mirror of
https://gitlab.com/80486DX2-66/gists
synced 2024-12-26 11:30:03 +05:30
387 lines
8.0 KiB
C
387 lines
8.0 KiB
C
/*
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* C programming idea: Handling temporary files like memory allocations
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* (allocating -> creating empty file, using -> locking for R/W,
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* freeing -> deleting).
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*
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* 20% AI, 80% human (the code is tested and reviewed)
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*
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* Warning: The current result is quick and dirty. Not for educational or
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* production purposes.
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*
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* GCC/Clang/TCC: Compile with -DTEST to set macro TEST as defined, with
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* -DDEBUG to enable debug mode
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*
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* To-Do: Add thread-safe versions of functions (use postfix `_r`)
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*/
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#include <errno.h>
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#include <inttypes.h>
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#include <math.h>
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#include <stdbool.h>
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#include <stdio.h>
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#include <stdlib.h>
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#include <string.h>
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#if _POSIX_VERSION >= 200112L
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# include <fcntl.h>
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# include <unistd.h>
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# define IS_POSIX 1
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#else
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# define IS_POSIX 0
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#endif
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#ifdef DEBUG
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# define LINE_FAIL(x) printf("failed on line %d\n", __LINE__ + x)
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# define DBG_PRINT(...) do { \
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printf(__VA_ARGS__); \
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fflush(stdout); \
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} while (0)
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#else
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# define LINE_FAIL(x)
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# define DBG_PRINT(...)
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#endif
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#define RETREAT(s) do { \
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perror(s); \
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exit(EXIT_FAILURE); \
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} while (0)
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typedef struct {
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bool locked;
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int ID;
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char* file_path;
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#if IS_POSIX
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int file;
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#else
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FILE* file;
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#endif
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} TempFile;
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TempFile* temp_files = NULL;
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size_t num_temp_files = 0;
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int tf_alloc(size_t n, size_t type_size);
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int tf_free(int ID);
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int tf_write(int ID, size_t offset, void* src, size_t data_size);
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int tf_read(int ID, size_t offset, void* dest, size_t data_size);
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int tf_alloc(size_t n, size_t type_size) {
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DBG_PRINT("tf_alloc(%zu, %zu)\n", n, type_size);
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// Create an empty file
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size_t len_digit;
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if (num_temp_files == 0)
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len_digit = 1;
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else
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len_digit = (size_t) floor(log10((double) num_temp_files)) + 1;
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size_t file_path_len = len_digit + strlen("tf_.tmp");
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char* file_path = malloc((file_path_len + 1) * sizeof(char));
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if (file_path == NULL) {
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LINE_FAIL(-2);
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return -1;
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}
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int res = snprintf(file_path, file_path_len + 1, "tf_%" PRIuMAX ".tmp",
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(uintmax_t) num_temp_files);
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if ((size_t) res != file_path_len) {
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LINE_FAIL(-2);
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return -1;
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}
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#if IS_POSIX
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int file = open(file_path, O_RDWR | O_CREAT);
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if (file == -1) {
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#else
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FILE* file = fopen(file_path, "w+b");
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if (file == NULL) {
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#endif
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LINE_FAIL(-2);
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return -1;
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}
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// Allocate memory for the TempFile struct
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TempFile* temp_file = malloc(sizeof(TempFile));
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if (temp_file == NULL) {
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LINE_FAIL(-2);
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return -1;
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}
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// Assign the ID, file path, file handler
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temp_file->locked = false;
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temp_file->ID = num_temp_files;
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temp_file->file_path = strdup(file_path);
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temp_file->file = file;
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// Allocate/reallocate memory for the temp_files structure
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if (temp_files == NULL)
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temp_files = malloc(sizeof(TempFile));
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else
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temp_files = realloc(temp_files, num_temp_files * sizeof(TempFile));
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if (temp_files == NULL) {
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LINE_FAIL(-2);
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return -1;
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}
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// Add the temp file to the array
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temp_files[num_temp_files++] = *temp_file;
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return temp_file->ID;
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}
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int tf_free(int ID) {
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DBG_PRINT("tf_free(%d)\n", ID);
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size_t index = (size_t) ID;
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if (temp_files[index].locked) {
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errno = EBUSY;
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return -1;
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}
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temp_files[index].locked = true;
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#if IS_POSIX
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close(temp_files[index].file);
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#else
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fclose(temp_files[index].file);
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#endif
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// Delete the file
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if (remove(temp_files[index].file_path) != 0) {
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LINE_FAIL(-1);
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return -1;
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}
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free(temp_files[index].file_path);
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// Shift the remaining temp files in the array
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for (size_t i = index; i < num_temp_files - 1; i++)
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temp_files[i] = temp_files[i + 1];
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// Reallocate memory for the temp_files array
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if (--num_temp_files > 0) {
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DBG_PRINT("num_temp_files = %zu\n", num_temp_files);
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if ((temp_files = realloc(temp_files, num_temp_files
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* sizeof(TempFile))) == NULL) {
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LINE_FAIL(-2);
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return -1;
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}
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}
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temp_files[index].locked = false;
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return 0;
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}
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int tf_write(int ID, size_t offset, void* src, size_t data_size) {
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DBG_PRINT("tf_write(%d, %zu, %p, %zu)\n", ID, offset, src, data_size);
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size_t index = (size_t) ID;
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if (temp_files[index].locked) {
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errno = EBUSY;
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return -1;
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}
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temp_files[index].locked = true;
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#if IS_POSIX
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// Check file handler for -1
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int file = temp_files[index].file;
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if (file == -1)
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#else
