************************************/ int fat_putcluster(struct fat_mountpt_s *fs, unsigned int clusterno, size_t startsector) { /* Verify that the cluster number is within range. Zero erases the cluster. */ if (clusterno == 0 || (clusterno >= 2 && clusterno < fs->fs_nclusters)) { /* Okay.. Write the next cluster into the FAT. The way we will do * this depends on the type of FAT filesystm we are dealing with. */ switch (fs->fs_type) { case FSTYPE_FAT12 : { size_t fatsector; unsigned int fatoffset; unsigned int fatindex; ubyte value; /* FAT12 is more complex because it has 12-bits (1.5 bytes) * per FAT entry. Get the offset to the first byte: */ fatoffset = (clusterno * 3) / 2; fatsector = fs->fs_fatbase + SEC_NSECTORS(fs, fatoffset); /* Make sure that the sector at this offset is in the cache */ if (fat_fscacheread(fs, fatsector)< 0) { /* Read error */ break; } /* Output the LS byte first handling the 12-bit alignment within * the 16-bits */ fatindex = fatoffset & SEC_NDXMASK(fs); if ((clusterno & 1) != 0) { value = (fs->fs_buffer[fatindex] & 0x0f) | startsector << 4; } else { value = (ubyte)startsector; } fs->fs_buffer[fatindex] = value; /* With FAT12, the second byte of the cluster number may lie in * a different sector than the first byte. */ fatindex++; if (fatindex >= fs->fs_hwsectorsize) { /* Read the next sector */ fatsector++; fatindex = 0; /* Set the dirty flag to make sure the sector that we * just modified is written out. */ fs->fs_dirty = TRUE; if (fat_fscacheread(fs, fatsector) < 0) { /* Read error */ break; } } /* Output the MS byte first handling the 12-bit alignment within * the 16-bits */ if ((clusterno & 1) != 0) { value = (ubyte)(startsector >> 4); } else { value = (fs->fs_buffer[fatindex] & 0xf0) | (startsector & 0x0f); } fs->fs_buffer[fatindex] = value; } break; case FSTYPE_FAT16 : { unsigned int fatoffset = 2 * clusterno; size_t fatsector = fs->fs_fatbase + SEC_NSECTORS(fs, fatoffset); unsigned int fatindex = fatoffset & SEC_NDXMASK(fs); if (fat_fscacheread(fs, fatsector) < 0) { /* Read error */ break; } FAT_PUTFAT16(fs->fs_buffer, fatindex, startsector & 0xffff); } break; case FSTYPE_FAT32 : { unsigned int fatoffset = 4 * clusterno; size_t fatsector = fs->fs_fatbase + SEC_NSECTORS(fs, fatoffset); unsigned int fatindex = fatoffset & SEC_NDXMASK(fs); if (fat_fscacheread(fs, fatsector) < 0) { /* Read error */ break; } FAT_PUTFAT32(fs->fs_buffer, fatindex, startsector & 0x0fffffff); } break; default: return ERROR; } /* Mark the modified sector as "dirty" and return success */ fs->fs_dirty = 1; return OK; } return ERROR; } /**************************************************************************** * Name: fat_nextdirentry * * Desciption: Read the next directory entry from the sector in cache, * reading the next sector(s) in the cluster as necessary. * ****************************************************************************/ int fat_nextdirentry(struct fat_dirinfo_s *dirinfo) { struct fat_mountpt_s *fs = dirinfo->fs; unsigned int cluster; unsigned int ndx; /* Increment the index to the next 32-byte directory entry */ ndx = dirinfo->fd_index + 1; /* Check if all of the directory entries in this sectory have * been examined. */ if (ndx >= DIRSEC_NDIRS(fs)) { /* Yes, then we will have to read the next sector */ dirinfo->fd_currsector++; /* For FAT12/16, the root directory is a group of sectors relative * to the first sector of the fat volume. */ if (!dirinfo->fd_currcluster) { /* For FAT12/13, the boot record tells us number of 32-bit directories * that are contained in the root directory. This should correspond to * an even number of sectors. */ if (ndx >= fs->fs_rootentcnt) { /* When we index past this count, we have examined all of the entries in * the root directory. */ return ERROR; } } else { /* Not