#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <fcntl.h>
#include <string.h>
#include <errno.h>
#include <sys/stat.h>
#define BUFFER_SIZE 256
int main(void) {
// 1. Standard C Library buffered stream output
printf("--- FreeBSD libc Demonstration ---\n");
// Path to examine (FreeBSD OS release text file)
const char *filepath = "/etc/os-release";
// 2. Interacting via POSIX system call wrappers in libc
struct stat file_stat;
// stat() retrieves information about the file attributes
if (stat(filepath, &file_stat) == -1) {
// fprintf and strerror use libc error handling configurations
fprintf(stderr, "Error checking file '%s': %s\n", filepath, strerror(errno));
return EXIT_FAILURE;
}
printf("File size of %s: %ld bytes\n\n", filepath, (long)file_stat.st_size);
// 3. Open the file descriptor using open()
int fd = open(filepath, O_RDONLY);
if (fd == -1) {
fprintf(stderr, "Failed to open '%s': %s\n", filepath, strerror(errno));
return EXIT_FAILURE;
}
printf("--- Content of %s ---\n", filepath);
// 4. Low-level read loop bypassing stdio buffering
char buffer[BUFFER_SIZE];
ssize_t bytes_read;
while ((bytes_read = read(fd, buffer, sizeof(buffer) - 1)) > 0) {
// Null-terminate buffer before printing safely
buffer[bytes_read] = '\0';
// write() prints directly to standard output descriptor (1)
if (write(STDOUT_FILENO, buffer, bytes_read) == -1) {
fprintf(stderr, "Write error: %s\n", strerror(errno));
close(fd);
return EXIT_FAILURE;
}
}
if (bytes_read == -1) {
fprintf(stderr, "Read error: %s\n", strerror(errno));
}
// 5. Explicitly release resource descriptor
close(fd);
return EXIT_SUCCESS;
}