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// Check file handler for NULL
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FILE* file = temp_files[index].file;
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if (file == NULL)
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#endif
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return -1;
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// Set the position
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#if IS_POSIX
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if (lseek(file, offset, SEEK_SET) == -1) {
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#else
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if (fseek(file, offset, SEEK_SET) == -1) {
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#endif
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LINE_FAIL(-1);
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return -1;
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}
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// Write the data to the file
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#if IS_POSIX
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ssize_t
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#else
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size_t
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#endif
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bytes_written =
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#if IS_POSIX
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write(file, src, data_size);
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#else
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fwrite(src, 1, data_size, file);
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#endif
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if (
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#if IS_POSIX
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(size_t)
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#endif
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bytes_written != data_size) {
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errno = EIO;
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return -1;
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}
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#if IS_POSIX
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if (fsync(file) == -1) {
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LINE_FAIL(-1);
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return -1;
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}
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#else
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fflush(file);
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#endif
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temp_files[index].locked = false;
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return 0;
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}
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int tf_read(int ID, size_t offset, void* dest, size_t data_size) {
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DBG_PRINT("tf_read(%d, %zu, %p, %zu)\n", ID, offset, dest, data_size);
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size_t index = (size_t) ID;
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if (temp_files[index].locked) {
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errno = EBUSY;
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return -1;
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}
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temp_files[index].locked = true;
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#if IS_POSIX
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int file = temp_files[index].file;
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if (file == -1)
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#else
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FILE* file = temp_files[index].file;
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if (file == NULL)
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#endif
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return -1;
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// Read the data from the file
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void* src = malloc(data_size);
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if (src == NULL) {
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#if IS_POSIX
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close(file);
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#else
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fclose(file);
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#endif
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LINE_FAIL(-7);
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return -1;
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}
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memset(src, 0, data_size); // clear destination
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// Set the position
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#if IS_POSIX
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if (lseek(file, offset, SEEK_SET) == -1) {
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#else
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if (fseek(file, offset, SEEK_SET) == -1) {
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#endif
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LINE_FAIL(-1);
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return -1;
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}
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// read bytes
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#if IS_POSIX
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ssize_t bytes_read = read(file, src, data_size);
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#else
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size_t bytes_read = fread(src, 1, data_size, file);
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#endif
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memcpy(dest, src, data_size);
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free(src); // Free the allocated memory
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if (
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#if IS_POSIX
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(size_t)
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#endif
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bytes_read != data_size) {
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errno = EIO;
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return -1;
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}
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#ifdef DEBUG
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printf("Read: ID = %d, src = %p, size = %zu -> '",
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ID, dest, data_size);
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for (size_t i = 0; i < data_size; i++)
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printf("0x%02" PRIX8 "%c", *((uint8_t*)((uint8_t*)dest + i)),
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i == (data_size - 1) ? '\'' : ' ');
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printf("\n");
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fflush(stdout);
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#endif
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temp_files[index].locked = false;
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return 0;
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}
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#ifdef TEST
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int main(void) {
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DBG_PRINT("started\n");
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#define ARRAY_1_LEN 4
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#define ARRAY_2_LEN 16
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int ID_1 = tf_alloc(ARRAY_1_LEN, sizeof(int));
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int ID_2 = tf_alloc(ARRAY_2_LEN, sizeof(uint16_t));
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if (ID_1 == -1 || ID_2 == -1)
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RETREAT("tf_alloc");
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DBG_PRINT("allocated memory\n");
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int test_data_1[ARRAY_1_LEN] = {123, 456, 789, -123};
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DBG_PRINT("initialized array 1\n");
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uint16_t test_data_2[ARRAY_2_LEN];
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for (size_t i = 0; i < ARRAY_2_LEN; i++)
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test_data_2[i] = 1 << i;
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DBG_PRINT("initialized array 2\n");
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for (size_t i = 0; i < ARRAY_1_LEN; i++)
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if (tf_write(ID_1, i * sizeof(int), &test_data_1[i], sizeof(int)) == -1)
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RETREAT("tf_write");
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DBG_PRINT("wrote array 1\n");
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for (size_t i = 0; i < ARRAY_2_LEN; i++)
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if (tf_write(ID_2, i * sizeof(uint16_t), &test_data_2[i],
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sizeof(uint16_t)) == -1)
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RETREAT("tf_write");
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DBG_PRINT("wrote array 2\n");
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// round-trip
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test_data_1[0] = 111;
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test_data_1[1] = 222;
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test_data_1[2] = 333;
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test_data_1[3] = 444;
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DBG_PRINT("filled array 1 with garbage\n");
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for (size_t i = 0; i < 16; i++)
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test_data_2[i] ^= 1;
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DBG_PRINT("filled array 2 with garbage\n");
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for (size_t i = 0; i < ARRAY_1_LEN; i++)
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if (tf_read(ID_1, i * sizeof(int), &test_data_1[i], sizeof(int)) == -1)
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RETREAT("tf_read");
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DBG_PRINT("restored array 1\n");
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for (size_t i = 0; i < ARRAY_2_LEN; i++)
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if (tf_read(ID_2, i * sizeof(uint16_t), &test_data_2[i],
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sizeof(uint16_t)) == -1)
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RETREAT("tf_read");
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DBG_PRINT("restored array 2\n");
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DBG_PRINT("Values (1): ");
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for (size_t i = 0; i < ARRAY_1_LEN; i++)
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DBG_PRINT("%d%c", test_data_1[i], i == (ARRAY_1_LEN - 1) ? '\n' : ' ');
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DBG_PRINT("Values (2): ");
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for (size_t i = 0; i < ARRAY_2_LEN; i++)
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DBG_PRINT("%d%c", test_data_2[i], i == (ARRAY_2_LEN - 1) ? '\n' : ' ');
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tf_free(ID_1);
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tf_free(ID_2);
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DBG_PRINT("freed both files\n");
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return 0;
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}
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#endif
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