os/kernel/vfs.c

#include <stdint.h>
#include <stdarg.h>
#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#include <errno.h>
#include "vfs.h"
typedef struct _vfs_mapping_struct {
  char* mntpnt;
  uint32_t type;
  struct _vfs_mapping_struct* next;
} vfs_mapping;

static const char** drv_names;
static fs_drv* drvs;
static uint32_t max_drvs;
static uint32_t next_drv_indx;
static vfs_mapping* head_mapping;
static vfs_mapping* tail_mapping;

FILE* stdin=NULL;
FILE* stdout=NULL;
FILE* stderr=NULL;


static int vfsstrcmp(const char* s1,const char* s2) {
    int i;
    for (i = 0; s1[i] == s2[i]; i++) {
        if (s1[i] == '\0') return 0;
    }
    if (s1[i] == '\0') return 0;
    return s1[i] - s2[i];
}

void init_vfs() {
  drvs=malloc(sizeof(fs_drv)*32);
  drv_names=malloc(sizeof(const char**)*32);
  max_drvs=32;
  next_drv_indx=0;
  head_mapping=NULL;
  tail_mapping=NULL;
}

uint32_t register_fs(fs_drv drv,const char* type) {
  if (next_drv_indx==max_drvs) {
    drvs=realloc(drvs,sizeof(fs_drv)*(max_drvs+32));
    drv_names=realloc(drv_names,sizeof(char*)*(max_drvs+32));
    max_drvs+=32;
  }
  drvs[next_drv_indx]=drv;
  drv_names[next_drv_indx]=type;
  next_drv_indx++;
  return next_drv_indx-1;
}

char mount(char* mntpnt,char* dev,char* type) {
  uint32_t i;
  for (i=0;i<next_drv_indx;i++) {
    const char* name=drv_names[i];
    if (strcmp(name,type)==0) {
      break;
    }
  }
  char ok=drvs[i](FSOP_MOUNT,NULL,mntpnt,dev);
  if (ok) {
    if (head_mapping==NULL) {
      vfs_mapping* mapping=malloc(sizeof(vfs_mapping));
      mapping->mntpnt=malloc(sizeof(char)*(strlen(mntpnt)+1));
      strcpy(mapping->mntpnt,mntpnt);
      mapping->type=i;
      mapping->next=NULL;
      head_mapping=mapping;
      tail_mapping=mapping;
    } else {
      vfs_mapping* mapping=malloc(sizeof(vfs_mapping));
      mapping->mntpnt=malloc(sizeof(char)*(strlen(mntpnt)+1));
      strcpy(mapping->mntpnt,mntpnt);
      mapping->type=i;
      mapping->next=NULL;
      tail_mapping->next=mapping;
    }
    return 1;
  } else {
    return 0;
  }
}

FILE* fopen(const char* filename,const char* mode) {
  vfs_mapping* mnt=head_mapping;
  vfs_mapping* mntpnt=NULL;
  const char* path;
  uint32_t mntpnt_len=0;
  for (;mnt!=NULL;mnt=mnt->next) {
    char* root=mnt->mntpnt;
    if (strlen(root)>mntpnt_len) {
      if (vfsstrcmp(root,filename)==0) {
        mntpnt=mnt;
        mntpnt_len=strlen(root);
      }
    }
  }
  if (mntpnt) {
    path=filename+mntpnt_len;
    FILE* stream=malloc(sizeof(FILE));
    stream->mntpnt=mntpnt->mntpnt;
    stream->path=path;
    if (strcmp(mode,"w")==0) {
      stream->wr=1;
      stream->rd=0;
    } else if (strcmp(mode,"r+")==0) {
      stream->wr=1;
      stream->rd=1;
    } else {
      stream->wr=0;
      stream->rd=1;
    }
    stream->type=mntpnt->type;
    stream->pos=0;
    stream->eof=0;
    stream->error=0;
    char ok=drvs[mntpnt->type](FSOP_OPEN,stream,NULL,NULL);
    if (ok) {
      return stream;
    } else {
      free(stream);
      return NULL;
    }
  }
  return NULL;
}

int fgetc(FILE* stream) {
  if (!stream->rd) {
    errno=EBADF;
    stream->error=1;
    return EOF;
  }
  int c;
  drvs[stream->type](FSOP_GETC,stream,&c,NULL);
  return c;
}

