#include <stdio.h> #include <time.h> #include <errno.h> #include <string.h> #include <fcntl.h> #include <unistd.h> /* Global error log file */ static FILE *g_error_log = NULL; /* Initialize error log */ int init_error_log(const char *log_path) { g_error_log = fopen(log_path, "a"); if (!g_error_log) { perror("Failed to open error log"); return -1; } return 0; } /* Close error log */ void close_error_log(void) { if (g_error_log) { fclose(g_error_log); g_error_log = NULL; } } /* Get formatted timestamp */ void get_timestamp(char *buffer, size_t size) { time_t now = time(NULL); struct tm *tm_info = localtime(&now); strftime(buffer, size, "%Y-%m-%d %H:%M:%S", tm_info); } /* Centralized error logger */ void log_error(const char *context) { char timestamp[32]; get_timestamp(timestamp, sizeof(timestamp)); /* Print to stderr */ fprintf(stderr, "[%s] ERROR in %s | errno=%d (%s)n", timestamp, context, errno, strerror(errno)); /* Write to log file */ if (g_error_log) { fprintf(g_error_log, "[%s] ERROR in %s | errno=%d (%s)n", timestamp, context, errno, strerror(errno)); fflush(g_error_log); } } /* Example function that triggers failures */ void demo_failures(void) { int fd; fd = open("nonexistent.txt", O_RDONLY); if (fd == -1) { log_error("open(nonexistent.txt)"); } if (write(-1, "test", 4) == -1) { log_error("write(invalid_fd)"); } } int main(void) { if (init_error_log("error.log") != 0) { return 1; } demo_failures(); close_error_log(); return 0; }