Re-add filesize utility

.gitignore

@@ -104,8 +104,8 @@
 !/src/filesize
 /src/filesize/*
 
-!/src/filesize/size.c
-!/src/filesize/
+!/src/filesize/filesize.c
+!/src/filesize/filesize.h
 
 # /src/logging
 !/src/logging

src/filesize/filesize.c

@@ -0,0 +1,286 @@
+/**
+ * @author      : Aidan Mullen (git@acm.contact)
+ * @file        : filesize
+ * @created     : Wednesday Jun 19, 2024 21:10:14 EDT
+ */
+
+#include <stdio.h>
+#include <string.h>
+
+#include "filesize.h"
+
+/* Test FILENAME_MAX on different platforms. */
+
+char filename[FILENAME_MAX];
+char name[FILENAME_MAX];
+
+/*
+ * ===========
+ * Buffer Size
+ * ===========
+ *
+ * Buffer size is chosen at compilation; it limits the block-size chosen by the
+ * user. When the block size is greater than the buffer, overflow occurs.
+ *
+ * The buffer size is defined in bytes.
+ *
+ * Larger buffer sizes are less accurate, which may be possible to fix if a
+ * position is set at the end of the read block, then the remaining area is
+ * read using a smaller buffer size.
+ */
+
+ /* This buffer size selection should be relegated to the options.ini file. */
+
+#define BUFFER 1073741824
+
+#if !defined(BUFFER) || BUFFER == 1
+
+char buf[1]; /* 1B */
+
+#elif BUFFER == 2
+
+char buf[2]; /* 2B */
+
+#elif BUFFER == 4
+
+char buf[4]; /* 4B */
+
+#elif BUFFER == 8
+
+char buf[8]; /* 8B */
+
+#elif BUFFER == 16
+
+char buf[16]; /* 16B */
+
+#elif BUFFER == 32
+
+char buf[32]; /* 32B */
+
+#elif BUFFER == 64
+
+char buf[64]; /* 64B */
+
+#elif BUFFER == 128
+
+char buf[128]; /* 128B */
+
+#elif BUFFER == 256
+
+char buf[256]; /* 256B */
+
+#elif BUFFER == 512
+
+char buf[512]; /* 512B */
+
+#elif BUFFER == 1024
+
+char buf[1024]; /* 1KB */
+
+#elif BUFFER == 2048
+
+char buf[2048]; /* 2KB */
+
+#elif BUFFER == 4096
+
+char buf[4096]; /* 4KB */
+
+#elif BUFFER == 8192
+
+char buf[8192]; /* 8KB */
+
+#elif BUFFER == 1048576
+
+char buf[1048576]; /* 1MB */
+
+#elif BUFFER == 536870912
+
+char buf[536870912]; /* 512MB */
+
+#elif BUFFER == 1073741824
+
+char buf[1073741824]; /* 1GB */
+
+#else
+
+char buf[BUFFER];
+
+#endif
+
+unsigned long int bsize = BUFFER;
+
+fpos_t pos;
+fpos_t end;
+
+/*
+ * ===============
+ * Fallback Reader
+ * ===============
+ *
+ * The reader counts each record in the file, then adds the value of the records
+ * (in bytes) in order to return the filesize.
+ *
+ * Fallback function in-case a platform solution is not present.
+ * Note that, depending on the buffer size, this method may be somewhat
+ * inaccurate, as a higher buffer size will only measure in records equivalent
+ * to its value, and may stop before reaching the end of the file; it may be
+ * possible to account for this by restarting the file-read at the endpoint
+ * found by fread with a lower buffer size, but this would require that fseek
+ * and ftell are not used, since these often use signed 32-bit integers that
+ * limit the maximum size they can read to ~2GB.
+ */
+
+int get_size_fallback(void)
+{
+    /*
+    unsigned long int size = 0;
+    unsigned long int record = 0;
+    */
+    unsigned long size = 0;
+    unsigned long record = 0;
+
+    FILE * file;
+
+    /* If mode is CLI */
+    printf("Enter a filename: ");
+
+    fgets(filename, sizeof(filename), stdin);
+
+    /* Compare filename with \r\n and remove them. */
+    filename[strcspn(filename, "\r\n")] = 0;
+
+    strcpy(name, filename);
+    printf("Reading file \"%s\"...\n", name);
+
+    file = fopen(filename, "rb");
+
+    printf("Warning: Using fallback reader; process may be slow.\n");
+    printf("Initial buffer size: %lu\n", bsize);
+
+    if (file)
+    {
+        fgetpos(file, &pos);
+
+        printf("Attempting to read file...\n");
+
