file_allocate

file_allocate.c

@@ -0,0 +1,67 @@
+#define _GNU_SOURCE /* Required for linux fallocate */
+#include <fcntl.h>
+#include <linux/falloc.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <unistd.h>
+
+int posix_falloc(void);
+int file_trunc(void);
+int linux_falloc(void);
+
+#define FILENAME "allocated.bin"
+
+int main(void) {
+    posix_falloc();
+    file_trunc();
+    linux_falloc();
+
+    return EXIT_SUCCESS;
+}
+
+int posix_falloc(void) {
+    int fd = open(FILENAME, O_CREAT | O_WRONLY, 0666);
+    if (fd == -1) {
+        return EXIT_FAILURE;
+    }
+
+    off_t length = 1024 * 1024; // 1 MB
+    int   ret = posix_fallocate(fd, 0, length);
+    if (ret != 0) {
+        return EXIT_FAILURE;
+    }
+
+    close(fd);
+    remove(FILENAME);
+    return EXIT_SUCCESS;
+}
+
+int linux_falloc(void) {
+    int fd = open(FILENAME, O_CREAT | O_WRONLY, 0666);
+    if (fd == -1) {
+        perror("Error");
+        return EXIT_FAILURE;
+    }
+
+    off_t length = 1024 * 1024; // 1 MB
+    if (fallocate(fd, 0, 0, length) == -1) {
+        perror("fallocate");
+        return EXIT_FAILURE;
+    }
+
+    close(fd);
+    remove(FILENAME);
+    return EXIT_SUCCESS;
+}
+
+int file_trunc(void) {
+    int fd = open(FILENAME, O_CREAT | O_WRONLY, 0666);
+    if (fd == -1) {
+        perror("Error");
+        return EXIT_FAILURE;
+    }
+    off_t length = 1024 * 1024; // 1 MB
+    ftruncate(fd, length);
+    remove(FILENAME);
+    return EXIT_SUCCESS;
+}