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Commit bd40377

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nirjarigandhinirjarigandhi
committedApr 9, 2021
Final Commit
0 parents  commit bd40377

8 files changed

+902
-0
lines changed
 

‎.gitkeep

Whitespace-only changes.

‎Makefile

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FLAGS= -Wall -Werror -fsanitize=address -g
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OBJ = simfs.o initfs.o printfs.o simfs_ops.o
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DEPENDENCIES = simfs.h simfstypes.h
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all : simfs
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simfs : ${OBJ}
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gcc ${FLAGS} -o $@ $^
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%.o : %.c ${DEPENDENCIES}
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gcc ${FLAGS} -c $<
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clean :
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rm -f *.o simfs

‎initfs.c

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#include <stdio.h>
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#include <stdlib.h>
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#include "simfs.h"
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/* Create a simulated file system structure in the file specified by
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* filename. This function overwrites whatever was in the file
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* filename.
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*/
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void
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initfs(char *filename) {
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fentry files[MAXFILES];
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fnode fnodes[MAXBLOCKS];
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int i;
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int bytes_used = sizeof(fentry) * MAXFILES + sizeof(fnode) * MAXBLOCKS;
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FILE *fp = openfs(filename, "w");
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/* Initialize the metadata structures */
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for(i = 0; i < MAXFILES; i++) {
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files[i].name[0] = '\0';
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files[i].size = 0;
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files[i].firstblock = -1;
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}
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for(i = 0; i < MAXBLOCKS; i++) {
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fnodes[i].blockindex = -i;
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fnodes[i].nextblock = -1;
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}
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for (i = 1; i < MAXBLOCKS && i <= (bytes_used - 1) / BLOCKSIZE; i++) {
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fnodes[i].blockindex = i;
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}
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/* Write the metadata to the file. */
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if(fwrite(files, sizeof(fentry), MAXFILES, fp) < MAXFILES) {
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fprintf(stderr, "Error: write failed on init\n");
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closefs(fp);
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exit(1);
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}
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if(fwrite(fnodes, sizeof(fnode), MAXBLOCKS, fp) < MAXBLOCKS) {
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fprintf(stderr, "Error: write failed on init\n");
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closefs(fp);
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exit(1);
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}
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/* Write buffer bytes to the file to fill the current block. */
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int bytes_to_write = (BLOCKSIZE - (bytes_used % BLOCKSIZE)) % BLOCKSIZE;
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char zerobuf[BLOCKSIZE] = {0};
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if (bytes_to_write != 0 && fwrite(zerobuf, bytes_to_write, 1, fp) < 1) {
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fprintf(stderr, "Error: write failed on init\n");
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closefs(fp);
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exit(1);
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}
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closefs(fp);
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}

‎printfs.c

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#include <stdio.h>
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#include <stdlib.h>
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#include "simfs.h"
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/* Print the contents of the file system file in a readable form. */
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void
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printfs(char *filename) {
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fentry files[MAXFILES];
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fnode fnodes[MAXBLOCKS];
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char block[BLOCKSIZE + 1];
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int i;
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FILE *fp = openfs(filename, "r");
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if ((fread(files, sizeof(fentry), MAXFILES, fp)) == 0) {
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fprintf(stderr, "Error: could not read file entries\n");
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closefs(fp);
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exit(1);
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}
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if ((fread(fnodes, sizeof(fnode), MAXBLOCKS, fp)) == 0) {
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fprintf(stderr, "Error: could not read fnodes\n");
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closefs(fp);
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exit(1);
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}
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int bytes_used = sizeof(fentry) * MAXFILES + sizeof(fnode) * MAXBLOCKS;
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int bytes_to_read = (BLOCKSIZE - (bytes_used % BLOCKSIZE)) % BLOCKSIZE;
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if (bytes_to_read != 0 && fseek(fp, bytes_to_read, SEEK_CUR) != 0) {
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fprintf(stderr, "Error: seek failed during print\n");
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closefs(fp);
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exit(1);
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}
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printf("File entry structures:\n");
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for (i = 0; i < MAXFILES; i++) {
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printf("[%d] \"%s\"\t%hu\t%hd\n",
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i,
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files[i].name,
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files[i].size,
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files[i].firstblock);
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}
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printf("\nFile node structures:\n");
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for (i = 0; i < MAXBLOCKS; i++) {
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printf("[%d] %hd\t%hd\n",
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i,
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fnodes[i].blockindex,
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fnodes[i].nextblock);
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}
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/* Write the raw file data to standard out */
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printf("\nFile blocks:\n");
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while (fread(block, 1, BLOCKSIZE, fp) == BLOCKSIZE) {
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fwrite(block, BLOCKSIZE, 1, stdout);
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}
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if (ferror(fp)) {
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fprintf(stderr, "Error: could not read data block\n");
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closefs(fp);
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exit(1);
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}
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printf("\n");
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closefs(fp);
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}