+        for
+            (
+             size = 0;
+             (fread(buf, sizeof * buf, bsize, file) == bsize);
+             (record = size)
+            )
+            {
+                (size = size + bsize);
+                fgetpos(file, &end);
+                printf("Read: [ %luB ]\n", size);
+
+                if (record == size)
+                {
+                    printf("No appropriately sized blocks remaining.\n");
+                    break;
+                }
+            }
+
+        /*
+         * ==============
+         * Small File Fix
+         * ==============
+         *
+         * If result is 0, try again with lower block size, as small
+         * files cannot be read when the selected size is larger than them.
+         */
+
+        record = 0;
+
+        if (size == 0)
+        {
+            while (bsize > 1)
+            {
+                printf("Attempting to read with lower buffer size...\n");
+
+                bsize = (bsize/2);
+                /* bsize = 1; */
+                fsetpos(file, &pos);
+                printf("Buffer size lowered to %luB\n", bsize);
+
+                while (fread(buf, sizeof * buf, bsize, file) == bsize)
+                    {
+                        size = size + bsize;
+                        fgetpos(file, &pos);
+                        printf("Read: [ %luB ]\n", size);
+
+                        if (record == size)
+                        {
+                            printf("No appropriately sized blocks remaining.\n");
+                            break;
+                        }
+
+                        record = size;
+                    }
+            }
+        }
+
+        /*
+         * ==============
+         * Large File Fix
+         * ==============
+         *
+         * Using a large buffer to read large files quickly resulted in an
+         * inaccurate filesize.
+         *
+         * This block lowers the block size at the end of the reading, and
+         * attempts to read data after the current position in the file. It
+         * repeats this until the buffer size is one byte.
+         *
+         * The accuracy should be around plus-or-minus one byte when reading.
+         */
+
+        while (size > 0)
+        {
+            printf("Checking for remaining data...\n");
+
+            bsize = (bsize/2);
+
+            fsetpos(file, &end);
+
+            while (fread(buf, sizeof * buf, bsize, file) == bsize)
+            {
+                size = size + bsize;
+                fgetpos(file, &end);
+                printf("Read: [ %luB ]\n", size);
+
+                if (record == size)
+                {
+                    printf("No appropriately sized blocks remaining.\n");
+                    break;
+                }
+
+                record = size;
+            }
+            if (bsize > 1)
+            {
+                continue;
+            }
+            else
+            {
+                printf("Buffer at minimum size; stopping.\n");
+                break;
+            }
+        }
+
+        printf("No further data to read; stopping.\n");
+
+        fclose(file);
+
+        printf("Final buffer size: %luB\n", bsize);
+        printf("\nFilesize: %luB\n", size);
+    }
+    else
+    {
+        printf("Error: file not found.\n");
+    }
+
+    return(size);
+}
+
+/* --- end of SIZE_C --- */

src/filesize/filesize.h

@@ -0,0 +1,15 @@
+/**
+ * @author      : Aidan Mullen (git@acm.contact)
+ * @file        : sfileize
+ * @created     : Wednesday Jun 19, 2024 21:13:29 EDT
+ */
+
+#ifndef FILESIZE_H
+
+#define FILESIZE_H
+
+#endif /* end of include guard SIZE_H */
+
+int get_size_fallback(void);
+
+/* --- end of SIZE_H --- */