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mirror of https://gitlab.com/80486DX2-66/gists synced 2024-12-25 17:19:46 +05:30
gists/c-programming/reverse-ramdisk.c

397 lines
8.2 KiB
C

/*
* reverse-ramdisk.c
*
* C programming idea: Handling temporary files like memory allocations
* (allocating -> creating empty file, using -> locking for R/W,
* freeing -> deleting).
*
* 20% AI, 80% human (the code is tested and reviewed)
*
* Warning: The current result is quick and dirty. Not for educational or
* production purposes.
*
* GCC/Clang/TCC: Compile with -DTEST to set macro TEST as defined, with
* -DDEBUG to enable debug mode
*
* To-Do: Test: Fix the bug with invalid next size to reallocate
* To-Do: Test: Automate the test verification
*
* Author: Intel A80486DX2-66
* License: Creative Commons Zero 1.0 Universal
*/
#include <errno.h>
#include <inttypes.h>
#include <math.h>
#include <stdbool.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#if _POSIX_VERSION >= 200112L
# include <fcntl.h>
# include <unistd.h>
# define IS_POSIX 1
#else
# define IS_POSIX 0
#endif
#ifdef DEBUG
# define LINE_FAIL(x) printf("failed on line %d\n", __LINE__ + x)
#else
# define LINE_FAIL(x)
#endif
#if defined(DEBUG) || defined(TEST)
# define DBG_PRINT(...) do { \
printf(__VA_ARGS__); \
fflush(stdout); \
} while (0)
#else
# define DBG_PRINT(...)
#endif
#define RETREAT(s) do { \
perror(s); \
exit(EXIT_FAILURE); \
} while (0)
typedef struct {
bool locked;
int ID;
char* file_path;
#if IS_POSIX
int file;
#else
FILE* file;
#endif
} TempFile;
TempFile* temp_files = NULL;
size_t num_temp_files = 0;
int tf_alloc(size_t n, size_t type_size);
int tf_free(int ID);
int tf_write(int ID, size_t offset, void* src, size_t data_size);
int tf_read(int ID, size_t offset, void* dest, size_t data_size);
int tf_alloc(size_t n, size_t type_size) {
DBG_PRINT("tf_alloc(%zu, %zu)\n", n, type_size);
// Create an empty file
size_t len_digit;
if (num_temp_files == 0)
len_digit = 1;
else
len_digit = (size_t) floor(log10((double) num_temp_files)) + 1;
size_t file_path_len = len_digit + strlen("tf_.tmp");
char* file_path = malloc((file_path_len + 1) * sizeof(char));
if (file_path == NULL) {
LINE_FAIL(-2);
return -1;
}
int res = snprintf(file_path, file_path_len + 1, "tf_%" PRIuMAX ".tmp",
(uintmax_t) num_temp_files);
if ((size_t) res != file_path_len) {
LINE_FAIL(-2);
return -1;
}
#if IS_POSIX
int file = open(file_path, O_RDWR | O_CREAT);
if (file == -1) {
#else
FILE* file = fopen(file_path, "w+b");
if (file == NULL) {
#endif
LINE_FAIL(-2);
return -1;
}
// Allocate memory for the TempFile struct
TempFile* temp_file = malloc(sizeof(TempFile));
if (temp_file == NULL) {
LINE_FAIL(-2);
return -1;
}
// Assign the ID, file path, file handler
temp_file->locked = false;
temp_file->ID = num_temp_files;
temp_file->file_path = strdup(file_path);
temp_file->file = file;
// Allocate/reallocate memory for the temp_files structure
if (temp_files == NULL)
temp_files = malloc(sizeof(TempFile));
else
temp_files = realloc(temp_files, num_temp_files * sizeof(TempFile));
if (temp_files == NULL) {
LINE_FAIL(-2);
return -1;
}
// Add the temp file to the array
temp_files[num_temp_files++] = *temp_file;
return temp_file->ID;
}
int tf_free(int ID) {
DBG_PRINT("tf_free(%d)\n", ID);
size_t index = (size_t) ID;
if (temp_files[index].locked) {
errno = EBUSY;
return -1;
}
temp_files[index].locked = true;
#if IS_POSIX
close(temp_files[index].file);
#else
fclose(temp_files[index].file);
#endif
// Delete the file
if (remove(temp_files[index].file_path) != 0) {
LINE_FAIL(-1);
return -1;
}
free(temp_files[index].file_path);
// Shift the remaining temp files in the array
for (size_t i = index; i < num_temp_files - 1; i++)
temp_files[i] = temp_files[i + 1];
// Reallocate memory for the temp_files array
if (--num_temp_files > 0) {
DBG_PRINT("num_temp_files = %zu\n", num_temp_files);
if ((temp_files = realloc(temp_files, num_temp_files
* sizeof(TempFile))) == NULL) {
LINE_FAIL(-2);
return -1;
}
}
temp_files[index].locked = false;
return 0;
}
int tf_write(int ID, size_t offset, void* src, size_t data_size) {