‎simfs.c

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/* This program simulates a file system within an actual file. The
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* simulated file system has only one directory, and two types of
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* metadata structures defined in simfstypes.h.
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*/
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/* Simfs is run as:
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* simfs -f myfs command args
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* where the -f option specifies the actual file that the simulated file system
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* occupies, the command is the command to be run on the simulated file system,
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* and args represents a list of arguments for the command. Note that
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* different commands take different numbers of arguments.
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*/
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#include <stdio.h>
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#include <unistd.h>
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#include <stdlib.h>
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#include <string.h>
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#include "simfs.h"
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// We use the ops array to match the file system command entered by the user.
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#define MAXOPS 6
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char *ops[MAXOPS] = {"initfs", "printfs", "createfile", "readfile",
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"writefile", "deletefile"};
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int find_command(char *);
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int
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main(int argc, char **argv)
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{
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int oc; /* option character */
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char *cmd; /* command to run on the file system */
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char *fsname; /* name of the simulated file system file */
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char *usage_string = "Usage: simfs -f file cmd arg1 arg2 ...\n";
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/* Get and check the arguments */
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if(argc < 4) {
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fputs(usage_string, stderr);
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exit(1);
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}
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while((oc = getopt(argc, argv, "f:")) != -1) {
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switch(oc) {
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case 'f' :
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fsname = optarg;
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break;
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default:
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fputs(usage_string, stderr);
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exit(1);
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}
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}
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/* Get the command name */
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char *end_ptr;
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char *end_ptr2;
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cmd = argv[optind];
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optind++;
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switch((find_command(cmd))) {
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case 0: /* initfs */
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initfs(fsname);
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break;
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case 1: /* printfs */
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printfs(fsname);
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break;
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case 2: /* createfile */
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if (argc == 5){
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createFile(argv[optind], fsname);
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}
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else if (argc > 5){
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fprintf(stderr, "Error: Too many arguments provided.\n");
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}
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//fprintf(stderr, "Error: createfile not yet implemented\n");
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break;
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case 3: /* readfile */
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//check if end_ptr and 2 are empty otherwise return error
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if (argc == 7){
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int start = strtol(argv[optind+1], &end_ptr,10);
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int length = strtol(argv[optind+2], &end_ptr2, 10);
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if (strlen(end_ptr) ==0 && strlen(end_ptr2)==0){
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readFile(argv[optind], start, length, fsname);
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}
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else{
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fprintf(stderr, "Error: Incorrect parameters.\n");
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}
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}
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else if (argc > 7){
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fprintf(stderr, "Error: Too many arguments provided.\n");
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}
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else if (argc< 7){
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fprintf(stderr, "Error: Not enough arguments provided.\n");
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}
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//fprintf(stderr, "Error: readfile not yet implemented\n");
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break;
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case 4: /* writefile */
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if (argc == 7){
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int start = strtol(argv[optind+1], &end_ptr,10);
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int length = strtol(argv[optind+2], &end_ptr2, 10);
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if (strlen(end_ptr) ==0 && strlen(end_ptr2)==0){
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writeFile(argv[optind], start, length, fsname);
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}
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else{
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fprintf(stderr, "Error: Incorrect parameters.\n");
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}
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}
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else if (argc > 7){
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fprintf(stderr, "Error: Too many arguments provided.\n");
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}
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else if (argc< 7){
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fprintf(stderr, "Error: Not enough arguments provided.\n");
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}
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//fprintf(stderr, "Error: writefile not yet implemented\n");
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break;
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case 5: /* deletefile */
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if (argc == 5){
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deleteFile(argv[optind], fsname);
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}
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else if (argc > 5){
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fprintf(stderr, "Error: Too many arguments provided.\n");
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}
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//fprintf(stderr, "Error: deletefile not yet implemented\n");
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break;
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default:
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fprintf(stderr, "Error: Invalid command\n");
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exit(1);
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}
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return 0;
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}
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/* Returns a integer corresponding to the file system command that
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* is to be executed
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*/
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int
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find_command(char *cmd)
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{
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int i;
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for(i = 0; i < MAXOPS; i++) {
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if ((strncmp(cmd, ops[i], strlen(ops[i]))) == 0) {
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return i;
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}
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}
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fprintf(stderr, "Error: Command %s not found\n", cmd);
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return -1;
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}

‎simfs.h

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#include <stdio.h>
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#include "simfstypes.h"
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/* File system operations */
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void printfs(char *);
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void initfs(char *);
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void createFile(char *filename, char *fsname);
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void deleteFile(char *filename, char *fsname);
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void readFile(char *filename, int start, int length, char *fsname);
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void writeFile(char *filename, int start, int length, char *fsname);
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/* Internal functions */
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FILE *openfs(char *filename, char *mode);
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void closefs(FILE *fp);

‎simfs_ops.c

+590
Large diffs are not rendered by default.

‎simfstypes.h

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typedef struct file_entry {
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char name[12]; // An empty name means the fentry is not in use.
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unsigned short size;
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short firstblock; // A -1 indicates that no file blocks have been allocated.
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} fentry;
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typedef struct file_node {
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short blockindex; // Negative value means this block is not in use.
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short nextblock; // A -1 indicates there is no next block of data.
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} fnode;
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#define MAXFILES 8
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#define MAXBLOCKS 32
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#define BLOCKSIZE 128

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