a FAT12/16 root directory, check if we have examined the entire * cluster comprising the directory. * * The current sector within the cluster is the entry number divided * byte the number of entries per sector */ int sector = ndx / DIRSEC_NDIRS(fs); /* We are finished with the cluster when the last sector of the cluster * has been examined. */ if (sector >= fs->fs_fatsecperclus) { /* Get next cluster */ cluster = fat_getcluster(fs, dirinfo->fd_currcluster); /* Check if a valid cluster was obtained. */ if (cluster < 2 || cluster >= fs->fs_nclusters) { /* No, we have probably reached the end of the cluster list */ return ERROR; } /* Initialize for new cluster */ dirinfo->fd_currcluster = cluster; dirinfo->fd_currsector = fat_cluster2sector(fs, cluster); } } } /* Save the new index into dirinfo->fd_currsector */ dirinfo->fd_index = ndx; return OK; } /**************************************************************************** * Name: fat_finddirentry * * Desciption: Given a path to something that may or may not be in the file * system, return the directory entry of the item. * ****************************************************************************/ int fat_finddirentry(struct fat_dirinfo_s *dirinfo, const char *path) { struct fat_mountpt_s *fs = dirinfo->fs; size_t cluster; ubyte *direntry = NULL; char terminator; int ret; /* Initialize to traverse the chain. Set it to the cluster of * the root directory */ cluster = fs->fs_rootbase; if (fs->fs_type == FSTYPE_FAT32) { /* For FAT32, the root directory is variable sized and is a * cluster chain like any other directory. fs_rootbase holds * the first cluster of the root directory. */ dirinfo->fd_startcluster = cluster; dirinfo->fd_currcluster = cluster; dirinfo->fd_currsector = fat_cluster2sector(fs, cluster); } else { /* For FAT12/16, the first sector of the root directory is a sector * relative to the first sector of the fat volume. */ dirinfo->fd_startcluster = 0; dirinfo->fd_currcluster = 0; dirinfo->fd_currsector = cluster; } /* fd_index is the index into the current directory table */ dirinfo->fd_index = 0; /* If no path was provided, then the root directory must be exactly * what the caller is looking for. */ if (*path == '\0') { dirinfo->fd_entry = NULL; return OK; } /* Otherwise, loop until the path is found */ for (;;) { /* Convert the next the path segment name into the kind of * name that we would see in the directory entry. */ ret = fat_path2dirname(&path, dirinfo, &terminator); if (ret < 0) { /* ERROR: The filename contains invalid characters or is * too long. */ return ret; } /* Now search the current directory entry for an entry with this * matching name. */ for (;;) { /* Read the next sector into memory */ ret = fat_fscacheread(fs, dirinfo->fd_currsector); if (ret < 0) { return ret; } /* Get a pointer to the directory entry */ direntry = &fs->fs_buffer[DIRSEC_BYTENDX(fs, dirinfo->fd_index)]; /* Check if we are at the end of the directory */ if (direntry[DIR_NAME] == DIR0_ALLEMPTY) { return -ENOENT; } /* Check if we have found the directory entry that we are looking for */ if (direntry[DIR_NAME] != DIR0_EMPTY && !(DIR_GETATTRIBUTES(direntry) & FATATTR_VOLUMEID) && !memcmp(&direntry[DIR_NAME], dirinfo->fd_name, 8+3) ) { /* Yes.. break out of the loop */ break; } /* No... get the next directory index and try again */ if (fat_nextdirentry(dirinfo) != OK) { return -ENOENT; } } /* We get here only if we have found a directory entry that matches * the path element that we are looking for. * * If the terminator character in the path was the end of the string * then we have successfully found the directory entry that describes * the path. */ if (!terminator) { /* Return the pointer to the matching directory entry */ dirinfo->fd_entry = direntry; return OK; } /* No.. then we have found one of the intermediate directories on * the way to the final path target. In this case, make sure * the thing that we found is, indeed, a directory. */ if (!