int getc() {
  return fgetc(stdin);
}

char* fgets(char* str,int count,FILE* stream) {
  if (!stream->rd) {
    errno=EBADF;
    stream->error=1;
    return NULL;
  }
  int i;
  for (i=0;i<count-1;i++) {
    char c=fgetc(stream);
    if (c==EOF) {
      return NULL;
    } else if (c=='\n') {
      str[i]=c;
      i++;
      break;
    }
    str[i]=c;
  }
  str[i]='\0';
  return str;
}

size_t fread(void* buffer_ptr,size_t size,size_t count,FILE* stream) {
  if (!stream->rd) {
    errno=EBADF;
    stream->error=1;
    return 0;
  }
  char* buffer=(char*)buffer_ptr;
  size_t bytes=size*count;
  for (size_t i=0;i<bytes;i++) {
    int c=fgetc(stream);
    if (c==EOF) {
      return (size_t)(i/size);
    }
    buffer[i]=c;
  }
  return count;
}

int fputc(int c,FILE* stream) {
  if (!stream->wr) {
    errno=EBADF;
    stream->error=1;
    return EOF;
  }
  char ok=drvs[stream->type](FSOP_PUTC,stream,&c,NULL);
  if (ok) {
    return c;
  } else {
    return EOF;
  }
}

int putc(int c) {
  return fputc(c,stdout);
}

int fputs(const char* s,FILE* stream) {
  if (!stream->wr) {
    errno=EBADF;
    stream->error=1;
    return EOF;
  }
  size_t len=strlen(s);
  for (size_t i=0;i<len;i++) {
    int c=fputc(s[i],stream);
    if (c==EOF) {
      return EOF;
    }
  }
  return 1;
}

int puts(const char* s) {
  return fputs(s,stdout);
}

size_t fwrite(void* buffer_ptr,size_t size,size_t count,FILE* stream) {
  if (!stream->wr) {
    errno=EBADF;
    stream->error=1;
    return 0;
  }
  char* buffer=(char*)buffer_ptr;
  size_t bytes=size*count;
  for (size_t i=0;i<bytes;i++) {
    int c=fputc((uint8_t)buffer[i],stream);
    if (c==EOF) {
      return (size_t)(i/size);
    }
  }
  return count;
}

int vfprintf(FILE* stream,const char* format,va_list arg) {
  int c;
	for(;*format!='\0';format++) {
    if(*format!='%') {
  		c=fputc(*format,stream);
      if (c==EOF) {
        return EOF;
      }
      continue;
  	}
    format++;
		switch(*format) {
			case 'c': {
        int i=va_arg(arg,int);
				c=fputc(i,stream);
        if (c==EOF) {
          return EOF;
        }
				break;
      }
			case 'd': {
        int i=va_arg(arg,int); 		//Fetch Decimal/Integer argument
				if(i<0) {
					i=-i;
					fputc('-',stream);
				}
        char str[11];
        int_to_ascii(i,str);
				c=fputs(str,stream);
        if (c==EOF) {
          return EOF;
        }
				break;
      }
			// case 'o': {
      //   int i=va_arg(arg,unsigned int); //Fetch Octal representation
			// 	puts(convert(i,8));
			// 	break;
      // }
			case 's': {
        char* s=va_arg(arg,char*);
				c=fputs(s,stream);
        if (c==EOF) {
          return EOF;
        }
				break;
      }
			case 'x': {
        uint32_t i=va_arg(arg,uint32_t);
        char str[11];
        str[0]='\0';
        hex_to_ascii(i,str);
				c=fputs(str,stream);
        if (c==EOF) {
          return EOF;
        }
				break;
      }
		}
	}
  return 1;
}

int fprintf(FILE* stream,const char* format,...) {
  va_list arg;
  int code;
  va_start(arg,format);
  code=vfprintf(stream,format,arg);
  va_end(arg);
  if (code) {
    return strlen(format);
  } else {
    return EOF;
  }
}

int printf(const char* format,...) {
  va_list arg;
  int code;
  va_start(arg,format);
  code=vfprintf(stdout,format,arg);
  va_end(arg);
  if (code) {
    return strlen(format);
  } else {
    return EOF;
  }
}

int fseek(FILE* stream,long offset,int origin) {
  if (origin==SEEK_SET) {
    stream->pos=offset;
  }
  if (origin==SEEK_CUR) {
    stream->pos+=offset;
  }
  return 0;
}

long ftell(FILE* stream) {
  return stream->pos;
}

int fclose(FILE* stream) {
  drvs[stream->type](FSOP_CLOSE,stream,NULL,NULL);
  free(stream);
  return 0;
}

int feof(FILE *stream) {
  return stream->eof;
}

int ferror(FILE *stream) {
  return stream->error;
}