DBG_PRINT("tf_write(%d, %zu, %p, %zu)\n", ID, offset, src, data_size);
size_t index = (size_t) ID;
if (temp_files[index].locked) {
errno = EBUSY;
return -1;
}
temp_files[index].locked = true;
#if IS_POSIX
// Check file handler for -1
int file = temp_files[index].file;
if (file == -1)
#else
// Check file handler for NULL
FILE* file = temp_files[index].file;
if (file == NULL)
#endif
return -1;
// Set the position
#if IS_POSIX
if (lseek(file, offset, SEEK_SET) == -1) {
#else
if (fseek(file, offset, SEEK_SET) == -1) {
#endif
LINE_FAIL(-1);
return -1;
}
// Write the data to the file
#if IS_POSIX
ssize_t
#else
size_t
#endif
bytes_written =
#if IS_POSIX
write(file, src, data_size);
#else
fwrite(src, 1, data_size, file);
#endif
if (
#if IS_POSIX
(size_t)
#endif
bytes_written != data_size) {
errno = EIO;
return -1;
}
#if IS_POSIX
if (fsync(file) == -1) {
LINE_FAIL(-1);
return -1;
}
#else
fflush(file);
#endif
temp_files[index].locked = false;
return 0;
}
int tf_read(int ID, size_t offset, void* dest, size_t data_size) {
DBG_PRINT("tf_read(%d, %zu, %p, %zu)\n", ID, offset, dest, data_size);
size_t index = (size_t) ID;
if (temp_files[index].locked) {
errno = EBUSY;
return -1;
}
temp_files[index].locked = true;
#if IS_POSIX
int file = temp_files[index].file;
if (file == -1)
#else
FILE* file = temp_files[index].file;
if (file == NULL)
#endif
return -1;
// Read the data from the file
void* src = malloc(data_size);
if (src == NULL) {
#if IS_POSIX
close(file);
#else
fclose(file);
#endif
LINE_FAIL(-7);
return -1;
}
memset(src, 0, data_size); // clear destination
// Set the position
#if IS_POSIX
if (lseek(file, offset, SEEK_SET) == -1) {
#else
if (fseek(file, offset, SEEK_SET) == -1) {
#endif
LINE_FAIL(-1);
return -1;
}
// read bytes
#if IS_POSIX
ssize_t bytes_read = read(file, src, data_size);
#else
size_t bytes_read = fread(src, 1, data_size, file);
#endif
memcpy(dest, src, data_size);
free(src); // Free the allocated memory
if (
#if IS_POSIX
(size_t)
#endif
bytes_read != data_size) {
errno = EIO;
return -1;
}
#ifdef DEBUG
printf("Read: ID = %d, src = %p, size = %zu -> '",
ID, dest, data_size);
for (size_t i = 0; i < data_size; i++)
printf("0x%02" PRIX8 "%c", *((uint8_t*)((uint8_t*)dest + i)),
i == (data_size - 1) ? '\'' : ' ');
printf("\n");
fflush(stdout);
#endif
temp_files[index].locked = false;
return 0;
}
#ifdef TEST
int main(void) {
DBG_PRINT("started\n");
#define ARRAY_1_LEN 4
#define ARRAY_2_LEN 16
int ID_1 = tf_alloc(ARRAY_1_LEN, sizeof(int));
int ID_2 = tf_alloc(ARRAY_2_LEN, sizeof(uint16_t));
if (ID_1 == -1 || ID_2 == -1)
RETREAT("tf_alloc");
DBG_PRINT("allocated memory\n");
int test_data_1[ARRAY_1_LEN] = {123, 456, 789, -123};
DBG_PRINT("initialized array 1\n");
uint16_t test_data_2[ARRAY_2_LEN];
for (size_t i = 0; i < ARRAY_2_LEN; i++)
test_data_2[i] = 1 << i;
DBG_PRINT("initialized array 2\n");
for (size_t i = 0; i < ARRAY_1_LEN; i++)
if (tf_write(ID_1, i * sizeof(int), &test_data_1[i], sizeof(int)) == -1)
RETREAT("tf_write");
DBG_PRINT("wrote array 1\n");
for (size_t i = 0; i < ARRAY_2_LEN; i++)
if (tf_write(ID_2, i * sizeof(uint16_t), &test_data_2[i],
sizeof(uint16_t)) == -1)
RETREAT("tf_write");
DBG_PRINT("wrote array 2\n");
// round-trip
test_data_1[0] = 111;
test_data_1[1] = 222;
test_data_1[2] = 333;
test_data_1[3] = 444;
DBG_PRINT("filled array 1 with garbage\n");
for (size_t i = 0; i < 16; i++)
test_data_2[i] ^= 1;
DBG_PRINT("filled array 2 with garbage\n");
for (size_t i = 0; i < ARRAY_1_LEN; i++)
if (tf_read(ID_1, i * sizeof(int), &test_data_1[i], sizeof(int)) == -1)
RETREAT("tf_read");
DBG_PRINT("restored array 1\n");
for (size_t i = 0; i < ARRAY_2_LEN; i++)
if (tf_read(ID_2, i * sizeof(uint16_t), &test_data_2[i],
sizeof(uint16_t)) == -1)
RETREAT("tf_read");
DBG_PRINT("restored array 2\n");
DBG_PRINT("Values (1): ");
for (size_t i = 0; i < ARRAY_1_LEN; i++)
DBG_PRINT("%d%c", test_data_1[i], i == (ARRAY_1_LEN - 1) ? '\n' : ' ');
DBG_PRINT("Values (2): ");
for (size_t i = 0; i < ARRAY_2_LEN; i++)
DBG_PRINT("%d%c", test_data_2[i], i == (ARRAY_2_LEN - 1) ? '\n' : ' ');
tf_free(ID_1);
tf_free(ID_2);
DBG_PRINT("freed both files\n");
return 0;
}
#endif