Completion work of the discipline of Organization of Operating Systems of the Computer Engineering course at the Federal University of Santa Catarina (UFSC - Universidade Federal de Santa Catarina). The main goal was for the code to pass 100% of the tests without any kind of crash or memory leak, but that doesn't mean that this is 100% correct or that it should pass other tests.
The EX3 File System is a journaled file system that is commonly used by the Linux kernel.
We can see below an example about this file system, where we have the first 3 bytes to define the size of a block, the number of blocks and the number of inodes. Then we have the bitmap, which has no specific size, as it depends on the number of blocks used. After that we have the INODES vector and the next byte is the INODE root index. At the end we have the vector of blocks.
Site to open your binary files to understand better: https://hexed.it/
g++ -std=c++17 fs.cpp main.cpp sha256.cpp -o test -lgtest -lcrypto -lpthread
test.exe
FILE *fopen(const char *filename, const char *mode)
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filename − This is the C string containing the name of the file to be opened.
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mode − This is the C string containing a file access mode. It includes −
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"r" - Opens a file for reading. The file must exist.
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"w" - Creates an empty file for writing. If a file with the same name already exists, its content is erased and the file is considered as a new empty file.
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"a" - Appends to a file. Writing operations, append data at the end of the file. The file is created if it does not exist.
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"r+" - Opens a file to update both reading and writing. The file must exist.
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"w+" - Creates an empty file for both reading and writing.
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"a+" - Opens a file for reading and appending.
int fseek(FILE *stream, long int offset, int whence)
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stream − This is the pointer to a FILE object that identifies the stream.
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offset − This is the number of bytes to offset from whence.
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whence − This is the position from where offset is added. It is specified by one of the following constants −
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SEEK_SET: Beginning of file
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SEEK_CUR: Current position of the file pointer
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SEEK_END: End of file
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size_t fwrite(const void *ptr, size_t size, size_t nmemb, FILE *stream)
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ptr − This is the pointer to the array of elements to be written.
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size − This is the size in bytes of each element to be written.
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nmemb − This is the number of elements, each one with a size of size bytes.
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stream − This is the pointer to a FILE object that specifies an output stream.
size_t fread(void * buffer, size_t size, size_t count, FILE * stream);
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buffer: Pointer to the buffer where data will be stored. A buffer is a region of memory used to temporarily store data
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size: The size of each element to be read in bytes
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count: Number of elements to be read
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stream: Pointer to the FILE object from where data is to be read