(DIR_GETATTRIBUTES(direntry) & FATATTR_DIRECTORY)) { /* Ooops.. we found something else */ return -ENOTDIR; } /* Get the cluster number of this directory */ cluster = ((uint32)DIR_GETFSTCLUSTHI(direntry) << 16) | DIR_GETFSTCLUSTLO(direntry); /* The restart scanning at the new directory */ dirinfo->fd_currcluster = dirinfo->fd_startcluster = cluster; dirinfo->fd_currsector = fat_cluster2sector(fs, cluster); dirinfo->fd_index = 2; } } /**************************************************************************** * Name: fat_dirtruncate * * Desciption: Truncate an existing file to zero length * ****************************************************************************/ int fat_dirtruncate(struct fat_mountpt_s *fs, struct fat_dirinfo_s *dirinfo) { #warning "File truncation logic not implemented" return -ENOSYS; } /**************************************************************************** * Name: fat_dircreate * * Desciption: Create a directory entry for a new file * ****************************************************************************/ int fat_dircreate(struct fat_mountpt_s *fs, struct fat_dirinfo_s *dirinfo) { #warning "File truncation logic not implemented" return -ENOSYS; } /**************************************************************************** * Name: fat_ffcacheflush * * Desciption: Flush any dirty sectors as necessary * ****************************************************************************/ int fat_ffcacheflush(struct fat_mountpt_s *fs, struct fat_file_s *ff) { int ret; /* Check if the ff_buffer is dirty. In this case, we will write back the * contents of ff_buffer. */ if (ff->ff_bflags && (FFBUFF_DIRTY|FFBUFF_VALID) == (FFBUFF_DIRTY|FFBUFF_VALID)) { /* Write the dirty sector */ ret = fat_hwwrite(fs, ff->ff_buffer, ff->ff_currentsector, 1); if (ret < 0) { return ret; } /* No longer dirty */ ff->ff_bflags &= ~FFBUFF_DIRTY; } return OK; } /**************************************************************************** * Name: fat_ffcacheread * * Desciption: Read the specified sector into the sector cache, flushing any * existing dirty sectors as necessary. * ****************************************************************************/ int fat_ffcacheread(struct fat_mountpt_s *fs, struct fat_file_s *ff, size_t sector) { int ret; /* ff->ff_currentsector holds the current sector that is buffered in * ff->ff_buffer. If the requested sector is the same as this sector, then * we do nothing. Otherwise, we will have to read the new sector. */ if (ff->ff_currentsector != sector || (ff->ff_bflags & FFBUFF_VALID) == 0) { /* We will need to read the new sector. First, flush the cached * sector if it is dirty. */ ret = fat_ffcacheflush(fs, ff); if (ret < 0) { return ret; } /* Then read the specified sector into the cache */ ret = fat_hwread(fs, ff->ff_buffer, sector, 1); if (ret < 0) { return ret; } /* Update the cached sector number */ ff->ff_currentsector = sector; ff->ff_bflags |= FFBUFF_VALID; } return OK; } /**************************************************************************** * Name: fat_ffcacheread * * Desciption: Invalidate the current file buffer contents * ****************************************************************************/ int fat_ffcacheinvalidate(struct fat_mountpt_s *fs, struct fat_file_s *ff) { int ret; /* Is there anything valid in the buffer now? */ if ((ff->ff_bflags & FFBUFF_VALID) != 0) { /* We will invalidate the buffered sector */ ret = fat_ffcacheflush(fs, ff); if (ret < 0) { return ret; } /* Then discard the current cache contents */ ff->ff_bflags &= ~FFBUFF_VALID; } return OK; } #endif /* CONFIG_FS_FAT */